An outline of Significant Tornado Alley in the United States, where the highest percentage of violent tornadoes occurTornado activity in the United States.
States such as Minnesota, Wisconsin, Illinois, Indiana, and Ohio are sometimes included in Tornado Alley. Research suggests that tornadoes are happening more often in the northern parts of Tornado Alley where it reaches the Canadian prairies.
Tornado alley geographical area
A diagram of tornado alley based on 1 tornado or more per decade. Rough location (red), and its contributing weather systems
Over the years, the location(s) of Tornado Alley have not been clearly defined. No definition of tornado alley has ever been officially chosen by the National Weather Service (NWS). Thus, differences in the place are because of the different criteria used.
The National Severe Storms Laboratory (NSSL) FAQ says that "Tornado Alley" is a term used by the media as a reference to areas that have more tornadoes. A study of 1921–1995 tornadoes concluded almost one-fourth of all significant tornadoes happen in this area.
Another criterion for the location of Tornado Alley (or Tornado Alleys) can be where the strongest tornadoes happen more often.
Origin of the term
The term "tornado alley" was first used in 1952 by U.S. Air Force meteorologists Major Ernest J. Fawbush (1915–1982) and Captain Robert C. Miller (1920–1998). They used it as the title of a research project to study severe weather in parts of Texas and Oklahoma.
How many tornadoes
The average tornado stays on ground for only 5 minutes. These figures, reported by the National Climatic Data Center for the period between 1991 and 2010, show the seventeen U.S. states with the most average number of tornadoes per 10,000 square miles (25,899.9km2) per year.
Florida: 12.2
Kansas: 11.7
Maryland: 9.9
Illinois: 9.7
Mississippi: 9.2
Iowa: 9.1
Oklahoma: 9
South Carolina: 9
Alabama: 8.6
Louisiana: 8.5
Arkansas: 7.5
Nebraska: 7.4
Missouri: 6.5
North Carolina: 6.4
Tennessee: 6.2
Indiana: 6.1
Texas: 5.9
Canadian tornadoes
About half of all Canadian tornadoes hit the Canadian prairies and Northern Ontario as far east as Lake Superior. Together, these areas make up the northernmost border of the U.S. Tornado Alley. Tornadoes up to EF5 in strength have been found in this region.
Schools in Tornado Alley often have tornado drills, and many homes may have tornado shelters where people can go for safety.