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Fujita Tornado Scale
The Fujita scale rates a tornado's
intensity by the damage it inflicts on human-built structures. It was
introduced in 1971 by T. Theodore Fujita of the University of Chicago
who developed the scale together with Allan Pearson, head of the
Forecast Center in Kansas City, Missouri.
Fujita scale measurements are issued after
a tornado has passed through an area, not while it is on the ground. It is
possible, but difficult, to make educated guesses as to the probable F
category while a tornado is on the ground. The official Fujita scale
measurement is determined after scientists examine radar tracking,
eye-witness testimonies, and the damage caused by the tornado.
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Category
F0 |
Wind speed |
<73 mi/h |
<115 km/h |
Relative frequency |
29% |
|
Potential damage |
Light damage. Some damage to chimneys; branches broken off trees;
shallow-rooted trees pushed over; sign boards damaged. |
|
Category
F1 |
Wind speed |
73–112 mi/h |
116–180 km/h |
Relative frequency |
40% |
|
Potential damage |
Moderate damage. Peels surface off roofs; mobile homes pushed off
foundations or overturned; moving autos blown off roads. |
|
Category
F2 |
Wind speed |
113–157 mi/h |
181–250 km/h |
Relative frequency |
24% |
|
Potential damage |
Considerable damage. Roofs torn off frame houses; mobile homes
demolished; boxcars overturned; large trees snapped or uprooted;
light-object missiles generated; cars lifted off ground. |
|
Category
F3 |
Wind speed |
158–206 mi/h |
251–330 km/h |
Relative frequency |
6% |
|
Potential damage |
Severe damage. Roofs and some walls torn off well-constructed houses;
trains overturned; most trees in forest uprooted; heavy cars lifted
off the ground and thrown. |
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Category
F4 |
Wind speed |
207–260 mi/h |
331–415 km/h |
Relative frequency |
2% |
|
Potential damage |
Devastating damage. Well-constructed houses leveled; structures with
weak foundations blown away some distance; cars thrown and large
missiles generated. |
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Category
F5 |
Wind speed |
261–318 mi/h |
416–510 km/h |
Relative frequency |
<1% |
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Potential damage |
Incredible damage. Strong frame houses leveled off foundations and
swept away; automobile-sized missiles fly through the air in excess of
100 meters (109 yd); trees debarked; incredible phenomena will occur. |
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Category
F6 |
Wind speed |
319–379 mi/h |
511–609 km/h |
Relative frequency |
<0.001% |
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Potential damage |
Inconceivable damage. No F6 tornadoes have actually been verified.
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