Season 39 Episode 10 | 52m 52s
In 2011, the worst tornado season in decades left a trail of destruction across the U.S., killing more than 550 people. Why was there such an extreme outbreak? How do such outbreaks form? With modern warning systems, why did so many die? Is our weather getting more extreme - and if so how bad will it get?
Expired: 12/15/15Video has closed captioning.