| F-Scale
Number |
Intensity
Phrase |
Wind
Speed |
Type
of Damage |
| F0 |
Gale
Tornado |
40-72
mph |
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 forests 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. |
| F6 |
Inconceivable
tornado |
319-379
mph |
These
winds are very unlikely. The small area of damage they might produce
would probably not be recognizable along with the mess produced by
F4 and F5 wind that would surround the F6 winds. Missiles, such as
cars and refrigerators would do serious secondary damage that could
not be directly identified as F6 damage. If this level is ever achieved,
evidence for it might only be found in some manner of ground swirl
pattern, for it may never be identifiable through engineering studies |
