Pagasa Artc 2021

ANNUAL REPORT ON PHILIPPINE
TROPICAL CYCLONES 2021
An official publication of the
Weather Division
Philippine Atmospheric, Geophysical and
Astronomical Services Administration (PAGASA)
Department of Science and Technology (DOST)
Quezon City, Philippines

May 2024
Annual Report on Philippine Tropical Cyclones 2021
Marine Meteorological Services Section, Weather Division

Philippine Atmospheric, Geophysical and Astronomical Services Administration
Department of Science and Technology
Address: PAGASA Weather and Flood Forecasting Center, Senator Miriam P. Defensor-
Santiago Avenue, Pinyahan, Quezon City 1100, Philippines
Email: typhoon.ops@pagasa.dost.gov.ph
Phone: (02) 8284-0800 ext. 4800
ISSN 2672-3190 (Print)

ISSN 2799-0575 (Online)
This is a publication of the Government of the Republic of the Philippines. No part of this publication
may be reproduced or transmitted in any form or by any means, electronic or mechanical, including
photocopy, recording or any information storage and retrieval system without permission in writing
from the publisher. Permission may be sought directly from the Weather Division of DOST-
PAGASA.
This Report shall be properly acknowledged in any work connected, either in full or partly, to this
publication.
DOST-PAGASA accepts no liability for any direct and/or indirect loss or damage to the user caused
using the data or documents in this publication.
For more information on publications of DOST-PAGASA

visit our website at bagong.pagasa.dost.gov.ph
PRINTED IN THE REPUBLIC OF THE PHILIPPINES
ii
The Annual Report on Philippine Tropical Cyclones (ARTC) is an annual technical report
published by the Philippine Atmospheric, Geophysical and Astronomical Services Administration
(PAGASA) which serves as the yearly compendium of technical reviews of tropical cyclones that
occurred within the Philippine Area of Responsibility based on the outputs of the post-season best
track analysis conducted by the tropical cyclone meteorologists of the agency. The report also
includes a summary of forecast and warning services provided by the agency for the entire season
and each tropical cyclone.
Cover image: Radar image of Super Typhoon ODETTE during its peak intensity over the waters east of Surigao del Norte
as seen from the PAGASA Doppler Weather Surveillance Radar in Hinatuan, Surigao del Sur.
iii
(This page is intentionally left blank)
iv
EXECUTIVE SUMMARY
The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA)

named 15 tropical cyclones (TCs) that occurred within the Philippine Area of Responsibility (PAR)
during the 2021 Philippine TC season. This year was deemed to be below normal relative to the
1991-2020 average, although no long-term increase or decrease in the annual number of TCs
within the PAR region was noted since 1991. The quarterly TC activity within the PAR region was
modulated by a weakening La Niña turning ENSO-neutral conditions during the first half and mid-
third quarter of the year and a re-developing La Niña on the fourth quarter, as well as the negative
Indian Ocean Dipole phase and the intra-seasonal variation of the North Pacific Subtropical High.
In general, majority of the TCs that occurred within the PAR region in 202 developed over the
Philippine Sea and Western North Pacific (WNP) south of 15°N and east of 125°E, with seven of
the 15 TCs forming within the PAR region. Two-thirds of the TCs that occurred within the PAR
region in 2021 had tracks that were generally oriented northwest-southeast, west northwest-east
southeast, or east-west as they passed within the PAR, while the second largest cluster of TC
tracks during the season, constituting 20% of the total TC events, were mainly recurving in nature
within the PAR region and had tracks ending over the East China Sea or the Sea of Japan. The
TCs that entered that PAR had an average lifespan of 7 days and 12 hours while the average
duration of these TCs inside the PAR was 3 days and 20.7 hours.
While the number of TCs that peaked at TD, TS/STS, and TY/STY within the PAR region was
lower than the climatological average (due to the below-normal TC activity), in terms of its
proportion to the total number of TCs in 2021, the number of TCs that peaked at TD were close to
the climatological average, while those that reached TS/STS and TY/STY were higher and lower
than average, respectively. Nevertheless, the proportions observed in 2021 for each intensity
categories were all within the range of near-normal values. Three of 15 TC events within the PAR
region this season reached super typhoon category while inside the PAR region. Combined
warning track and best track data from PAGASA since 1991 shows that the annual number of TCs
peaking at TS/STS and TY/STY categories entering the PAR region was stable since 1991, with
the slightly decreasing trend deemed to be not significant. On the other hand, the number of TCs
that remained as a TD within the PAR has been on a slightly increasing trend since 1991. However,
this was associated with the increased reliability of on-site and remote sensing observation
platforms being utilized by PAGASA forecasters for judging the formation of TDs.
The season also registered nine landfalling TCs, which was roughly 60% of the total TC events in
2021. This was slightly lower than the preceding season, and slightly higher (albeit near normal)
the climatological average. In terms of its proportion to the total number of TCs, the number of
landfalling TCs was above average but near normal, while the number of non-landfalling TCs
relative to the total was below normal. The number of landfalling TCs were equally divided between
the first and second half of the year. Consolidated track data continues to show a notably
decreasing trend in the number of TCs that cross the archipelago for the past three decades. Most
all of these landfalling TCs tracked over the central portion of the archipelago between Southern
Luzon and Northeastern Mindanao. Nearly half of the landfalling TCs during the season were
depressions at the time of initial landfall.
The total rainfall during TC days in the Philippines accounted for 40% to 70% of the total rainfall in
2020 over the western half of Luzon, 20 to 50% in other areas of Luzon, 20% to 50% over Visayas
(with higher proportions over Western Visayas), and 20% to 40% for most areas in Mindanao. It
was also observed that Palawan had similar observed proportions with those found in Panay
Island, which could be attributed to its geographic location. The observed rainfall during TC days
were notably higher (at least 1,000 mm) for most of Luzon (except mainland Palawan, most of
Quezon, Camarines Provinces, and Masbate), Eastern Visayas, Panay Island, and Caraga Region
than in any other areas. Highest rainfall accumulations during TC days were noted over some
areas in Benguet and La Union (with values reaching in excess of 2,000 mm).
As the operational arm responsible for the national TC forecasting and warning program, the
Weather Division issued 317 public TC products, 242 TC Warnings for Shipping, and 97 Significant
Meteorological Information for TC its end users during the 2021 season, in addition to the provision
v
of expert advice and briefings to public and private sector partners. A total of 11 TCs necessitated
the hoisting of Tropical Cyclone Wind Signals in all provinces or portions thereof except for most
of Bangsamoro and SOCCSKARGEN regions, and the southern half of Davao Region and
Zamboanga Peninsula. Wind signals were most frequently hoisted over Caraga Region, Eastern
Visayas, Extreme Northern Luzon, and most of Central and Western Visayas. These areas had
wind signal levels of at least 1 hoisted at least four times during the 2021 season.
Despite disaster risk reduction and management activities, the National Disaster Risk Reduction
and Management Council reported that the TC events of 2021 claimed the lives of 484 individuals,
making 2021 the 18th deadliest TC season since 1970 and the deadliest post-Yolanda season.
Data since 1970 shows no notable trend in the casualty count and death toll. However, data from
2015 suggests a generally increasing trend in number of deaths and injuries have been noted
since 2015, with the trend more pronounced in the latter. On the other hand, the number of missing
individuals has been on a slightly downward trend since 2015.
Furthermore, a total of 1,462 injured and 78 missing persons were reported. Aggregate cost of
damage across the country amounted to PHP 61.323 billion (adjusted for inflation), making it the
6th costliest TC season since 1970 and the 2nd costliest post-Yolanda season. Damage to public
infrastructure accounted for most of the total damage cost. While year-on-year fluctuations exist in
the reported damage cost, the aggregated annual cost of damage due to TC events has been
steadily increasing since 1970.
Verification statistics shows that over the past decade, PAGASA has been steadily improving in its
operational TC track forecast, although year-on-year fluctuations are also observed. In particular,
it can be seen that DPEs for this season were higher at all forecast times than in 2020.
Nevertheless, the mean DPE for the first 72 hours of PAGASA track forecasts during the 2021
season were the 2nd or 3rd lowest since 2014 (and potentially in the history of PAGASA), while
forecast positions beyond 72 hours were the 3rd lowest since 2018. Most of the typhoon and super
typhoon cases during the season showed relatively small position errors across various forecast
times. Most of the TCs that reported relatively large position errors for the season were associated
with considerable slow and righthand/poleward bias in track forecasts. The mean directional bias
across all forecast times and mean speed bias at 24-, 48-, and 72-hour were found to be small,
although a generally slow bias in the track forecasts was observed. On average, the hit rate of
forecast confidence circles during the 2021 season was 75.9% for the 24-hour forecast. The
corresponding hit rates for the 48-, 72-, 96-, and 120-hour forecasts were 71.3%, 74.0%, 66.7%,
and 71.8%.
vi
TABLE OF CONTENTS
National Tropical Cyclone Forecasting and Warning Program 1

Forecast Areas 3
Classification of Tropical Cyclones 6
Naming of Tropical Cyclones 7
Analysis and Forecast Process 9
Tropical Cyclone Product Description 11
Tropical Cyclone Wind Signal System 13
Product Dissemination 16
Expert Advice and Briefings 17
Post-Season Best Track Analysis of Philippine Tropical Cyclones 21

A Forensic-like Investigation 23
PAGASA Tropical Cyclone Publication Series 27
Philippine Tropical Cyclone Season of 2021: An Overview 29

General Statistics 31
Observed Trends within the PAR 34
Quarterly and Monthly Tropical Cyclone Activity 35
Rainfall during Tropical Cyclone Days 40
Extremes of Surface Meteorological Observations during Tropical Cyclone Days 44
Tropical Cyclone Impacts: Casualties and Damage 45
Provision of Tropical Cyclone Products and Wind Signals 48
Review of the Philippine Tropical Cyclones of 2021 51
Verification of Operational Tropical Cyclone Forecasts for 2021 133

Metrics of Track Forecast Verification 135
Summary of 2021 Forecast Position Errors 136
Current Limits of Verification 139
PAGASA Best Track Data for 2021 Tropical Cyclones 143
vii
The Annual Report on Philippine Tropical Cyclone (ARTC) 2021 was made possible through the
efforts of the following forecasters and meteorologists of the Weather Division
Robb P. Gile Author; meteorological data processing and

quality control; best track post-analysis
Samuel F. Duran Surface data processing and quality control
Ella Marie M. Soriano Satellite data collection and reanalysis;

copyreading
Maria Ana Glaiza G. Escullar Satellite data reanalysis
Charlie R. Rapadas Satellite data reanalysis
John Carlo S. Sugui Data visualization and GIS
This edition of the ARTC was published under the supervision of Mr. Juanito S. Galang, Weather
Services Chief of the Weather Division, and Mr. Christopher F. Perez, Assistant Weather
Services Chief of the Marine Meteorological Services Section
viii
NATIONAL TROPICAL CYCLONE
FORECASTING AND WARNING PROGRAM
2
National Tropical Cyclone

Forecasting and Warning Program
Since 18791, the government meteorological service2 of the Philippines has been providing tropical
cyclone (TC) forecasts and warnings to ensure the safety, well-being, and economic security of
the people, safeguard the environment, and promote national progress and sustainable
development. Created by law3 in 8 December 1972 as the successor to the Weather Bureau, the
Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) is a
scientific and technological services institute of the Department of Science and Technology
(DOST) mandated 4 to provide adequate, up-to-date, and timely information on atmospheric
phenomena especially during high impact weather events such as TC occurrences. As the national
meteorological and hydrological service (NMHS) of the Republic of the Philippines, PAGASA is
responsible for the national TC forecasting and warning program of the country.
To ensure its effective and efficient implementation, the Weather Division, through the Marine
Meteorological Services Section (MMSS), is primarily responsible for the operational activities
related to the national TC forecasting and warning program. The typhoon forecasters of the MMSS
implements the day-to-day activities related to TC operations of the agency in coordination with
operational forecasters from the Weather Forecasting Section (WFS) and Aeronautical
Meteorological Services Section (AMSS) of the Weather Division, as well as the forecasters from
the five (5) PAGASA Regional Services Divisions (PRSDs).
Forecast Areas
On average, the Western North Pacific (WNP) basin accounts for one-third of the TC activity on
the planet and sees activity all year round. With the Philippines receiving approximately 8 to 9 TC
landfalls every year and with indirect wind and water impacts also likely in the presence of other
weather systems (such as monsoons), the effective implementation of a TC forecasting and
warning program is essential to protect lives and properties and mitigating the worsening impacts
of these weather systems under a warming climate. To achieve this, PAGASA monitors TC activity
across multiple forecast areas within the WNP basin. Appropriate forecasts, warnings, and expert
advice are provided by the agency to the public and other stakeholders whenever a TC within
these forecast areas may bring impacts to land, sea areas, and airspace under PAGASA’s forecast
responsibility.
This section describes each of the areas of responsibility of PAGASA relevant to the
implementation of the national tropical cyclone forecasting and warning program for the 2021
season5.
Philippine Area of Responsibility
Originating as a storm warning area for shipping forecasts from the Philippines as agreed upon
with other member states of the Regional Association V of the World Meteorological Organization
(WMO)6, the Philippine Area of Responsibility (PAR) presently serves as the region in the WNP
wherein PAGASA has the responsibility for issuing tropical cyclone analyses, forecasts, and
warnings for both the public and maritime sectors. Domestic names are also provided for TCs that
occur within the PAR region.
The PAR region is geographically defined as the land and sea areas within the WNP basin
encompassed by rhumb lines that connect the coordinates 5°N 115°E, 15°N 115°E, 21°N 120°E,
1
The first typhoon warning of its kind in the Philippines was issued in 1879 indicating that a tropical cyclone was crossing
northern Luzon.
2
Observatorio Meteorológico de Manila (1865-1901), Weather Bureau (1901-1972), PAGASA (1972-present)
3
Presidential Decree No. 78 s. 1972, as amended.
4
Republic Act No. 10692 (PAGASA Modernization Act of 2015)
5
PAGASA TC forecast areas have been updated on 23 March 2022.
6
The extent of the PAR is based on Resolution 17 of the Fourth Session of WMO RA II (WMO-No. 181, 1966) and
Resolution 10 of the Fourth Session of WMO RA V (WMO-No. 187, 1966).
3
25°N 120°E, 25°N 135°E, and 5°N 135°E. This encompasses nearly all the land territory of the
Philippines except for the southernmost portions of Tawi-Tawi and some of the country's claims in
the Kalayaan Islands. The area also includes the entire Palau archipelago, nearly all of Taiwan, as
well as portions of the Malaysian state of Sabah and the Japanese prefecture of Okinawa. The
bodies of water within the PAR include all archipelagic seas of the Philippines7, West Philippine
Sea8, Luzon Strait, Mindanao Sea9, Sulu Sea, and most of the Philippine Sea.
Fig. 1.1. TC forecast areas of PAGASA within the WNP basin (2015-2022).
Extended Forecast Areas
In 2015, the Weather Division established the Extended Forecast Areas within the WNP basin to
address the increasing demand from the public, disaster managers, news outlets, and other
stakeholders for official information on TCs outside the PAR region. Larger than the PAR region,
these forecast areas were created to define the region where PAGASA will provide additional
public TC information.
The Tropical Cyclone Advisory Domain (TCAD) and the Tropical Cyclone Information Domain
(TCID) constitute the Extended Forecast Areas of PAGASA. These regions are geographically
defined as follows:
• The TCAD is the region in the WNP bounded by rhumb lines connecting the coordinates
4°N 114°E, 28°N 114°E, 28°N 145°E and 4°N 145°E, excluding the region identified as
the PAR.
• The TCID is the region in the WNP bounded by rhumb lines connecting the coordinates
0° 110°E, 35°N 110°E, 35°N 155°E and 0°N 155°E, excluding the region identified as the
PAR and TCAD.
7
These archipelagic seas are the Sibuyan Sea, Visayan Sea, Camotes Sea, Samar Sea, and Bohol Sea.
8
By virtue of Administrative Order No. 29 s. 2012, the West Philippine Sea is defined as the portion of the South China
Sea within the exclusive economic zone (EEZ) of the Philippines. However, for ease of explanation, the entirety of the
South China Sea will be referred to as the West Philippine Sea.
9
The portion of the Celebes Sea that lies north of the boundary line delimiting the overlapping EEZs of the Philippines and
Indonesia is referred to as the Mindanao Sea. This boundary line was agreed upon by both countries in 2014 was ratified
by the Philippine Senate under Senate Resolution No. 1048 in 2019.
4
High Seas and Offshore Waters Forecast Zones
Under the framework of the International Maritime Organization (IMO)/WMO World-Wide Met-
Ocean Information and Warning Service (WWMIWS) in accordance with Resolution A.1051(27),
as amended, and pursuant to the provisions of WMO-No. 49 Vol. I (Technical Regulations: General
Meteorological Standards and Recommended Practices), PAGASA, through the MMSS, is the
designated promulgation service for the provision of meteorological maritime safety information
(MSI) and other meteorological products and services relevant to shipping in waters within
PAGASA’s identified area of forecast responsibility, taking into account applicable standards and
guidelines set forth by the WMO and IMO.
Fig. 1.2. Marine forecast zones for the high seas and offshore waters.
The waters to which PAGASA has forecast responsibility include, but not limited to, the Sea Area
A110, Sea Area A211, and NAVTEX12 service area designated by the maritime administration in
coordination with the METAREA XI Coordinator and with full consideration to the full extent of the
maritime jurisdiction of the Philippines. Considering the vastness of offshore waters and the high
seas13 within the PAR region, as well as the Taiwan Strait, are subdivided into 15 marine forecast
zones to facilitate the efficient provision of meteorological MSI within the high seas and offshore
waters of the Philippines.
10
Sea Area A1, also referred to as coastal waters, is the region of sea or ocean within the coverage of at least one very
high frequency (VHF) coast radio station where continuous digital selective calling (DSC) alerting is available.
11
Sea Area A2 refers to the region of sea or ocean outside Sea Area A1 that falls within the range of at least one medium
frequency (MF) coast radio station with continuous DSC alerting.
12
Navigational telex or NAVTEX is a system for the broadcast and automatic reception of navigational and meteorological
warnings, meteorological forecasts, and other urgent safety-related messages broadcast to ship using narrow-band direct-
printing telegraphy.
13
In this context, offshore waters refer to the body of water outside of designated Sea Area A1 but situated with the
exclusive economic zone and extended continental shelf of the Philippines, while the high seas in this context refers to
the waters outside the designated Sea Area A1 and offshore waters.
5
Manila Flight Information Region
A Flight Information Region (FIR) is a specified region of airspace covering the entirety of the
Philippines and its surrounding waters (including the extreme eastern portion of Sabah, Malaysia
and northern half of Talaud Islands, Indonesia) where flight information service and alerting service
are provided by the country to which the International Civil Aviation Organization (ICAO) has
delegated operational control of the said airspace. In the Philippines, this airspace is referred to as
the Manila FIR. Shown in Fig. 1.3, the FIR is the region of airspace bounded by rhumb lines
connecting the coordinates 21°N 117.5°E, 21°N 121.5°E, 21°N 130°E, 7°N 130°E, 3.5°N 133°E,
3.5°N 132°E, 4°N 132°E, 4°N 120°E, 7.5°N 117.5°E, 8.41667°N 116.5°E, 10.5°N 114°E, 14.5°N
114°E, and 16.667°N 114°E.
Fig. 1.3. Manila Flight Information Region.
In accordance with Annex 3 of the Convention on International Civil Aviation (ICAO Annex 3) and
pursuant to Philippine Civil Aviation Regulations, Part 3 and Manual of Standards for Aeronautical
Meteorology, PAGASA is the designated and approved meteorological service provider for
international air navigation, with AMSS serving as the meteorological watch office (MWO) for
Manila FIR. The designated MWO is primarily responsible for, among others, the preparation of
SIGMET information for TCs within Manila FIR, supplying of SIGMET information to associated air
traffic services units, disseminate SIGMET, and coordinate its issuance with other MWOs of
adjacent FIRs.
Classification of Tropical Cyclones
All TCs occurring within the WNP basin are categorized by PAGASA according to their maximum
10-minute winds near the center. The current classification system, which has since been
updated14 in March 2022, follows a five-tier scale with tropical depressions as the weakest of the
categories and super typhoons as the strongest. The five-level system was originally introduced in
2015 following the onslaught of Super Typhoon Yolanda (Haiyan) in the Central Philippines in
14
The five tropical cyclone categories used by PAGASA was updated in March 2022 to harmonize the domestic definition
of Super Typhoon with equivalent peak categories used by other meteorological centers in the WNP basin. The new
definition has been retroactively applied to all TCs pre-March 2022.
6
order to give emphasis to violent cases of typhoons, as well as to distinguish TCs possessing gale-
force winds to those bearing storm-force winds (i.e., pre-2015 system classifies TCs with both
gale-force and storm-force maximum winds as tropical storms). Table 1.1 presents the TC
categories in use under the current scheme and equivalent range of maximum winds near the
center in Beaufort, knots (nautical miles per hour), kilometers per hour, and meters per second.
Table 1.1 Categories of TC used by PAGASA.

