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News Report on Multiple Tornado Alleys  
by Tornado Tim
Continuing research helps shed light on the idea of multiple tornado alleys in the US rather than one general area. Reading the research paper  "EVIDENCE OF SMALLER TORNADO ALLEYS ACROSS THE UNITED STATES BASED ON A LONG TRACK F3 TO F5 TORNADO CLIMATOLOGY STUDY FROM 1880 TO 2003" by  Chris Broyles and Casey Crosbie of the Storm Prediction Center in Norman, Oklahoma; data has been analyzed to show a historical representation of several smaller apparent tornado alleys across the United States as determined by a long track F3 to F5 tornadoes.

A map of the United States from 1880 to 2003 was constructed showing normalized frequencies of F3 to F5 tornadoes with path lengths of at least 25 miles.  This research gives a well needed upgrade to how we look at tornado prone areas in the US and I believe helps give a more accurate representation of areas not always known as tornado alley. I continue to believe most tornado alley maps do not represent the most dangerous areas in the US correctly, and have been vague in defining them to the public which may become a serious safety issue in the future.  I continue to believe we need to go to maps showing multiple tornado alleys in the US and not ignore overwhelming evidence that many of the most violent tornado areas in the US have been left off tornado alley maps for too long. While it may be true that tornado frequency may be highest in a small area in the US on a yearly basis, dangerous and violent tornadoes happen over many tornado alley sections within the US that may have prolonged droughts of tornadoes before being annihilated by large, long lived tornadoes again and again. These small tornado alleys are seen when looking at the US by a county to county assessment. Below are the most dangerous counties in the US for F3 to F5 tornadoes with path lengths longer than 25 miles. Most of these dangerous counties are not listed on most tornado alley maps. Maps based on this county by county look are far more accurate than today's maps.
(To find the number of long path F3 to F5 tornadoes affecting a county from 1880 to 2003, multiply the frequency by the square miles and divide by 1,000).
Below are the top nine areas.

Frequency County State Square Miles
19.28 Union MS 415
18.68 Simpson MS 589
17.30 Chester TN 289
15.63 Fillmore NE 576
15.46 Morgan AL 582
14.79 Jasper MS 676
13.91 Thayer NE 575
13.07 Bartow GA 459
12.62 Jackson AR 634

     Notice the two counties listed above from Nebraska.  These two counties border each other in southeast Nebraska.  Fillmore and Thayer Counties, had the highest frequencies in the Great Plains with 15.63 and 13.91 long path F3 to F5 tornadoes per 1,000 square miles, respectively. Nine long path F3 to F5 tornadoes affected Fillmore County and eight affected Thayer County during the 124 year period. In the great plains Nebraska comes above any listing for Kansas, Texas or Oklahoma which none of those 3 made the top 9 list.

      In 2004 Lancaster county in Southeast Nebraska had a long lived tornado that had a peak width of around 2 1/2 miles wide destroying the city of Hallam Nebraska proving the area to be one of the most dangerous in the US. The tornado event started 2 miles north of Daykin Nebraska, which is less than 5 miles from both Fillmore and Thayer Counties. In summary. f-scale rating was a maximim of f4 with a   maximum path length of 52 miles.

Also according to this research paper it says that the: "area with very high frequency of long path F3 to F5 tornadoes includes northern Mississippi, northern Alabama and western Tennessee. This vicinity includes the largest continuous area with six or greater long track F3 to F5 tornadoes per 1,000 square miles in the United States which is across northern Alabama extending to the northwest into western Tennessee. Union County in northeast Mississippi had the highest frequency in the United States with 19.28 long track F3 to F5 tornadoes per 1,000 square miles. The relatively small county had eight long track F3 to F5 tornadoes during the 124 year period."

Under their summary of this informative research paper they state the following information:
"The four most prominent tornado alleys that were identified in the United States include south-central Mississippi, east-central to northeast Oklahoma, southeast Nebraska and the area from western Tennessee to northeast Mississippi and northern Alabama. Other prominent alleys include northeast Kansas to central Iowa, northeast Arkansas, northwest Georgia, central Illinois to northwest Ohio, northwest Louisiana, northeast Nebraska, southeast Missouri to southwest Ohio and east to southeast North Carolina."

Most people would not be surprised to find that Oklahoma has one of the most dangerous cities in the US using this data, but look at the list of other cities toping the list. Below is the top 9 Cities for Long Track F3 to F5 Tornadoes in the United States from 1880 to 2003. The frequency of long track F3 to F5 tornadoes per 1,000 square miles is given for each city as a value.

Value City State
10.2 Tulsa OK
9.3 Shreveport LA
8.8 South Bend IN
7.6 Indianapolis IN
7.5 Huntsville AL
7.3 Topeka KS
6.9 Springfield IL
6.2 Jackson MS
6.0 Nashville TN

Thanks again to the following research paper as much of this information came from it.  Credit to: "EVIDENCE OF SMALLER TORNADO ALLEYS ACROSS THE UNITED STATES BASED ON A LONG TRACK F3 TO F5 TORNADO CLIMATOLOGY STUDY FROM 1880 TO 2003" by  Chris Broyles and Casey Crosbie of the Storm Prediction Center in Norman, Oklahoma.

NOTE:Many of the opinions in this article are the ideas and opinions of Tornado Tim.

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