The Fujita (F) Scale was originally developed by Dr. Tetsuya Theodore Fujita to estimate tornado wind speeds based on damage left behind by a tornado. An Enhanced Fujita (EF) Scale, developed by a forum of nationally renowned meteorologists and wind engineers, makes improvements to the original F scale. This EF Scale has been approved by the National Weather Service (NWS) and will replace the original F scale, which has been used to assign tornado ratings since 1971.
The National Weather Services implemented an Enhanced Fujita (EF) scale in 2007 to rate tornadoes in a more consistent and accurate manner. The original F scale has limitations, such as a lack of damage indicators, no account for construction quality and variability, and no definitive correlation between damage and wind speed. These limitations may have led to some tornadoes being rated in an inconsistent manner and, in some cases, an overestimate of tornado wind speeds.
Enhanced Fujita Tornado Scale
EF Number
3 Second Gust (mph)
0
65-85
1
86-110
2
111-135
3
136-165
4
166-200
5
Over 200
Severe Weather 101 - Tornadoes
About 1,200 tornadoes hit the United States yearly.