Maximum sustained winds near the center
Category of TC
Beaufort kt km/h m/s
Tropical Depression BF6 to BF7
22 to 33 39 to 61 10.8 to 17.1
(TD) (Strong winds)
Tropical Storm BF8 to BF9
34 to 47 62 to 88 17.2 to 24.4
(TS) (Gale-force winds)
Severe Tropical Storm BF10 to BF11
48 to 63 89 to 117 24.5 to 32.6
(STS) (Storm-force winds)
Typhoon BF12
64 to 99 118 to 184 32.7 to 51.2
(TY) (Typhoon-force winds)
Super Typhoon BF12
≥ 100 ≥ 185 ≥ 51.3
(STY) (Typhoon-force winds)
Naming of Tropical Cyclones
Brief History
The practice of using names to identify TC events in the WNP goes back several centuries, with
TCs being named after affected places, saints, or things they hit. Some of these TCs include the
Kamikaze of 1274 and 1281, the 1881 Haiphong Typhoon, the 1906 Hong Kong Typhoon, the
1912 China Typhoon, the 1922 Swatow Typhoon, and the 1934 Muroto Typhoon. In 1944, while
the world is in the midst of a global war, forecasters from the United States Army Air Forces based
in the newly established weather center at Saipan (Northern Mariana Islands) informally named
TCs after their wives and girlfriends. The practice reduced confusion when identifying these
weather systems during map discussions.
With the growing popularity of this naming practice among military forecasters, the United States
Armed Services began publicly assigning names for TCs within the WNP in 1945, thereby
formalizing the practice. Eventually, in 1959, the Joint Typhoon Warning Center (JTWC) assumed
the responsibility of assigning “international names” for TCs within the WNP. In 2000, Japan
Meteorological Agency, acting as the WMO Regional Specialized Meteorological Center - Tokyo
Typhoon Center (RSMC Tokyo), took over the naming responsibility from the JTWC.
Until 1962, the then-Weather Bureau has been relying on names assigned by the US military
(JTWC). However, this changed in 1963 when the bureau decided to separately assign domestic
names to TCs of at least TD category within the PAR region. One of the key reasons for the
adoption of domestic naming is the absence of names for TCs that do not reach tropical storm
category. These weather systems, despite their weaker winds, usually bring significant amount of
heavy rainfall that causes widespread flooding and rain-induced landslides. PAGASA has since
maintained this practice of assigning domestic names when it took over the functions of the
Weather Bureau in 1972.
7
Domestic Naming Scheme
PAGASA assigns a domestic name to a TC of at least tropical depression category that enters or
develops within the PAR region. Under the naming guidelines15 which has been in effect since
2001, all domestic names do not exceed nine letters and three syllables and not bear any negative
or offensive meaning. The names can be that of Filipino persons (male or female), places, animals,
flowers, plants/trees, or traits reflecting Filipino culture or tradition and can come from any local
language or dialects in the Philippines.
Four sets of regular names from A to Z of the English alphabet, excluding X, are being rotated
every year. The first TC of the year that occurs within the PAR will be given the name beginning
with letter A, the second B, the third C, and so on, until the 25th name is assigned. If the list is not
exhausted within the year, the first TC of the succeeding year will be given the name from the set
assigned for the succeeding year beginning with the letter A.
In addition, four sets of auxiliary names from A to J of the English alphabet are also rotated every
year in the same manner as the regular names. As such, each set of auxiliary names is paired with
a set of regular names. Auxiliary names are used in case the total number of TCs for the year
exceeds 25. In such an event, the 26th TC will be given the name from the auxiliary set beginning
with letter A, the 27th B, the 28th C, and so on, until auxiliary set is exhausted by the 35th TC of the
year. To date, all auxiliary names remained unused.
Retiring Domestic Names
Under the present naming guidelines, the domestic name of a TC, whether regular or auxiliary,
can be retired from the operational set through any of the two processes: decommissioning or
delisting.
A domestic name is decommissioned by PAGASA if the TC directly caused either or both the
deaths of at least 300 individuals or damage to infrastructure and agriculture amounting to at least
PHP 1,000,000,000.00 based on the final report or, in its absence, the last situational report issued
by the National Disaster Risk Reduction and Management Council (NDRRMC). The list of
approved decommissioned names and their corresponding replacements is presented to the public
within the first quarter of the year following the end of the TC season.
On the other hand, a domestic name can be delisted when there is a necessity for the name to be
replaced without meeting the criteria for decommissioning. Delisting can happen at any time during
the TC season (i.e., before the name is assigned to a TC) for various reasons. In such an event, a
delisted name is immediately replaced. An example of delisted name is the case of KANOR, which
was delisted prior to its supposed usage in September 2014 and was immediately replaced by
KARDING due to negative feedback from the public because a person involved in an infamous
series of inappropriate videos with a minor at that time shares the same name (i.e., “Mang Kanor”
scandal). Another example of delisted name was the case of Set III’s NONOY in 2015, which was
replaced by NONA even though the original name has already been used in three public TC
products. NONOY was delisted because of its perceived similarity with the nickname of then-
President Benigno Aquino III (“Noynoy”).
Since the adoption of domestic naming in 1963, PAGASA has decommissioned 71 names and
delisted 50 names from the operational listing.
Domestic names for the 2021 season
Table 1.2 presents the regular and auxiliary sets of names under Set I, which was the set of names
used during the 2021 season. Names under Set I were last used during the 2017 season and is
scheduled to be used again during the 2025 season (except for those that will be replaced in case
of decommissioning). A total of 15 names were used in 2021, with no new names that were used
for the first time this season. No names from the auxiliary set in 2021 were used.
15
A new naming protocol was introduced in 2001 following the decision of the agency to end the old domestic naming
scheme which has been in effect since 1963. The old naming scheme also has four (4) sets of regular and auxiliary names
but uses female Filipino names beginning with the letters of the Tagalog alphabet and ending with the suffix -ing.
8
The names JOLINA, MARING, and ODETTE were decommissioned after the conclusion of the
2021 season due to the magnitude and extent of reported casualties and damage to houses,
infrastructure, and agriculture. Their replacement names, JACINTO, MIRASOL, and OPONG, will
be introduced during the 2025 season.
Table 1.2. Regular and auxiliary domestic names during the 2021 season. Names in gray were
unused during the season while those in bold were decommissioned at the end of the season.
Regular Set I
Auring Fabian Kiko Paolo Uwan
Bising Gorio Lannie Quedan Verbena
Crising Huaning Maring Ramil Wilma
Dante Isang Nando Salome Yasmin
Emong Jolina Odette Tino Zoraida
Auxiliary Set I
Alamid Conching Emer Gerardo Isko
Bruno Dolor Florante Hernan Jerome
Analysis and Forecast Process
Tropical Cyclone Analysis
The routine analysis of TCs begins with the determination of the center position. The estimation of
the low-level circulation center is accomplished using a combination of satellite data
(geostationary, microwave, scatterometer (SCAT)), Doppler weather radar scans, and surface
meteorological observations16. In addition, satellite fix reports from other meteorological centers
and objective tools from the Cooperative Institute for Meteorological Satellite Studies (CIMSS)
(Wimmers and Velden 2010, 2016) are also routinely used as reference when finalizing the center
position analysis. The direction and speed of movement of TCs are derived from the six-hourly
displacement vectors of the center position.
The intensity of a TC in terms of maximum sustained winds and central pressure is primarily
estimated from the conversion of Dvorak Final T (FT) and Current Intensity (CI) numbers - unitless
parameters derived from the subjective analysis of satellite images using the Dvorak (1984)
method. These values are provided operationally by the PAGASA Meteorological Satellite Facility
and from satellite fix reports from other meteorological centers. Objective Dvorak estimates from
computerized algorithms (e.g., Olander and Velden 2019, Olander et al. 2021) are also taken into
consideration. The conversion from FT and CI numbers to maximum sustained winds and central
pressure is facilitated by a lookup table based on the relationship (Koba et al. 1991) between the
reanalyzed (i.e., post-operational analysis) CI number and the corresponding best track intensities
of WNP TCs during a six-year period in the 1980s when aircraft reconnaissance missions were
still being flown by the United States in the basin.
Initial estimates from the Dvorak method are refined using surface wind estimates from SCAT,
synthetic aperture radar (SAR), and microwave sensors, radial velocity analysis from Doppler
weather radars, weather map analysis using available surface observations, and other objective
tools from CIMSS (e.g., Herndon and Velden 2018). Cyclone phase analyses (Hart 2003) are also
consulted to diagnose extratropical transitions. The progression of eyewall replacement cycles
(ERC) in mature typhoons and its impact on the intensity analysis is analyzed both subjectively
using 85-82 GHz microwave images and objectively using ERC-relevant statistics derived from the
same microwave images (Wimmers 2018)
The maximum gust is derived from the maximum sustained wind estimate using a multiplier (gust
factor) that varies depending on both the exposure conditions near the center of a TC (Harper et
16
These observation data include reports of surface observation from fixed land stations (SYNOP or METAR), sea stations
or ship reports (SHIP), and meteorological buoys (moored or drifting; BUOY).
9
al. 2010) and the wind averaging period of the maximum sustained winds and maximum gust. For
the case of PAGASA, maximum sustained winds and maximum gust are estimated using 10-
minute and 3-second averaging.
The wind field of a TC is determined by estimating the spatial extent of strong winds17, gale-force
winds18, storm-force winds19, and typhoon-force winds20 associated with the TC circulation across
four quadrants (NE, SE, SW, and NW). The extent of these TC winds is primarily estimated using
the subjective analysis of SCAT, SAR, and microwave-based wind fields, sea surface wind fields
estimated from Himawari-8 low-level atmospheric motion vectors (AMV) (Nonaka et al. 2019),
objective wind field estimation tools (Knaff and DeMaria 2010; Knaff et al. 2016), and weather map
analysis using available surface observations.
TC analysis is undertaken four (4) times daily at 00, 06, 12, and 18 UTC for all TCs situated within
the PAR and the extended forecast areas. However, when a TC is forecast to make landfall or
pass within 30 nmi of the Philippine coastline within 24 hours, additional analyses21 are performed
at 03, 09, 15, and 21 UTC. Moreover, as a requirement for public TC products, the center positions
are also determined for the hour preceding the issuance time of the products.
All analysis parameters are compared by typhoon forecasters against operational estimates of
other TC warning centers for consistency purposes.
Tropical Cyclone Forecast
PAGASA issues track and intensity forecasts out to 120 hours, as well as the radii of probability
circles at each forecast time of the track forecast. Forecasts are 12-hourly up to 72 hours and 24-
hourly beyond 72 hours. Normally22, these forecasts are issued up to four (4) times daily with initial
times of 00, 06, 12, and 18 UTC, with additional forecasts23 provided at initial times of 03, 09, 15,
and 21 UTC when a TC is forecast to make landfall or pass within 30 nmi of the Philippine coastline
within 24 hours.
The primary basis for the track forecasts is the track forecast guidance from global and regional
deterministic models. Both simple and selective consensus methods are used to process these
model guidance products to create the track forecast. Global ensemble prediction systems from
major numerical weather prediction (NWP) centers are also employed as reference to refine the
track forecast. The environmental steering of the TC is also analyzed either by using hand-
analyzed upper-air charts (single layer approach) or satellite AMV-derived variable deep-layer
mean streamlines (Velden and Leslie 1991; Velden 1993) to serve as another reference for
diagnosing the forecast near-term motion of a TC. These maps are also compared against satellite
imagery analysis (e.g., water vapor channels) to determine synoptic environmental influences to
steering (e.g., midlatitude troughs, tropical upper tropospheric troughs, jet stream or westerlies).
Intensity forecasts are primarily based on several statistical (Tsai and Elsberry 2015, Gile et al.
2021) and statistical-dynamical (DeMaria 2009, Yamaguchi et al. 2018, Ono et al. 2019) TC
intensity guidance products. Dynamical intensity guidance from global and regional deterministic
models are also referenced when refining the intensity forecast, while cyclone phase forecast
based on global deterministic models (Hart 2003) serve as primary reference for forecasting
extratropical transitions. In addition, environmental influences (e.g., sea surface temperature,
ocean heat content, vertical wind shear, low-mid level moisture, and outflow) along and in the
surrounding region of the track forecast based on weather maps, satellite imageries, and oceanic
datasets are also considered. For near term intensity change of mature typhoons related to ERCs,
a predictive model of ERC initiation based on the objectively-derived ERC-relevant eyewall
statistics is also used (Wimmers 2018).
17
“Strong winds” is defined as near-surface winds of 22 to 33 kt or Beaufort Force 6 or 7.
18
“Gale-force winds” is defined as near-surface winds of 34 to 47 kt or Beaufort Force 8 or 9.
19
“Storm-force winds” is defined as near-surface winds of 48 to 63 kt or Beaufort Force 10 or 11.
20
“Typhoon-force winds” is defined as near surface winds of at least 64 kt or Beaufort Force 12.
21
Additional analyses are terminated once the TC has left the 30-nmi coastal buffer.
22
The frequency of the forecasts depends on the TC product being issued.
23
Additional forecasts are terminated once the TC has left the 30-nmi coastal buffer.
10
The track forecast issued by PAGASA incorporates the forecast confidence circles at each forecast
time. The forecast confidence circle shows the range into which the TC center is forecast to move
with 70% probability at each forecast time. The radii of these circles are statistically determined
based on the result of the most recent five (5)-year track forecast verification against combined
preliminary and final best track data. For the 2021 season, the radii of the forecast confidence
circles were 97 km, 161 km, 245 km, 293 km, and 434 km for the 24-, 48-, 72-, 96-, and 120-hour
forecast positions, respectively. Values for the 12-, 36-, and 60-hour forecast confidence circles
were interpolated based on aforementioned values.
For consistency, track and intensity forecasts are also compared by typhoon forecasters against
operational estimates of other TC warning centers for consistency purposes, taking into account
the differences in wind averaging times used by these centers.
Tropical Cyclone Product Description
Depending on the location of the TC within the forecast areas and the threat posed by the TC to
land and sea areas under PAGASA’s responsibility, the Weather Division issues different TC
products to the public, disaster managers, national government agencies, local government units,
and specialized end users (i.e., maritime and civil aviation sectors). This section presents the
description of various public, marine, and civil aviation TC products issued by the Weather Division
during the 2021 season.
Tropical Cyclone Advisory
The Tropical Cyclone Advisory (TCA) is a plain text product that provides information on the
analysis, forecast, and warning for a TC of at least TD category inside the TCAD that is projected
to enter the PAR within 120 hours. The TCA incorporates the following elements in the analysis
and forecast:
Analysis Center position

Direction and speed of movement
Maximum sustained winds
Maximum gust
12- 24-, 36- 48-, 72-, Center position

96- and 120-h forecasts Maximum sustained winds
Forecast confidence circle (as part of forecast chart)
In addition, TCA may include any warning and non-warning information relevant to the subject TC
such as the list of areas where tropical cyclone wind signals may be first hoisted, general outlook
of hazards which may affect land areas and coastal waters, narrative of track and intensity outlook,
and date and time of forecast entry to the PAR region.
TCAs are normally24 issued twice daily at 11:00 AM and 11:00 PM.
Tropical Cyclone Bulletins
The Tropical Cyclone Bulletin (TCB) 25 is a plain text product that provides information on the
analysis, forecast, and warning for a TC that is either within the PAR (irrespective of threat to land
areas) or still outside the PAR but the forecast scenario already necessitates the hoisting of tropical
cyclone wind signals over land areas of the country. The TCB contains the following elements in
the analysis and forecast:

24
The initial or final TCA may be issued at 5:00 AM, 11:00 AM, 5:00 PM, or 11:00 PM PHT.
25
TCB was first issued during Tropical Storm DANTE (CHOI-WAN) to replace the legacy Severe Weather Bulletin
(SWB).
11
Maximum gust
Extent of tropical cyclone winds
12- 24-, 36- 48-, 72-, Center position

Forecast confidence circle (as part of forecast chart)
TCBs may include warning information such as the list of areas where wind signals are or will be
hoisted, forecast hazards that will affect land areas and coastal waters (i.e., heavy rainfall, severe
winds, storm surge, high waves), landfall information, as well as non-warning information relevant
to the TC such as a narrative of track and intensity outlook and the forecast date and time the TC
will exit the PAR. In cases when a TC is at TY or STY category, the TCB may include emergency
statements related to areas affected and that will be affected in the next 3 hours by the violent
conditions within the eyewall.
TCBs are issued every six hours at 5:00 AM, 11:00 AM, 5:00 PM, and 11:00 PM. Additional
issuances are also made at 2:00 AM, 8:00 AM, 2:00 PM, and 8:00 PM if the TC is forecast to make
landfall or pass within 30 nmi of the Philippine coastline within the next 24 hours. The additional
issuances cease once the TC exits the 30-nmi coastal buffer.
Tropical Cyclone Warning for Shipping
The Tropical Cyclone Warning for Shipping, more commonly known as the “International Warning
for Shipping (IWS)” is a plain text product for marine vessels at sea that provides information on
the analysis and forecast for a TC within the PAR region that may pose threat to safety of maritime
traffic. As a meteorological MSI, the provision of IWS is in accordance with convention obligations
under SOLAS 1974 and all applicable WMO and IMO technical regulations, standards, and
guidelines.
The IWS incorporates the following elements in the analysis and forecast:

Central pressure
Extent of gale-, storm-, and typhoon-force winds
12- 24-, 36- 48-, 72-, Center position

In addition, IWS also contains a request to all marine vessels within the 300 nautical miles from
the center of the TC to transmit, using all available means, shipborne meteorological observations
every three (3) hours. To ensure prioritization in broadcasted MSI by radiocommunication facilities,
the phrase “SECURITE” is appended at the start of the IWS.
IWSs are normally26 issued four (4) times daily at 5:00 AM PHT, 11:00 AM PHT, 5:00 PM PHT,
and 11:00 PM PHT.
WC SIGMET for Civil Aviation
The WC SIGMET (Significant Meteorological Information for Tropical Cyclones) is a plain text
warning issued by the designated MWO (AMSS) to provide concise information concerning the
occurrence or expected occurrence of TCs of at least TS category within Manila FIR which may
affect the safety of aircraft operations. As a critical meteorological information for civil aviation, the
provision of SIGMET is accordance with the provisions of ICAO Annex 3 and all applicable
technical regulations, standards, and guidelines from the WMO, ICAO, and CAAP.
The WC SIGMET incorporates the following elements in the analysis and forecast:
26
The initial (final) IWS is done in conjunction with the issuance of the initial (final) SWB.
12

In addition, the WC SIGMET also contains the extent of cumulonimbus (CB) clouds associated
with the TC, often delineated by a radius from the center position of the TC or by a polygon, as
well as the height of the CB tops, expressed in terms of flight levels.
WC SIGMET is normally27 issued four (4) times daily at 5:00 AM PHT, 11:00 AM PHT, 5:00 PM
PHT, and 11:00 PM PHT.
Tropical Cyclone Updates in other Forecast Products
Aside from the TC products being issued, updates on the center position, intensity, and movement
of all TCs being monitored within the PAR and extended forecast areas (although forecast
parameters are not included to ensure conciseness) are also incorporated in the following forecast
and warning products:
• 24-Hour Public Weather Forecast issued by the WFS at 4:00 AM and 4:00 PM daily.
• Area Synopsis and 24-Hour Shipping Forecast issued by the MMSS at 4:00 AM and 4:00
PM daily.
• Regional or Local Weather Forecasts issued by the PRSDs at 5:00 AM and 5:00 PM daily.
Tropical Cyclone Wind Signal System
The Tropical Cyclone Wind Signal (TCWS) System is a five-level land warning in plain text format
used to warn land areas of TC winds of at least strong wind force on the Beaufort Scale for at most
36 hours before the onset of such meteorological conditions. This wind signal system is numbered
1 to 5, with higher signal number associated with higher general wind strength and short warning
lead time (i.e., hours before onset of wind threat).
Originally introduced in the 1930s to standardize typhoon wind warnings in the Far East region,
the TCWS system has been updated several times in the past to facilitate the warning of more
violent wind conditions and their potential impacts. The most recent changes in the system was
made in March 2022 to harmonize the wind warning system with the existing typhoon damage
scales for the Philippines, damage survey information, warning best practices from other tropical
cyclone warning centers in the WNP basin, and the results of severe wind risk analysis projects
undertaken by PAGASA researchers. However, for the purpose of this ARTC, this subsection
presents the TCWS system as it was implemented during the 2021 season. Table 1.3 presents
the wind signals of the TCWS system, the general wind strength associated with each wind signal,
description of potential damage to structures and vegetation, and the associated color of each
wind signal when presented on maps.
To ensure consistent interpretation, the generalized description of damage presented in Table 1.3
are defined below:
• Very light damage: Less than 5% of high-risk (HR) structures (and no damage to medium-
risk (MR) and low-risk (LR) structures
• Light damage: 10% HR, 5% MR, and 0% LR
• Moderate damage: 25% HR, 10% MR, and 5% LR
• Heavy damage: 50% HR, 25% MR, and 10% LR
• Very Heavy damage: 80% HR, 50% MR, and 25% LR
• Widespread damage: Nearly 100% HR; more than 80% MR; more than 50% LR.
27
The initial WC SIGMET is issued when a TC inside Manila FIR reaches TS category or when a TC of at least TS category
is about to enter Manila FIR within 12 hours. Cancellation of WC SIGMET is undertaken when the TC inside Manila FIR
weakens into a TD or when TC of at least TS category has moved out or is moving out of Manila FIR. All initial and final
WC SIGMET issuances are undertaken with close coordination with MWOs of adjacent FIR under the “Collaborative
SIGMET Issuance” (CSI) Scheme.
13
Moreover, the terms high-risk, medium-risk, and low-risk structures are defined as follows:
• High-risk structures: consist of old and densely built-up residential areas having light
material structures and organic roof materials, squatter/slum areas, zone of mixed
development, poor quality housing, warehouses, and old, dilapidated structures.
• Medium-risk structures: consist of older parts of city/town centers, timber
structures/galvanized iron roofs and generally belong to the middle-income group.
• Low-risk structures: consist of concrete/framed structures, low-density population/housing,
and usually the modern part of the city/town.
Table 1.3. PAGASA TCWS system during the 2021 season

General wind strength and description of potential damage to structures
TCWS
and vegetation
Wind Signal Strong winds which may cause up to very light damage is prevailing or
No. 1 expected to prevail within 36 hours from the time the signal was hoisted
Damaging gale- to storm-force winds28 which may cause light to moderate
Wind Signal
damage is prevailing or expected to prevail within 24 hours from the time
No. 2
the signal was hoisted
Destructive 29 typhoon force winds which may cause moderate to heavy
Wind Signal
damage is prevailing or expected to prevail within 18 hours from the time
No. 3
the signal was hoisted.
Very destructive 30 typhoon force winds which may cause heavy to very
Wind Signal
heavy damage is prevailing or expected to prevail within 12 hours from the
No. 4
time the signal was hoisted.
Devastating 31 typhoon force winds which may cause very heavy to
Wind Signal
widespread damage is prevailing or expected to prevail within 12 hours
No. 5
from the time the signal was hoisted.
Although a general description of damage per wind signal is presented in Table 1.3, a more
detailed description of potential damage to structures and vegetations resulting from the surface
wind conditions associated with each wind signal are presented in Table 1.4.
Owing to the presence of natural and artificial obstructions such as local topography or nearby
buildings, winds in a particular area (local winds) may be substantially stronger from the general
wind strength (regional winds) over the provincial or sub-provincial locality implied by the wind
signal. Compared to the prevailing regional winds, the local winds are generally stronger over
offshore water, on high ground (e.g., mountainous areas), and in areas where channeling effect
between obstructions occur. On the other hand, local winds are weaker in areas that are sheltered
from the prevailing wind direction. In addition, the general wind strength associated with each wind
signal is in terms of mean winds defined as the speed of the wind averaged over a 10-minute
period at 10 meters above the ground. As such, a locality may experience gusts (instantaneous
peak values of surface wind speed) that are higher than the range of wind speeds expressed by
the highest TCWS raised during the passage of a TC.
28
If the TC is still at TS category, the statement for TCWS #2 changes from “Damaging gale- to storm-force winds…” to
“Damaging gale-force winds…”
29
Typhoon-force winds of up to 170 km/h.
30
Typhoon-force winds of more than 170 km/h but not exceeding 220 km/h.
31
Typhoon-force winds more than 220 km/h.
14
Table 1.4. Potential damage to structures and vegetation associated with the surface wind
conditions at each wind signal level.
Wind
Damage to structures Damage to vegetation
Signal
TCWS • Very light or no damage to low-risk • Some banana plants are tilted, a few
#1 structures. downed and leaves are generally
• Light damage to medium- to high-risk damaged.
structures • Twigs of small trees may be broken.
• Slight damage to some houses of very • Rice crops, however, may suffer
light materials or makeshift structures significant damage when it is in its
in exposed communities. flowering stage.
TCWS • Light to moderate damage to high-risk • Most banana plants, a few mango
#2 structures. trees, ipil-ipil, and similar types of
• Very light to light damage to medium- trees are downed or broken.
risk structures. • Some coconut trees may be tilted
• No damage to very light damage to with few others broken.
low-risk structures. • Rice and corn may be adversely
• Unshielded, old, dilapidated affected.
schoolhouses, makeshift shanties, • Considerable damage to shrubbery
and other structures of light materials and trees with some heavy-foliaged
are partially damaged or unroofed. trees blown down.
• A number of nipa and cogon houses
may be partially or totally unroofed.
• Some old, galvanized iron (G.I.) roofs
may be peeled or blown off.
• Some wooden, old electric posts are
tilted or downed.
• Some damage to poorly constructed
signs/billboards.
• In general, the winds may bring light to
moderate damage to the exposed
communities.
TCWS • Heavy damage to high–risk structures. • Almost all banana plants are
#3 • Moderate damage to medium-risk downed.
structures. • Some big trees (acacia, mango, etc.)
• Light damage to low-risk structures. are broken or uprooted.
• Increasing damage (up to more than • Dwarf-type or hybrid coconut trees
50%) to old, dilapidated residential are tilted or downed.
structures and houses of light • Rice and corn crops may suffer
materials. Majority of all nipa and heavy losses.
cogon houses may be unroofed or • Damage to shrubbery and trees with
destroyed. foliage blown off; some large trees
• Houses of medium strength materials blown down.
(old, timber, or mixed timber-CHB
structures, usually with G.I. roofing’s)
and some warehouses or bodega-type
structures are unroofed.
• There may be widespread disruption
of electrical power and communication
services.
15
Table 1.4. (Continuation)

TCWS • Heavy damage to high–risk structures. • Almost all banana plants are
#3 • Moderate damage to medium-risk downed.
structures. • Some big trees (acacia, mango, etc.)
• Light damage to low-risk structures. are broken or uprooted.
• Increasing damage (up to more than • Dwarf-type or hybrid coconut trees
50%) to old, dilapidated residential are tilted or downed.
structures and houses of light • Rice and corn crops may suffer
materials. Majority of all nipa and heavy losses.
cogon houses may be unroofed or • Damage to shrubbery and trees with
destroyed. foliage blown off; some large trees
• Houses of medium strength materials blown down.
(old, timber, or mixed timber-CHB
structures, usually with G.I. roofing’s)
and some warehouses or bodega-type
structures are unroofed.
• There may be widespread disruption
of electrical power and communication
services.
TCWS • Very heavy damage to high–risk • There is almost total damage to
#4 structures. banana plantation.
• Heavy damage to medium-risk • Most mango trees, ipil-ipil, and
structures. similar types of large trees are
• Moderate damage to low-risk downed or broken.
structures. • Coconut plantation may suffer
• Considerable damage to structures of extensive damage.
light materials (up to 75% are totally • Rice and corn plantation may suffer
and partially destroyed) with complete severe losses.
failure of roof structures.
• Many houses of medium-built
materials are unroofed with extensive
damage to doors and windows; some
with collapsed walls.
• A few houses of first-class materials
are partially damaged.
• All signs/billboards are blown down.
TCWS • Widespread damage to high-risk • Total damage to banana plantation.

