Here is a quick look at the Fujita Tornado Intensity Scale:
Category F0: Gale tornado (40-72 mph); light damage. Some damage to chimneys; break branches off trees; push over shallow-rooted trees; damage to sign boards.
Category F1: Moderate tornado (73-112 mph); moderate damage. The lower limit is the beginning of hurricane wind speed; peel surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads.
Category 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.
Category F3: Severe tornado (158-206 mph); Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown.
Category F4: Devastating tornado (207-260 mph); Devastating damage. Well- constructed houses leveled; structure with weak foundation blown off some distance; cars thrown and large missiles generated.
Category F5: Incredible tornado (261-318 mph); Incredible damage. Strong frame houses lifted off foundations and carried considerable distance to disintegrate; automobile sized missiles fly through the air in excess of 100 yards; trees debarked; incredible phenomena will occur.
More Weather Facts...
On this date in 1936, a pair of F4 tornadoes killed 203 people and injured 1,600 in Gainsville, Georgia. The twister sisters cut a path of devastation four blocks wide through the city, wrecking Gainsville's business district and demolishing the Cooper Pants factory. More than 70 people were killed in that one building.