Tornado Alleys: What exactly are they?
Tornadoes occur all over the United States, but there are areas where there is a substantially higher risk of tornadoes. These locations are called “tornado alleys.”Many believe that tornado alleys are simply the locations at which the most intense tornados occur; tornadoes that are typically classified as F4 or F5 on the Fujita scale (Baker). Tornados rated this high on the Fujita scale are the most destructive storms ever recorded. The most common tornado alley stretches from Texas to Minnesota (Bluestein 72). However, there is no commonly defined boundary for tornado alley because of the consistently changing weather conditions (7). For example, “Dixie Alley” was named to mark the area in the U.S. Southeast that experiences devastating tornadoes occurring in the spring during violent storms (Spotts).
These alleys are produced by, “warm moist air, strong wind shear, high values of buoyancy, and a mechanism for beginning the storm, which can include heating the ground, [and] lifting stable air so that buoyancy can be attained” (Bluestein 72). The warm moist air travels in from the southeast, gulf area and meets with the cold dry air from the northwest. This sometimes combines with the warm dry air from the southwest as well. The powerful Jet Stream provokes of the storms as the fronts collide due to its westerly winds that circle the globe miles above the earth (Deare). The reason why th motion e location of tornadoes in Tornado Alley varies within a single year is due to the fact that these fronts collide in different locations. The fronts will not always meet in the same place and then cause a storm in that one spot. Rather, they collide throughout different areas of the Midwest, leading to the variability of tornado location (Hyndman and Hyndman, 473). It should also be noted that tornadoes typically develop in areas that have a low-pressure center. These low-pressure areas change frequently based on temperature, water in the atmosphere, and other environmental conditions. As
these low-pressure areas change location due to the seasons, the starting points for tornadoes also change (476). The best season for tornadoes is the spring due
to the abundance of new warm moist air mixing with the cold air left over from
the winter.
A study by Harold E. Brooks of the National Severe Storms Laboratory in Norman included computer simulations using past information of tornados to predict the frequency of future tornadoes. They found that any specific spot in tornado alley can expect a twister approximately every 4,000 to 10,000 years (Perkins). In fact, according to tornado expert Thomas Grazulis, ”the frequency of actual destruction of any given house in the heart of tornado alley is only about once in 10,000 to 1,000,000 years”(9). This rare frequency is especially apparent in the state of Nevada where tornadoes occur every five million years or so. Only a tiny fraction of the storms produced each year actually include tornadoes (Perkins). Although it seems that there is a low frequency of tornadoes in tornado alley based on specific locations, tornadoalley as one entity experiences higher frequencies of tornadoes compared to other parts of the world.
Due to the fact that the specified tornado alleys are usually densely populated, tornadoes are spotted more often and cause more damage than they do in areas thatare not as populated, such as the Western United States and parts of the Great Plains. Therefore, there are no tornado alleys located in this area because if tornados do occurhere there is no damage and they are then not reported (Perkins).
Regardless of the name “tornado alley,” it is important to always remember the people who do live in tornado alley. Residents do not live in constant fear, but they do have to keep an eye on the sky during the peak of tornado season. Outdoor activities are regularly enjoyed at all times of the year, despite the high risk of tornadoes. Those individuals that reside in these areas have disaster plans prepared for the event of a tornado (“Living in Tornado Alley”). When a disaster does strike a community a multitude of aid and assistance is offered to them.
No matter where one considers tornado alley to be, there are multiple factors that create a “tornado alley.” This causes the frequency of a tornado to strike a specific location to be low, but the general, widespread area to be high. Tornado alleys cover most of the United States making tornado-watching part of everyday life for most Americans.
Page created by the "Tornado Alley Research Group" at Illinois State University, Geology 207 Honors Section: Brian Kulaga, Rachel Foster, Kim Caldwell and Kayley Pyne.
Click here to take a look at a very informational map presentation including multiple tornado alleys, information about each of them, and population densities for all.
References:
Baker, Tim. "Where is Tornado Alley." Research History. 16 April 2011: N.P. Web. 12 Oct. 2011.http://www.researchhistory.org/?p=2141
Bluestein, Howard B. Tornado Alley: Monster Storms of the Great Plains. New York: Oxford UP, 2008. Print.
Deare, M.J. "Tornado Alley Maps: Are Tornadoes More Frequent and More Severe Now?" Nature in the News. 23 May 2011: N.P. Web. Accessed 8 Oct. 2011.http://blackjackoak.wordpress.com/2011/05/23/tornado-alley-maps-are-tornadoes-more-frequent-and-more-severe-now/
Grazulis, Thomas. The Tornado: Nature's Ultimate Windstorm. Norman, Oklahoma: University of Oklahoma Press, 2011. Print.
"Living in Tornado Alley." NaturesWrath.ORG. WordPress, 24 Aug. 2011: N.P. Web. Accessed 10 Oct. 2011. http://natureswrath.org/2011/08/24/living-in-tornado-alley/?utm_source=rss
Perkins, Sid. "TORNADO ALLEY, USA. (cover story)." Science News 161.19 (2002): 296. MasterFILE Premier. EBSCO. Web. Accessed 7 Oct. 2011.
Spotts, Pete. "'Dixie Alley' as Dangerous as the Better-Known Tornado Alley, say Scientists." Christian Science Monitor. 27 Apr. 2011: N.P.EBSCO. Web. Accessed 7 Oct. 2011.
Tracton, Steve. "Tornado Alley: What's That???." Washington Post. 26
March 2010: N.P. Web.10 Nov. 2011. http://voices.washingtonpost.com/capitalweathergang/2010/04/tornado_alley_wh
eres_that.html
Bluestein, Howard B. Tornado Alley: Monster Storms of the Great Plains. New York: Oxford UP, 2008. Print.
Deare, M.J. "Tornado Alley Maps: Are Tornadoes More Frequent and More Severe Now?" Nature in the News. 23 May 2011: N.P. Web. Accessed 8 Oct. 2011.http://blackjackoak.wordpress.com/2011/05/23/tornado-alley-maps-are-tornadoes-more-frequent-and-more-severe-now/
Grazulis, Thomas. The Tornado: Nature's Ultimate Windstorm. Norman, Oklahoma: University of Oklahoma Press, 2011. Print.
"Living in Tornado Alley." NaturesWrath.ORG. WordPress, 24 Aug. 2011: N.P. Web. Accessed 10 Oct. 2011. http://natureswrath.org/2011/08/24/living-in-tornado-alley/?utm_source=rss
Perkins, Sid. "TORNADO ALLEY, USA. (cover story)." Science News 161.19 (2002): 296. MasterFILE Premier. EBSCO. Web. Accessed 7 Oct. 2011.
Spotts, Pete. "'Dixie Alley' as Dangerous as the Better-Known Tornado Alley, say Scientists." Christian Science Monitor. 27 Apr. 2011: N.P.EBSCO. Web. Accessed 7 Oct. 2011.
Tracton, Steve. "Tornado Alley: What's That???." Washington Post. 26
March 2010: N.P. Web.10 Nov. 2011. http://voices.washingtonpost.com/capitalweathergang/2010/04/tornado_alley_wh
eres_that.html