The United States has the largest number of tornadoes of any country in the world. More than 1000 tornadoes are reported each year on average across the country. The public has the notion that tornadoes cause more fatalities than most other weather events. However, during the last 30 years, more people have drowned in floods (an average of 140 per year) and killed by lightning (an annual average of 81) than by tornadoes (a yearly average of 69 fatalities).
Tornado statistics have been compiled for more than a century. However, statistics from the entire country are only reliable since 1950, when the predecessor to the National Weather Service's Storm Prediction Center (SPC) at Norman, OK began research into tornadoes. This center routinely posts an updated SPC Monthly Tornado Statistics list of the total number of tornadoes and tornado fatalities for the last several years. Identifying the number of tornadoes is not an easy task. Preliminary statistics (PRELIM) are based upon numbers that have been obtained from the Local Storm Reports submitted by the National Weather Service Offices within hours after a tornado has been reported. A list of final statistics (FINAL) concerning the number of reported tornadoes is prepared following the checking and verification of more detailed information. The final numbers may vary considerably from the preliminary list. A killer tornado is, by definition, a tornado that has caused at least one fatality.
Inspection of the most recent list (valid through Monday, 26 November 2001) reveals that during the first eleven months of 2001, roughly 1018 tornadoes have been reported across the United States. As of late November, 37 people have lost their lives this year in 20 killer tornadoes. (Note that these statistics were posted before the tornado that took a life in western Tennessee late Monday night.) Even with one month remaining, the number of tornadoes in 2001 remains below the large numbers that were reported during the last several years. One possible explanation is that the circulation regime was not favorable for severe weather development. Many areas across the Southeast and Plains continued under drought conditions. However, according to the National Weather Service, Iowa and Minnesota experienced record numbers of tornadoes as of mid-November.
A record number of tornadoes (1424) were reported in 1998. In contrast, only 656 tornadoes were reported in 1987. After years of relatively few tornado-related deaths, 1998 also saw the largest number of fatalities (130) since 1974 when 366 people lost their lives during a year that had a memorable tornado outbreak on 3-4 April. A relatively large number of fatalities (95) also occurred during the following year (1999), with roughly half (48 fatalities) occurring as 6 killer tornadoes moved through central Oklahoma near Oklahoma City on the evening of 3 May 1999. Four of these tornadoes were rated F-4 on the Fujita Scale, and one was an incredible F5 tornado.
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Prepared by Edward J. Hopkins, Ph.D., email
hopkins@meteor.wisc.edu
© Copyright, 2001, The American Meteorological Society.