The Enhanced Fujita Scale: How tornadoes get their rating

QUAD CITIES, Iowa/Ill. (KWQC) - Meteorologists at the National Weather Service in the Quad Cities have been busy over the past couple weeks assessing damage from the severe weather outbreak on March 31 and April 4-5.

On average, there are 800 tornadoes reported each year in the United States, and each one is given a rating between zero and five on the Enhanced Fujita (EF) Scale.

As of April 11, more than two dozen tornadoes have been confirmed in eastern Iowa and western Illinois from the two separate severe weather outbreaks.

Many of them were rated EF-2 on the Enhanced Fujita Scale.

The EF scale has been in place since February 1, 2007, an update to the “Fujita Scale” created by Dr. Ted Fujita of the University of Chicago in 1971.

The scale assigns a ratings based on estimated wind speed relating to damage done by tornadoes, based on 28 separate damage indicators.

Damage surveys are conducted by the National Weather Service in the hours and days after tornadoes occur to determine the rating.

An EF-0 is a tornado causes minor damage with estimated winds of 65-85 mph.

An EF-1 tornado causes moderate damage with 86-110 mph winds.

The National Weather Service said the damage caused in Rock Island on April 1 was from an EF-1 tornado. Several homes were damaged, along with trees being uprooted and powerlines being snapped.

An EF-2 causes considerable damage with estimated wind speeds of 110-135 mph.

Cars can be lifted off the ground and homes can be shifted. Mobile homes can also be destroyed.

A farm in Tipton, Iowa was destroyed by an EF-2 tornado on March 31. There was also an EF-2 in Colona, Ill.

EF-3 tornadoes have winds up to 165 mph and causes severe damage to larger buildings, vehicles and trees.

An EF-4 tornado caused major damage in Keota, Iowa on March 31.

Extreme damage was seen with peak winds estimated to be 170 miles per hour.

EF-4 tornadoes can have winds up to 200 mph.

Any tornadoes with estimated winds exceeding 200 mph is an EF-5, destroying anything in its path.

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