Where has the tornado threat been greatest in the US?
By John Roach, AccuWeather staff writer
April 22, 2019, 8:18:27 AM EDT
The 2019 tornado season so far continues a recent shift in terms of which states had the greatest threat of a tornado. And it has not been the states that make up Tornado Alley where that shift has taken place.
An AccuWeather analysis of tornado data over the last five years shows tornadoes have been more common in Dixie Alley states than they have been traditionally over the last 30 years, based on states' annual number of tornadoes per 10,000 square miles and using data from the National Oceanic and Atmospheric Administration’s (NOAA) Storm Prediction Center.
Mississippi received 15.7 tornadoes per 10,000 square miles from 2014 to 2018, according to the AccuWeather analysis of states averaging at least 20 tornadoes a year. Alabama was second with 11.8 and Louisiana was third with 11.7. The list of the top 10 states is shown below.
"Traditionally people consider Kansas, Nebraska and Oklahoma as being the most active for tornadoes," said AccuWeather founder and CEO Dr. Joel N. Myers. "But the total number of tornadoes for a state can be misleading in terms of risk for a person because of the different sizes of the states. By using this more scientific approach, we can examine the risk to a person in Kansas compared to someone in Alabama or Texas.
"We believe this is a better way to look at the tornado data to see what the real threat to an individual is," Myers said.
An average of 3.5 tornadoes occur per 10,000 square miles in the U.S. each year, according to NOAA. That means Mississippi had more than four times the national average, while Alabama and Louisiana experienced more than three times the average, as did Kansas, Illinois and Iowa.
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"What we don’t want to lose sight of is that over the last 20 or 30 years, tornado research has been looking at the South more intently than it ever has before," said AccuWeather Senior Meteorologist Dan Kottlowski. "More people now live in the Deep South – Mississippi, Alabama, Georgia and those places – than ever before. So more people are exposed to those tornadoes."
So far in 2019, Dixie Alley states have continued to be the ones with the greatest tornado threat. "The Deep South states are also prone to nocturnal tornadoes," explained AccuWeather Expert Senior Meteorologist Tyler Dewvall, "which only increases the danger for those states."
Alabama has received the most tornadoes in 2019 with 62, according to preliminary severe weather reports from NOAA. Georgia is second with 43, followed by Mississippi with 36, Texas with 26 and Louisiana with 12. The data is preliminary and subject to revision.
Previously, several other states were shown to have the greatest tornado threat based on the results from a 20-year tornado study by NOAA from 1991-2010 showing the average annual number of tornadoes per 10,000 square miles.
Florida was first with 12.2, followed by Kansas with 11.7, Maryland with 9.9, Illinois with 9.7 and Mississippi with 9.2, according to the study; the top 10 from the study is farther below.
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Here are the states with the highest average annual number of tornadoes per 10,000 square miles from 2014 to 2018, according to an AccuWeather analysis of NOAA numbers for states averaging at least 20 tornadoes a year.
Here are the states with the highest average annual number of tornadoes per 10,000 square miles from 1991 to 2010, according to NOAA.
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