Travel with the "stormchasers" as they view the awesome power of tornadoes sweeping across the land and seek to understand how they are created. Tornadoes, one of nature's most powerful and frightening weather phenomenon, occur in this country at the alarming rate of over 1,000 a year. At peak speeds of 70 miles per hour with interior winds of up to 300 miles per hour, they are massively destructive to society, with 10 percent of these storms causing over $300 million in property damage and at least 125 deaths each year.

In an effort to accurately forecast these violent storms, NOVA follows a "chase team" as scientists utilize the latest tracking techniques to move closer to their terrifying targets. In spectacular footage, NOVA examines the worst day in tornado history when 148 different twisters touched down across the South and the Ohio Valley- killing 315 people and causing $600 million in damage. Witness first-hand accounts of the 1984 tornado that hit Barneveld, Wisconsin without warning at vicious wind speeds up to 250 miles per hour.