(Updated 29 August 2003.  Comments to Harold Brooks)


What is the total annual threat of severe thunderstorms in the United States?

Total Threat

The mean number of days per year with one or more events within 25 miles of a point is shown here. The fill interval for tornadoes is 0.2, with the purple starting at 0.2 days. For the nontornadic threats, the fill interval is 1, with the purple starting at 1. For the significant (violent), it's 5 days per century (millenium)

All Severe Weather

Period

Any Tornado

Thunderstorm winds (50 kts or greater or damaging)

Hail (3/4 inch diam. or greater or damaging) 
1980-1999
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1980-1984
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1985-1989
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1990-1994
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1995-1999 gif gif gif

"High-End" Severe Weather

Period

Significant Tornado (F2 or greater) 

Violent Tornado (F4 or greater)

Thunderstorm winds (65 kts or greater) 

Hail (2 inch diam. or greater)
1921-1995
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1980-1994
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