Tornado Alley is a section of the United States which is especially prone to frequent, severe tornadoes, especially when compared to the rest of the United States. Several states in this region are famous for their twisters; the states of Oklahoma and Kansas, for example, are very well-known for their vicious tornadoes. Especially during the time of year when tornadoes are most common, known colloquially as tornado season, Tornado Alley tends to be in the news a lot.
Although the term “Tornado Alley” is frequently thrown around, there is actually some dispute as to which region of the United States should be classified as Tornado Alley. Most maps focus on the Great Plains states between the Rocky Mountains and the Appalachians, with many specifically highlighting the states which are in the direct middle of the United States, while others may wander as far as Florida.
The dispute over the boundaries of Tornado Alley is rooted in arguments about how to define Tornado Alley. If one goes by frequency of tornadoes alone, the map will be much larger, as states like Florida have a lot of tornadoes every year, although they are relatively small. Strength alone will generate a much smaller map, which may create a definition which is too narrow; a region with five really big tornadoes every year might not experience as much damage as an area with 15 smaller tornadoes, for example. As a result, most maps try to incorporate strength, frequency, and records about the amount of damage caused by tornadoes every year.
States in Tornado Alley often have building codes which directly address the frequency of tornadoes, in an attempt to make structures safer. Visitors may notice a larger number of tornado shelters and cellars designed to protect people in the event of a tornado, and building designs are often focused on deflection of and resistance to tornadoes. In addition, insurance may be higher in Tornado Alley states, and schools may be encouraged to hold regular drills and tornado safety classes to ensure that children know what to do in a tornado.
In all the discussion of where Tornado Alley is, some scientists forget to explain why the area is so prone to tornadoes. The frequency of tornadoes in the region is directly linked to the flat landscape, which allows warm humid air from the South to flow up and meet cold dry fronts from the North. In the areas where these flows of air meet, the conditions are ripe for spawning tornadoes.