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Farmers Almanac
The 2014 Farmers Almanac
Farmers' Almanac

Tornado Damage – Fujita Scale

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Fujita Tornado Damage Scale, Winds, Tornado Season

My heart goes out to all the victims of tornadoes this Spring.  We indicated in our publication that it would be an active season, but tornadoes are among the most ferocious storms. They are somewhat arbitrary as to where they land and the damage they leave behind.

The storm that hit the Boy Scouts in Iowa captures all of our hearts. When we lose a young person, we lose their potential. Reading about the four boys makes us even sadder for what might have been. This was a Category 3 tornado which makes me wonder how powerful are tornadoes and what is the rating system. Here is the system as presented by NOAA

Fujita Tornado Damage Scale

Developed in 1971 by T. Theodore Fujita of the University of Chicago

F0 < 73 Light damage. Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.
F1 73-112 Moderate damage. Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads.
F2 113-157 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.
F3 158-206 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.
F4 207-260 Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.
F5 261-318 Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur.

*** IMPORTANT NOTE ABOUT F-SCALE WINDS: Do not use F-scale winds literally. These precise wind speed numbers are actually guesses and have never been scientifically verified. Different wind speeds may cause similar-looking damage from place to place — even from building to building. Without a thorough engineering analysis of tornado damage in any event, the actual wind speeds needed to cause that damage are unknown. The Enhanced F-scale will be implemented February 2007.

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