#5 structures. • Most tall trees are broken, uprooted,
• Heavy damage to medium risk or defoliated.
structures. • Coconut trees are stooped, broken
• Very heavy damage to low-risk or uprooted.
structures. • Few plants and trees survived.
• Electrical power distribution and
communication services severely
disrupted.
• All signs/billboards blown down.
Product Dissemination
For Public Tropical Cyclone Products
Ensuring the effective and efficient dissemination of public TC products to end users is the shared
responsibility of the Weather Division and the PRSDs especially during periods of high impact
16
weather events in the country. As such, public TC products are disseminated using both digital
and paper-based platforms which include fax, electronic mail (email), short messaging service
(SMS), official website, and social media in accordance with domestic requirements and quality
standards. Moreover, the Weather Division continuously communicates with the NDRRMC to
ensure timely dissemination of abbreviated versions of public TC products to the public through
the Emergency Cell Broadcast System (ECBS)32.
For Marine Tropical Cyclone Products
The timely and efficient dissemination of IWS and other similar meteorological MSI to mariners of
vessels within the sea areas under PAGASA’s forecast responsibility is the shared responsibility
of PAGASA (as the national meteorological service and MSI promulgation service) and the.,
Philippine Coast Guard (PCG; as the maritime radiocommunications service) in accordance with
convention obligations under SOLAS 1974. As such, constant coordination with these authorities
or centers is in place to ensure that marine TC products are broadcasted through the shore-based
radiocommunication facilities 33 of the PCG, taking into consideration the provisions under
applicable WMO and IMO technical regulations.
Apart from GMDSS communications platforms, marine TC products are also available for
distribution through the digital and paper-based platforms in use for the dissemination of public TC
products, as well as through the WMO Global Telecommunications System as part of regional
exchange of TC forecast and warning information. GTS-based dissemination of the IWS uses the
abbreviated headings WTPH20 RPMM, WTPH21 RPMM, and WTPH22 RPMM.
For Aeronautical Tropical Cyclone Products
Pursuant to applicable technical regulations, standards, and agreements between PAGASA and
CAAP and in accordance with convention obligations of ICAO Annex 3, PAGASA is responsible
for the timely and efficient dissemination of WC SIGMET to other Aeronautical Meteorological
Offices (AMOs) designated by PAGASA, local air traffic services units, other MWOs (especially
those involved in the CSI scheme), designated centers for VOLMET or D-VOLMET34 broadcast,
responsible ROBEX35 centers and regional operational meteorological (OPMET) data banks, and
other civil aviation users through the Aeronautical Fixed Telecommunications Network (AFTN) and
other identified dissemination mechanisms.
Apart from the identified communication platforms, WC SIGMET is also distributed in digital and
paper-based platforms in use for the dissemination of public TC products, as well as through the
WMO Global Telecommunications System as part of regional exchange of TC forecast and
warning information. The abbreviated heading WCPH31 RPLL is used for the GTS-based
dissemination of the WC SIGMET.
Expert Advice and Briefings
Apart from the distribution of public and marine TC products through multiple digital and paper-
based dissemination platforms, PAGASA performs expert advice and briefing to various end users
and stakeholders using traditional and emerging media platforms to ensure that preparation,
mitigation, and adaptation measures undertaken by the public, disaster managers, government
agencies and institutions, and specialized sectors during TC events are risk-informed, scenario-
driven, and evidence-based.
32
The ECBS is an alert broadcast system in the Philippines designed to disseminate emergency alerts and warning to
mobile devices via cell broadcast system. This system is being implemented by the NDRMMC and all telecommunications
companies in the country in accordance with Republic Act No. 10639 (Free Mobile Disaster Alerts Act).
33
Under the Global Maritime Distress and Safety System (GMDSS), these platforms include marine VHF/MF/HF coast
radio stations, NAVTEX coast stations, and HF narrow band direct printing (NBDP).
34
VOLMET and D-VOLMET (Digital VOLMET) refer to meteorological information for aircraft in flight, which is a worldwide
network of radio stations broadcasting TAF, SIGMET, and METAR reports on shortwave and VHF frequencies.
35
ROBEX or the Regional OPMET Bulletin Exchange is scheme established by ICAO to ensure the most efficient exchange
of OPMET information within ASIA/PAC and MID Regions, as well as with other ICAO regions, as well as ensure the
implementation of OPMET-related standards and recommended practices in ICAO Annexes 3 and 10 and relevant
provisions of air navigational plans of the ASIA/PAC and MID Regions.
17
PAGASA meteorologists at the national and local levels undertake regular public briefings and
press conferences at regular intervals 36 . These are broadcasted via television, radio, and the
internet via the official website, social media, and video streaming/sharing platforms. In addition,
duty forecasters answer to interview requests37 from news outlets and phone queries from the
public and other interested parties and end users.
To support risk-informed, evidence-based decision making of the national government and local
government units ahead of an impending TC passage, PAGASA meteorologists provide expert
advice through detailed briefings and decision support to disaster managers at the national and
local governments. These include pre-disaster risk assessment meetings of the NDRRMC
Operations Center by the Weather Division and local disaster risk reduction and management
offices and phone briefings to heads of local governments by PRSDs. For the private sector,
forecasters also give expert advice to business continuity planners and managers, especially when
TCs (and other weather systems that are enhanced by them) will affect the economic centers of
the country and likely cause significant disruption to their business activities.
These expert briefings and advices to the public and private sectors are supported by continuous
information, education, and communication campaigns such as lectures, speaking engagements,
and seminar-workshops to ensure that they effectively utilize the meteorological information that
PAGASA provides them for their decision-making.
References
DeMaria, M., 2009: A Simplified Dynamical System for Tropical Cyclone Intensity Prediction.
Mon. Wea. Rev., 137, 68-82, doi: 10.1175/2008MWR2513.1
Dvorak, V, 1984: Tropical cyclone intensity analysis using satellite data. NOAA Tech. Rep.
NESDIS 11, 47 pp.
Gile, R. P., J. C. S. Sugui, J. S. Galang, E. O. Cayanan, H.-C. Tsai, Y.-L. Lin, A.-M. Chia, P.-Y.
Lin, K.-C. Lu, and B. J.-D. Jou, 2021: Application of Weighted Analog Intensity Prediction (WAIP)
guidance on Philippine tropical cyclone events. Terr. Atmos. Ocean. Sci., 32, 669-691, doi:
10.3319/TAO.2021.03.03.01
Hart, R. E., 2003: A Cyclone Phase Space Derived from Thermal Wind and Thermal Asymmetry.
Mon. Wea. Rev.,131, 585-626, https://doi.org/10.1175/1520-
0493(2003)131<0585:ACPSDF>2.0.CO;2
Harper, B. A., J. Kepert, and J. Ginger, 2010: Guidelines for converting between various wind
averaging periods in tropical cyclone conditions. WMO/TD No. 1555, 54 pp,
https://www.wmo.int/pages/prog/www/tcp/documents/WMO_TD_1555_en.pdf
Herndon, D., and C. S. Velden, 2018: An Update on the SATellite CONsensus (SATCON)
Algorithm for Estimating Tropical Cyclone Intensity. 33rd Conf. Hurr. Trop. Meteor. Ponte Vedra,
FL, Amer. Meteor. Soc., 284,
https://ams.confex.com/ams/33HURRICANE/webprogram/Paper340235.html.
Knaff, J.A. and M. DeMaria, 2010: NOAA/NESDIS Multiplatform Tropical Cyclone Surface Wind
Analysis. User Manual, 25 pp, https://www.ssd.noaa.gov/PS/TROP/MTCSWA_UM.pdf.
Knaff, J.A., C.J. Slocum, K.D. Musgrave, C.R. Sampson, and B.R. Strahl, 2016: Using Routinely
Available Information to Estimate Tropical Cyclone Wind Structure. Mon. Wea. Rev., 144, 1233-
1247, https://doi.org/10.1175/MWR-D-15-0267.1
36
Regular public briefings during TC days are typically within 30 minutes of the issuance of SWBs (except during additional
issuances of SWBs). However, special public briefings may be held during issuances of TCAs or when a significant change
in the forecast scenario is present.
37
These interviews may be on camera, through phone patch, or using a video conferencing platform.
18
Koba, H., T. Hagiwara, S. Osano, and S. Akashi, 1991: Relationships between CI number and
minimum sea level pressure/maximum wind speed of tropical cyclones (English translation).
Geophys. Mag., 44, 15-25.
Nonaka, K., S. Nishimura, and Y. Igarashi, 2019: Utilization of Estimated Sea Surface Wind Data
Based on Himawari-8/9 Low-level AMVs for Tropical Cyclone Analysis. RSMC Tokyo-Typhoon
Center Tech. Rev. No. 21, 16 pp, https://www.jma.go.jp/jma/jma-eng/jma-center/rsmc-hp-pub-
eg/techrev/text21-3.pdf.
Olander, T. L. and C. S. Velden, 2019: The Advanced Dvorak Technique (ADT) for Estimating
Tropical Cyclone Intensity: Update and New Capabilities. Wea. Forecasting, 22, 905-922, doi:
10.1175/WAF-D-19-0007.1
Ono, M., S. Notshuhara, J. Fukuda, Y. Igarashi, and K. Bessho, 2019: Operational Use of the
Typhoon Intensity Forecasting Scheme Based on SHIPS (TIFS) and Commencement of Five-
day Tropical Cyclone Intensity Forecasts. RSMC Tokyo-Typhoon Center Tech. Rev. No. 21, 17
pp, https://www.jma.go.jp/jma/jma-eng/jma-center/rsmc-hp-pub-eg/techrev/text21-2.pdf
Tsai, H.-C. and R. L. Elsberry, 2015: Seven-Day Intensity and Intensity Spread Predictions in
Bifurcation Situations with Guidance-On-Guidance for Western North Pacific Tropical Cyclones.
Asia-Pac. J. Atmos. Sci., 54, 421-430, doi: 10.1007/s13143-018-0008-0
Velden. C. S., and L. M. Leslie, 1991: The Basic Relationship between Tropical Cyclone Intensity
and the Depth of the Environmental Steering Layer in the Australian Region. Wea. Forecasting,
6, 244-253, https://doi.org/10.1175/1520-0434(1991)006<0244:TBRBTC>2.0.CO;2.
Velden, C. S., 1993: The relationship between tropical cyclone motion, intensity, and the vertical
extent of the environmental steering layer in the Atlantic basin. 20th Conf. Hurr. and Trop
Meteor., San Antonio, TX, Amer. Meteor. Soc.
Wimmers, A. J., and C. S. Velden, 2010: Objectively Determining the Rotational Center of
Tropical Cyclones in Passive Microwave Satellite Imagery. J. Appl. Meteor. Climatol., 49, 2013-
2034, https://doi.org/10.1175/2010JAMC2490.1
Wimmers, A. J., and C. S. Velden, 2016: Advancements in Objective Multisatellite Tropical

Cyclone Center Fixing. J. Appl. Meteor. Climatol., 55, 197-212, https://doi.org/10.1175/JAMC-D-
15-0098.1
Wimmer, A. J., 2018: Improved Eyewall Replacement Cycle Forecasting Using a Modified
Microwave-Based Algorithm (ARCHER). NOAA/OAR Joint Hurricane Testbed Final Rep, 16 pp,
https://www.nhc.noaa.gov/jht/15-17reports/Wimmers_197_progress_reportFINAL_113018.pdf
Yamaguchi, M., H. Owada, U. Shimada, M. Sawada, T. Iriguchi, K. D. Musgrave, and M.

DeMaria, 2018: Tropical Cyclone Intensity Prediction in the Western North Pacific Basin Using
SHIPS and JMA/GSM. SOLA, 14, 138-143, https://doi.org/10.2151/sola.2018-024.
19
20
POST-SEASON BEST TRACK ANALYSIS
OF PHILIPPINE TROPICAL CYCLONES
22
Post-Season Best Track Analysis

of Philippine Tropical Cyclones
A Forensic-like Investigation
The determination of analysis parameters such as center position, intensity, and motion of a
tropical cyclone (TC) valid at a given synoptic time utilizes meteorological observation data from a
wide array of platforms and formats, each having varying degrees of observation latency 1 .
However, in an operational environment, the rigid time schedule of each forecast cycle2 not only
adds the element of time pressure to the conduct of TC analysis but also limits the amount and
type of observation data that can be considered to those with relatively low latency. As such, the
duty forecaster’s exercise of professional judgment within time constraints based on the
observation data that was available at that time heavily influences the determination of the analysis
parameters in an operational setting. The best estimates of these parameters are referred to as
an “operational track” and may incorporate (although minimized) short-term motions, especially
when analysis parameters are estimated at three (3)-hour intervals, which may be
unrepresentative of the overall motion of the TC.
After the termination of operational activities for a particular TC event, the Philippine Atmospheric,
Geophysical, and Astronomical Services Administration (PAGASA) collects all conventional and
unconventional observation data not only from the domestic weather observation network but also
those from other meteorological centers in the Western North Pacific (WNP) basin, including those
that were not available to forecasters in both real and near real-time. Afterwards, the operational
track is reviewed by performing a forensic-like analysis, which involves the re-construction of the
motion and intensity change of TC throughout its lifespan using all the collected meteorological
data and without the tight time constraints of the operational environment. This procedure is called
a “best track analysis” and the final product of this investigation satisfies the basic components of
the accepted definition3 of “best track”:
"A subjectively-smoothed representation of the motion and intensity change of a TC over

its lifetime. The best track of a TC contains the latitude and longitude of the center position
and the intensity in terms of maximum sustained winds4 and central pressure at intervals
of three (3) or six (6) hours. Best track positions and intensities, which are based on a
post-event assessment of all collected meteorological data, may differ from values
contained in operational advisories or bulletin and will also not generally reflect any short-
term erratic motion.”
A fundamental component of this definition that differentiates operational track from a best track is
that the latter provides three (3)- or six (6)-hourly representative estimates of the TC center
position. Plotted center fixes derived from observation data often reveal a series of irregular
movements, such include trochoidal motion or other wobbles, which do not generally persist for
more than a few hours. These are unrepresentative of the overall motion. A subjectively-smoothed
"best track" that does not focus on these short-period transient motions is ideal.
The subjective smoothing procedure means that center positions in the operational track may be
re-positioned” in the best track and from a sampling perspective, this re-positioning is part of a
filtering procedure that is administered to avoid aliasing small-scale noise. For a given time series
with data points ΔT apart, the smallest wavelength which can be depicted accurately is about 4 x
ΔT. Since the TC analysis times of PAGASA are at least three (3) hours apart, the smallest periods
which can be adequately represented are on the order of 12 hours. Thus, the typhoon forecaster
1
Latency is the amount of time between the time of an observation and the time that the observation becomes available to
forecasters in a form that they can assess and analyze.
2
The forecast cycle is the 3-hour period beginning with a synoptic time (usually 00, 06, 12, and 18 UTC) where the (1)
gathering, processing, and displaying of meteorological observation and forecast guidance, (2) determination of analysis
information, (3) the formulation of forecast policy, and (4) preparation and issuance of relevant TC products and briefing
materials are accomplished.
3
PAGASA adopted the definition of “best track” from the National Hurricane Center (Avila 2002)
4
Both operational and best track intensities are estimated at 10-minute averaging periods.
23
in charge of best track analysis might try to avoid analyzing oscillations with a period less than 12
hours.
Best track analysis also allows the typhoon forecaster to adjust analysis parameters post real-time
when, even in the absence of short-period transient motions, the re-constructed motion and
intensity change of the TC based on all collected observation data do not agree with the values in
the operational track. To better explain this, Fig. 2.1 shows both the operational and best track
position and intensities of Tropical Storm DANTE (CHOI-WAN) - one of the TCs of the 2021 season
whose best track considerably changed from its operational track.
Although the operational and best tracks still featured the generally northwestward motion, the
looping movement on 18 to 19 February and a landfall along the east coast of the country, Fig. 2.1
also shows considerable differences that significantly changes the narrative of DANTE. For
instance, it had a wider looping path from 18 to 19 February in the best track compared to the
operational track. In addition, the “wavy” like nature of the track after the looping motion as the
storm made its way towards the country was minimized in the best track.
Operationally, DANTE was analyzed to have skirted the extreme northern portion of Eastern
Samar and the extreme eastern portion of Northern Samar before making its final landfall over
Bicol Region as a tropical depression. It weakened into a remnant low over Albay at 06 UTC on
22 February. In comparison, the best track showed DANTE making landfall in Eastern Samar as
a tropical depression. It weakened into a remnant low near the boundary junction of Samar Island
provinces at 00 UTC on 22 February (i.e., 6 hours earlier).
A best track analysis may also result in an upward or downward revision of intensity estimates at
each synoptic time. A good example of this case for the 2021 season is Typhoon JOLINA. As a
considerably small TC, the operational analysis of its intensity was challenging. During the warning
period, it was only PAGASA who upgraded JOLINA into a typhoon prior to its initial landfall over
Eastern Samar due to the timely arrival of the 13 UTC 06 September synoptic report5 from Guiuan
station and the presence of a radar eye signature. JOLINA was analyzed at that time to have
maintained typhoon status for 6 hours as it crossed Samar Island. The best track still showed
JOLINA reaching typhoon category prior to landfall but only maintained it for 3 hours.
The operational track of JOLINA showed the TC maintaining its severe tropical storm category for
the remainder of its passage across the archipelago. However, a post-real time high resolution
surface wind field from a synthetic aperture radar (SAR) overpass of the TC when it over the waters
west of Marinduque revealed maximum winds reaching 65-70 kt, clearly indicating that it re-
intensified into a typhoon prior or during its passage over Marinduque and maintained this strength
before making landfall in Batangas. This re-intensification was represented in the best track data.
Through best track analysis, important statistics of the season (e.g., number of landfalling TCs for
the year or month and the number of TCs that developed within or outside the PAR) or individual
TCs (e.g., actual storm duration, peak intensity, landfall point and time) can be updated
accordingly. While best track serves as the best available representation of the synoptic-scale
development and movement of TCs, these are by no means perfect. In fact, best track data can
be further revised or refined in the future to incorporate meteorological data that were not available
during the initial post-season best track analysis, as well as other latest information and research
results.
At the present, TC meteorologists from PAGASA perform both preliminary best track analysis in
near-real time and post-season best track analysis after the season has ended to correct position
and intensity estimates, with the latter benefitting from a larger set of real time, near-real time, and
post-real time meteorological data and analyses.
5
The report indicated average winds of 32 m/s and peak gust of 38 m/s.
24
Fig 2.1. Operational (left) and best (right) track positions and intensities (as categories) of Tropical
Storm AURING (DUJUAN). Line color indicates the category of TC. Shaded circles with date labels
indicate 00 UTC positions while open circles indicate 12 UTC positions.
25
Fig 2.2. Operational (left) and best (right) track positions and intensities (as categories) of Typhoon
JOLINA (CONSON). Line color indicates the category of TC. Shaded circles with date labels
indicate 00 UTC positions while open circles indicate 12 UTC positions.
26
PAGASA Tropical Cyclone Publication Series
The typhoon forecasters of the Marine Meteorological Services Section, Weather Division are
responsible for the publication of the “Annual Report on Philippine Tropical Cyclones (ARTC)”
every year. Published within two years after the termination of a particular TC season, the ARTC
provides a yearly compendium of technical reviews of TCs that occurred within the Philippine Area
of Responsibility (PAR) based on the outputs of the post- season best track analysis. Also included
are the operational activities of PAGASA during the TC season and the summary of post-season
verification of official forecasts against the best track data.
The first issue of an annual report of this kind was “Tropical Cyclones of 1948”, published by the
Climatological Division under the direction of Dr. Casimiro del Rosario, Director of the then-
Weather Bureau. The publication of this yearly compendium of best track information of each
Philippine TC continued for decades and was eventually taken over by PAGASA (then under the
Ministry of National Defense) when it was formed in 1972 after the Weather Bureau was abolished.
In December 1981, a new report series, the “Annual Tropical Cyclone Report” (ATCR) was issued
by the Tropical Cyclone Division (TCD) of the National Weather Office (NWO), with its first issue
covering the TC season of 1977. The old series under the Climatological Division continued,
although the ATCR became the definitive technical report series of PAGASA due to its more
comprehensive content.
The new series continued even after PAGASA was transferred to the National Science and
Technology Authority (now the Department of Science and Technology) in 1984. However, with
the dissolution of the Tropical Cyclone Division and the downsizing of the Weather Branch (WB;
the successor to the NWO) in the succeeding years, the new publishing unit of the ARTC lacked
the dedicated manpower to continue the best track analysis and the generation of these reports.
In the early 1990s, the WB terminated both the best track analysis and the publication of the ARTC.
The final issue of the ARTC covered the 1991 TC season.
Fig. 2.2. Launch issues of the ATCR (1977 season, left) and ARTC (2017 season, right).
Several attempts were made to revive the publication of a TC technical report series. In March
2019, following creation of the Tropical Cyclone Group (TCG)6 within the Weather Division (the
successor to the WB), the publication of a TC report series resumed with the first issue of the
“Annual Report on Philippine Tropical Cyclones” (ARTC). The launch issue covered the TC season
of 2017 and was based on the operational track dataset of the season as the TCG was still in the
6
The TCG is a unit of the Marine Meteorological Services Section responsible for the implementation of the tropical cyclone
operational activities of the Weather Division.
27
process of finalizing the procedures for best track analysis. The first best track dataset in more
than 25 years was released by the Weather Division in June 2020 as part of the 2018 ARTC.
The ARTC is available in both print (ISSN 2672-3190) and digital (ISSN 2799-0575) versions, the
latter of which is available in the official website of PAGASA.
References
Avila, L. A., 2002: Best Track Determination at NHC. 25th Conf. on Hurr. and Trop. Meteor., San
Diego, CA, Amer. Meteor. Soc., 11C.1, https://ams.confex.com/ams/pdfpapers/36320.pdf
28
PHILIPPINE TROPICAL CYCLONE SEASON
OF 2021: AN OVERVIEW
30
Philippine Tropical Cyclone Season

