Tornadoes

Tornadoes

Cool, Maritime polar air from the Rocky Mountains, added to the Warm, maritime Tropical air pumped onto the continent from the Gulf of Mexico due to the lack of mountain barriers is the perfect set-up for severe weather and tornadoes. Where these two air masses meet, an area of the US called Tornado Alley forms. Tornado alley stretches from the far southern tip of South Dakota, to the southern part of Texas. It also stretches from the eastern edge of Colorado, eastward to as far as central-Illinois. The most prevalent time of the year for tornadoes is the springtime, from March to November, however, Tornadoes can happen at about any time during the year. In the southern states, Tornadoes are most likely to occur from March to May, where as the More Northern States in Tornado alley face Tornadoes particularly from April to June.

The average tornado travels at around 72 miles per hour, follows a path of about 41.6 miles long, and has a diameter of between 143ft and 960ft. Most tornadoes move toward the northeast, within the zone of southwest winds, and form ahead of a cold front, which is associated with the narrow, vertically developed clouds tornadoes form in. There are on average 770 tornadoes in the US per year, with most of them happening in the spring and summer.

from Spring 2001 Class webpage: http://www.gened.arizona.edu/gloclim/Continents/namerica/Tornado.html

Source: http://www.aoml.noaa.gov
	Hurricane Andrew Sequence Hurricane Floyd