Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards.
F1
Moderate tornado
73-112 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
113-157 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
158-206 mph
Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted
F4
Devastating tornado
207-260 mph
Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.
F5
Incredible tornado
261-318 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.