The term Tornado Alley was coined in 1952 by U.S. Air Force meteorologists Captain Robert C. Miller and Major Ernest J. Fawbush in a 1952 paper studying severe weather patterns in midwestern states. Tornado Alley traditionally refers to the corridor-shaped region in the Midwestern United States where tornadoes typically occur.
While it is not an official designation, the states most commonly included are Texas, Oklahoma, Kansas, Nebraska, Indiana, Ohio, Missouri, Iowa, and South Dakota. However, experts say that the data indicates Tornado Alley is shifting east as more activity is occurring in the belt between Louisiana and Illinois. While not geographically part of tornado alley, Florida has one of the highest incidents of tornadoes per square mile. Tornadoes have appeared in every state, though they occur most frequently in the southern part of the country.
According to the National Oceanic and Atmospheric Administration, which tracks data on weather patterns in the United States, approximately 1,000 tornadoes are reported annually.
Tornadoes are measured on the Enhanced Fujita Scale, which classifies tornadoes with ratings from EF-0 to EF-5, according to their estimated wind speeds and damage assessments following an event.
An EF-0 is characterized by wind gusts estimated between 105 and 137 kilometers per hour (65 and 85 miles per hour) and minor environmental damage, including broken tree branches and damaged chimneys.
An EF-1 has wind gusts between 138 and 177 kilometers per hour (86 and 110 miles per hour) and causes minor environmental damage. Smaller structures may be flipped, roof tiles and windows may be damaged, and tree trunks may snap.
An EF-2 is characterized by gusts between 178 and 217 kilometers per hour (111 and 135 miles per hour). The environmental damage is considerable and may include destroyed mobile homes, damaged roofs, flying debris, and uprooted trees.
At an EF-3, wind gusts between 218 and 266 kilometers per hour (136 and 165 miles per hour) occur. Severe damage is observed, such as walls ripped from buildings and several uprooted trees.
An EF-4 is characterized by wind gusts estimated between 267 and 322 kilometers per hour (166 and 200 miles per hour). Devastating environmental damage is also present, including destroyed homes and cars that have been blown away.
An EF-5 is characterized by winds at or above 322 kilometers per hour (over 200 miles per hour). At this level, a tornado can lift homes off their foundations, strip bark from trees, and throw debris the size of a car through the air.
The average tornado only stays on the ground for 5 minutes, and approximately 77% rate between EF-0 and EF-1, with about 95% below EF-3. Only .01% of tornadoes reach the highest category of EF-5. Even so, tornadoes can cause many fatalities and significant property damage at any level.
In 2021, there were 1,377 tornadoes that accounted for 101 deaths. The states in Tornado Alley tend to see the most severe of these storms and incur the most fatalities.
The nation's deadliest tornado struck the heart of Tornado Alley, hitting Missouri, Illinois, and Indiana. The 1925 tri-state tornado outbreak hit Missouri, Illinois, and Indiana, leaving an estimated 1.5 billion dollars in damage and 695 fatalities. More recently, the 2011 super outbreak in Joplin, Missouri claimed 158 lives and caused $2.8 billion in damages.
The following states, most of which make up Tornado Alley, see the most tornado activity in an average year:
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