NASHVILLE, Tenn. (WKRN) — It’s the 50-year anniversary of the first tornado rating scale put into use in the United States. Today, this scale has been upgraded and uses rigorous damage guide points to determine the rating of a tornado.

It started back in February 1971. Dr. Theodore Fujita invented the Fujita Scale in an effort to provide more insight to a tornado’s intensity & area. Three years later, it was used in the Super Outbreak of April 1974 that impacted many areas from the Gulf Coast to the Great Lakes.

The F-Scale was measured this way:

F-040-72 MPH Winds
F-173-112 MPH Winds
F-2113-157 MPH Winds
F-3158-206 MPH Winds
F-4207-260 MPH Winds
F-5261-318 MPH Winds

In January 2007, the National Weather Service switched to the Enhanced Fujita (EF) Scale. This was changed because construction of various structures changed, improving their strength to withstand a storm.

This new rating protocol is based a 28-point damage scale indicator, and depending on the degree of damage will determine the type of rating it is given.

EF-065-85 MPH Winds
EF-186-110 MPH Winds
EF-2111-135 MPH Winds
EF-3136-165 MPH Winds
EF-4166-200 MPH Winds
EF-5>200 MPH Winds

Type of damage is expected from each tornado rating

EF-0: Relatively minor damage expected. Shingles blown off, gutter & siding damage, branches off trees and shallowed rooted trees uprooted.

EF-1: Moderate damage. Mobile homes at these speeds can overturn or heavily damaged. Roof damage is more significant with windows broken.

EF-2: Considerable damage. Homes shifted off the foundation, cars tossed, large trees uprooted or destroyed.

EF-3: Severe damage. Flattening levels of structures. Bark off of trees is pulled off by the shear force of this type of tornado.

EF-4: Extreme damage. Homes completely leveled. Cars tossed far away from original location.

EF-5: Massive damage. Foundation slab of a home is all that remains. Steel-reinforced concrete structures sustain heavy damage. Trees totally debarked.

The only F-5/EF-5 tornado ever recorded in the state of Tennessee was April 16, 1998 in Wayne & Lawrence counties. It’s been called “The Forgotten F5.” Thankfully, there were no fatalities reported.

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