Tornadoes

Extreme Weather: Tornadoes Tornadoes A tornado is a violently rotating column of air that is capable of winds up to 300 mph. Tornadoes are classifed on the Fujita Scale, as shown below. Scientists think tornadoes are formed in a supercell thunderstorm. Only about 1% of all supercells go on to be tornadoes. Warm, dry air from Mexico and cool, moist air from Canada mix, and produce clouds, which start to rotate. This rotation is what produces a tornado and keeps the storm going. Winds shape a column of air that descends from the supercell, which touches the ground. A tornado has now been produced. Most tornadoes in the U.S. occur in the plains area between the Rockies and the Appalachians nicknamed "Tornado Alley". Unfortunately, though we think we know how tornadoes are produced, predicting them is very difficult. With the help of new weather technology, such as Doppler radar (shown below), meteorologists have managed to increase the lead time -- the amount of time between tonado prediction and occurrence -- to an average of 13 minutes.