“This is the biggest ever,” Bluestein said.
Video of the El Reno supercell and 2.6-mile wide EF-5 tornado in Oklahoma on May 31, 2013 uploaded to YouTube by NickNolteWx
The previous widest tornado on record was the F4-rated (on the 0-5 scale) Wilber – Hallam, Nebraska twister that touched down on May 22, 2004. It had a maximum width of 2.5 miles.
In addition to revising the path width of the El Reno tornado, the National Weather Service upgraded its intensity rating from EF-3 (on the 0-5 Enhanced Fujita scale) to EF-5, the highest level. The upgrade arose not due to the funnel’s girth, but because of astonishing wind speed information sensed from several mobile doppler radar units driven into the field by research meteorologists in pursuit of the tornado.
Bluestein, a University of Oklahoma professor, said two of his graduate students clocked wind speeds as high as 296 mph on their radar while observing the storm, which carved a 16.2-mile path over a period of 40 minutes.
That 296 mph gust came close to matching the highest wind speed ever measured on Earth. Joshua Wurman, another leading tornado researcher who runs the Center for Severe Weather Research, said his team recorded 301 mph winds in a tornado that struck near Moore, Okla. on May 3, 1999.
(Note: Doppler radar estimated winds are not considered official by the World Meteorological Organization, which requires direct measurements from anemometers or the like. Officially, the strongest wind gust ever recorded was 253 mph in tropical cyclone Olivia at Barrow Island, Australia in 1996.)
Wurman and his team were also in the field measuring winds from the El Reno storm and estimated speeds of 246-258 mph (in a different location from Bluestein’s team) using two of their mobile doppler radars, known as Doppler on Wheels.
On the EF-scale, storms earn a rating of 5 if damage surveys suggest winds reached at least 200 mph. Recently, some tornadoes that were preliminarily rated at lower EF levels based on damage have been revised after evaluating doppler radar measurements from field observers.
“In fact, NWS, my grad student and I conferred [to arrive at the EF upgrade],” Bluestein said.
Bluestein added that data from his team’s doppler radar also helped confirm the unprecedented width of the El Reno storm.
“[Our data show] the width of high winds show was over 2 miles,” he said. “It’s remarkable.”
UPDATE, 2:10 p.m.: The Weather Channel’s Greg Forbes provides some additional, incredible detail about the tornado’s winds on his Facebook page:
Fastest winds were in the multiple suction vortices revolving about the parent tornado. They were traveling about 185 mph as they were steered along within the parent tornado winds and had winds about their own axis of about 100 mph that added to the parent tornado’s winds.
There have only been eight F5/EF-5 tornadoes in Oklahoma since 1950, the Weather Underground reports, and two of them have hit in the past two weeks. The other hit Moore on May 20, killing 24 people.
On average, over 1,000 tornadoes hit the U.S. each year, and only one might be an EF5, reports National Climatic Data Center.
Another chaser death identified
The deaths of pioneering storm chaser Tim Samaras, his son, Paul Samaras, and chase partner Carl Young in the El Reno storm were widely reported Sunday and Monday. Samaras was considered a professional, with over 30 years of chasing experience and led a legitimate research operation.
From his pickup, amateur storm chaser Richard Charles Henderson took a cellphone photo of the first tornado Friday and excitedly sent it to a friend.
Minutes later, that tornado would kill him.
UPDATE, 4:05 p.m.: Here’s a startling animation that shows storm chasers (triangles) dodging the incoming El Reno tornado (white blob).
Image uploaded by Whacky Rat via YouTube, who indicates the tornado path and its size representation are based on radar and path information from the National Weather Service. Chaser positions are from the Spotter Network.