It's a tornado! It's a cyclone! No, it's a...supertwister! This "Nova" documentary explores the cutting-edge technology involved in tracking especially violent storms, and profiles the people who put their lives on the line to follow and examine these destructive events in the hopes that valuable data gathered will help save lives in the future. 60 min. Widescreen; Soundtracks: English Dolby Digital stereo, DVS.