Last year, the National Oceanic and Atmospheric Administration (NOAA) identified 1,341 tornadoes in the US. Of these, 31% occurred in three states: Mississippi, Alabama, and Texas.
These three states, which all border the Gulf Coast, are part of “Dixie Alley,” a tornado-prone area in the Southeastern US.
Which states have the most and least tornadoes?
Over the past five years, Mississippi has had the most tornadoes, averaging 115 per year. Texas has an annual average of 96, while Alabama averages 90. On average, states experience around 24 tornadoes every year.
Alaska and Hawaii are the only states without a tornado in the past five years.
Are tornadoes still concentrated in Tornado Alley?
Tornado Alley is a region covering the Great Plains known for its tornado activity. While its exact boundaries are debated, it generally encompasses parts of Kansas, Nebraska, Iowa, Oklahoma, and northern Texas. Supercell thunderstorms, which can cause violent tornadoes, are much more common in the Great Plains.
Tornadoes are formed when warm, humid air near the ground meets cooler dry air in the sky in an unstable updraft. In the Tornado and Dixie Alleys, warm air from the Gulf of Mexico tends to meet cooler air coming from Canada, creating peak tornado conditions.
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Over the past decade, researchers have identified a decrease in tornados throughout Tornado Alley and an increase in Dixie Alley, which includes parts of eastern Texas, Louisiana, Alabama, and Mississippi. They are still investigating whether the trend is related to human-caused climate change or natural variability.
Within these states, tornadoes concentrate in smaller areas, potentially due to topographic features such as mountains or rivers. A county-level map helps highlight some of the more tornado-prone regions in the country.
Counties don’t provide perfect comparisons due to size differences. Washington County, Colorado and Mobile County, Alabama had the highest number of tornadoes across the past five years, at 27 and 24 respectively. However, Washington County encompasses 2,513 square miles, more than double the land area of Mobile County (1,230 square miles). Still, it highlights some of the patterns of tornadoes throughout the country.
When do tornadoes happen?
Tornado season is primarily April – June, but varying weather patterns mean different parts of the country experience increases at different times of the year. Dixie Alley experiences a later tornado season than the Midwest, with many tornadoes occurring in late fall (October and November). In recent years, tornadoes in winter months have also been deadly. In 2022, tornadoes claimed 25 lives, including 7 in November and December.