08/11/99- Updated 05:23 PM ET


Source: National Oceanic and Atmospheric Administration

Where twisters strike most

Tornadoes have hit all 50 U.S. states. But this doesn't happen every year. The 30-year average number of tornadoes per year in Alaska, Rhode Island, and Vermont is closer to zero than to one. In Oklahoma and Texas, the average jumps to 52 and 126, respectively, though the high number in Texas is mainly due to the size of the Lone Star state.

To account for the different sizes of states, tornado averages for the USA are compared by looking at the annual number per 10,000 square miles, which is about the size of Vermont. For example, Oklahoma is about 70,000 square miles, or about seven Vermonts. If the entire state averages 52 tornadoes every year, then the number per year per 10,000 square miles is 52 divided by seven, which equals a little more than seven. The map above shows more detail than just a state breakdown, which is why only parts of Oklahoma and Texas are in black - more than six tornadoes per year per 10,000 square miles.

While no state is immune to a twister's violent winds, there are places where they touch down more often. The highest concentration of tornadoes is in Oklahoma and Texas, and in Florida. Frequent thunderstorms in western Florida contribute significantly to the number of twisters. Most Florida tornadoes, however, are "weak."
 

  • Fewer thunderstorms rumble across the Plains each year, but the storms form in an area where the chance for tornadoes is higher in the spring and early summer due to enhanced low-level wind shear. In fact, the geography of this part of the central USA favors the development of the largest and most dangerous tornadoes, earning it the name "tornado alley."
  •  
  • GREAT USA TODAY LINKS:

    • The University of Nebraska presents these reports as an educational institution to the university community.  No further reproduction of this report should occur without first receiving permission of USATODAY.com.
     
     
    UNL
    University of Nebraska-Lincoln
    High Plains Climate Center

     

      RETURN TO SALT LAKE CITY TORNADO WEB SITE