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Tornadoes Impact Our Lives

Tornadoes are produced by large (supercell) thunderstorms that often grow to over 40,000 feet. The map below shows the average number of tornadoes per year in the United States.

		Which two states have the highest number of tornadoes per year per 10,000 sq miles? Texas and Florida Oklahoma and Indiana Oklahoma and Texas Florida and Indiana
		Why do so many tornadoes form in this part of the South central plains of North America? Many important crops are grown here. The land is very flat. The area has unstable atmospheric conditions that can cause supercell thunderstorms. This region of the U.S. is known for dry, cool surface air temperatures.
		The Central Plains is conducive to the type of thunderstorms (supercells) that spawn tornadoes. It is in this region that cool, dry air in the upper levels of the atmosphere caps warm, humid surface air. This situation leads to a very unstable atmosphere and the development of severe thunderstorms.
		Look at the map at the right. The blue lines show the paths of tornadoes produced by storms on April 3rd & 4th, 1974. Why are the lines all parallel and pointing in a Southwest to North direction? The storms were moving from the Southwest to the Northeast. The storms follow major highways.