The science behind the EF scale: How we measure tornado strength

Yahoo

23-04-2025

BUFFALO, N.Y. (WIVB) — When a tornado tears through an area, the main question after the fact is, 'How strong was it?' That's where the Enhanced Fujita Scale, more commonly known as the EF scale, comes into play.
The EF scale is the scale that meteorologists use to survey damage and estimate a tornado's maximum wind speeds. Created by Dr. Ted Fujita in 1971, the original Fujita (F) scale was implemented to estimate wind speeds based on observed damage, with no specific criteria as to what constitutes damage levels.
To this day, the maximum speed reached by a tornado is an estimate, never an observed number.
The Fujita scale ranged from F0 having max gusts of <73 mph, F1 of 73-112 mph, F2 with 113-157 mph, F3 with 158-206 mph, F4 with 207-260 mph, and finally, F5, indicating speeds of up to 261-318 mph.
The original Fujita scale overestimated the wind necessary to create the amount of damage observed because there were no levels of destruction used within the system. This is where an upgrade came along almost 40 years later.
The Enhanced Fujita (EF) scale launched on February 1, 2007, to get more precise wind speed estimates by incorporating 28 damage indicators and eight degrees of damage.
The damage indicators range from damage to hard or softwood trees, to high rises, to automobile showrooms to take into account different structures that hold up differently in strong wind events. The degrees of damage range from barely visible, extremely minor damage to complete destruction.
The EF scale includes EF-0 (weak, 65-85 mph), EF-1 (weak, 86-110 mph), EF-2 (strong, 111-135 mph), EF-3 (strong, 136-165 mph), EF-4 (violent, 166-200 mph), and EF-5 (violent, >200 mph). For comparison, an F-3 tornado was 158-206 mph before enhancement, and the higher end of that would reach an EF-5 in today's scale.
Here in Western New York, we see lower-end, weaker tornadoes every once in a while, including the four that touched down last summer. Those ranged from EF-0s to EF-2s.
The strongest recorded tornado in WNY was an F-4, which would be an EF-5 in today's scale. It occurred on May 31, 1985. It entered Chautauqua County from the PA border and passed just south of the town of Clymer. The tornado had winds in excess of 200 mph and traveled 28 miles before dissipating.
We've covered four tornado warnings in our viewing region so far this year, the first three being in our Pennsylvania counties. More could pop up from now through summer.
Sara Stierly is a meteorologist who joined the 4 Warn Weather team in February 2025. See more of her work, here.
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