Tornadoes are exciting to watch on TV.  They were even the subject of a Hollywood movie, but anyone who lives in the midwest will tell you, these things are nothing to mess with.  Tornadoes are ranked from F0 to F5 by meteorologists.  F0's are very weak, about 40 to 50 mph, and can cause light damage to trees and billboards.  F3s are about 170mph and they can rip off roofs and walls from well constructed houses.  An F4 can toss a truck several feet away.  But amazing as this is: these aren't the worst ones.  Every now and then a very devestating F5 appears, like the one recently in Moore, Oklahoma.  F5s are known as "The Finger of God" and there have only been 51 of these in recorded history.  In this Nova special, we meet scientists in the front ranks of the battle to understand these extreme weather events. We also meet storm survivors whose lives have been upended, and learn how we can protect ourselves and our communities for the uncertain future.

Thursday, June 27 at 7:00pm