Three tornadoes converge to wreak havoc on Chicago, disrupting the power grid and creating the worst super-storm in history: a category 6 twister.Three tornadoes converge to wreak havoc on Chicago, disrupting the power grid and creating the worst super-storm in history: a category 6 twister.Three tornadoes converge to wreak havoc on Chicago, disrupting the power grid and creating the worst super-storm in history: a category 6 twister.