Damage Scale
Like hurricanes, tornadoes are classified based on estimated wind speeds and the damage typically associated with each category. When a tornado occurs, trained NWS personnel assess the damage in comparison to a list of Damage Indicators – a table that describes various types of damage for different kinds of buildings (detailed table available at http://www.spc.noaa.gov/efscale/ef-scale.html). This table helps produce an estimate of the range of wind speeds the tornado likely produced.
Enhanced Fujita Tornado Damage Scale
(Note: The Enhanced Fujita Tornado Damage Scale differs from the original Fujita scale in that it takes into account quality of construction and different types of structures and vegetation. Wind speeds are estimated from damage, not measured. Since damage can vary greatly from block to block or even building to building, rating tornadoes by the damage caused is subjective.)
| Classification | Estimated Winds (3 second gust) |
|---|---|
| EF0 | 65-85 mph (105-137 km/h) |
| EF1 | 86-110 mph (138-178 km/h) |
| EF2 | 111-135 mph (179-218 km/h) |
| EF3 | 136-165 mph (219-216 km/h) |
| EF4 | 166-200 mph 267-322 km/h) |
| EF5 | Over 200 mph (Over 322 km/h) |
Most tornadoes spawned by tropical cyclones are relatively weak (EF0-EF1 based on the Enhanced Fujita Tornado Damage Scale), but a significant number have been EF2 or greater and have caused considerable damage.