Fujita Scale

The Fujita Scale or Fujita Pearson Scale uses the amount and type of damage to categorize different tornadoes. It was developed by Tetsuya Theodore Fujita (see below) and Allen Pearson. Wind speeds are estimated from the damage by a surveyor. The surveyor comes in after the tornado has passed and checks the damage. The official Fujita Scale rating is taken by National Weather Service. The Fujita Scale goes from F0 (less damage) to F5 (most damage). There is also an unofficial rating of rating of F6 that may be added to the Fujita Scale. A tornado in Oklahoma is said to have surpassed the rating of F5, with about 318 mph winds.

Scale	Intensity	Wind Estimate (mph)	Damage Done
F-0	Gale Tornado	40-72	Damage to chimney's; branches broken off trees; pushes over shallow rooted trees; sign boards damaged
F-1	Moderate Tornado	73-112	Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed.
F-2	Significant Tornado	113-157	Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated
F-3	Severe Tornado	158-206	Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted
F-4	Devastating Tornado	207-260	Well-constructed houses leveled; structures with weak foundations blown some distance; cars thrown and large missiles generated
F-5	Incredible Tornado	261-318	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-enforced concrete structures badly damaged.
F-6 Note: This is not an official Fujita Scale Rating	Inconceivable Tornado	319-379	These winds are very unlikely, but seemed possible when a tornado in Oklahoma reached speeds of 318 mph. An F6 tornado has never occurred, but if it did occur, it would be hard to distinguish the damage of an F6 tornado from a F4 tornado or a F5 tornado. 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.

The Fujita Scale was developed by Tetsuya Theodore Fujita. Ted Fujita, a Japanese scientist came to the U.S. in the 1950's. When he arrived he commenced work on analyzing thunderstorms as individual weather systems that he called mesoscale systems. He also introduced the idea of tornado families. A tornado family are individual tornadoes but they were spawned by the same thunderstorm. He also introduced concepts of thunderstorm architecture. in 1974 he was able to map the entire path of the 148 thunderstorms in the Super outbreak of 1974 using the Fujita Scale intensity contours. His ability to simplify meteorological concepts helped to aid in public education. Ted Fujita also worked with weather related aircraft disasters, thunderstorms, hurricanes and typhoons. He died at the age of 78 in 1998.