of 2021: An Overview
General Statistics
The overview of the tracks of the tropical cyclones (TCs) that were observed within the Philippine
Area of Responsibility (PAR) in 2021 is presented in Fig. 3.1. A total of 15 TCs were observed
within the PAR region during the 2021 season. Compared to the 30-year average1 of 20.2, the TC
activity for the year within the PAR for this year is below normal2 (Fig. 3.2). In general, most of the
TCs that occurred within the PAR region developed over the waters of the Philippine Sea and
Western North Pacific (WNP) south of 15°N and east of 125°E. Seven of the 15 TCs formed over
the Philippine Sea inside the PAR region. Of those that formed outside the PAR, four developed
over the waters near or surrounding the Federated States of Micronesia, two over the Philippine
Sea west of the Northern Mariana Islands, and one over the offshore waters of southern China. A
notable case for this year was that of Severe Tropical Storm (STS) ISANG, which was first tracked
as a tropical depression (TD) less than 300 km west of the International Date Line. Most of the
2021 TCs degenerated into remnant lows over land, while the rest transitioned into a post-tropical3
low or cyclone at the end of their tropical lifespan.
Fig. 3.1. PAGASA best track of TCs that occurred within the PAR in 2021. The filled circles in the
tracks are the “genesis points” or locations where the TCs were first noted as a tropical depression
on the best track data. The tracks are identified using the first letter of the domestic names of the
TCs. The red dash line marks the limits of the PAR.
Fig. 3.1 shows that within the PAR region, two-thirds of the TCs that occurred within the PAR
region in 2021 had tracks that were generally oriented northwest-southeast, west northwest-east
southeast, or east-west as they passed within the PAR. These tracks mainly originated from the
Philippine Sea and terminated over mainland China, the coastal waters of China or Vietnam, or
the mainland Southeast Asia. The second largest cluster of TC tracks during the season,
constituting 20% of the total TC events, were mainly recurving in nature within the PAR region and
had tracks ending over the East China Sea or the Sea of Japan. Majority of the TCs within the
PAR region during the 2021 season passed over the land or sea areas of the PAR south of 20°N.
1
The reference period of the 30-year normal/average is 1991-2020.
2
Beginning with the Annual Report on Philippine Tropical Cyclones 2021, a value is deemed near normal if it lies within
80.1-120% of the normal value. This follows the definition in use by PAGASA’s Climatology and Agrometeorology
Division (CAD),
3
Post-tropical lows or cyclones can be either subtropical or extratropical in nature.
31
The country also witnessed a total of nine landfalling TCs in 2021, which is 60% of the total number
of TCs that occurred within the PAR. The number of landfalling TCs were equally divided between
the first and second half of the year, although the months of May, September, and October had
equal number of landfalling TCs (i.e., two each). Relative to the climatological average (8.4 TCs),
the number of landfalling TCs in 2021 was near normal (Fig. 3.2). In terms of its proportion to the
total number of TCs for the 2021 season, the number of landfalling TCs was above average but
near normal, while the number of non-landfalling TCs relative to the total number of TCs for the
year was below normal (Fig. 3.3). Most of the landfalling TCs this season were at TD category at
the time of their initial4 TC landfalls. With maximum winds of 110 kt and central pressure of 920
hPa, Super Typhoon (STY) KIKO had the highest intensity of any TC during the 2021 season at
the time of initial landfall.
Fig. 3.2. The climatological normal of all TC occurrences within the PAR, depressions, storms (i.e.,
tropical storm and severe tropical storm categories), typhoons (i.e., typhoon and super typhoon
categories), landfalling TCs, and non-landfalling TCs (blue bars) compared with those observed
during the 2021 season (orange bars). Categorization of intensities is based on the peak intensity
within the PAR region only. The errors bars indicate the range of near normal values.
Fig. 3.3. Similar to Fig. 3.2, but the number of depressions, storms, typhoons, landfalling TCs, and
non-landfalling TCs are expressed as proportion of the climatological average number of TCs (for
normal values) and the total number of TCs that occurred within the PAR in 2021 (for the 2021
season). The errors bars indicate the range of near normal values.
Table 3.1 lists down the duration of occurrence of each 2021 TC event from its genesis or formation
to its weakening to an area of low pressure or transitioning into post-tropical low or cyclone, while
Table 3.2 presents the duration of these TCs within the PAR. The TCs that occurred within the
4
Initial TC landfall refers to the first occurrence of a landfall of a TC of at least TD category in the Philippine archipelago.
32
PAR in 2020 had an average lifespan5 of 7 days and 12 hours. Of those that occurred within the
PAR this season, Typhoon FABIAN was the longest-lasting, with a basin-wide lifespan reaching
14 days. On the other hand, Tropical Storm (TS) CRISING and TD NANDO were the shortest-
lasting of the 2021 TCs within the PAR region, with a basin-wide lifespan of only 2 days. Within
the PAR region, TCs lasted an average of 3 days and 20.7 hours. Lasting 9 days, STY BISING
remained within the PAR longer than any other TC in 2021. On the other hand, TS HUANING only
logged 6 hours within the PAR, making it the TC with the shortest period of occurrence within the
PAR for the year.
Table 3.1 also shows that during their lifespans in the WNP basin, eight of the 15 TCs in 2021
peaked at TS or STS category, while five reached typhoon (TY) or STY category. Three of the
2021 TCs, BISING, KIKO, and ODETTE, reached STY category with peak intensities happening
inside the PAR region. Peaking at 120 kt and 895 hPa, STY BETTY was the most intense TC to
occur both within the WNP basin and the PAR region in 2021, although it remained mainly over
the Philippine Sea. The strongest TC to make landfall based on intensity at the time of initial landfall
was STY KIKO (110 kt and 920 hPa). On the other hand of the scale, TD EMONG had the weakest
basin-wide peak intensity of the 15 TCs in 2021 (i.e., 30 kt and 1002 hPa). While LANNIE had a
lower peak intensity within the PAR region (i.e., 25 kt and 1002 hPa) than EMONG, the former was
able to reach TS category outside the PAR. LANNIE was also the weakest TC to hit the Philippine
landmass based on initial landfall intensity. Table 3.2 shows that in terms of peak intensity reached
within the PAR, six peaked at TS or STS category, five reached TY or STY category within the
PAR, while the rest remained as TD.
Table 3.1. Key basin-wide parameters of each TC that occurred within the PAR region in 2021.
Basin-wide peak intensity
Domestic International Basin-wide tropical Date/s and
Name Name lifespan* (UTC) MWXD PRES time/s of
(kt) (hPa) occurrence*
(UTC)
AURING DUJUAN (2101) 02/16 18 to 02/22 00 45 994 02/19 00
BISING SURIGAE (2102) 04/12 12 to 04/25 00 120 895 04/17 18
CRISING Unnamed 05/12 00 to 05/14 00 35 1002 05/13 00
DANTE CHOI-WAN (2103) 05/29 12 to 06/05 06 40 996 05/31 06,
06/03 00
EMONG Unnamed 07/03 18 to 07/06 06 30 1002 07/04 06
FABIAN IN-FA (2106) 07/15 18 to 07/29 18 80 955 07/21 00
GORIO MIRINAE (2110) 08/03 18 to 08/10 00 50 980 08/07 18
HUANING LUPIT (2109) 08/02 12 to 08/09 00 45 985 08/04 18,
08/08 18
ISANG OMAIS (2112) 08/10 12 to 08/24 00 55 992 08/21 12
JOLINA CONSON (2113) 09/05 06 to 09/13 00 65 985 09/06 12,
09/07 21
KIKO CHANTHU (2114) 09/05 18 to 09/18 06 115 910 09/10 06
LANNIE LIONROCK (2117) 10/03 12 to 10/10 18 35 992 10/08 00
MARING KOMPASU (2118) 10/07 06 to 10/14 18 55 975 10/11 12
NANDO Unnamed 10/07 12 to 10/09 12 30 996 10/09 06
ODETTE RAI (2122) 12/12 00 to 12/21 06 105 915 12/16 00,
12/18 18
* Provided as MM/DD HH. MXWD: Maximum winds. PRES: Central pressure.
Note: OMAIS had a period when it was tracked as a tropical low from 08/15 12 UTC to 08/18 06 UTC.
Fig. 3.2 shows that the number of TCs that peaked at TD, TS/STS, and TY/STY within the PAR
region was lower than the climatological average, although those reaching TS/STS remained
within the range of near-normal values and those peaking at TD and TY/STY were below normal.
However, in terms of its proportion to the total number of TCs of the year (Fig. 3.3), those that
peaked at TD were close to the climatological average, while those that reached TS/STS and
5
Lifespan is defined as the duration beginning with the synoptic time when the TC was first noted as TD and ending with
the synoptic time when the TC either weakened into an area of low pressure or completed its post-tropical transition (without
re-developing or re-transitioning into a TC at a later point).
33
TY/STY were higher and lower than average, respectively. Nevertheless, the proportions observed
in 2021 for each intensity categories were all within the range of near-normal values.
Table 3.2. Period of occurrence and duration within the PAR, peak category within the PAR, and
landfall occurrence of each TC that occurred within the PAR region in 2020.
Period within the PAR Peak
Domestic
International Name Inclusive dates and category Landfall
Name Duration
times (UTC) in PAR
AURING DUJUAN (2101) 02/16 19 to 02/22 00 5d 5h TS Yes
BISING SURIGAE (2102) 04/15 21 to 04/24 21 9d STY No
CRISING Unnamed 05/12 00 to 05/14 00 2d TS Yes
DANTE CHOI-WAN (2103) 05/29 15 to 06/05 01 6d 10h TS Yes
EMONG Unnamed 07/03 18 to 07/06 01 2d 7h TD Yes
FABIAN IN-FA (2106) 07/15 18 to 07/23 14 7d 20h TY No
GORIO MIRINAE (2110) 08/03 18 to 08/04 06 12h TD No
HUANING LUPIT (2109) 08/06 21 to 08/07 03 6h TS No
ISANG OMAIS (2112) 08/19 01 to 08/22 06 3d 5h STS No
JOLINA CONSON (2113) 09/05 06 to 09/09 13 4d 7h TY Yes
KIKO CHANTHU (2114) 09/07 10 to 09/12 06 4d 20 h STY Yes
LANNIE LIONROCK (2117) 10/03 12 to 10/05 21 2d 9h TD Yes
MARING KOMPASU (2118) 10/07 06 to 10/12 04 4d 22h STS Yes
NANDO Unnamed 10/08 11 to 10/09 12 1d 1h TD No
ODETTE RAI (2122) 12/14 10 to 12/18 05 3d 19h STY Yes
Observed Trends within the PAR
Fig. 3.4 presents the yearly number of TCs occurring within the PAR and its corresponding 5-year
running mean and linear trend, as well as the 5-year running mean and linear trend of the number
of TCs peaking as TD, TS/ STS, and TY/STY within the PAR, and the number of landfalling and
non-landfalling TCs in Philippines since 1991. The trend is based on the combined best track and
warning track data from PAGASA.
Except for interannual variability in the number of TC cases within the PAR every year, there was
no considerable increase or decrease in its long-term trend since 1991. In terms of landfalling TCs,
a notably decreasing trend in the number of TCs that crossed the archipelago since 1991, although
yearly values exhibited considerable interannual variability. The annual number of TCs peaking at
TS/STS and TY/STY categories entering the PAR region was also found to be stable since 1991,
with the slightly decreasing trend deemed to be not significant. On the other hand, the number of
TCs that remained as a TD within the PAR has been on a slightly increasing trend since 1991. The
increased reliability of on-site and remote sensing observation platforms being utilized by PAGASA
forecasters had been a factor in identifying more TD cases in recent years, potentially resulting in
the slightly increasing trend that was noted.
The observed trend in the annual number of TC occurrences within the PAR, the number of TCs
peaking at TS/STS categories within the PAR, and the number of landfalling TCs in the Philippines
remained consistent with those found by Cinco et al. (2016), although the same could not be said
with the trends in terms of number of TCs peaking at TD and TY/STY categories. The investigation
by Cinco et al. (2016), which used data from 1971 to 2013, noted a stable number of TD cases
and considerably decreasing trend in TCs peaking at TY/STY within the PAR.
34
Fig. 3.4. Number of TCs that occurred in the PAR region per peak category within the PAR since
1991 – (a) all categories, (b) TD, (c) TS/STS, and (d) TY/STY; and TCs that (e) crossed (or made
landfall; LF) and (f) did not cross the Philippines (including close approach cases; NLF) from 1991
to 2021. Dashed lines show five-year running mean and dotted red lines show linear trends.
Quarterly and Monthly Tropical Cyclone Activity
To make better sense of the progression of TC activity within the PAR region during the 2021
season, Figs. 3.5 presents the best track of TCs that occurred during January-March, April-June,
July-September, and October-December 2021. In addition, the number of TC events per month
within the PAR during the 2021 season and the corresponding monthly climatological averages
are presented in Fig. 3.6. In both figures, the TCs were grouped in their corresponding quarter or
month of occurrence based on the date and time (in UTC) it was first tracked within the PAR region.
Furthermore, to make sense of the observed TC activity, quarterly mean global sea surface
temperature (SST) and outgoing longwave radiation (OLR) maps are provided in Figs. 3.7 and 3.8,
respectively based on gridded analyses from the Tokyo Climate Center, Climate Prediction
Division of the Japan Meteorological Agency (JMA).
35
Fig 3.5. Best track of TCs that occurred within the PAR during (a) January to March, (b) April to
June, (c) July to September, and (d) October to December 2021. Red tracks are TCs that made
landfall over the Philippine archipelago. The region enclosed by the black dash line is the PAR
region
Fig. 3.6. Monthly number of TC occurrences within the PAR region for the 2021 season compared
to the climatological normal (1991-2020).
36
(a)
(b)
(c)
(d)
Fig. 3.7. Quarterly mean SST anomalies based on COBE-SST2 and MGDSST for the period of
(a) January to March, (b) April to June, (c) July to September, and (d) October to December 2021.
Contours and shading show SST anomalies at 0.5°C intervals. Gray shading indicates maximum
sea ice coverage.
37
(a) (b)
(c) (d)
Fig. 3.8. Quarterly mean OLR anomalies based on COBE-SST2 and MGDSST for the period of
(a) January to March, (b) April to June, (c) July to September, and (d) October to December 2021.
Shading shows OLR anomalies at 10 W/m2 intervals.
The first quarter (January to March) of the 2021 season saw a period of relative quiescence within
the PAR region. The period was also characterized by the gradual weakening phase of a La Niña
event which began in the boreal summer of 2020 (Fig. 3.7a) (JMA 2021). Tropical convection was
enhanced over the Philippines and the Maritime Continent for the period (Fig. 3.7a). The first TC
of the season and the only TC for the first quarter of the year, TS AURING, developed over the
Philippine Sea and made landfall as a weak depression over Eastern Samar. While a TC activity
for the month of February was an above average condition, the TC activity for the quarter was
deemed near normal.
Under the influence of a weakening La Niña which eventually transitioned into ENSO-neutral
conditions (albeit with below normal SST) (Fig. 3.7b) towards the beginning of the boreal summer
(e.g., June), the second quarter (April to June) of 2021 was a near normal period for TC activity.
During the period, the strongest TC to ever form before the active months of the WNP basin (e.g.,
May to December) occurred within the PAR region. STY BISING, which formed in April, remained
over the Philippine Sea throughout its lifetime. Two other landfalling TCs, TS CRISING and TS
DANTE, formed during the month of May, with the latter crossing the archipelago during the first
few days of June.
The third quarter (July to September) is climatologically considered to be most active months of
the year in terms of TC activity both within the PAR region and the WNP basin. In 2021,
atmospheric and oceanographic conditions indicated ENSO-neutral conditions initially during this
period (albeit with below normal sea surface temperatures (SST) in the Eastern Pacific) (Fig. 3.7c),
which eventually developed into a La Niña towards the end of the quarter. The TC activity during
the period was slightly below normal within the PAR region (i.e., seven TCs for 2021 against 8 to
12 on average) and was attributed to the negative phase of the Indian Ocean Dipole (IOD) (Fig.
3.7c) and a generally suppressed convective activity across the Asian summer monsoon region
during the period (Fig. 3.8c) (JMA 2021). Of the seven TCs this quarter, more than half remained
far from the Philippine landmass (TY FABIAN, STS GORIO, TS HUANING, STS ISANG). The
38
landfalling events were TD EMONG (which passed over Batanes) in July and TY JOLINA (which
crossed Eastern Visayas and Southern Luzon) and STY KIKO (which passed over Batanes) in
September. During these quarter, two TCs (GORIO and HUANING), which occurred in a reverse-
oriented monsoon trough configuration, followed atypical southwest-to-northeast tracks. Of the
non-landfalling TCs during the period, TY FABIAN severely enhanced the Southwest Monsoon
following the mechanism identified by Cayanan et al. (2011) and Bagtasa (2019).
The below-normal activity during the third quarter of 2021 was characterized by a below normal
July and September activity and a nearly average August activity. It is possible that distribution of
TC cases each month for the quarter was greatly influenced by the observed intra-seasonal
variations in the North Pacific Subtropical High (NPSH) (Fig. 3.6). For instance, the westward
expansion of NPSH was weaker the normal in July, and was stronger than normal in September.
This synoptic pattern could also explain the generally landfalling nature of TC tracks observed in
September 2021.
(a)
(b)
Fig. 3.9. Mean 850 hPa stream function and anomaly for (a) July and (b) September 2021.
Contours show stream functions at 2.5 x 106 m2/s intervals, while the shading shows stream
function anomalies at 2 x 106 m2/s intervals. Areas with hatch have altitudes exceeding 1,600 m.
Figures courtesy of the Tokyo Climate Center, Climate Prediction Division of JMA.
The fourth quarter (October to December) of 2021 marked the full redevelopment of La Niña
conditions in the tropical Eastern and Central Pacific (a condition which will persist until February
2023) (Fig. 3.7d). Despite the persistence of the negative IOD phase, enhanced tropical convection
have been noted over the Philippine region due to La Niña (Fig 3.8d). During this quarter, four TCs
occurred within the PAR region. Except for TD NANDO, which underwent a binary interaction with
STS MARING and was eventually assimilated by it, all TCs during the fourth quarter of 2021 made
landfall in the country. The strongest of them was STY ODETTE, which underwent rapid
intensification prior to landfall and traversed the central portion of the Philippine archipelago.
Consistent with climatology, the four TCs followed a generally west northwestward or westward
path across the PAR region.
The TC activity during the quarter within the PAR was found to be below normal compared to the
climatological average. Examination of monthly activity showed that while the TC activity during
October and December was near normal, no TC occurred within the PAR for the month of
November. Synoptic analysis at the lower atmosphere revealed the anomalous westward
39
expansion of the NPSH during the said month towards the Philippine Sea (Fig. 3.10a), which
suppressed tropical convection over the said region (Fig. 3.10b). Consistent with negative IOD,
convection over much of the Maritime Continent remained enhanced.
(a)
(b)
Fig. 3.10. (a) Mean 850 hPa stream function and anomaly and (b) mean OLR anomaly for
November 2021. Contours show stream functions at 2.5 x 106 m2/s intervals, while the shading
shows stream function anomalies at 2 x 106 m2/s intervals for (a) and at 10 W/m2 intervals for (b).
Areas in (a) with hatch have altitudes exceeding 1,600 m. Figures courtesy of the Tokyo Climate
Center, Climate Prediction Division of JMA.
Rainfall during Tropical Cyclone Days
Aside from the eyewall, immediate rain bands, or surface troughs of the TC, the country can also
experience rainfall in the presence of the TC within the PAR through its interaction with the
prevailing monsoon system. For instance, distant heavy rainfall events related to a TC occurrence
within the PAR may be observed because of the TC enhancement of the Southwest Monsoon
(Cayanan et al. 2011; Bagtasa 2019) or the enhanced moisture convergence in shear lines during
strong Northeast Monsoon surges in the presence of a TC or other cyclonic disturbance (Yokoi
and Matsumoto 2008; Ogino et al. 2018; Olaguera et al. 2020). To capture these distant
precipitation events, instead of using a predetermined radius6 from the TC center to delineate TC
rainfall as suggested in existing literature (Jiang et al. 2008; Kubota and Wang 2009; Bagtasa
2017), this section presents the observed and estimated TC-related rainfall in the country using
TC days7 as delineating metric.
Fig. 3.11a presents the total rainfall over the country during TC days based on gauge-adjusted
satellite-based rainfall estimates (Mega et al. 2019) of the Global Satellite Mapping of Precipitation
(Kubota et al. 2020). The total rainfall during TC days in the Philippines shows that the observed
6
Existing studies suggest using 10° radius (approximately 1100 km) from the TC center to delineate TC
rainfall because rainfall amount decreases with a larger TC influence radius and becomes almost constant
from around a 10° radius onward.
7
TC days are meteorological days with at least one tropical cyclone within the PAR region irrespectively of
its proximity to the Philippine archipelago
40
rainfall was notably higher (at least 1,000 mm) for most of Luzon (except mainland Palawan, most
of Quezon, Camarines Provinces, and Masbate), Eastern Visayas, Panay Island, and Caraga
Region. The remaining areas of Luzon and Visayas had rainfall amounts of at least 500-750 mm.
For other areas of Mindanao, portions of Zamboanga Peninsula and Davao Region, and much of
Bangsamoro and SOCCSKSARGEN received rainfall not exceeding 750 mm, while the other
areas had values not exceeding 1,000 to 1,250 mm. The rainfall distribution presented a rainfall
maximum region covering the western portions of Northern and Central Luzon, Catanduanes,
portions of Mindoro, Surigao del Norte, and portions of Agusan del Norte and Surigao del Sur, with
values generally exceeding 1,500 mm in most areas. Some areas in Benguet and La Union
received total rainfall during TC days that reached in excess of 2,000 mm.
When compared against the total rainfall for 2021 (Fig. 3.11b), the total rainfall in Ilocos Region,
Cordillera Administrative Region and most of Central Luzon, Metro Manila, CALABARZON, and
MIMAROPA during TC days accounted for 40 to 70% of the total rainfall for the year. For the other
areas of Luzon, total rainfall during TC days accounted for 20 to 50% of annual rainfall. For
Visayas, the total rainfall during TC days in 2020 constituted 30% to 50% of the year-long rainfall
in Western Visayas and 20 to 40% elsewhere. It was also observed that Palawan had similar
observed proportions with those found in Panay Island, which could be attributed to its geographic
location. In most areas of Mindanao, TC-related rainfall was 20% to 40% of the total rainfall for the
year.
(a) (b)
Fig. 3.6. GSMaP-Gauge nationwide estimates of (a) total rainfall (mm) during TC days and (b) its
percentage contribution to the total rainfall in 2021.
To determine the extent of rainfall during TC days under the different monsoon regimes, the total
rainfall during TC days were aggregated in terms of the approximate periods of each regime based
on the discussion of Williams et al. (1993). For this report, the 2021 season was divided into four
monsoon regimes. January to March were considered to be the mid and late phases of the
Northeast Monsoon of 2020-2021 (NEM1) (although this regime was excluded in the report
because no TC occurred during this period), while April and May were categorized as the inter-
monsoon period or the trade winds regime (TWR). The months of June to October, the longest of
the regimes, cover the onset, prevalence, and withdrawal of the Southwest Monsoon (SWM).
Lastly, the period of November to December coincides with the early phase of the Northeast
Monsoon of 2021-2022 (NEM2).
The observed rainfall across the country during the TC days of NEM1 was associated with a single
TC occurrence (TS AURING). Cumulative rains were at least 100 mm across most of Bicol,
Eastern Visayas, and Caraga Region (reaching up to 300 mm in this region in particular), as well
as some isolated areas in Negros Oriental. Other areas of the country received less than 100 mm
41
during TC days of NEM1. TC-day rainfall during NEM1 accounted for up to 20% of the total NEM1
rainfall and the total TC-day rainfall for 2021.
Most of the higher rainfall accumulations during the TWR were situated over Bicol Region, Eastern
Visayas, Caraga, and Davao Region, with values ranging from 100 to 500 mm. In the rest of
mainland Mindanao, the total TC-day rainfall during TWR was up to 250 mm in most areas, with
isolated areas in excess of 250 mm but not exceeding 500 mm. The rest of the country received
up to 100 mm in most areas, with isolated areas not exceeding 250 mm. The rainfall during TC
days of TWR accounted for the following proportions of the total TWR rainfall of the following areas:
• Between 30% and 100% of total TWR rainfall over most of Cagayan Valley.
• Between 30% and 80% for Eastern Visayas.
• Between 20% and 90% for most of Central Luzon and Bicol Region.
• Between 20% and 70% for CALABARZON, Western Visayas, and Central Visayas.
• Between 20% and 50% for Mindanao.
• Up to 50% for the rest of the country.
Due to the relatively shorter duration of the TWR compared with other monsoon regimes, despite
the passage of three TC events during the period, TC-day rainfall during TWR accounted for 10 to
50% of total rainfall in 2020 in Mindanao (especially in the Davao Region), up to 30% over Bicol
Region, and Eastern Visayas, up to 20% over mainland Palawan and the rest of Visayas, and up
to 10% over the rest of the country.
The SWM period accounted for more than half of the 15 TCs of the 2021 season (i.e., 10 TCs).
Estimates show that most of Luzon (particular the western half) and Western Visayas received
total rainfall of at least 750 mm for the TC days of the SWM, while the rest of Visayas had between
250 and 1,000 mm. Mindanao, being the area not fully exposed to the SWM and to landfalling TCs
during the said period, received between 100 and 750 mm of total TC-day rainfall during the SWM
(except for Dinagat Islands and Surigao del Norte), whose total rainfall ranged from 500 to 1,000
mm). Rainfall distribution show three distinct maximum areas: the Ilocos Region-western Cordillera
Administrative Region area, the western portion of Central Luzon (Tarlac, Pampanga, Zambales,
Bataan), and the Occidental Mindoro-Calamian Islands area. The areas had total SWR TC-day
rainfall of at least 1,000 mm, with maximum values in excess of 1,500 mm.
As a proportion of the total rainfall during the SWM regime, TC days during the SWM account for
50 to 80% of the SWM total rainfall over Northern Luzon, Central Luzon, and the western portion
of Southern Luzon, and 40 to 70% over the Visayas, the rest of Luzon, and Dinagat Islands. The
rest of country. For the rest of Mindanao, the rainfall during SWM TC days only constituted 20 to
50% of the total SWM rainfall in the area (the higher proportions of which were over the northern
and western regions).
The rainfall during TC days of the SWM accounted for at least 30% of the total rainfall for the year.
The share was 50 to 100% for Luzon, with the northern and western portions of the island group
having higher proportions (at least 80%). The western half of Visayas also received TC-day rainfall
during the SWM period that accounted for 50 to 100% (i.e., higher portions in Panay Island), while
the eastern half had between 50 to 80%. For Mindanao, the TC-day rainfall accounted for 50% to
90% of total rainfall in 2021 over Zamboanga Peninsula, Bangsamoro, Northern Mindanao, and
SOCCSKSARGEN regions, and between 30 and 60% over the remaining regions. These show
that much of the total rainfall observed in 2021, especially over the western portion of the country,
were generated, directly (during the landfall or close approach) or indirectly (through monsoon
enhancement or interaction with other synoptic weather systems) during the TC days of the SWM.
However, such large proportions could be attributed to the larger number of TC cases during the
period of SWM, as well as the generally longer period of SWM (five months) compared to NEM1
(three months), TWR (two months), and NEM2 (two months).
42
Total Rainfall (mm) Proportion of Total Proportion of Total Rainfall

Regime Rainfall during TC Days
NEM1
TWR
SWM
NEM2
Fig 3.12. GSMaP-Gauge nationwide estimates of the total rainfall (mm) during TC days of NEM1,
TWR, SWM, and NEM2 and its corresponding percentage contribution to the total rainfall observed
during each monsoon regime and the total TC-day rainfall in 2021.
43
Only one TC, STY ODETTE, occurred within the PAR occurred during the NEM2 period.
Comparing the rainfall distribution map against those from SWM shows a shift in the maximum
rainfall region from the western section of Luzon to the eastern section of Mindanao – consistent
with the change in the general synoptic patterns associated with the transition from SWM to NEM2.
While similarity exists between the distribution of total TC-day rainfall of NEM2 and NEM1 (given
their similar long-term synoptic characteristics), the location of the maximum rainfall region was
heavily dictated by the TCs that occurred during these periods, especially since NEM2 and NEM1
only had one TC case each.
Owing to the nature of ODETTE’s path and the prevailing monsoon regime, the NEM2 TC-day
rainfall was at least 100 mm over the eastern and southern portions of Visayas, the northern and
eastern portions of Mindanao, and portions of Palawan, as well as in isolated portions of Bicol
Region, Aurora, and Quezon. The rainfall maximum was in Caraga region, with accumulated TC-
day rainfall not exceeding 500 mm.
The rainfall during TC days for NEM2 constituted up to 60% of the total NEM2 rainfall over upland
Northern Luzon (despite having generally lower accumulated rainfall), up to 40% over Mindanao,
Central Visayas, and portions of Central Luzon and Palawan, and up to 30% in other areas of the
country. In terms of its share of the total rainfall of 2021, the total TC-day rainfall during NEM2
rainfall accounted for 10 to 30% in Caraga, Davao, and Central Visayas regions and not exceeding
20% in other areas of the country.
Extremes of Surface Meteorological Observations

