The Fujita Scale
Dr. T. Theodore Fujita developed the Fujita Tornado Damage Scale (F-Scale) to provide estimates of tornado strength based on damage surveys. Since it’s practically impossible to make direct measurements of tornado winds, an estimate of the winds based on damage is the best way to classify a tornado.
The new Enhanced Fujita Scale (EF-Scale) addresses some of the limitations identified by meteorologists and engineers since the introduction of the Fujita Scale in 1971.
The new scale identifies 28 different free standing structures most affected by tornadoes taking into account construction quality and maintenance. The range of tornado intensities remains as before, zero to five, with ‘EF-0′ being the weakest, associated with very little damage and ‘EF-5′ representing complete destruction, which was the case in Greensburg, Kansas on May 4th, 2007, the first tornado classified as ‘EF-5′. The EF scale was adopted on February 1, 2007.
The Storm Prediction Center has a brief description of the Enhanced Fujita Scale.
|F0||Gale tornado||65-85 mph||Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards.|
|F1||Moderate tornado||86-110 mph||The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed.|
|F2||Significant tornado||111-135 mph||Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated.|
|F3||Severe tornado||136-165 mph||Roof and some walls torn off well constructed houses; trains overturned; most trees in fores uprooted|
|F4||Devastating tornado||166-200 mph||Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.|
|F5||Incredible tornado||>200 mph||Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-inforced concrete structures badly damaged.|