The Park

The Storm

Pictures

Tornado Information

Tornado Safety

References

Home

Hazard Map of Historic Tornadoes in and Around Chippewa County.

-map courtesy of ESRI/FEMA online

Tornadoes are one of the most violent storms on the earth with wind speeds that can exceed 300 mph. The central United States is home to about 70% of all the tornadoes on the earth. Tornadoes are formed when warm (>75F), moist air from the Gulf of Mexico meets a mass of cold, dry air coming from the Rocky Mountains or down from Canada at speeds greater than 50 mph. The polar jet stream also meets these two air masses. The warm, moist gulf air rises and releases its latent heat, as it raises it gets spun in counterclockwise by the cold air mass and the polar jet stream. Tornadoes are formed at the trailing end of a super cell thunderstorm. A super cell is a tilted thunderstorm that has light rain on the leading edge followed by heavy rain, hail, and then tornadoes.

Supercell formation - noaa 2005

There are three main destructive properties of thunderstorms:

1) High wind speeds.

2) Powerful up-drafting winds with lifting capabilities.

3) Explosive events associated with pressure differences in buildings.

-McGraw Hills Text Natural Disasters 2002

The Fujita Scale is used to measure tornado strength and damage!

Fujita Wind Damage Scale

 - McGraw Hills text Natural disasters 2002

-graphic courtesy of e11-hour.org