during Tropical Cyclone Days
Tables 3.3 and 3.4 present the extremes of rainfall, gust wind, and mean sea level pressure
observations recorded by the network of manned surface weather stations (i.e., both synoptic and
agrometeorological research stations) of PAGASA during the passage of landfalling (including
close-approaching) and non-landfalling tropical cyclones. Compared to real-time reports, these
data have undergone post-real time quality control from the Meteorological Guides and Standards
Section, Engineering and Technical Services Division and the Climatology and Agrometeorology
Data Section, Climatology and Agrometeorology Division. The data was retrieved through the
PAGASA Unified Meteorological Information System.
Table 3.3. Extremes of land-based rainfall observations in the Philippines during TC days in 2021.
Value Active TC and date /
Parameter Location
(mm) time of occurrence
Highest storm duration
STY KIKO
rainfall (landfalling or close- Itbayat, Batanes 688.2
07 to 12 September
approaching TCs)
Highest storm duration Mt. Cabuyao, Tuba, TY FABIAN
984.4
rainfall (other TCs) Benguet 15 to 23 July
Highest 24-hour accumulated
STS MARING
rainfall (landfalling or close- Baguio City 625.3
11 October
approaching TCs)
Highest 24-hour accumulated Catarman, Northern STY BISING
265.5
rainfall (other TCs) Samar 18 April
Rainfall observations show that the four of the five highest storm duration rainfall observed
nationwide were caused by TC interacting with another synoptic-scale weather system which
directly affected the country at the time of the passage (e.g., enhanced Southwest Monsoon).
However, in terms of the peak 24-hour accumulated rainfall, all of the five highest reported
nationwide were brought by the direct influence of the TC itself. In terms of mean sea level pressure
and gust wind extremes, the lowest and highest reported values, respectively, were from Basco,
Batanes during the passage of STY KIKO (which directly hit the weather station).
44
Table 3.4. Extremes of land-based gust wind and mean sea level pressure observations in the
Philippines during TC days for TCs whose passage resulted in the hoisting of wind signals.
Active TC and date /
Parameter Location Value
time of occurrence
Lowest mean STY KIKO
sea level Basco, Batanes 927.9 hPa 0000 UTC,
pressure 11 September 2021
86 m/s STY KIKO
Highest 3-s
Basco, Batanes (309.6 km/h, 2350 UTC
peak gust
167.2 kt) 10 September 2021
Tropical Cyclone Impacts: Casualties and Damage
Year-on-year statistics of dead, injured, and missing persons due to TC occurrences within the
PAR region are presented in Fig. 3.13. Based on official report provided to PAGASA by the
National Disaster Risk Reduction and Management Council (NDRRMC), the 2021 TC season in
the Philippines resulted in 2,024 casualties – 484 dead, 1,462 injured, and 78 missing individuals.
This made the 2021 season both the 18th deadliest TC season since 1970 and the deadliest season
following the onslaught of STY YOLANDA in 2013. Moreover, 2020 was also the 16th worst season
since 1970 and 2nd worst since 2013 in terms of the total casualty count. At 23.9%, the proportion
of deaths to casualties during the 2021 season was the 43rd highest since 1970 and 4th highest
since 2013. Since 1970, TC events have claimed the lives of at least 34,919 people and caused
injuries to at least 76,496 individuals. While there is an interannual variability to the casualty
statistics, no notable trends were observed in terms of casualty count and death toll since 1970.
However, a generally increasing trend in number of deaths and injuries have been noted since
2015, with the trend more pronounced in the latter. The number of missing individuals, on the other
hand, has been on a slightly downward trend since 2015.
The combined nationwide cost of damage to agriculture and infrastructure due to TCs of 2021 (Fig.
3.14) amounted to PHP 61.323 billion. Damage to infrastructure accounted for the majority (54.9%)
of the total cost. When adjusted for inflation using the published consumer price index (CPI) of the
Philippine Statistics Authority, the 2021 season was the 6th costliest TC season since 1970 and
the 2nd costliest season post-STY YOLANDA. While year-on-year fluctuations exist in the reported
damage cost, the aggregated annual cost of damage due to TC events has been steadily
increasing since 1970.
Data from the NDRRMC (Table 3.5) also shows that the casualties and aggregated cost of damage
reported for the 2020 season were attributed to TS AURING, STY BISING, TS CRISING, TS
DANTE, TY JOLINA, STY KIKO, TS LANNIE, STS MARING, AND STY ODETTE. With 405
deaths, STY ODETTE was the deadliest TC to occur in 2021. It also had the highest number of
reported casualties (1,828 individuals). The reported dead, injured, and missing individuals due to
ODETTE accounted for 83.7, 93.8, and 90.3% of the total number of dead, injured, and missing
individuals for the entire 2021 season. Only this TC met the decommissioning criteria of PAGASA
in terms of death toll8.
In terms of damage cost, three TCs (JOLINA, MARING, and ODETTE) resulted in damage to
agriculture and infrastructure with amounts exceeding the criteria 9 for the decommissioning of
domestic names. Of these, TY Ulysses was the costliest TC of the 2020 season. Traversing the
northeastern portion of Mindanao, much of Visayas (including Metro Cebu), and the central portion
of Palawan, this STY resulted in damage to properties amounting to PHP 51.706 billion – roughly
84.3% of the total cost of damage caused by TC events in 2021.
8
Deaths of at least 300 individuals as reported by the NDRRMC.
9
Damage of at least PHP 1 billion as reported by the NDRRMC.
45
Fig. 3.13. Statistics of (a) dead, (b) injured, and (c) missing persons caused by tropical cyclones
in the PAR region from 1970 to 2021. Actual number of persons are presented in (a) to (c), while
(d) shows these numbers as a percentage of the total casualties. The y-axis in (a) to (c) uses a
logarithmic (base 10) scale.
46
Fig. 3.14. Yearly total cost of damage (in PHP millions) caused by tropical cyclones in the PAR
region from 1970 to 2021. The cost values are adjusted to 2021-equivalent values to account for
inflation using the annual average CPIs (2018=100) published by the Philippine Statistics Authority.
The red dash line presents the linear trend of the adjusted cost of damage.
Table 3.5. Casualty and cost of damage statistics caused by TCs that occurred within the PAR
region in 2021. Note that other TCs were not included due to the absence of reported information
from the NDRRMC.
Name of Casualties Cost of damage (PHP millions)
TC Dead Injured Missing Total Agriculture Infrastructure Total
AURING 1 2 4 7 106.778 53.052 159.830
BISING 9 20 0 29 261.911 10.870 272.781
CRISING 0 4 2 6 23.164 - 23.164
DANTE 3 0 0 3 152.110 157.638 309.748
JOLINA 20 33 4 57 1,349.221 63.676 1,412.897
KIKO 0 27 0 27 37.355 - 37.355
LANNIE 3 0 0 3 12.225 - 12.225
MARING 43 5 16 64 3,321.719 4,066.475 7,388.194
ODETTE 405 1,371 52 1,828 22,368.179 29,338.185 51,706.364
TOTAL 484 1,462 78 2,024 27,632.661 33,689.897 61,322.558
Following the termination of the 2021 season, on 27 January 2022, the names JOLINA, MARING,
and ODETTE were decommissioned from Set I of the official list domestic names and were
subsequently replaced by JACINTO, MIRASOL, AND OPONG, respectively. These replacements
will be first introduced during the 2025 TC season. Furthermore, in its 55th Session on 07 to 09
March 2023, the Typhoon Committee noted the request of PAGASA to retire the equivalent
international names of JOLINA (CONSON), MARING (KOMPASU), and ODETTE (RAI). These
names were eventually replaced by LUC-BINH (for CONSON), TOKEI (for KOMPASU), and
SARBUL (for RAI) during the 56th Session of the Typhoon Committee on 27 February to 01 March
2024
47
Provision of Tropical Cyclone Products and Wind Signals
As the national meteorological and hydrological service of the Philippines, PAGASA issued 317
public TC products throughout the 2021 TC season. These included 19 Tropical Cyclone
Advisories (TCA), 68 Severe Weather Bulletins (SWB) and 230 Tropical Cyclone Bulletins (TCB).
To ensure the safety of all vessels and aircraft enroute or at ports or aerodromes, a total of 242
Tropical Cyclone Warnings for Shipping (IWS) and 97 Significant Meteorological Information
(SIGMET) were issued by PAGASA to the maritime and civil aviation sectors, respectively. Due to
its length of occurrence within the PAR, STY BISING warranted the issuance of 38 public TC
products, 37 IWS and 21 SIGMET – the highest of any TC in 2021. Table 3.5 presents the summary
of issued TC products during the 2021 season.
Table 3.6 also shows that 11 of the 15 TCs in 2021 triggered the hoisting of Tropical Cyclone Wind
Signals in the country due to the threat of strong to typhoon-force winds. During the season, wind
signals were hoisted by PAGASA in all provinces or portions thereof except for most of
Bangsamoro and SOCCSKARGEN regions, and the southern half of Davao Region and
Zamboanga Peninsula. Due to the nature of its track, the passage of TS DANTE resulted in the
hoisting of wind signals in 59 provinces (or portions thereof) – more than any TC during the season.
Fig. 3.15a presents the map showing the frequency of hoisting wind signals during the 2021
season across the different localities of the country. Due to the nature of the observed TC events
during the season, wind signals were most frequently hoisted over Caraga Region, Eastern
Visayas, Extreme Northern Luzon, and most of Central and Western Visayas. These areas had
wind signal levels of at least 1 hoisted at least four times during the 2021 season.
Fig. 3.15b shows the highest level of wind signal that was hoisted in each provincial or sub-
provincial locality in the country during the 2021 season. Owing to the passage of STY KIKO and
STY ODETTE, Wind Signal No. 4 was the highest level of wind warning hoisted over any portion
of the country during the year. The figure shows an east-to-west oriented band of Wind Signal Nos.
3 to 4 over Visayas, Caraga Region, and Palawan due to STY ODETTE and over northeastern
mainland Cagayan and Extreme Northern Luzon due to STY KIKO. Furthermore, the passage of
TY JOLINA also resulted in a band of Wind Signal No. 3 across the central portion of Eastern
Visayas, which extends northwestward towards Bicol Region and the Bondoc Peninsula of
southeastern Quezon.
Table 3.6. Summary of TC products and hoisting of wind signals for each TC in 2021.
No. of TC products issued No. of
Highest wind
Name of provinces
Public signal level
TC TCA TCB IWS SIGMET under wind
products hoisted
signal
AURING 1 24 25 22 8 36 Wind Signal No. 2
BISING 5 33 38 37 21 27 Wind Signal No. 2
CRISING 0 11 11 6 2 20 Wind Signal No. 2
DANTE 1 35 36 26 16 59 Wind Signal No. 2
EMONG 0 13 13 9 0 2 Wind Signal No. 1
FABIAN 0 31 31 31 0 2 Wind Signal No. 1
GORIO 0 2 2 2 0 0 -
HUANING 0 2 2 2 0 0 -
ISANG 1 14 15 14 2 0 -
JOLINA 0 26 26 16 14 42 Wind Signal No. 3
KIKO 4 29 33 20 12 9 Wind Signal No. 4
LANNIE 0 15 15 10 0 25 Wind Signal No. 1
MARING 0 29 29 23 10 29 Wind Signal No. 2
NANDO 1 5 6 5 0 0 -
ODETTE 6 29 35 19 12 46 Wind Signal No. 4
* TCB superseded SWB beginning with TS DANTE.
48
(a) (b)
Fig. 3.15. (a) Frequency of hoisting TCWS per province or sub-provincial locality during the 2020
season and (b) the highest level of TCWS hoisted per locality.
References
Bagtasa, G., 2017: Contribution of Tropical Cyclones to Rainfall in the Philippines. J. Climate, 30,
3621–3633, https://doi.org/10.1175/JCLI-D-16-0150.1
Bagtasa, G., 2019: Enhancement of Summer Monsoon Rainfall by Tropical Cyclones in

Northwestern Philippines. J. Meteor. Soc. Japan, 97, 967-976,
https://doi.org/10.2151/jmsj.2019-052
Cayanan, E. O., T.-C. Chen, J. C. Argete, M.-C. Yen, and P. D. Nilo, 2011: The Effect of Tropical
Cyclones on Southwest Monsoon Rainfall in the Philippines. J. Meteor. Soc. Japan, 89A,
123-139, https://doi.org/10.2151/jmsj.2011-A08.
Cinco, T. A., and Coauthors, 2016: Observed trends and impacts of tropical cyclones in the
Philippines. Int. J. Climatol., 36, 4638-4650, https://doi.org/10.1002/joc.4659.
Japan Meteorological Agency, 2022: Annual Report on the Activities of the RSMC Tokyo -
Typhoon Center 2021. Accessed 10 January 2024, https://www.jma.go.jp/jma/jma-eng/jma-
center/rsmc-hp-pub-eg/AnnualReport/2021/Text/Text2021.pdf
Jiang, H., J. B. Halverson, J. Simpson, and E. Zipser, 2008: Hurricane ‘‘rain potential’’ derived
from satellite observations aids overland rain prediction. J. Appl. Meteor. Climatol., 47, 944–
959, https://doi.org/10.1175/2007JAMC1619.1
Kubota, H., and B. Wang, 2009: How much do tropical cyclones affect seasonal and interannual
rainfall variability over the western North Pacific? J. Climate, 22, 5495–5510,
https://doi.org/10.1175/2009JCLI2646.1
Kubota, T. and Coauthors, 2020: Global Satellite Mapping of Precipitation (GSMaP) Products in
the GPM Era. Satellite Precipitation Measurement, V. Levizzani, C. Kidd, D. Kirschbaum, C.
Kummerow, K. Nakamura, F.J. Turk, Eds., Springer, 355-374, https://doi.org/ 10.1007/978-3-
49
030-24568-9
Mega, T., T. Ushio, M. T. Matsuda, T. Kubota, M. Kachi, and R. Oki, 2019: Gauge-Adjusted
Global Satellite Mapping of Precipitation. IEEE Transactions on Geoscience and Remote
Sensing, 57, 1928-1935, https://doi.org/10.1109/TGRS.2018.2870199
Ogino, S.-Y., P. Wu, M. Hattori, N. Endo, H. Kubota, T. Inoue, and J. Matsumoto, 2018: Cold
surge event observed by radiosonde observation from the research vessel “Hakuho-maru”
over the Philippine Sea in December 2012. Prog. Earth Planet. Sci., 5, 9,
https://doi.org/10.1186/s40645-017-0163-4
Olaguera, L.M., J. Matsumoto, J.M.B. Dado, and G.T.T. Narisma, Non-tropical Cyclone Related
Winter Heavy Rainfall Events over the Philippines: Climatology and Mechanisms. Asia-
Pacific J. Atmos. Sci., https://doi.org/10.1007/s13143-019-00165-2
Williams, F. R., G. H. Jung, and R. E. Englebretson, 1993: Forecasting Handbook for the
Philippine Islands and Surrounding Waters. Naval Research Laboratory Final Report No.
NRL/PU/7541--92-0001, 357 pp, https://apps.dtic.mil/sti/citations/ADA277993
Yokoi, S. and J. Matsumoto, 2008: Collaborative Effects of Cold Surge and Tropical Depression–
Type Disturbance on Heavy Rainfall in Central Vietnam. Mon. Wea. Rev., 136, 3275–3287,
https://doi.org/10.1175/2008MWR2456.1
50
REVIEW OF THE PHILIPPINE
TROPICAL CYCLONES OF 2021
44
Review of the Philippine

Tropical Cyclones of 2021
This section of the report contains the individual reviews of each Western North Pacific (WNP)
tropical cyclone (TC) that occurred within the Philippine Area of Responsibility (PAR) during the
2021 season based on the result of post-season best track analysis of the Marine Meteorological
Services Section, Weather Division. Each individual TC review includes the following information:
• A map showing the best track positions and intensities (as categories).
• A summary of the meteorological history of the TC presented in a tabular format.
• The top station-observed extremes of the following surface weather observation over land
during the occurrence of the TC within the PAR, including the corresponding dates and
times of observation:
o Highest storm duration1 rainfall (in mm)
o Highest 24-hour rainfall (in mm)
o Highest peak 3-second gust speed (in m/s)2 and direction (as cardinal direction
and bearing)
o Lowest sea level pressure (in hPa)
The last two parameters are only provided for TCs whose passage within the PAR region
resulted in the hoisting of TC wind signals.
• A summary of TC products provided by the Weather Division during the occurrence of the
TC within the PAR region and Manila FIR, the number of provinces3 where TC wind signals
were hoisted and the highest wind signal hoisted during the occurrence of the TC.
• A summary of casualties and damage statistics associated with the TC event based on
aggregated reports and official communications from the National Disaster Risk Reduction
and Management Council (NDRRMC) through the Disaster Statistics Unit, Operations
Service of the Office of Civil Defense; and,
• A map showing the distribution of storm-duration rainfall over the land areas within the
PAR region based on gauge-corrected satellite retrievals of the Global Satellite Mapping
of Precipitation Project (GSMAP; Kubota et al. 2020) and reports from the PAGASA
surface weather observation network. It must be noted that satellite retrievals may or may
not be coherent with ground observations.
Relevant weather radar images, if available, and other figures pertinent to the best track analysis
of each TC event are also included
1
Storm duration refers to the storm duration refers to the meteorological days the TC was inside the PAR region.
2
Despite the use of kt as primary unit of wind speed in all TC-related information, m/s is used as standard unit for 10-m
wind observations from PAGASA manned weather stations.
3
For this purpose, a province is counted even if not all its municipalities or cities were placed under a wind signal.
Furthermore, Metro Manila is counted as one (1) province, while other highly urbanized and independent component
cities are counted under the province to which they are commonly geographically grouped.
45
46
Tropical Storm AURING 16 to 22 February

DUJUAN (2101) 2021
Basin-wide peak intensity:

Tropical Storm
45 kt (85 km/h)
994 hPa
Developed:
18 UTC, 16 February 2021
Degenerated:
00 UTC, 22 February 2021
Duration within the PAR:

5 days and 5 hours
Peak category within the PAR:

Tropical Storm
Highest wind signal hoisted:

Wind Signal No. 2
Fig. 4.1.1. Best track position and intensities of Tropical Storm AURING.
47
Summary of Meteorological History
Table 4.1.1. Key information about Tropical Storm AURING

Parameter Details
First tracked as a tropical 12 UTC, 13 February 2021
low pressure area Over the sea southeast of Palau
Developed into a TC 18 UTC, 16 February 2021

Over the Philippine Sea near Palau
Weakened into a 00 UTC, 22 February 2021
remnant low In the vicinity of Matuguinao, Samar
Period of occurrence 5 days and 6 hours
(lifetime)
Entered the PAR region 19 UTC, 16 February 2021
Exited the PAR region Not applicable

(within the PAR)
Peak intensity Tropical Storm: 45 kt (85 km/h), 994 hPa
(lifetime) 00 UTC, 19 February 2021
(within the PAR region) 00 UTC, 19 February 2021
Observed landfalls Philippines:
2130 UTC, 21 February 2021 (TD): Can-avid, Eastern Samar
Elsewhere:
None
Extremes of Surface Weather Observations during TC Days

Based on quality-controlled reports from PAGASA manned surface weather stations
Table 4.1.2. Highest storm duration (17 to 21 February 2021) rainfall over land.
Rainfall
Location of weather station
(mm)
Pili, Camarines Sur 217.6
Borongan City, Eastern Samar 152.4
Hinatuan, Surigao del Sur 148.2
Surigao City, Surigao del Norte 133.8
Dumaguete City, Negros Oriental 131.9
Table 4.1.3. Highest 24-hour rainfall over land.

Rainfall
Location of weather station Date
(mm)
Pili, Camarines Sur 102.6 20 February 2021
Juban, Sorsogon 91.0 21 February 2021
Dumaguete City, Negros Oriental 71.7 17 February 2021
Surigao City, Surigao del Norte 70.3 21 February 2021
Maasin City, Southern Leyte 66.2 21 February 2021
48
Table 4.1.4. Lowest mean sea level pressure over land.

Minimum Date (MM/DD) and
MSLP (hPa) Time (UTC)
Juban, Sorsogon 1005.2 02/21 1800
Borongan City, Eastern Samar 1005.4 02/21 0600
Hinatuan, Surigao del Sur 1005.6 02/20 2100
Surigao City, Surigao del Norte 1006.2 02/20 2100
Tacloban City, Leyte 1006.7 02/21 0700
Table 4.1.5. Highest peak gust over land.

Peak gust Peak gust
Location of weather station Date and Time (UTC)
speed (m/s) direction
Guiuan, Eastern Samar 20 NNE (030) 02/17 1450
NNE (020) 02/19 0000
Surigao City, Surigao del Norte 16 NNE (030) 02/19 0312
Legazpi City, Albay 15 NE (040) 02/19 0106
Butuan City, Agusan del Norte 14 N (350) 02/19 1233
Borongan City, Eastern Samar 12 N (360) 02/19 0520
Maasin City, Southern Leyte 12 NE (040) 02/19 0523
Tacloban City, Leyte 12 NNE (020) 02/19 0412
Summary of Warning Information
Number of TC products issued

• Severe Weather Bulletins: 24
• Tropical Cyclone Advisories: 1
• Tropical Cyclone Warning for Shipping: 22
• WC SIGMET: 8
Hoisting of TC Wind Signals

• Highest wind signal level hoisted: Wind Signal No. 2
• No. of provinces with hoisted wind signal: 36
Reported Casualties and Cost of Damage

Based on reports from the Office of Civil Defense
Number of reported casualties: 1 dead, 2 injured, and 4 missing

Total cost of damage: PHP 159,830,171.02
• Damage to agriculture: PHP 106,777,735.00
• Damage to infrastructure: PHP 53,052,436.02
49
Fig. 4.1.2. Storm duration rainfall over land during the passage of Tropical Storm AURING within
the PAR based on GSMAP (left) and surface weather station reports (right). The best track is also
overlaid as a solid thick black line.
50
Fig. 4.1.3. Distribution of highest level of wind signal hoisted per province or sub-provincial locality
during the passage of Tropical Storm AURING. The best track is also overlaid as a solid thick white
line.
51
Super Typhoon BISING 12 to 25 April 2021

SURIGAE (2102)

Super Typhoon
120 kt (220 km/h)
895 hPa
Developed:
12 UTC, 12 April 2021
Transitioned:
00 UTC, 25 April 2021

9 days

Super Typhoon

Wind Signal No. 2
Fig. 4.2.1. Best track position and intensities of Super Typhoon BISING.
52
Table 4.2.1. Key information about Super Typhoon BISING.

Parameter Details
First tracked as a tropical 18 UTC, 9 April 2021
low pressure area Over the sea near Yap, Federated States of Micronesia
Developed into a TC 12 UTC, 12 April 2021

Over the sea near Yap, Federated States of Micronesia
Transitioned into a post- 00 UTC, 25 April 2021
tropical low Over the Philippine Sea southwest of Ogasawara Islands, Japan
(lifetime)
Entered the PAR region 21 UTC, 15 April 2021
Exited the PAR region 21 UTC, 24 April 2021
Period of occurrence 9 days

(within the PAR)
Peak intensity Super Typhoon: 120 kt (220 km/h), 895 hPa
(lifetime) 18 UTC, 17 April 2021
(within the PAR region) 18 UTC, 17 April 2021
None
Elsewhere:
None

Table 4.2.1. Highest storm duration (16 to 24 April 2021) rainfall over land.
Rainfall
(mm)
Virac, Catanduanes 520.8
Catarman, Northern Samar 348.1
Legazpi City, Albay 191.6

Rainfall
(mm)
Catarman, Northern Samar 265.5 18 April 2021
Virac, Catanduanes 252.2 19 April 2021
Pili, Camarines Sur 141.6 17 April 2021
Catbalogan City, Samar 124.2 18 April 2021
Guiuan, Eastern Samar 102.9 17 April 2021
53

Virac, Catanduanes 998.4 04/18 2000
Catarman, Northern Samar 998.8 04/18 0900
Guiuan, Eastern Samar 999.4 04/18 0800
Catbalogan City, Samar 1000.6 04/18 0700

Peak gust Peak gust
Virac, Catanduanes 30 WNW (290) 04/18 2230
Guiuan, Eastern Samar 26 W (280) 04/18 0747
Tacloban City, Leyte 22 WNW (290) 04/18 0830
Basco, Batanes 21 N (360) 04/21 1732
NNE (020) 04/21 1948
Borongan City, Eastern Samar 20 SW (230) 04/18 0800-0900*
* No specific time reported, but happened within this range of synoptic hours.

• WC SIGMET: 21



54
Fig. 4.2.2. Storm duration rainfall over land during the passage of Super Typhoon BISING within
55
Fig. 4.2.3. Distribution of highest level wind signal hoisted per province or sub-provincial locality
during the passage of Super Typhoon BISING. The best track is also overlaid as a solid thick white
line.
56
Fig. 4.3.4. Radar imagery (PPI 440-km range)of Super Typhoon BISING at 1701 UTC, 17 April
2024 near its peak intensity. Data from the PAGASA Guiuan Weather Surveillance Radar Station.
A concentric eyewall signature is evident from the image. Black dots were radar eye fix marks from
the station personnel.
57
Tropical Storm CRISING 12 to 14 May 2021

UNNAMED

Tropical Storm
35 kt (65 km/h)
1002 hPa
Developed:
00 UTC, 12 May 2021
Degenerated:
00 UTC, 14 May 2021

2 days

Tropical Storm

Wind Signal No. 2
Fig. 4.3.1. Best track position and intensities of Tropical Storm CRISING.
58
Table 4.3.1. Key information about Tropical Storm CRISING.

Parameter Details
First tracked as a tropical 00 UTC, 11 May 2021
low pressure area Over the Philippine Sea near Palau
Developed into a TC 00 UTC, 12 May 2021

Over the Philippine Sea east of Davao Region
Weakened into a 00 UTC, 14 May 2021
remnant low In the vicinity of Damulog, Bukidnon
(lifetime)
Entered the PAR region Not applicable

(within the PAR)
(lifetime) 00 UTC, 13 May 2021
(within the PAR region) 00 UTC, 13 May 2021
1300 UTC, 13 May 2021 (TD): Baganga, Davao Oriental
Elsewhere:
None

Table 4.3.2. Highest storm duration (12 to 13 May 2021) rainfall over land.
Rainfall
(mm)
Hinatuan, Surigao Del Sur 100.4
Surigao City, Surigao Del Norte 87.8
PCA Bago-Oshiro, Davao City 75.9
Davao International Airport, Davao City 62.0

Rainfall
(mm)
Hinatuan, Surigao del Sur 84.1 13 May 2021
PCA Bago-Oshiro, Davao City 74.8 12 May 2021
Surigao City, Surigao del Norte 72.8 13 May 2021
Borongan City, Eastern Samar 53.0 13 May 2021
Puerto Princesa City, Palawan 42.4 13 May 2021
59

Cotabato City 1003.8 05/13 0600
General Santos City 1004.2 05/13 0600
Davao International Airport, Davao City 1005.2 05/13 0600
El Salvador City, Misamis Oriental 1005.4 05/13 0900
Hinatuan, Surigao del Sur 1005.7 05/13 0700

Peak gust Peak gust
Hinatuan, Surigao del Sur 14 E (90) 05/13 0900-1000*

• WC SIGMET: 2



• Damage to infrastructure: No report
60
Fig. 4.3.2. Storm duration rainfall over land during the passage of Tropical Storm CRISING within
61
during the passage of Tropical Storm CRISING. The best track is also overlaid as a solid thick
white line.
62
Tropical Storm DANTE 29 May to 05 June

CHOI-WAN (2103) 2021

Tropical Storm
40 kt (75 km/h)
996 hPa
Developed:
12 UTC, 29 May 2021
Transitioned:
06 UTC, 05 June 2021

6 days and 10 hours

Tropical Storm

Wind Signal No. 2
Fig. 4.4.1. Best track position and intensities of Tropical Storm DANTE.
63
Table 4.4.1. Key information about Tropical Storm DANTE.

Parameter Details
First tracked as a tropical 06 UTC, 28 May 2021
low pressure area Over the sea south of Yap, Federated States of Micronesia
Developed into a TC 12 UTC, 29 May 2021

Over the sea southeast of Palau
Transitioned into a post- 06 UTC, 05 June 2021
tropical low Over the East China Sea west of Okinawa Islands, Japan
(lifetime)
Entered the PAR region 15 UTC, 29 May 2021
Exited the PAR region 01 UTC, 05 June 2021

(within the PAR)
(lifetime) 06 UTC, 31 May 2021
00 UTC, 03 June 2021
(within the PAR region) 06 UTC, 31 May 2021
00 UTC, 03 June 2021
1230 UTC, 01 June 2021 (TS): Borongan City, Eastern Samar
1410 UTC, 01 June 2021 (TS): Zumarraga, Samar (Majaba Is.)
1420 UTC, 01 June 2021 (TS): Zumarraga, Samar (Bagatao Is.)
1430 UTC, 01 June 2021 (TS): Daram, Samar
1630 UTC, 01 June 2021 (TS): Pio V. Corpus, Masbate
1930 UTC, 01 June 2021 (TS): Balud, Masbate
2200 UTC, 01 June 2021 (TS): San Fernando, Romblon
0010 UTC, 02 June 2021 (TS): Romblon, Romblon
0140 UTC, 02 June 2021 (TS): Corcuera, Romblon
1030 UTC, 02 June 2021 (TS): Tingloy, Batangas
1220 UTC, 02 June 2021 (TS): Calatagan, Batangas
Elsewhere:
None

Table 4.4.2. Highest storm duration (29 May to 04 June 2021) rainfall over land.
Rainfall
(mm)
Maasin City, Southern Leyte 470.0
San Jose, Occidental Mindoro 197.0
Coron, Palawan 183.5
Guiuan, Eastern Samar 170.8
Abucay, Bataan 167.9
64

Rainfall
(mm)
Maasin City, Southern Leyte 395.4 01 June 2021
San Jose, Occidental Mindoro 137.3 02 June 2021
El Salvador City, Misamis Oriental 121.8 30 May 2021
Hinatuan, Surigao Del Sur 104.0 31 May 2021
Abucay, Bataan 103.0 02 June 2021

Romblon City, Romblon 998.6 06/02 0030
Calapan City, Oriental Mindoro 999.1 06/02 1600
Baguio City 1001.7 06/02 1800

Peak gust Peak gust
Romblon City, Romblon 22 N(360) 06/02 0200-0300*
Abucay, Bataan 20 SE(140) 06/02 1500-1600*
Guiuan, Eastern Samar 20 WSW(240) 06/01 1230
San Jose, Occidental Mindoro 19 WSW(240) 06/02 0300
Basco, Batanes 17 SSE(150) 06/03 0115
SSE(150) 06/03 0400
Catarman, Northern Samar 17 NE(40) 06/01 1300-1400*
Calapan City, Oriental Mindoro 16 SW(220) 06/02 0754
Itbayat, Batanes 16 WSW(250) 06/04 0428
Mactan-Cebu International 16 N(10) 05/30 0608
Airport, Lapu-Lapu City
Sangley Pt., Cavite City, Cavite 16 ENE(060) 06/02 1214

• Tropical Cyclone Bulletins: 35
• Tropical Cyclone Warning for Shipping issued: 26
• WC SIGMET: 16

65


Fig. 4.4.2. Storm duration rainfall over land during the passage of Tropical Storm DANTE within
66
during the passage of Tropical Storm DANTE. The best track is also overlaid as a solid thick white
line.
67
Tropical Depression EMONG 3 to 6 July 2021

UNNAMED

Tropical Depression
30 kt (55 km/h)
1002 hPa
Developed:
18 UTC, 03 July 2021
Degenerated:
06 UTC, 06 June 2021

2 days and 7 hours

Tropical Depression

Wind Signal No. 1
Fig. 4.5.1. Best track position and intensities of Tropical Depression EMONG.
68
Table 4.5.1. Key information about Tropical Depression EMONG.

