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Government Documents: Frequently Asked Weather Questions

information and resource guides from Government Documents Department

Where can I find information on tornadoes that have occured in Tulsa County?

Using the National Weather Service Southern Region Headquarters web site, you can view information on tornadoes have occured in Tulsa County between the years 1875 - 2010.

What is the average number of tornadoes that strike Oklahoma each year?

Between the years 1953 - 2004, an average of 57 struck Oklahoma each year.

What is the difference between the warning siren for flood and tornado in Tulsa?

The Tulsa Area Management Agency's emergency operations center controls 75 sirens to warn people about tornadoes, flash flood and attacks during war. All are three minutes long. A tornado warning is a steady, high pitched tone; flash flood is an alternating high-low signal; the attack is an unbroken, wavering signal.

What measurement is used to indicate the severity of a tornado?

The Fujita, or F-Scale, was developed in 1971 by T. Theodore Fujita of the University of Chicago. The original scale was updated in 2007. The updated scale, known as the Enhanced F-Scale, is set of wind-speed estimates - not measurements - based on damage surveys. Its estimates at the point of damage are based on a judgement of eight levels of damage indicators.

The Enhanced F-Scale:

  • EF Number 0, 65-85 mph
  • EF Number 1, 86-110 mph
  • EF Number 2, 111-135 mph
  • EF Number 3, 136-165 mph
  • EF Number 4, 166-200 mph
  • EF Number 5, Over 200 mph

The original F-Scale:

  • F-0 (Gale tornado) 40-72 mph
  • F-1 (Moderate tornado) 73-112 mph
  • F-2 (Significant tornado) 113-157
  • F-3 (Severe tornado) 158-206 mph
  • F-4 (Devastating tornado) 207-260 mph
  • F-5 (Incredible tornado) 261-318 mph
  • F-6 (Inconceivable tornado) 319 - 379 mph