In 2011 there were more than 1,200 confirmed tornadoes in the United States and more than 500 casualties, making it one of the most devastating on record. With recorded instances of tornadoes in the U.S. doubling in the past 50 years, it is more important than ever to understand the trends in tornado activity and, if possible, predict future patterns of such extreme weather events.
A 2006 study in Weather and Forcasting, the journal of the American Meteorological Society, “Evolution of the U.S. Tornado Database: 1954-2003,” traced the recorded history of tornadoes between 1954 and 2003 in order to map historical patterns and build future probability models.
Results of the study conclude that:
- Increases in reported tornado activity (from 600 per year in the 1950s to 1,200 per year in the 2000s) were at least partially due to increased public awareness, improved Doppler radar capability and National Weather Service vigilance.
- Despite the increase in the number of reported tornadoes, the numbers of F1 (and greater) tornadoes has remained constant at around 500 reports per year.
- “Big tornado days” are more likely to occur slightly earlier in the year and have a shorter likely time frame than the overall tornado season.
Beyond the usefulness of this forecasting tool for those in tornado-prone regions, the study could have applications in enforcing of building codes and in setting appropriate insurance premiums based on historical and predictive models.
Keywords: disasters, safety, weather