Parameter Details
First tracked as a tropical 00 UTC, 03 July 2021
low pressure area Over the Philippine Sea northwest of Palau
Developed into a TC 18 UTC, 03 July 2021

Over the Philippine Sea east of Eastern Visayas
Weakened into a 06 UTC, 06 July 2021
remnant low Over the Taiwan Strait off the coast of Fujian, China
(lifetime)
Exited the PAR region 0100 UTC, 06 July 2021

(within the PAR)
Peak intensity Tropical Depression: 30 kt (55 km/h), 1002 hPa
(lifetime) 06 UTC, 04 July 2021
(within the PAR region) 06 UTC, 04 July 2021
1030 UTC, 05 July 2021 (TD): Uyugan, Batanes
Elsewhere:
None

Table 4.5.2. Highest storm duration (03 to 05 July 2021) rainfall over land.
Rainfall
(mm)
Baler, Aurora 205.6
Iba, Zambales 168.8
Alabat, Quezon 159.0
Tayabas City, Quezon 140.8

Rainfall
(mm)
Iba, Zambales 166.8 03 July 2021
Alabat, Quezon 154.2 03 July 2021
Baler, Aurora 122.0 05 July 2021
Virac, Catanduanes 85.8 05 July 2021
Tanay, Rizal 81.3 03 July 2021
69

Baguio City 1001.5 07/05 0600
Tuguegarao City, Cagayan 1002.4 07/05 0700
1003.3 07/05 1000
Basco, Batanes
07/05 1100
Aparri, Cagayan 1003.6 07/05 0700
Laoag City, Ilocos Norte 1003.6 07/04 0600
Calayan, Cagayan 1004.0 07/05 0900
Sinait, Ilocos Sur 1004.0 07/04 0600
Note: Itbayat Synoptic Weather Station may have similar or lower minimum MSLP, but was not recorded
since the barometer was inoperative at the time of passage.

Peak gust Peak gust
Basco, Batanes 20 E(090) 07/04 1538
Baguio City 10 ESE(110) 07/04 0256
Baler, Aurora 10 WNW(290) 07/05 1155
Calayan, Cagayan 10 E(090) 07/05 0200-0300*

• TC Warning for Shipping issued: 9
• WC SIGMET: 0


Number of reported casualties: No report

Total cost of damage: No report
• Damage to agriculture: No report
70
Fig. 4.5.2. Storm duration rainfall over land during the passage of Tropical Depression EMONG
within the PAR based on GSMAP (left) and surface weather station reports (right). The best track
is also overlaid as a solid thick black line.
71
during the passage of Tropical Depression EMONG. The best track is also overlaid as a solid thick
white line.
72
Typhoon FABIAN 15 to 29 July 2021

IN-FA (2106)

Typhoon
80 kt (150 km/h)
955 hPa
Developed:
18 UTC, 15 July 2021
Degenerated:
18 UTC, 29 July 2021

7 days and 20 hours

Typhoon

Wind Signal No. 1
Fig. 4.6.1. Best track position and intensities of Typhoon FABIAN.
73
Table 4.6.1. Key information about Typhoon FABIAN.

Parameter Details
First tracked as a tropical 06 UTC, 14 July 2021
low pressure area Over the Philippine Sea west of Northern Mariana Islands (US)
Developed into a TC 18 UTC, 15 July 2021

Over the Philippine Sea far east of Northern Luzon
Weakened into a remnant 18 UTC, 29 July 2021
low In the vicinity of Cangzhou City, Heibei, China
(lifetime)
Exited the PAR region 14 UTC, 23 July 2021

(within the PAR)
Peak intensity Typhoon: 80 kt (150 km/h), 955 hPa
(lifetime) 00 UTC, 21 July 2021
(within the PAR region) 00 UTC, 21 July 2021
None
Elsewhere:
0700 UTC, 25 July 2021 (TY): Zhoushan City, Zhejiang, China
(Mount Putuo Is.)
(Lianghengshan Is.)
(Zhoushan Is.)
0130 UTC, 25 July 2021 (STS): Jiaxing City, Zhejiang, China

Table 4.6.2. Highest storm duration (15 to 23 July 2021) rainfall over land.
Rainfall
(mm)
Mt. Cabuyao, Tuba, Benguet 984.4
Iba, Zambales 770.5
La Trinidad, Benguet 729.6
Cubi Point, Subic Bay International Airport 636.2
74

Rainfall
(mm)
Mt. Cabuyao, Tuba, Benguet 246.8 20 July 2021
Abucay, Bataan 218.1 23 July 2021
Baguio City 214.6 22 July 2021
Iba, Zambales 213.6 22 July 2021
Port Area, Manila 206.9 23 July 2021

Basco, Batanes 992.5 07/22 2100
Aparri, Cagayan 996.1 07/23 2100
Casiguran, Aurora 996.7 07/23 0900
Baler, Aurora 997.0 07/22 1500

Peak gust Peak gust
Baler, Aurora 26 WNW(290) 07/22 1445
Baguio City 20 SW(220) 07/23 0336
Basco, Batanes 20 WNW(290) 07/23 0135
WNW(290) 07/23 0420
W(280) 07/23 0735
W(280) 07/23 1116
W(280) 07/23 1322
Laoag City, Ilocos Norte 13 SW(220) 07/23 0354
Aparri, Cagayan 12 SW(220) 07/23 0841
Itbayat, Batanes 12 W(270) 07/22 2245
Casiguran, Aurora 10 SW(220) 07/22 0410
SW(220) 07/23 1755
SW(220) 07/23 2055

• WC SIGMET: 0

75


Fig. 4.6.2. Storm duration rainfall over land during the passage of Typhoon FABIAN within the
PAR based on GSMAP (left) and surface weather station reports (right). The best track is also
overlaid as a solid thick black line on the upper right corner of the figure.
76
during the passage of Typhoon FABIAN. The best track is outside the domain of this image.
77
Fig. 4.6.4. Composite radar reflective image of Typhoon INFA at 0240 UTC, 23 July 2021, while
nearing the Miyako Islands in the southern Ryukyu archipelago. Image courtesy of Central
Weather Administration of Taiwan.
78
Severe Tropical Storm GORIO 03 to 10 August 2021

MIRINAE (2110)

Severe Tropical Storm
50 kt (95 km/h)
980 hPa
Developed:
18 UTC, 03 August 2021
Transitioned:

12 hours

Tropical Depression

None
Fig. 4.7.1. Best track position and intensities of Severe Tropical Storm GORIO
79
Table 4.7.1. Key information about Severe Tropical Storm GORIO.

Parameter Details
First tracked as a tropical 06 UTC, 01 August 2021
low pressure area Over the East China Sea near Okinawa Islands, Japan
Developed into a TC 18 UTC, 03 August 2021

Over the Philippine Sea near Miyako Islands, Japan
Transitioned into a post- 00 UTC, 10 August 2021
tropical low Over the sea far east of mainland Japan
(lifetime)
Exited the PAR region 06 UTC, 04 August 2021
Period of occurrence 12 hours

(within the PAR)
Peak intensity Severe Tropical Storm: 50 kt (95 km/h), 980 hPa
(lifetime) 18 UTC, 07 August 2021
(within the PAR region) 18 UTC, 03 August 2021
None
Elsewhere:
None

Table 4.7.2. Highest storm duration (3 to 4 August 2021) rainfall over land.
Rainfall
(mm)
Baguio City 123.7
Itbayat, Batanes 77.8

Rainfall
(mm)
Abucay, Bataan 147.0 04 August 2021
Mt. Cabuyao, Tuba, Benguet 130.8 03 August 2021
Baguio City 89.3 03 August 2021
La Trinidad, Benguet 77.3 04 August 2021
Itbayat, Batanes 56.0 03 August 2021
80

• WC SIGMET: 0

• Highest wind signal level hoisted: None


Fig. 4.7.2. Storm duration rainfall over land during the passage of Severe Tropical Storm GORIO
is outside the domain of the figure.
81
Tropical Storm HUANING 02 to 09 August 2021

LUPIT (2109)

Tropical Storm
45 kt (85 km/h)
985 hPa
Developed:
Transitioned:

6 hours

Tropical Storm

None
Fig. 4.8.1. Best track position and intensities of Tropical Storm HUANING
82
Table 4.8.1. Key information about Tropical Storm HUANING.

Parameter Details
low pressure area In the vicinity of Guangxi, China

Over the West Philippine Sea off the coast of Guangdong, China
tropical low In the vicinity of Saihaku District, Tottori, Japan
(lifetime)
Entered the PAR region 21 UTC, 06 August 2021
Period of occurrence 6 hours

(within the PAR)
None
Elsewhere:
0320 UTC, 05 August 2021 (TS): Shantou City, Guangdong,
China (Nan’ao Is.)
0850 UTC, 05 August 2021 (TS): Zhangzhou City, Fujian, China
0010 UTC, 06 August 2021 (TS): Kinmen, Taiwan (Lesser
Kinmen Is.)
0100 UTC, 06 August 2021 (TS): Kinmen, Taiwan (Kinmen Is.)
0100 UTC, 07 August 2021 (TS): Hsinchu City, Taiwan
1100 UTC, 08 August 2021 (TS): Minamisatsuma City,
Kagoshima, Japan
1900 UTC, 08 August 2021 (TS): Suō-Ōshima, Yamaguchi,
Japan
1930 UTC, 08 August 2021 (TS): Kure City, Hiroshima, Japan
(Kurahashi-jima Is.)
2000 UTC, 08 August 2021 (TS): Kure City, Hiroshima, Japan
(mainland)
83

Table 4.8.2. Highest storm duration (7 August 2021) rainfall over land.
Rainfall
(mm)
Echague, Isabela 64.3
General Santos City 47.2
Baguio City 27.0

Rainfall
(mm)
Echague, Isabela 64.3 07 August, 2021
General Santos City 47.2 07 August, 2021
Baguio City 27.0 07 August, 2021
Pili, Camarines Sur 14.4 07 August, 2021
La Trinidad, Benguet 13.6 07 August, 2021

• WC SIGMET: 0



84
Fig. 4.8.2. Storm duration rainfall over land during the passage of Tropical Storm HUANING within
overlaid as a solid thick black line on the upper left corner of the figure.
85
Severe Tropical Storm ISANG 10 to 24 August 2021

OMAIS (2112)

55 kt (100 km/h)
992 hPa
Developed:
Transitioned:

3 days and 5 hours


None
Fig. 4.9.1. Best track position and intensities of Severe Tropical Storm ISANG
86
Table 4.9.1. Key information about Severe Tropical Storm ISANG.

Parameter Details
low pressure area Over the sea northwest of Line Islands, Kiribati

Over the sea northeast of Marshall Islands
tropical low Over the Sea of Japan off the coast of North Gyeongsang, South
Korea (Ulleung Is.)
Period of occurrence 10 days and 12 hours*

(lifetime)
Entered the PAR region 01 UTC, 19 August 2021

(within the PAR)
None
Elsewhere:
1140 UTC, 23 August 2021 (TS): Seogwipo City, Jeju, South
Korea
1350 UTC, 23 August 2021 (TS): Yeosu City, South Jeolla, South
Korea (Yeondo Is.)
1430 UTC, 23 August 2021 (TS): Tongyeong City, South
Gyeongsang, South Korea (Hado Is.)
1450 UTC , 23 August 2021 (TS): Goseong County, South
Gyeongsang, South Korea
* During its period of occurrence, ISANG degenerated into a tropical low on 12 UTC, 15 August 2021. It re-
developed into a tropical depression on 12 UTC, 18 August 2021.

Table 4.9.2. Highest storm duration (19 to 22 August 2021) rainfall over land.
Rainfall
(mm)
Echague, Isabela 120.2
Indang, Cavite 100.9
Muñoz City, Nueva Ecija 98.2
Bayombong, Nueva Vizcaya 87.7
87

Rainfall
(mm)
Virac, Catanduanes 73.2 20 August, 2021
Bayombong, Nueva Vizcaya 72.8 20 August, 2021
Ambulong, Tanauan City, Batangas 64.6 19 August, 2021
Indang, Cavite 61.6 21 August, 2021
Echague, Isabela 60.1 20 August, 2021

• WC SIGMET: 2



88
Fig. 4.9.2. Storm duration rainfall over land during the passage of Severe Tropical Storm ISANG
is also overlaid as a solid thick black line on the upper right corner of the figure.
89
Typhoon JOLINA 05 to 13 September

CONSON (2113) 2021

Typhoon
65 kt (120 km/h)
985 hPa
Developed:
06 UTC, 05 September 2021
Degenerated:

4 days and 7 hours

Typhoon

Wind Signal No. 3
Fig. 4.10.1. Best track position and intensities of Typhoon JOLINA.
90
Table 4.9.1. Key information about Typhoon JOLINA.

Parameter Details
First tracked as a tropical 18 UTC, 04 September 2021
low pressure area Over the Philippine Sea far east of Eastern Visayas
Developed into a TC 06 UTC, 05 September 2021

Over the Philippine Sea east of Eastern Visayas
Weakened into a remnant 00 UTC, 13 September 2021
low Over the West Philippine Sea off the coast of Quảng Nam,
Vietnam

(lifetime)
Exited the PAR region 13 UTC, 09 September 2021

(within the PAR)
(lifetime) 12 UTC, 06 September 2021
21 UTC, 07 September 2021*
(within the PAR region) 12 UTC, 06 September 2021
21 UTC, 07 September 2021*
1400 UTC, 06 September 2021 (TY): Hernani, Eastern Samar
1750 UTC, 06 September 2021 (STS): Villareal, Samar
(Lamingao Is.)
1800 UTC, 06 September 2021 (STS): Villareal, Samar
(Guintarcan Is.)
1910 UTC, 06 September 2021 (STS): Daram, Samar
2230 UTC, 06 September 2021 (STS): Santo Niño, Samar (Santo
Niño Is.)
2320 UTC, 06 September 2021 (STS): Almagro, Samar (Kerikite
Is.)
0040 UTC, 07 September 2021 (STS): Tagapul-an, Samar
0200 UTC, 07 September 2021 (STS): Palanas, Masbate
1740 UTC, 07 September 2021 (STS): Torrijos, Marinduque
2340 UTC, 07 September 2021 (TY): San Juan, Batangas
0900 UTC, 08 September 2021 (TS): Mariveles, Bataan
1130 UTC, 08 September 2021 (TS): San Antonio, Zambales
Elsewhere:
None
* A second peak intensity was determined through best track analysis. Refer to Fig. 4.10.6 for context.
91

Table 4.10.2. Highest storm duration (05 to 09 September 2021) rainfall over land.
Rainfall
(mm)
Indang, Cavite 240.5
Guiuan, Eastern Samar 199.4

Rainfall
(mm)
Mt. Cabuyao, Tuba, Benguet 187.8 09 September 2021
Tayabas City, Quezon 166.8 08 September 2021
Catbalogan City, Samar 152.1 06 September 2021
Guiuan, Eastern Samar 150.1 06 September 2021
Tacloban City, Leyte 141.2 06 September 2021

Guiuan, Eastern Samar 991.6 09/06 1300
Masbate City, Masbate 997.2 09/07 0400
Ambulong, Tanauan City, Batangas 998.2 09/08 0500
Calapan City, Oriental Mindoro 1001.1 09/08 0000

Peak gust Peak gust
Guiuan, Eastern Samar 38 W (260) 09/06 1230
Ambulong, Tanauan City, 24 N (360) 09/08 0336
Batangas
Tanay, Rizal 23 SSE (160) 09/06 1840
Catbalogan City, Samar 22 N (360) 09/06 1822
Borongan City, Eastern Samar 20 NE (040) 09/06 1315
Masbate City, Masbate 20 ENE (070) 09/07 0319

• WC SIGMET: 14

92


Total cost of damage: PHP 1,412,897,089.10
• Damage to agriculture: PHP 1,349,221,036.10
Fig. 4.10.2. Storm duration rainfall over land during the passage of Typhoon JOLINA within the
PAR based on GSMAP (left) and surface weather station reports (right). The best track is also
93
during the passage of Typhoon JOLINA. The best track is also overlaid as a solid thick white line.
94
Fig. 4.10.4. Radar imagery PPI 440-km range) of Typhoon JOLINA at 1400 UTC, 06 September
2021 while making landfall over Hernani, Eastern Samar. Data from the PAGASA Guiuan Weather
Surveillance Radar Station. Black dots were radar eye fix marks from the station personnel. Radar
images, along with Fig. 4.10.5 and surface weather observation from Guiuan Synoptic Weather
Station, triggered the upgrading of JOLINA into a typhoon as 1200 UTC of the same day – the only
meteorological center to do so during the warning period.
95
Fig. 4.10.5. Color-enhanced 89 GHz microwave overpass of then-Severe Tropical Storm JOLINA
over the waters off Eastern Samar at 0855 UTC (left) and 0950 UTC (right) on 06 September 2021.
These images, along with Fig. 4.10.4 and surface weather observation from Guiuan Synoptic
Weather Station, triggered the upgrading of JOLINA into a typhoon as 1200 UTC of the same day
– the only meteorological center to do so during the warning period. Image courtesy of US Naval
Research Laboratory – Monterey.
Fig. 4.10.6. 10-m wind speed estimates over the location of Typhoon JOLINA and its surrounding
waters from a synthetic aperture radar overpass at 2139 UTC, 07 September 2021. This post-real
time data resulted in JOLINA’s second intensification into Typhoon category in the PAGASA best
track data. Data from NOAA/NESDIS/STAR.
96
Super Typhoon KIKO 05 to 18 September

CHANTHU (2114) 2021

Super Typhoon
115 kt (215 km/h)
910 hPa
Developed:
Transitioned:

4 days and 20 hours

Super Typhoon

Wind Signal No. 4
Fig. 4.11.1. Best track position and intensities of Super Typhoon KIKO.
97
Table 4.9.1. Key information about Super Typhoon KIKO.

Parameter Details
First tracked as a tropical 06 UTC, 05 September 2021
low pressure area Over the Philippine Sea southwest of Guam (US)
Developed into a TC 18 UTC, 05 September 2021

Over the Philippine Sea west of Guam (US)
Transitioned into a post- 06 UTC, 18 September 2021
tropical low Over the sea off the coast of Shizuoka, Japan
(lifetime)
Entered the PAR region 10 UTC, 07 September 2021
Exited the PAR region 06 UTC, 12 September 2021

(within the PAR)
(lifetime) 06 UTC, 10 September 2021
(within the PAR region) 06 UTC, 10 September 2021
0030 UTC, 11 September 2021 (STY): Ivana, Batanes
Elsewhere:
0930 UTC, 17 September 2021 (STS): Fukutsu City, Fukuoka,
Japan
1330 UTC, 17 September 2021 (TS): Kaminoseki City,
Yamaguchi, Japan (Nagashima Is.)
1340 UTC, 17 September 2021 (TS): Kaminoseki City,
Yamaguchi, Japan (mainland)
1400 UTC, 17 September 2021 (TS): Suō-Ōshima, Yamaguchi,
Japan
1600 UTC, 17 September 2021 (TS): Matsuyama City, Ehime,
Japan (Gogo Is.)
1620 UTC, 17 September 2021 (TS): Matsuyama City, Ehime,
Japan (mainland/Shikoku Is.)
2110 UTC, 17 September 2021 (TS): Wakayama City,
Wakayama, Japan
98

Table 4.11.2. Highest storm duration (07 to 12 September 2021) rainfall over land.
Rainfall
(mm)
Itbayat, Batanes 688.2
Basco, Batanes 604.9
Iba, Zambales 345.4
Cubi Point, Subic Bay International Airport 332.8

Rainfall
(mm)
Itbayat, Batanes 510.0 11 September 2021
Basco, Batanes 420.7 11 September 2021
Mt. Cabuyao, Tuba, Benguet 187.8 09 September 2021
Tayabas City, Quezon 166.8 08 September 2021
Iba, Zambales 137.2 11 September 2021

Basco, Batanes 927.9 09/11 0000
Aparri, Cagayan 1000.9 09/10 1800
Baguio City 1002.4 09/09 0600
09/10 0600

Peak gust Peak gust
Basco, Batanes 86 ESE(120) 09/10 2350
Itbayat, Batanes 60 E(090) 09/11 0140
Calayan, Cagayan 30 W(270) 09/10 1900-2000*
Aparri, Cagayan 15 NNE(020) 09/10 0545
Baler, Aurora 13 W(270) 09/09 2040
Laoag City, Ilocos Norte 13 WSW(250) 09/11 0325
S(180) 09/12 0244
Note: The wind instrument at Basco Synoptic Weather Station was totally damaged after the 86 m/s peak
gust was observed.

• WC SIGMET: 12
99



Fig. 4.11.2. Storm duration rainfall over land during the passage of Super Typhoon KIKO within
100
during the passage of Super Typhoon KIKO. The best track is also overlaid as a solid thick white
line.
101
Fig. 4.11.4. Radar imagery of Super Typhoon KIKO at 1555 UTC (top; 1-km CAPPI 200-km range)
and 2100 UTC (bottom; PPI 440-km range), 10 September 2021 while moving towards Batanes at
peak intensity. Data from the PAGASA Aparri Weather Surveillance Radar Station. Concentric
eyewall signature can be noted on both images.
102
Fig. 4.11.5. Composite radar reflective image of Super Typhoon KIKO at 0030 UTC, 11 September
2021 at the time of landfall in Ivana, Batanes. Deterioration of eyewall region is evident in this stage
of KIKO’s passage. Image courtesy of Central Weather Administration of Taiwan.
103
Tropical Storm LANNIE 03 to 10 October 2021

LIONROCK (2117)

Tropical Storm
35 kt (65 km/h)
992 hPa
Developed:
12 UTC, 03 October 2021
Degenerated:

2 days and 9 hours

Tropical Storm

Wind Signal No. 1
Fig. 4.12.1. Best track position and intensities of Tropical Storm LANNIE.
104
Table 4.12.1. Key information about Tropical Storm LANNIE.

Parameter Details
First tracked as a tropical 18 UTC, 01 October 2021
Developed into a TC 12 UTC, 03 October 2021

Over the Philippine Sea off the coast of Surigao del Sur
Weakened into a remnant 18 UTC, 10 October 2021
low In the vicinity of Thạch Thành District, Thanh Hoa, Vietnam
(lifetime)
Exited the PAR region 21 UTC, 05 October 2021

(within the PAR)
(lifetime) 00 UTC, 08 October 2021
(within the PAR region) 18 UTC, 04 October 2021
1900 UTC, 03 October 2021 (TD): Socorro, Surigao del Norte
2000 UTC, 03 October 2021 (TD): Surigao City, Surigao del
Norte (Hinatuan Is.)
Norte (Nonoc Is.)
Norte (Hikdop Is.)
2230 UTC, 03 October 2021 (TD): San Ricardo, Southern Leyte
0000 UTC, 04 October 2021 (TD): Padre Burgos, Southern Leyte
0220 UTC, 04 October 2021 (TD): Ubay, Bohol
0610 UTC, 04 October 2021 (TD): Dalaguete, Cebu
0730 UTC, 04 October 2021 (TD): Bindoy, Negros Oriental
2200 UTC, 04 October 2021 (TD): Linapacan, Palawan (Calibang
Is.)
Elsewhere:
1210 UTC, 08 October 2021 (TS): Wanning City, Hainan, China
0900 UTC, 10 October 2021 (TD): Thái Thụy District, Thái Bình,
Vietnam
105

Table 4.12.2. Highest storm duration (03 to 05 October 2021) rainfall over land.
Rainfall
(mm)
Casiguran, Aurora 191.8
Iloilo City 183.2

Rainfall
(mm)
Casiguran, Aurora 129.4 05 October 2021
Borongan City, Eastern Samar 108.0 03 October 2021
Surigao City, Surigao del Norte 107.7 03 October 2021
Calayan, Cagayan 96.4 03 October 2021
Virac, Catanduanes 91.8 04 October 2021

Dauis, Bohol 1002.6 10/04 0600
Dumaguete City, Negros Oriental 1002.7 10/04 0800
Hinatuan, Surigao Del Sur 1002.7 10/04 0600
Mactan-Cebu International Airport, 1002.8 10/04 0800
Lapu-Lapu City
10/04 0700
Coron, Palawan 1003.0 10/04 1900
10/04 0700
Butuan City, Agusan del Norte 1003.1 10/04 0600

Peak gust Peak gust
Guiuan, Eastern Samar 22 NNE(030) 10/03 2116
Tacloban City, Leyte 18 ESE(110) 10/03 1116
Cuyo, Palawan 12 NNE(020) 10/04 1141
San Jose, Occidental Mindoro 12 SW(230) 10/05 1207
Mactan-Cebu International 11 N(360) 10/04 0000-0100*
Masbate City, Masbate 11 E(090) 10/03 1405
Borongan City, Eastern Samar 10 NE(040) 10/04 0200-0300*
Surigao City, Surigao del Norte 10 NE(040) 10/03 1822
106

• WC SIGMET: 0



Fig. 4.12.2. Storm duration rainfall over land during the passage of Tropical Storm LANNIE within
107
during the passage of Tropical Storm LANNIE. The best track is also overlaid as a solid thick white
line.
108
Severe Tropical Storm MARING 07 to 14 October 2021

KOMPASU (2118)

55 kt (100 km/h)
975 hPa
Developed:
Degenerated:

4 days and 22 hours


Wind Signal No. 2
Fig. 4.13.1. Best track position and intensities of Severe Tropical Storm MARING.
109
Table 4.13.1. Key information about Severe Tropical Storm MARING.

