Using the Enhanced Fujita (EF) scale, a tornado can have wind speeds of more than 200 miles per hour. The EF scale categorizes tornadoes based on the extent of damage they cause and are not actual wind speed measurements.
The EF scale was named after Dr. Ted Fujita, a University of Chicago research scientist who developed the first version of the scale in 1971. The scale is also called the "F" scale. The National Weather Service officially adopted it in 2007.
The EF scale goes from F-0 to F-5, with an F-0 being the slowest wind speeds and F-5 being the highest. The speed classifications are as follows:
- F-0: winds from 65-85 mph
- F-1: winds from 86-110 mph
- F-2: winds from 111-135 mph
- F-3: winds from 136-165 mph
- F-4: winds from 167-200 mph
- F-5: winds more than 200 mph
Because it is not possible to get an exact scientific measurement of wind speeds inside tornadoes, wind speed is based on damage. Because construction standards vary, the updated version of the scale gives detailed descriptions of damage to 28 types of buildings and objects.
An example of description damage for a small barn includes an eight-number decree of damage scale. A one indicates a minimal threshold of visual damage. A five indicates a collapsed roof, and an eight indicates the building's total destruction.