VORTEK LLC

OKLAHOMA REMAINS THE MOST TORNADO-PRONE STATE DURING MAY

April 29, 2008

As part of an ongoing company-funded research study of tornadic risk assessment, by means of the Site Assessment of Tornado Threat (SATT) software*, VorTek has determined the rankings of the top twenty tornado-prone states for the month of May. The rankings, based on National Weather Service data from 1950 through 2006, are as follows:
 

Rank

State

ACF (%)

Disturbed Land Area (Acres) 

1

Oklahoma

0.01717

7549

2

Kansas

0.01631

8539

3

Nebraska

0.01541

7555

4

Pennsylvania

0.01058

3047

5

Iowa

0.00909

3258

6

Arkansas

0.00602

2007

7

Illinois

0.00592

2107

8

Alabama

0.00590

1918

9

South Dakota

0.00452

2199

10

Ohio

0.00367

963

11

Kentucky

0.00365

  927

12

Texas

0.00338

5668

13

Wisconsin

0.00331

1152

14

Indiana

 0.00306

703

15

Missouri

0.00303

1336

16

Mississippi

 0.00276

  834

17

Georgia

0.00265

  985

18

Tennessee

0.00262

  691

19

North Carolina

0.00234

  731

20

South Carolina

0.00234

  452

 

The ACF "Annual Coverage Fraction" represents the average fraction of land area within the boundaries of the state disturbed by tornadoes during May for the 57-year period from 1950 through 2006. The "disturbed land area" represents the average number of acres of land within the boundaries of the state disturbed by tornadoes during May for the same 57-year period.