Parameter Details

Over the Philippine Sea far east of Bicol Region
low In the vicinity of Phaxay District, Xiangkhouang, Laos
(lifetime)
Exited the PAR region 04 UTC, 12 October 2021

(within the PAR)
1130 UTC, 11 October 2021 (STS): Calayan, Cagayan (Camiguin
Is.)
1300 UTC, 11 October 2021 (STS): Aparri, Cagayan (Fuga Is.)
Elsewhere:
0740 UTC, 13 October 2021 (STS): Wanning City, Hainan, China
1030 UTC, 14 October 2021 (TD): Tĩnh Gia District, Thanh Hóa,
Vietnam

Rainfall
(mm)
Baguio City 674.4
Dagupan City, Pangasinan 249.7
Aparri, Cagayan 227.2
Calayan, Cagayan 218.2
110

Rainfall
(mm)
Baguio City 625.3 11 October 2021
Mt. Cabuyao, Tuba, Benguet 500.8 10 October 2021
Dagupan City, Pangasinan 241.3 11 October 2021
San Jose, Occidental Mindoro 140.8 09 October 2021
Aparri, Cagayan 138.4 11 October 2021

Laoag City, Ilocos Norte 979.6 10/11 1800
Aparri, Cagayan 981.4 10/11 1100
Sinait, Ilocos Sur 982.0 10/11 2000

Peak gust Peak gust
Basco, Batanes 34 NE(040) 10/11 0606
Calayan, Cagayan 28 SE(140) 10/11 1400
Itbayat, Batanes 25 NNE(020) 10/11 0403
Aparri, Cagayan 24 NW(320) 10/11 0034
Baler, Aurora 24 WNW(290) 10/11 0800
Dagupan City, Pangasinan 22 WNW(290) 10/11 0300-0400*

• WC SIGMET: 10



• Damage to infrastructure: PHP 4,066,475,133.35
111
Fig. 4.13.2. Storm duration rainfall over land during the passage of Severe Tropical Storm
MARING within the PAR based on GSMAP (left) and surface weather station reports (right). The
best track is also overlaid as a solid thick black line.
112
during the passage of Severe Tropical Storm MARING. The best track is also overlaid as a solid
thick white line.
113
Fig. 4.13.4. Himawari-8 RGB true color enhanced visible image of the large monsoonal circulation
that contained both MARING and NANDO. Binary interaction occurred between these two TCs,
with MARING eventually assimilating the circulation of NANDO.
114
Tropical Depression NANDO 07 to 09 October 2021

UNNAMED

Tropical Depression
30 kt (55 km/h)
996 hPa
Developed:
Degenerated:

1 day and 1 hour

Tropical Depression

None
Fig. 4.14.1. Best track position and intensities of Tropical Depression NANDO.
115
Table 4.14.1. Key information about Tropical Depression NANDO.

Parameter Details
low pressure area Over the sea near Northern Mariana Islands (US)

Over the Philippine Sea far west of Guam (US)
low Over the Philippine Sea far east of Bicol Region
(lifetime)
Entered the PAR region 11 UTC, 08 October 2021
Period of occurrence 1 day and 1 hour

(within the PAR)
None
Elsewhere:
None

Rainfall
(mm)
San Jose, Occidental Mindoro 140.8
Tacloban City, Leyte 83.0
Catbalogan City, Samar 72.5
Catarman, Northern Samar 62.1

Rainfall
(mm)
San Jose, Occidental Mindoro 140.8 09 October 2021
Virac, Catanduanes 93.8 09 October 2021
Tacloban City, Leyte 64.8 08 October 2021
Echague, Isabela 48.6 09 October 2021
Dipolog City, Zamboanga del Norte 41.4 09 October 2021
116

• WC SIGMET: 0



Fig. 4.14.2. Storm duration rainfall over land during the passage of Tropical Depression NANDO
is outside the domain of the figure.
117
Super Typhoon ODETTE 12 to 21 December

RAI (2122) 2021

Super Typhoon
105 kt (195 km/h)
915 hPa
Developed:
00 UTC, 12 December 2021
Degenerated:

3 days and 19 hours

Super Typhoon

Wind Signal No. 4
Fig. 4.15.1. Best track position and intensities of Super Typhoon ODETTE.
118
Table 4.15.1. Key information about Super Typhoon ODETTE.

Parameter Details
First tracked as a tropical 06 UTC, 03 December 2021
low pressure area Over the Philippine Sea north northeast of Palau
Developed into a TC 00 UTC, 12 December 2021

Over the sea south of Yap, Federated States of Micronesia
Weakened into a remnant 06 UTC, 21 December 2021
low Over the West Philippine Sea off the coast of Guangdong, China
(lifetime)
Entered the PAR region 10 UTC, 14 December 2021
Exited the PAR region 05 UTC, 18 December 2021

(within the PAR)
(lifetime) 00 UTC, 16 December 2021
(within the PAR region) 00 UTC, 16 December 2021
0530 UTC, 16 December 2021 (STY): Pilar, Surigao del Norte
0610 UTC, 16 December 2021 (STY): Del Carmen, Surigao del
Norte (Poneas Is.)
0630 UTC, 16 December 2021 (STY): Del Carmen, Surigao del
Norte (Kangbangyo Is.)
0710 UTC, 16 December 2021 (STY): Cagdianao, Dinagat
Islands
0850 UTC, 16 December 2021 (STY): San Ricardo, Southern
Leyte
0940 UTC, 16 December 2021 (STY): Padre Burgos, Southern
Leyte
1110 UTC, 16 December 2021 (STY): Pres. Carlos P. Garcia,
Bohol (Lapinig Is.)
1140 UTC, 16 December 2021 (STY): Ubay, Bohol
1400 UTC, 16 December 2021 (TY): Carcar City, Cebu
1530 UTC, 16 December 2021 (TY): Guihulngan City, Negros
Oriental
0830 UTC, 17 December 2021 (TY): Roxas, Palawan
Elsewhere:
None
119

Table 4.15.2. Highest storm duration (14 to 18 December 2021) rainfall over land.
Rainfall
(mm)
Dauis, Bohol 240.9
Malaybalay City, Bukidnon 218.4
Butuan City, Agusan del Norte 215.7
Note: Maasin City Synoptic Weather Station may have similar or higher storm duration rainfall but the station
rain gauge suffered from extensive damage during the passage of the STY.

Rainfall
(mm)
Surigao City, Surigao del Norte 267.6 16 December 2021
Dauis, Bohol 230.6 16 December 2021
Malaybalay City, Bukidnon 165.6 16 December 2021
Puerto Princesa City, Palawan 156.5 17 December 2021
Virac, Catanduanes 135.7 17 December 2021
Note: Maasin City Synoptic Weather Station may have similar or higher peak 24-hour rainfall but the station
rain gauge suffered from extensive damage during the passage of the STY.

Maasin City, Southern Leyte 944.2 12/16 1100
Mactan-Cebu International Airport, 974.3 12/16 1243
Lapu-Lapu City
Dauis, Bohol 986.9 12/16 1400
Puerto Princesa City, Palawan 989.2 12/17 1000

Peak gust Peak gust
Surigao City, Surigao del Norte 58 S(190) 12/16 0841
Maasin City, Southern Leyte 55 SE(130) 12/16 1113
Mactan-Cebu International 45 NE(040) 12/16 1241
Guiuan, Eastern Samar 38 NE(050) 12/16 0816
Dauis, Bohol 31 WNW(290) 12/16 1335
Note: Maasin City Synoptic Weather Station may have experienced stronger gusts after this peak value but
were not recorded as the wind instrument failed during the passage of the STY.

• WC SIGMET: 10
120


Number of reported casualties: 405 dead, 1,371 injured, and 52 missing

• Damage to infrastructure: PHP 29,338,185,355.94
Fig. 4.15.2. Storm duration rainfall over land during the passage of Super Typhoon ODETTE within
121
during the passage of Super Typhoon ODETTE. The best track is also overlaid as a solid thick
white line.
122
Fig. 4.15.4. Radar imagery (PPI 480-km range) of Super Typhoon ODETTE at 0300 UTC, 16
December 2021 while at peak intensity. Data from the PAGASA Hinatuan Weather Surveillance
Radar Station. A concentric eyewall signature is evident from the image.
123
Fig. 4.15.5. Radar imagery (PPI 440-km range) of Super Typhoon ODETTE at 0532 UTC, 16
December 2021 while making landfall over Pilar, Surigao del Norte. Data from the PAGASA
Guiuan Weather Surveillance Radar Station. A concentric eyewall signature is evident from the
image. Black dots were radar eye fix marks from the station personnel, although best track analysis
revealed that the fixes were shifted to the north of the actual path due to station personnel tracking
the centroid of the outer eyewall.
Fig. 4.15.6. Radar imagery (surveillance mode) of Super Typhoon ODETTE at 1100 UTC, 16
December 2021 as it neared Bohol. Data from the PAGASA Mactan Weather Surveillance Radar
Station. Deterioration in the northwest and southeast sectors of the eyewall is noted.
124
VERIFICATION OF OPERATIONAL TROPICAL
CYCLONE FORECASTS FOR 2021
134
Verification of Operational Tropical

Cyclones Forecasts for 2021
This section reports the result of the verification of operational track forecasts for the 15 tropical
cyclones (TCs) that occurred within the Philippine Area of Responsibility (PAR). These operational
track forecasts (up to five days ahead) were verified against the TC best track data from the
Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA). Track
forecasts with initial times at 00, 03, 06, 09, 12, 15, 18, and 21 UTC were evaluated, provided that
the corresponding initial intensity is at least 34 kt (i.e., at least tropical storm (TS) category). The
non-inclusion of forecasts with initial intensity of less than 34 kt is based on the operational practice
of the Regional Specialized Meteorological Center (RSMC) – Tokyo Typhoon Center. As such,
2021 TCs that did not reach TS category on the best track or those TCs whose initial intensities in
all operational track forecasts were TD despite reaching TS category at some point in the best
track were excluded from the verification. Based on these, no position errors were provided for
EMONG, GORIO, LANNIE, and NANDO.
Metrics of Track Forecast Verification
To measure the performance of operational track forecasts, the direct positional error (DPE),
along-track error (ATE), and cross-track error of the valid 24-, 48-h, 72-h, 96-, and 120-hour
forecast positions were calculated using the verification subsystem of the PAGASA Integrated
System for Typhoon Operations (PISTON) 1 . Heming (2016) defines DPE as the great circle
distance between the observed position and forecast position at the same forecast validity time.
The metric serves as a basic indication of the track forecast performance but does not provide
information on the speed or directional bias of a forecast. Such information is provided by the
specific forecast bias indicators called ATE and CTE.
To provide a visualized explanation of the ATE and CTE and their relationship with DPE, the
metrics are diagrammatically presented in Fig. 5.1. The DPE can be represented as the
hypotenuse of a right triangle whose sides comprise the component of the position error along the
track (or the ATE) and the component across the track (or the CTE). ATE, the measure of forecast
speed bias, is the component of the DPE along the direction2 of the observed TC track. On the
other hand, CTE, the measure of forecast directional bias, is the component of the DPE in the
direction perpendicular to the aforementioned direction of the observed track.
Unlike the DPE, which is a non-negative number, ATE and CTE can be both positive and negative
in value, with the sign being indicative of the nature of the bias of the track forecast. A positive ATE
would indicate that the official track forecast has a fast bias while a negative ATE would indicate a
slow bias in the forecast. Similarly, CTE is deemed positive if the forecast position lies to the right
of the “extrapolated” observed track looking in the observed direction of motion of the TC in the
northern hemisphere. This means that for a non-recurving TC moving east to west, a positive CTE
would indicate a poleward bias in the track forecast of the TC.
1
PISTON is a web-based graphical man-and-machine interactive application tool that integrates various subjective and
objective guidance tools and provide other important information to facilitate typhoon forecast operations. This system aims
to improve the efficiency of typhoon operations and reduce, but not eliminate, the forecasters’ reliance on paper-based
charts for forecast and warning preparation and issuance.
2
The direction of the observed track at a particular ATE or CTE calculation is represented by the extrapolation of the line
formed by connecting the observed position of the TC at forecast validity time and the observed position 6 hours before.
The extrapolated line is also referred to in this document as the “extrapolated” observed track for the purpose of CTE
calculation.
135
Fig. 5.1. Diagrammatic explanation of the metrics of operational track forecast performance. Figure
adapted from Heming (2016).
Summary of 2021 Forecast Position Errors
For the 219 track forecasts issued by PAGASA during 2021 season, the mean DPEs were 77.8,
137.4, 197.7, 260.6, and 317.6 km for the 24-, 48-, 72-, 96-, and 12-hour forecast positions. The
annual mean errors in the forecast of TC center position at the 12- to 120-hour forecast times since
2014 are shown in Fig. 5.2. It can be seen that the operational TC track forecasts of PAGASA have
steadily improved within the last decade, although year-on-year fluctuations are also observed
partly due to differences in the characteristics of TCs occurring within the PAR each year, the
overall synoptic environment, and influences of seasonal to interannual climate variability. In
particular, it can be seen that DPEs for this season were higher at all forecast times than in 2020.
Nevertheless, the mean DPE for the first 72 hours of PAGASA track forecasts during the 2021
season were the 2nd or 3rd lowest since 2014 (and potentially in the history of PAGASA), while
forecast positions beyond 72 hours were the 3rd lowest since 2018. The improvements seen in the
operational track forecasts are partially attributed to the increased usage of multi-model consensus
approach using the guidance information from a combination of global deterministic, regional
deterministic, and global ensemble numerical weather prediction (NWP) models.
The details for position errors for each TC that occurred within the PAR region during the 2020
season are presented in Table 5.1. Track forecasts for AURING, CRISING, DANTE, HUANING,
and JOLINA were characterized by large position errors. Except for AURING, whose forecasts had
a fast and lefthand/equatorward bias, these TCs had a considerable slow and righthand/poleward
bias in their track forecasts. The case of TS DANTE was really notable as PAGASA was
consistently forecasting an early recurvature based on NWP model guidance at that time, but the
TC maintained a generally northwestward track across the archipelago and did not recurve until it
was already over the waters west of Ilocos Region (Fig. 5.3). On the other hand, TCs that peaked
at typhoon (TY) and super typhoon (STY) categories showed considerably small position errors
across different forecast times, with STY BISING and STY ODETTE having position errors less
than 100 km within the first 72 hours of the track forecasts, less than 200 km at 96-hour, and less
than 300 km at 120-hour forecast.
Fig. 5.4 shows the histogram of position errors of operational 24-, 48-, 72-, 96-, and 120-hour
forecasts from PAGASA for the 2020 season. About 76.3% of 24-hour, 80.2% of 48-hour, 80.5%
of 72-hour, 85.9% of 96-hour, and 78.9% of 120-hour forecasts had position errors of up to 100
km, 200 km, 300 km, 400 km, and 500 km, respectively.
For the speed and directional biases of the operational track forecast of the 2021 season, the
scatter diagram of position errors of operational 24-, 48-, 72-, 96-, and 120-hour forecasts in the
along- (ATE) and cross-track directions (CTE) are provided in Fig. 5.5. The mean directional bias
across all forecast times and mean speed bias at 24-, 48-, and 72-hour were found to be small
(e.g., less than 50 km). However, at all forecast times, a generally slow bias in the track forecasts
was observed.
136
Fig. 5.2. Annual mean DPE of operational 24-, 48-, 72-, 96-, and 120-hour forecast positions from
2014 to 2021. Best track data was used to verify forecasts since 2018, while preliminary or warning
tracks were used for the years prior.
Fig. 5.3. Track forecasts issued by PAGASA for TS DANTE (thin blue lines with multicolored
markers) compared with its best track positions (thick, light blue line with red markers).
Table 5.2 shows the hit rate of operational 24-, 48-, 72-, 96-, and 120-hour forecast positions for
each TC and for the entire 2021 season. Hit rate is defined as the ratio of the number of forecast
confidence circles within which the verifying TC center position fell to the total number of circles.
For the 2021 season, the radii of the forecast confidence circles were 97 km, 161 km, 245 km, 293
km, and 434 km for the 24-, 48-, 72-, 96-, and 120-hour forecast positions, respectively. On
average, the hit rate of forecast confidence circles during the 2021 season was 75.9% for the 24-
hour forecast. The corresponding hit rates for the 48-, 72-, 96-, and 120-hour forecasts were
71.3%, 74.0%, 66.7%, and 71.8%.
137
Table 5.1. Mean errors of operational 24-, 48-, 72-, 96-, and 120-hour forecasts for each of the TC
that occurred within the PAR region. N represents the number of forecast positions that were
verified against the PAGASA best track data.
24-hour 48-hour 72-hour 96-hour 120-hour
Forecast Forecast Forecast Forecast Forecast
TC Name
Mean N Mean N Mean N Mean N Mean N
(km) (km) (km) (km) (km)
AURING 160.1 10 315.0 9 365.3 5 462.3 1 - -
BISING 42.3 36 81.3 32 121.1 28 139.0 24 191.6 20
CRISING 139.6 1 - - - - - - - -
DANTE 126.6 24 284.6 16 402.9 10 488.9 7 724.8 3
EMONG - - - - - - - - - -
FABIAN 51.9 25 106.8 25 182.8 25 253.9 25 304.4 22
GORIO - - - - - - - - - -
HUANING 123.6 2 - - - - - - -
ISANG 75.6 8 113.2 5 243.0 2 - - - -
JOLINA 121.9 22 238.5 14 345.5 11 447.3 8 490.2 3
KIKO 68.6 27 124.7 20 218.8 15 338.4 13 522.0 9
LANNIE - - - - - - - - - -
MARING 83.6 20 106.8 12 133.6 9 239.9 6 273.5 3
NANDO - - - - - - - - - -
ODETTE 40.7 28 51.2 24 96.1 18 187.6 15 259.5 11
Mean 77.8 203 137.4 157 197.7 123 260.6 99 317.6 71
(N: total)
Table 5.2. Hit rates of operational 24-, 48-, 72-, 96-, and 120-hour forecast confidence circles for
each of the TC that occurred within the PAR region. N represents the number of forecast
confidence circles within which the verifying TC center position fell.
24-hour 48-hour 72-hour 96-hour 120-hour
Forecast Forecast Forecast Forecast Forecast
TC Name
Ratio Ratio Ratio Ratio Ratio
N N N N N
(%) (%) (%) (%) (%)
AURING 30.0 3 0.0 0 0.0 0 0.0 0 - -
BISING 100.0 36 93.8 30 96.4 27 100.0 24 100.0 20
CRISING 0.0 0 - - - - - - - -
DANTE 41.7 10 25.0 4 30.0 3 42.9 3 0.0 0
EMONG - - - - - - - - - -
FABIAN 96.0 24 96.0 24 88.0 22 56.0 14 63.6 14
GORIO - - - - - - - - - -
HUANING 50.0 1 - - - - - - - -
ISANG 87.5 7 100.0 5 50.0 1 - - - -
JOLINA 50.0 11 14.3 2 18.2 2 25.0 2 33.3 1
KIKO 77.8 21 70.0 14 66.7 10 46.2 6 33.3 3
LANNIE - - - - - - - - - -
MARING 70.0 14 75.0 9 88.9 8 66.7 4 66.7 2
NANDO - - - - - - - - - -
ODETTE 96.4 27 100.0 24 100.0 18 86.7 13 100.0 11
Mean 75.9 154 71.3 112 74.0 91 66.7 66 71.8 51
(N: total)
Radii of forecast
confidence circle
97 km 161 km 245 km 293 km 454 km
138
Current Limits of Verification
Since the 2021 edition, the Annual Report on Philippine Tropical Cyclones (ARTC) has been
featuring best track-based track forecast verification statistics. However, users are advised to take
note of the following limitations in relation to the presented forecast position error statistics:
1. The DPE, ATE, and CTE values from 2014 to 2017 are considered preliminary because
of the absence of best track positions to serve as verifying dataset.
2. Although the provision of five-day TC track forecasts commenced in 2015, Fig. 5.1 only
included the verification scores for the 96- and 120-hour forecasts starting in 2018 due to
the lack of an extended track data (either best track or warning track) from PAGASA for
the years 2015 to 2017 which can be used to evaluate the performance at these forecast
times (i.e., forecast positions at 96- and 120-hour usually lie outside the PAR region and
observed track data up to the 2017 season are only limited to the PAR region).
3. The provision of official forecast verification statistics ended in 1991 with the publication of
the final annual tropical cyclone report of PAGASA. At the time of writing, efforts were
underway to retrieve official track forecasts for the 1992 to 2013 seasons that were not yet
digitized in order to facilitate its recalculation. Verification statistics using warning track as
verifying dataset will be made available for these years in the succeeding editions of the
ARTC once these data becomes available. In the absence of verification scores from 1992
to 2013, Fig. 5.2. did not incorporate the verification scores from 1991 and earlier seasons.
4. Other operational centers provide an operational forecast skill score and mean
improvement ratios by comparing the official track forecast performance against a
generally accepted benchmark, usually a climatological model. For track forecasts, the
CLIPER model (Aberson 1998; Neumann 1972; Merrill 1980) serves as the benchmark
prediction to assess operation skill. At this time, PAGASA track forecasts are not yet
evaluated against these benchmarks, but such comparison is planned for the upcoming
ARTCs once the model becomes available for operational use.
5. While PAGASA has commenced the provision of quantitative intensity forecasts in 2021,
verification result of the intensity forecasts will be provided beginning in the 2022 edition
of the ARTC. However, an updated issue of the ARTC 2021 may also be released at a
later date to incorporated intensity forecast verification for the 2021 season.
References
Aberson, S. D., 1998: Five-Day Tropical Cyclone Track Forecasts in the North Atlantic Basin.
Wea. Forecasting, 13, 1005-1015, https://doi.org/10.1175/1520-
0434(1998)013<1005:FDTCTF>2.0.CO;2
Heming, J. T., 2016: Tropical cyclone tracking and verification techniques for Met Office
numerical weather prediction models .Met. Applications, 24, 1-8,
https://doi.org/10.1002/met.1599
Neumann, C. J., 1972: An Alternate to the HURRAN (Hurricane Analog) Tropical Cyclone
Forecast System. NOAA Tech. Memo. NWS SR-62, 24 pp,
https://repository.library.noaa.gov/view/noaa/3605
Merrill, R. T., 1980: A Statistical Tropical Cyclone Motion Forecasting System for the Gulf of
Mexico. NOAA Tech. Memo. NWS NHC-14, 21 pp,
https://repository.library.noaa.gov/view/noaa/7028
139
(a)
(b) (c)
(d) (e)
Fig. 5.4. Histogram of position errors of operational (a) 24-, (b) 48-, (c) 72-, (d) 96-, and (e) 120-
hour forecasts from PAGASA for the 2021 season.
140
(a)
(b) (c)
(d) (e)
Fig. 5.5. Histogram of position errors of operational (a) 24-, (b) 48-, (c) 72-, (d) 96-, and (e) 120-
hour forecasts from PAGASA for the 2021 season. The red triangle denotes the mean ATE and
CTE for each forecast time.
141
142
PAGASA BEST TRACK DATA FOR
2021 TROPICAL CYCLONES
144
PAGASA Best Track Data

for 2021 Tropical Cyclones
The following information are the details of the Philippine Atmospheric, Geophysical and
Astronomical Services Administration (PAGASA) best track data for each tropical cyclone (TC) of
the 2021 season. Provided in a tabular format, each entry consists of the following information
• Date and time of analysis (DTG; Format: MM/DD HH) in Coordinated Universal Time
(UTC);
• Latitude (CLAT) and longitude (CLON) coordinates of the center position rounded off to
the nearest 0.1°N and 0.1°E respectively;
• Maximum sustained winds (MXWD) at 10-minute averaging in knots (kt) and rounded off
to the nearest 5 kt; and,
• Sea level pressure at the estimated center position (PRES) in hectopascal (hPa) and
rounded off to the nearest even integer for estimates of 990 hPa and higher or to the
nearest 5 hPa for estimates below 990 hPa.
If the disturbance is classified as a low pressure area or post-tropical low/cyclone at a particular

