The tornado that touched down near El Reno, Okla., last week has been upgraded to an EF-5, with winds near the surface of 296 mph, the National Weather Service in Norman said Tuesday.
At 2.6 miles, it is the widest tornado on record in U.S. history, said Rick Smith, warning coordination meteorologist for the Norman branch of the weather service. That eclipses the 2.5-mile-wide tornado that hit Hallam, Neb., on May 22, 2004.
“This is mind-boggling stuff,” Smith said of the preliminary data collected by storm survey teams and mobile radar.
The tornado was on the ground for more than 16 miles on a path generally traveling east, then southeast, then sharply northeast before ending its 40-minute journey by lifting at 6:43 p.m.
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The El Reno tornado had three to five smaller internal vortices within the main circulation, Smith said, and they were racing along at up to 185 mph. The tighter internal vortices were crossing each other inside the main tornado, he said, creating “all kind of violent motions.”
These smaller tornadoes did not hit any structures, he said. If they had, he added, “any house would have been completely swept clean on the foundation.”
Storm chasers Tim and Paul Samaras and Carl Young were among those killed by the tornado. While Smith declined to address their circumstances specifically, he said, “You can imagine how people could get in trouble.”
“This would be a very dangerous situation if you were not well aware of your surroundings,” he added.
A tornado that’s 2.5 miles wide “would not look like a tornado to a lot of people.”
“This was an exceptionally dangerous storm to be anywhere close to,” he added.
Veteran chaser and weather researcher Jon Davies, who was tracking the El Reno tornado with his wife, Shawna, said a careful assessment of radar data and conversations with other chasers gave him a clearer picture of how Young and the Samarases may have been killed.
“It looks like the tornado doubled speed for a period after it turned left, maybe going as fast as 40 miles per hour for a short time,” Davies said via e-mail. “That may help explain how Tim got caught.”
They were deploying probes in the tornado’s expected path, Davies said, but could not escape when the tornado dramatically increased in speed.
Tim Samaras was found strapped into the crushed and crumpled chase vehicle, while his son Paul and Young had been thrown hundreds of feet into nearby fields.
El Reno was initially measured as an EF-3 tornado based on damage found in the rural area. But wind speed measurements collected by mobile Doppler radar detected far higher wind speeds than the damage suggested, Smith said.
Mobile radar equipment has been used to refine tornado measurements twice in Kansas in just the past few weeks: A massive tornado that just missed Rozel on May 18 in western Pawnee County was upgraded from an EF-2 to an EF-4, and a tornado that formed the next day near Clearwater and threatened Wichita before lifting was upgraded from an EF-1 to an EF-2.
It’s not yet clear whether the El Reno tornado will go down as the strongest tornado on record, Smith said. The Moore, Okla., tornado of May 3, 1999, had documented winds of more than 300 mph.
“We are so fortunate that this did not impact a densely populated area,” Smith said of the El Reno tornado. If it had, “it would have been catastrophic.”
El Reno Mayor Matt White agreed. He said that while the city of 18,000 residents suffered significant damage – including its vocational-technical center and a cattle stockyard that was reduced to a pile of twisted metal – it could have been much worse.
“If it was two more miles this way, it would have wiped out all of downtown, almost every one of our subdivisions and almost all of our businesses,” White said. “It would have taken out everything.”
At least six tornadoes touched down from the storm system that pounded the Oklahoma City metropolitan area, Smith said, and there could have been more. A tornado that developed southeast of the El Reno tornado actually rotated clockwise – the opposite direction of most tornadoes.
“This is going to be studied for a long time,” Smith said of the El Reno tornado. “You’ll be hearing about this in conferences for many, many years.”
The severe weather, which included flash floods in the wake of heavy rains, killed at least 19 people. Several others remain missing.
Contributing: Associated Press