The Fujita Scale of Tornado Damage

F-0: (Light Damage) Chimneys are damaged, tree branches are broken, shallow-rooted trees are toppled.
 

F-1: (Moderate Damage) Roof surfaces are peeled off, windows are broken, some tree trunks are snapped, unanchored manufactured homes are over-turned, attached garages may be destroyed.

F-2: (Considerable Damage) Roof structures are damaged, manufactured homes are destroyed, debris becomes airborne (missiles are generated), large trees are snapped or uprooted.

F-3: (Severe Damage) Roofs and some walls are torn from structures, some small buildings are destroyed, non-reinforced masonry buildings are destroyed, most trees in forest are uprooted.

F-4: (Devastating Damage) Well-constructed houses are destroyed, some structures are lifted from foundations and blown some distance, cars are blown some distance, large debris becomes airborne.

F-5: (Incredible Damage) Strong frame houses are lifted from foundations, reinforced concrete structures are damaged, automobile-sized debris be-comes airborne, trees are completely debarked.

Safety and Preparedness It is important to remain alert to signs of an approaching tornado and seek shelter if threatening conditions exist. Look for environmental clues including a dark sky, large hail or a loud roar. If a warning is issued, move to a pre-designated shelter such as a basement; stay away from windows; get out of automobiles and lie flat in a ditch or depression; do not try to outrun a tornado in your car.
The Fujita Scale was first proposed by Dr. Fujita in 1971. It is used by meterologists to estimate the speed of winds after a tornado by studying the damage caused by the tornado to structures. Recently the scale has been used to confirm the idea that some hurricane damage is caused by torndoes that form within hurricanes.
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