synoptic time, the indicator L or XT is written on the MXWD field, respectively.
The best track position and intensity information is always provided at standard synoptic times
(00, 06, 12, and 18 UTC). In the case of a landfalling TC or a TC that passed within 30 nmi of the
Philippine coastline, best track entries are provided at intermediate synoptic times as well (03,
09, 15, and 21 UTC) beginning at the point when the TC is 24 hours from landfall or its closest
approach1. The best track data reverts to using standard synoptic times once the TC is more
than 30 nmi from the Philippine coastline. The best track information covers the time the TC was
first classified as a tropical depression to either its weakening into a low pressure area or
transitioning into a post-tropical low/cyclone.
The best track positions and intensities in this report supersede the warning track 2 and the
provisional track3 that were issued by the Weather Division, PAGASA.
1
This reference event is used for non-landfalling TCs that passed within 30 nmi of the Philippine coast line.
2
Dataset containing the positions and intensities of a TC at standard (and if possible, intermediate) synoptic times that
were issued in real time during the warning period.
3
An initial version of the best track of a TC based on the revision of the operational track following a near-real time
reanalysis of positions and intensities.
145
Table 6.1. Best track positions and intensities of Table 6.2. Best track positions and intensities of
Tropical Storm AURING (DUJUAN) Super Typhoon BISING (SURIGAE)
DTG CLAT CLON MXWD PRES DTG CLAT CLON MXWD PRES
02/16 18 6.8 135.1 25 1004 04/12 12 6.5 140.3 25 1006
02/17 00 6.6 134.3 25 1004 04/12 18 7.0 139.7 25 1006
02/17 06 6.5 133.7 30 1002 04/13 00 7.4 139.2 25 1006
02/17 12 6.5 133.2 30 1000 04/13 06 7.7 138.8 30 1004
02/17 18 6.7 132.8 30 1000 04/13 12 8.0 138.3 30 1004
02/18 00 7.0 132.5 35 998 04/13 18 8.2 137.9 35 1000
02/18 06 7.3 132.1 35 998 04/14/ 00 8.4 137.6 40 998
02/18 12 7.2 131.9 40 996 04/14 06 8.7 137.3 40 998
02/18 18 7.1 131.6 40 996 04/14 12 8.8 137.0 45 994
02/19 00 7.0 131.2 45 994 04/14 18 8.8 136.8 45 994
02/19 06 6.8 130.4 45 994 04/15 00 8.7 136.6 50 990
02/19 12 6.3 130.5 40 996 04/15 06 8.6 136.1 55 985
02/19 18 6.1 131.0 40 996 04/15 12 8.6 135.8 60 980
02/20 00 6.4 131.3 40 996 04/15 18 8.7 135.3 65 975
02/20 06 6.9 131.1 35 998 04/16 00 8.9 134.6 70 970
02/20 12 7.4 130.4 30 1000 04/16 06 9.2 133.8 75 965
02/20 18 7.8 129.7 30 1000 04/16 12 9.5 133.1 80 960
02/20 21 8.0 129.4 30 1000 04/16 18 10.0 132.1 95 945
02/21 00 8.3 129.1 30 1000 04/17 00 10.7 131.1 100 935
02/21 03 8.6 128.8 30 1000 04/17 06 11.4 130.1 105 920
02/21 06 9.0 128.4 30 1000 04/17 12 12.0 129.2 115 900
02/21 09 9.6 127.6 30 1002 04/17 18 12.6 128.4 120 895
02/21 12 10.1 127.0 25 1004 04/18 00 13.1 127.7 110 905
02/21 15 10.8 126.4 25 1004 04/18 06 13.4 127.1 105 920
02/21 18 11.5 125.9 25 1006 04/18 12 13.6 126.8 100 930
02/21 21 11.9 125.5 25 1006 04/18 18 13.9 126.5 100 930
02/22 00 12.2 125.1 L 1008 04/19 00 14.2 126.4 100 930
04/19 06 14.5 126.3 100 930
04/19 12 14.8 126.3 95 935
04/19 18 15.1 126.2 95 935
04/20 00 15.5 126.1 95 935
04/20 06 15.9 126.0 95 935
04/20 12 16.4 125.9 95 935
04/20 18 17.0 125.5 95 935
04/21 00 17.5 125.2 95 935
04/21 06 18.1 124.9 95 935
04/21 12 18.8 124.8 90 945
04/21 18 19.3 124.8 85 955
04/22 00 19.7 124.9 85 950
04/22 06 20.3 125.4 85 955
04/22 12 20.9 126.1 80 960
04/22 18 21.6 127.0 75 965
04/23 00 22.3 128.0 70 970
04/23 06 23.1 129.0 65 975
04/23 12 23.4 129.9 60 980
04/23 18 23.3 130.5 55 985
04/24 00 23.0 131.2 50 990
04/24 06 22.7 131.8 45 992
04/24 12 22.2 132.8 40 994
04/24 18 21.7 134.1 40 994
04/25 00 21.8 136.0 XT 996
146
Tropical Storm CRISING Tropical Storm DANTE (CHOI-WAN)
05/12 00 6.5 131.4 25 1006 05/29 12 5.9 135.6 25 1004
05/12 06 6.6 131.0 25 1006 05/29 18 6.1 134.3 25 1004
05/12 12 6.8 130.4 25 1006 05/30 00 6.3 133.5 30 1002
05/12 18 7.0 129.8 30 1004 05/30 06 6.6 132.7 30 1000
05/12 21 7.1 129.5 30 1004 05/30 12 6.9 131.9 30 1000
05/13 00 7.2 129.1 35 1002 05/30 18 7.3 131.4 35 998
05/13 03 7.3 128.6 35 1002 05/31 00 8.0 130.8 35 998
05/13 06 7.4 128.0 35 1002 05/31 06 9.0 129.8 40 996
05/13 09 7.5 127.2 35 1002 05/31 12 9.5 129.1 40 996
05/13 12 7.5 126.7 30 1004 05/31 18 9.8 128.3 40 996
05/13 15 7.5 126.4 30 1004 05/31 21 9.9 127.8 40 996
05/13 18 7.5 126.1 25 1006 06/01 00 10.0 127.3 40 996
05/13 21 7.5 125.7 25 1006 06/01 03 10.5 127.0 40 996
05/14 00 7.5 125.0 L 1008 06/01 06 11.1 126.7 40 996
06/01 09 11.5 126.2 40 996
06/01 12 11.7 125.6 40 996
06/01 15 11.7 124.6 35 998
06/01 18 11.8 123.6 35 998
06/01 21 12.1 122.8 35 998
06/02 00 12.6 122.3 35 998
06/02 03 13.0 121.9 35 998
06/02 06 13.3 121.5 35 998
06/02 09 13.5 121.1 35 998
06/02 12 13.8 120.7 35 998
06/02 15 14.3 120.3 35 998
06/02 18 14.9 120.0 35 998
06/02 21 15.9 119.5 35 998
06/03 00 16.7 118.9 40 996
06/03 06 17.5 118.1 40 996
06/03 12 18.5 118.3 40 996
06/03 18 19.5 118.4 40 996
06/04 00 20.2 118.7 40 996
06/04 06 20.9 119.5 35 998
06/04 12 22.0 121.3 30 1000
06/04 18 23.1 122.5 30 1000
06/05 00 24.8 123.8 35 998
06/05 06 26.7 125.9 XT 1000
Table 6.5. Best track positions and intensities of

Tropical Depression EMONG
DTG CLAT CLON MXWD PRES
07/03 18 12.7 132.4 25 1004
07/04 00 13.5 131.3 25 1004
07/04 06 14.4 130.1 30 1002
07/04 12 15.6 128.6 30 1002
07/04 18 16.9 127.1 30 1002
07/04 21 17.7 126.1 30 1002
07/05 00 18.4 125.2 30 1002
07/05 03 18.8 124.6 30 1002
07/05 06 19.5 123.5 30 1002
07/05 09 20.1 122.3 30 1002
07/05 12 20.6 121.7 30 1002
07/05 15 21.2 121.4 30 1002
07/05 18 21.7 120.9 30 1002
07/06 00 22.3 120.0 25 1004
07/06 06 23.6 118.4 L 1004
147
Typhoon FABIAN (IN-FA) Severe Tropical Storm GORIO (MIRINAE)
07/15 18 17.4 135.0 25 1006 08/03 18 24.5 125.8 25 998
07/16 00 17.6 134.8 25 1006 08/04 00 24.8 126.1 25 998
07/16 06 18.0 134.6 25 1004 08/04 06 25.1 126.4 25 998
07/16 12 18.8 134.4 25 1004 08/04 12 25.6 126.9 25 998
07/16 18 19.7 134.1 25 1004 08/04 18 26.0 127.2 30 996
07/17 00 20.5 133.6 30 1002 08/05 00 26.3 127.4 30 996
07/17 06 21.1 133.2 30 1000 08/05 06 26.8 128.1 35 994
07/17 12 21.6 132.8 30 1000 08/05 12 26.9 128.9 40 992
07/17 18 22.1 132.6 35 998 08/05 18 26.9 130.1 40 992
07/18 00 22.5 132.5 35 998 08/06 00 27.0 131.8 40 990
07/18 06 22.8 132.4 40 996 08/06 06 27.3 133.3 40 990
07/18 12 23.2 132.3 40 996 08/06 12 27.7 134.8 45 985
07/18 18 23.5 132.2 45 990 08/06 18 28.4 136.4 45 985
07/19 00 23.9 131.9 50 985 08/07 00 29.5 137.6 45 985
07/19 06 24.0 131.7 50 985 08/07 06 30.9 138.5 45 985
07/19 12 24.0 131.5 55 980 08/07 12 31.9 138.9 45 985
07/19 18 24.2 131.2 55 980 08/07 18 33.2 139.5 50 980
07/20 00 24.4 130.8 60 975 08/08 00 34.1 140.7 50 980
07/20 06 24.7 129.8 65 970 08/08 06 35.2 142.2 50 980
07/20 12 24.5 129.0 70 965 08/08 12 36.1 143.6 50 980
07/20 18 24.1 128.2 75 960 08/08 18 36.8 145.1 45 985
07/21 00 24.1 127.9 80 955 08/09 00 37.7 147.5 45 985
07/21 06 24.2 127.2 80 955 08/09 06 38.3 149.7 45 985
07/21 12 24.0 126.6 80 955 08/09 12 38.6 152.2 40 990
07/21 18 23.7 126.2 80 955 08/09 18 38.6 154.5 40 992
07/22 00 23.5 126.0 80 955 08/10 00 38.7 158.3 XT 992
07/22 06 23.5 125.9 80 955
07/22 12 23.6 125.8 80 955 Table 6.8. Best track positions and intensities of
07/22 18 23.8 125.5 80 955 Tropical Storm HUANING (LUPIT)
07/23 00 24.2 125.4 80 955 DTG CLAT CLON MXWD PRES
07/23 06 24.6 125.1 80 955 08/02 12 20.9 111.8 25 996
07/23 12 24.8 125.0 75 960 08/02 18 21.0 112.7 25 996
07/23 18 25.5 124.9 75 960 08/03 00 21.3 113.4 30 994
07/24 00 26.4 124.7 75 960 08/03 06 21.5 113.7 30 994
07/24 06 27.2 124.3 75 960 08/03 12 21.2 114.1 30 994
07/24 12 28.1 124.0 75 960 08/03 18 21.0 114.8 30 994
07/24 18 28.7 123.7 75 960 08/04 00 21.2 115.5 35 992
07/25 00 29.7 123.0 65 970 08/04 06 21.5 115.8 35 992
07/25 06 30.0 122.5 65 970 08/04 12 21.7 116.4 40 990
07/25 12 30.2 122.0 60 975 08/04 18 22.5 116.8 45 985
07/25 18 30.4 121.6 55 980 08/05 00 23.1 116.9 45 985
07/26 00 30.6 121.2 50 985 08/05 06 23.5 117.1 40 990
07/26 06 30.8 120.9 50 985 08/05 12 23.9 117.3 40 990
07/26 12 31.0 120.5 45 985 08/05 18 24.2 117.7 35 992
07/26 18 31.2 120.0 40 985 08/06 00 24.4 118.2 35 992
07/27 00 31.3 119.5 40 985 08/06 06 24.7 118.9 35 992
07/27 06 31.4 119.0 35 985 08/06 12 25.0 119.3 35 992
07/27 12 31.5 118.9 35 985 08/06 18 25.1 119.8 35 992
07/27 18 32.2 118.2 30 990 08/07 00 24.8 120.7 35 992
07/28 00 32.7 117.6 30 990 08/07 06 25.6 122.8 35 992
07/28 06 33.1 117.0 30 990 08/07 12 27.2 124.5 35 992
07/28 12 33.3 116.9 30 990 08/07 18 28.3 125.8 40 990
07/28 18 33.9 116.8 30 990 08/08 00 29.3 126.6 40 990
07/29 00 34.9 116.7 30 990 08/08 06 30.1 127.7 40 990
07/29 06 35.8 117.1 25 992 08/08 12 31.5 130.6 40 990
07/29 12 37.1 117.4 25 992 08/08 18 33.7 132.3 45 985
07/29 18 38.5 117.6 L 992 08/09 00 35.3 133.4 XT 980
148
Severe Tropical Storm ISANG (OMAIS) Typhoon JOLINA (CONSON)
08/10 12 12.3 178.8 25 1008 09/05 06 10.8 130.4 25 1006
08/10 18 12.4 178.1 30 1006 09/05 12 10.4 129.6 30 1004
08/11 00 12.4 177.3 30 1006 09/05 15 10.1 129.0 30 1004
08/11 06 12.3 176.6 30 1006 09/05 18 10.0 128.6 35 1000
08/11 12 12.2 175.9 30 1006 09/05 21 10.1 128.2 40 998
08/11 18 12.3 175.2 30 1006 09/06 00 10.3 127.7 45 996
08/12 00 12.5 174.5 30 1006 09/06 03 10.5 127.2 50 994
08/12 06 12.6 173.6 30 1004 09/06 06 10.8 126.8 55 992
08/12 12 12.7 172.3 30 1004 09/06 09 11.0 126.4 60 990
08/12 18 12.7 170.8 30 1004 09/06 12 11.2 125.9 65 985
08/13 00 12.7 169.5 30 1004 09/06 15 11.4 125.4 60 990
08/13 06 12.6 168.0 30 1004 09/06 18 11.6 124.9 60 990
08/13 12 12.6 166.3 30 1006 09/06 21 11.8 124.6 55 992
08/13 18 12.5 164.9 25 1008 09/07 00 12.0 124.3 55 992
08/14 00 12.4 163.7 25 1008 09/07 03 12.2 123.8 55 992
08/14 06 12.3 162.2 25 1008 09/07 06 12.4 123.5 50 994
08/14 12 12.3 160.5 25 1010 09/07 09 12.7 123.1 50 994
08/14 18 12.3 158.8 25 1010 09/07 12 12.9 122.8 55 992
08/15 00 12.6 157.0 25 1010 09/07 15 13.1 122.4 55 992
08/15 06 12.9 155.7 25 1010 09/07 18 13.3 122.0 60 990
08/15 12 13.1 154.4 L 1012 09/07 21 13.5 121.7 65 985
08/15 18 13.7 153.1 L 1012 09/08 00 13.7 121.4 55 992
08/16 00 13.8 151.6 L 1012 09/08 03 13.9 121.1 50 994
08/16 06 13.6 149.8 L 1010 09/08 06 14.1 120.8 50 994
08/16 12 13.3 148.2 L 1010 09/08 09 14.4 120.5 45 996
08/16 18 13.2 146.6 L 1008 09/08 12 14.8 120.1 40 998
08/17 00 13.2 145.2 L 1010 09/08 15 15.4 119.4 40 998
08/17 06 13.3 143.5 L 1008 09/08 18 15.6 119.1 40 998
08/17 12 13.5 141.9 L 1010 09/09 00 15.7 118.3 40 998
08/17 18 13.7 140.6 L 1008 09/09 06 15.8 116.8 40 998
08/18 00 14.2 139.1 L 1010 09/09 12 15.8 115.0 45 994
08/18 06 14.6 138.4 L 1008 09/09 18 15.9 113.9 50 990
08/18 12 15.0 137.8 25 1008 09/10 00 15.7 112.8 50 990
08/18 18 15.6 137.0 25 1006 09/10 06 15.7 112.1 50 990
08/19 00 16.7 135.4 25 1008 09/10 12 15.6 111.4 50 990
08/19 06 17.5 134.0 25 1006 09/10 18 15.6 110.8 50 990
08/19 12 17.9 133.1 25 1006 09/11 00 15.6 110.1 45 992
08/19 18 18.4 131.9 30 1004 09/11 06 15.5 109.6 45 992
08/20 00 18.7 131.0 30 1006 09/11 12 15.3 109.3 40 994
08/20 06 18.9 130.1 30 1004 09/11 18 15.2 109.2 35 996
08/20 12 19.3 129.6 35 1002 09/12 00 15.2 109.2 30 998
08/20 18 20.1 129.2 40 1000 09/12 06 15.3 109.1 30 998
08/21 00 21.3 128.4 45 998 09/12 12 15.3 109.1 25 1000
08/21 06 22.1 127.7 50 996 09/12 18 15.5 109.0 25 1000
08/21 12 22.9 127.0 55 992 09/13 00 15.8 108.8 L 1002
08/21 18 23.5 126.5 55 992
08/22 00 24.3 125.9 50 994
08/22 06 25.1 125.3 45 994
08/22 12 25.9 125.0 40 996
08/22 18 27.2 124.8 40 996
08/23 00 29.0 125.3 40 996
08/23 06 31.3 125.7 35 998
08/23 12 33.6 127.0 35 998
08/23 18 36.1 129.5 35 998
08/24 00 37.5 131.4 XT 998
149
Super Typhoon KIKO (CHANTHU) Tropical Storm LANNIE (LIONROCK)
09/05 18 13.4 138.9 25 1006 10/03 12 8.7 127.2 25 1004
09/06 00 13.5 138.6 25 1004 10/03 15 9.1 126.7 25 1004
09/06 06 13.9 138.4 30 1002 10/03 18 9.5 126.2 25 1002
09/06 12 14.6 137.9 35 1000 10/03 21 9.9 125.5 25 1002
09/06 18 15.2 137.4 45 996 10/04 00 10.1 125.0 25 1004
09/07 00 15.6 136.6 50 992 10/04 03 10.0 124.4 25 1004
09/07 06 16.1 135.6 65 980 10/04 06 9.8 123.6 25 1002
09/07 12 16.3 134.6 75 970 10/04 09 9.7 122.6 25 1002
09/07 18 16.3 133.5 80 960 10/04 12 10.0 121.7 25 1004
09/08 00 16.0 132.4 90 945 10/04 15 10.4 121.1 25 1004
09/08 06 15.7 131.3 95 940 10/04 18 10.8 120.6 25 1002
09/08 12 15.5 130.3 95 940 10/04 21 11.2 120.0 25 1002
09/08 18 15.4 129.1 100 935 10/05 00 11.8 119.1 25 1002
09/09 00 15.5 128.0 105 930 10/05 03 12.1 118.6 25 1002
09/09 06 15.8 127.1 105 930 10/05 06 12.4 118.1 25 1002
09/09 12 16.1 126.0 100 940 10/05 12 13.0 116.9 25 1002
09/09 15 16.3 125.4 100 940 10/05 18 13.9 115.3 25 1002
09/09 18 16.6 125.0 100 935 10/06 00 14.4 114.3 25 1000
09/09 21 16.9 124.5 105 930 10/06 06 15.0 113.3 25 1000
09/10 00 17.1 124.1 105 930 10/06 12 15.7 112.3 30 998
09/10 03 17.5 123.7 110 920 10/06 18 16.0 112.0 30 998
09/10 06 17.8 123.5 115 910 10/07 00 16.4 111.7 30 998
09/10 09 18.3 123.2 115 910 10/07 06 16.9 111.4 30 996
09/10 12 18.7 122.8 115 910 10/07 12 17.2 111.3 30 996
09/10 15 19.1 122.5 115 910 10/07 18 17.4 111.1 35 994
09/10 18 19.5 122.3 115 910 10/08 00 17.9 110.9 35 992
09/10 21 19.9 122.1 115 915 10/08 06 18.5 110.9 35 992
09/11 00 20.3 122.0 110 920 10/08 12 19.1 110.6 35 992
09/11 03 20.7 121.7 110 925 10/08 18 19.3 110.0 35 992
09/11 06 21.0 121.6 105 930 10/09 00 19.6 110.2 35 994
09/11 09 21.3 121.8 105 930 10/09 06 19.8 110.3 35 994
09/11 12 21.8 121.9 100 935 10/09 12 20.0 109.8 35 994
09/11 15 22.2 121.9 100 935 10/09 18 20.4 109.0 35 996
09/11 18 22.8 122.0 95 940 10/10 00 20.7 108.0 35 996
09/12 00 23.8 122.3 90 945 10/10 06 20.6 106.9 30 1000
09/12 06 25.2 122.3 90 945 10/10 12 20.4 106.2 25 1002
09/12 12 26.2 122.7 85 950 10/10 18 20.3 105.6 L 1004
09/12 18 27.6 123.1 85 955
09/13 00 29.1 123.5 80 960
09/13 06 30.7 123.3 75 965
09/13 12 30.9 123.2 70 970
09/13 18 31.4 123.5 65 975
09/14 00 31.3 123.8 60 980
09/14 06 30.9 124.3 55 985
09/14 12 30.5 124.7 50 990
09/14 18 30.2 125.2 45 992
09/15 00 30.3 125.7 45 992
09/15 06 30.4 125.9 45 992
09/15 12 30.2 125.7 45 992
09/15 18 30.2 125.4 50 990
09/16 00 30.4 125.0 50 990
09/16 06 31.1 125.3 50 990
09/16 12 31.7 125.8 50 990
09/16 18 32.3 126.4 50 990
09/17 00 32.9 127.5 50 990
09/17 06 33.5 129.2 50 990
09/17 12 33.8 131.6 45 992
09/17 18 34.0 134.1 40 994
09/18 00 34.5 136.7 30 1000
09/18 06 34.4 137.6 XT 1000
150
Table 6.13. Best track positions and intensities of

Severe Tropical Storm MARING (KOMPASU) Table 6.14. Best track positions and intensities of
DTG CLAT CLON MXWD PRES Tropical Depression NANDO
10/07 12 13.5 129.9 25 1002 10/07 12 14.2 138.7 25 1004
10/07 18 12.9 130.2 25 1000 10/07 18 15.2 137.9 25 1004
10/08 00 12.5 130.2 30 996 10/08 00 16.1 136.8 30 1002
10/08 06 12.3 130.1 35 994 10/08 06 16.7 135.8 30 1002
10/08 12 12.2 129.9 35 994 10/08 12 17.1 134.8 30 1002
10/08 18 11.9 129.8 40 992 10/08 18 16.9 133.1 30 1000
10/09 00 11.7 130.3 40 992 10/09 00 16.3 131.5 30 0998
10/09 06 12.6 131.1 40 992 10/09 06 15.7 130.2 30 0996
10/09 12 14.3 130.4 45 990 10/09 12 14.9 129.1 L 0996
10/09 18 15.6 130.1 45 990
10/10 00 17.1 128.8 45 990 Table 6.15. Best track positions and intensities of
10/10 06 17.6 128.0 45 990 Super Typhoon ODETTE (RAI)
10/10 15 18.5 126.0 45 985 12/12 00 4.8 145.0 25 1002
10/10 18 18.7 125.3 45 985 12/12 06 4.9 144.0 25 1002
10/10 21 18.7 124.9 45 985 12/12 12 5.0 143.2 25 1002
10/11 00 18.7 124.4 50 980 12/12 18 5.1 142.6 25 1002
10/11 03 18.7 123.7 50 980 12/13 00 5.3 142.0 30 1000
10/11 06 18.7 123.0 50 980 12/13 06 5.7 140.9 35 0998
10/11 09 18.8 122.3 50 980 12/13 12 6.3 139.7 40 0996
10/11 12 18.9 121.7 55 975 12/13 18 6.8 138.6 45 0992
10/11 15 18.9 121.0 55 975 12/14 00 7.4 137.1 50 0990
10/11 18 18.9 120.3 55 975 12/14 06 7.8 135.6 50 0990
10/11 21 18.9 119.7 55 975 12/14 12 8.2 134.7 55 0985
10/12 00 18.9 119.1 55 975 12/14 18 8.7 133.4 60 0980
10/12 06 18.8 117.3 55 975 12/15 00 8.9 132.3 65 0975
10/12 12 18.8 116.2 55 975 12/15 06 9.1 131.0 70 0970
10/12 18 19.1 114.6 55 975 12/15 09 9.1 130.7 75 0965
10/13 00 19.1 112.8 55 975 12/15 12 9.1 130.2 75 0965
10/13 06 19.1 111.0 55 975 12/15 15 9.2 129.6 80 0960
10/13 12 18.9 109.3 45 985 12/15 18 9.4 129.0 85 0955
10/13 18 18.7 108.5 40 992 12/15 21 9.5 128.3 95 0935
10/14 00 18.9 107.5 35 996 12/16 00 9.7 127.6 105 0915
10/14 06 19.6 106.7 30 1000 12/16 03 9.8 126.8 105 0915
10/14 12 19.4 105.5 25 1004 12/16 06 9.9 126.0 105 0915
10/14 18 19.3 103.1 L 1006 12/16 09 10.0 125.2 100 0925
12/16 12 10.1 124.3 95 0935
12/16 15 10.1 123.4 90 0945
12/16 18 10.1 122.5 85 0950
12/16 21 10.1 121.9 80 0955
12/17 00 10.1 121.2 80 0955
12/17 03 10.2 120.5 80 0955
12/17 06 10.3 119.9 80 0955
12/17 09 10.3 119.2 80 0955
12/17 12 10.4 118.6 80 0955
12/17 15 10.6 118.0 80 0955
12/17 18 10.8 117.4 80 0955
12/18 00 11.0 116.0 85 0945
12/18 06 11.2 114.7 95 0935
12/18 12 11.8 113.4 100 0925
12/18 18 12.6 112.2 105 0915
12/19 00 13.1 111.4 100 0920
12/19 06 13.9 110.8 90 0940
12/19 12 14.8 110.6 80 0960
12/19 18 15.9 110.6 70 0970
12/20 00 17.2 110.8 60 0980
12/20 06 18.1 111.3 50 0990
12/20 12 19.0 112.1 40 1000
12/20 18 19.8 112.8 35 1004
12/21 00 20.6 113.8 30 1006
12/21 06 21.5 115.2 L 1008
151
152

Pagasa Artc 2021

Uploaded by

Copyright:

Available Formats

Pagasa Artc 2021

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Pagasa Artc 2021

Uploaded by

Copyright:

Available Formats

ANNUAL REPORT ON PHILIPPINE

TROPICAL CYCLONES 2021

An official publication of the

Quezon City, Philippines

Marine Meteorological Services Section, Weather Division

ISSN 2672-3190 (Print)

For more information on publications of DOST-PAGASA

PRINTED IN THE REPUBLIC OF THE PHILIPPINES

(This page is intentionally left blank)

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA)

National Tropical Cyclone Forecasting and Warning Program 1

Post-Season Best Track Analysis of Philippine Tropical Cyclones 21

Philippine Tropical Cyclone Season of 2021: An Overview 29

Review of the Philippine Tropical Cyclones of 2021 51

Verification of Operational Tropical Cyclone Forecasts for 2021 133

PAGASA Best Track Data for 2021 Tropical Cyclones 143

Robb P. Gile Author; meteorological data processing and

Ella Marie M. Soriano Satellite data collection and reanalysis;

John Carlo S. Sugui Data visualization and GIS

(This page is intentionally left blank)

National Tropical Cyclone

Philippine Area of Responsibility

Extended Forecast Areas

High Seas and Offshore Waters Forecast Zones

Manila Flight Information Region

Fig. 1.3. Manila Flight Information Region.

Classification of Tropical Cyclones

Table 1.1 Categories of TC used by PAGASA.

Naming of Tropical Cyclones

Domestic Naming Scheme

Retiring Domestic Names

Domestic names for the 2021 season

Analysis and Forecast Process

Tropical Cyclone Analysis

Tropical Cyclone Forecast

Tropical Cyclone Product Description

Tropical Cyclone Advisory

Analysis Center position

12- 24-, 36- 48-, 72-, Center position

Tropical Cyclone Bulletins

Analysis Center position

12- 24-, 36- 48-, 72-, Center position

Tropical Cyclone Warning for Shipping

Analysis Center position

12- 24-, 36- 48-, 72-, Center position

WC SIGMET for Civil Aviation

Analysis Center position

Tropical Cyclone Updates in other Forecast Products

Tropical Cyclone Wind Signal System

Table 1.3. PAGASA TCWS system during the 2021 season

Table 1.4. (Continuation)

TCWS • Widespread damage to high-risk • Total damage to banana plantation.

For Public Tropical Cyclone Products

For Marine Tropical Cyclone Products

For Aeronautical Tropical Cyclone Products

Expert Advice and Briefings

Wimmers, A. J., and C. S. Velden, 2016: Advancements in Objective Multisatellite Tropical

Yamaguchi, M., H. Owada, U. Shimada, M. Sawada, T. Iriguchi, K. D. Musgrave, and M.

(This page is intentionally left blank)