Mammoth Oklahoma tornado was widest ever recorded – almost strongest, too

The tornado that ripped through El Reno, Okla., on Friday was the widest tornado ever recorded and had winds that hit nearly 300 miles per hour, close to the highest wind speed ever measured, the National Weather Service reported Tuesday.

The record-setting twister was 2.6 miles wide at its maximum and carved a 16.2 mile path across mostly rural land west of Oklahoma City. It tops the previous record-holding tornado, which hit Hallam, Neb., on May 22, 2004, and was 2.5 miles wide.

For comparison, USA Today notes that Manhattan is 2.3 miles wide at its widest point. 

The National Weather Service also upgraded the tornado to its most powerful class, an EF-5 ranking, on Tuesday. The agency upgraded the ranking from an EF-3 after surveying damage from the twister. The tornado and subsequent flooding killed 18 people, including four storm chasers.

El Reno now joins the Moore, Okla., tornado as the second EF-5 to hit Oklahoma in less than two weeks, another record for the state, according to the National Weather Service’s Norman, Okla., office.

But Friday's massive tornado avoided the highly populated areas around Oklahoma City, and forecasters said that likely saved lives. When the winds were at their most powerful, no structures were nearby, said Rick Smith, chief warning coordination meteorologist for the weather service's office in Norman. 

“The impacts were horrible of what happened, where it hit, and what happened to people and structures,” Mr. Smith told the Oklahoman. "But we are so fortunate that this did not impact densely populated areas. This would have been ... I don't even want to imagine what it would have been.”

El Reno is about 25 miles west of Oklahoma City and has a population of about 17,000, according to its website. Moore has more than 55,000 residents, according to 2010 census data. 

Winds during Friday’s giant twister also nearly broke records.  

A mobile doppler radar at the University of Oklahoma measured winds greater than 295 miles an hour at several times and locations within along the south side of the tornado, according to the Oklahoman. 

Howard Bluestein, a University of Oklahoma professor, told The Washington Post that two of his graduate students clocked wind speeds as high as 296 miles per hour on their mobile doppler unit while observing the storm from the east.

The World Meteorological Organization requires direct measurements from anemometers for official wind speeds, meaning the strongest wind gust on record is officially 235 miles per hour in tropical cyclone Olive at Barrow Island, Australia, in 1996. Yet during a 1999 tornado in Moore, the team of Joshua Wurman, director of the Center for Weather Research, measured wind speeds of 301 miles per hour.

For observers of Friday’s super-tornado, the 2.6-mile path may have been difficult to identify as a tornado.

"A two and a half mile wide tornado would not look like a tornado to a lot of people," the National Weather Service’s Smith said.

On average, more than 1,000 tornadoes hit the US each year, and only one might be an EF-5, reports National Climatic Data Center. 

• Material from the Associated Press was used in this report