The National Weather Service uses the EF Scale to rate a tornado based on wind speeds and damage.
The Enhanced Fujita Scale (EF Scale) has been used since 2007 and the National Weather Service is the only federal agency with the authority to provide an official EF Scale rating of a tornado.
When the NWS surveys damage from a tornado officials compare the damage to a list of Damage Indicators (DIs) and Degrees of Damage (DoD) , which help them estimate the range of wind speeds the tornado likely produced.
The EF scale is a set of wind estimates, not measurements, based on damage. It uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to 28 indicators.
Damage Indicators include barns, homes, mobile homes, motels, fast food restaurants, shopping malls, schools, hardwood trees, softwood trees, and many more.
After the range of wind speeds is determined, they assign an EF-0 to EF-5 rating. The goal is to give the tornado an EF Scale rating based on the highest wind speed that occurred within the damage path.
---> View the full list of damage indicators from the National Weather Service.
| EF Rating | 3 Second Gust (mph) |
|---|---|
| EF-0 | 65-85 |
| EF-1 | 86-110 |
| EF-2 | 111-135 |
| EF-3 | 136-165 |
| EF-4 | 166-200 |
| EF-5 | Over 200 |