(CNN) -- The National Weather Service has increased the damage rating of the tornado that struck El Reno, Oklahoma, on May 31 to EF-5. The weather service has also determined that the tornado was 2.6 miles wide, making it the widest U.S. tornado on record.
EF-5 is the highest possible rating for tornadoes on the Enhanced Fujita scale.
The upgrade was based on information from a Doppler On Wheels (DOW) that measured low level winds of 296 miles per hour.
This tornado is double the width of the May 20 tornado in Moore, Oklahoma.
The F-4 Wilber-Hallam, Nebraska, tornado May 22, 2004 was the previous record holder for the widest tornado on record at 2.5 miles wide.
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