First Alert Weather Academy: How tornadoes are rated

First Alert Weather Academy: How tornadoes are rated

SAVANNAH, Ga. (WTOC) - Fifty years ago this week a devastating tornado in Lubbock, Texas led to the creation of a tornado rating system.

The tornado killed 26, injured over 1,500 and caused $250 million of damage, which is over a billion dollars in today's market.

Path of Lubbock tornado, May 11, 1970 (Source: National Weather Service)
Path of Lubbock tornado, May 11, 1970 (Source: National Weather Service)

Upon visiting Lubbock in 1970, Dr. Ted Fujita used the damage as the first reference point for the Fujita scale, rating the tornado an F-5 with estimated wind topping out at 261 miles per hour.

The original Fujita scale went into effect in 1971, ranking tornadoes on a scale of F0 to F5 by estimating tornado wind speeds based on damage caused by the tornado.

This scale served an important purpose, but led to some inconsistencies in the ratings due to a lack of damage indicators, and not accounting for construction quality.

The EF Scale went into effect in 2007
The EF Scale went into effect in 2007 (Source: NOAA)

In 2007, a group of meteorologists and wind engineers developed the Enhanced Fujita Scale, replacing the original Fujita Scale.

The EF Scale is more detail oriented and takes into account additional variables that the National Weather Service uses when they determine a wind speed rating for a tornado.

Once safe, the National Weather Service sends out a survey team to asses and rate the damage.

There are 28 damage indicators in the EF Scale. including: trees, building types and other structures.

Each of these damage indicators has an additional 8 degrees of damage which range from initial visible damage all the way to complete destruction. (You can read about these damage indicators here.)

The updated rating system realigned the wind speed range comparable to a tornadoes classification given by the National Weather Service.

EF-0

65-85 miles per hour
65-85 miles per hour (Source: Gray TV)

EF-1

86-110 miles per hour
86-110 miles per hour (Source: Gray TV)

EF-2

111-135 miles per hour
111-135 miles per hour (Source: Gray TV)

EF-3

136-165 miles per hour
136-165 miles per hour (Source: Gray TV)

EF-4

166-200 miles per hour
166-200 miles per hour (Source: Gray TV)

EF-5

200+ miles per hour
200+ miles per hour (Source: Gray TV)

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