Synonyms

F-scale; Fujita Scale

Definition

Enhanced Fujita Tornado Scale: A system for classifying tornadoes intensity in the United States according to six categories from EF0 to EF5 based on the degree of damage to one or more of 28 damage indicators, such as various types of buildings, towers, and trees.

Dr. T. Theodore Fujita introduced the Fujita Scale, or F-scale, in 1971. Dr. Fujita (1920–1998) was a professor of meteorology at the University of Chicago. His goals were to categorize each tornado by its intensity and area as well as estimate a wind speed associated with the damage caused by the tornado. He surveyed every tornado from the Super Outbreak of April 3–4, 1974 and the F-scale became the official basis for rating tornadoes in the United States. The F-scale contained six categories from F0 to F5 and ranked tornadoes based on damages to homes and other buildings. A range of wind speeds was associated with each damage category.

In the late 1990s, engineers from Texas Tech University and others who studied tornado damage questioned whether the wind-speed ranges associated with the stronger categories in the F-scale were appropriate for the damage descriptions. Meetings between meteorologists and engineers resulted in an Enhanced Fujita Scale, or EF-scale, that was adopted for use in the United States in February 2007. The EF-scale maintained the EF0 to EF5 categories of the original F-scale, but wind-speed ranges associated with the categories were changed (Table 1). In addition, 28 damage indicators were identified and an accompanying guide was developed to associate the degree of damage on each damage indicator with EF-scale and respective wind speed. Wind speed in the EF-scale is taken to be the 3-s gust (mph) at 10 m height. The relationships between degree of damage and wind speed continue to be discussed and revisions of the EF-scale may occur as more information becomes available.

Fujita Tornado Scale, Table 1 Enhanced Fujita Scale for tornado damage

Cross-references

Beaufort Wind Scale

Doppler Weather Radar

Dust Devil

Dust Storm

Dvorak Classification of Hurricanes

Hurricane

Snowstorm and Blizzard

Thunderstorms

Tornado