Deadly El Reno, OK tornado sets new record

ElRenoTornado

RICHMOND, Va. (WTVR) – The deadly tornado that tracked through rural areas of El Reno, OK on Friday, May 31, 2013 is unfortunately one for the record books.

Not only was the tornado’s life-span well-documented, it was also incredibly well-scanned by mobile doppler radars studying the supercell storm. This data from a new, experimental radar from the University of Oklahoma confirmed the width, track and wind speeds of the tornado, which actually had several vortices rotating within the tornado itself.

ElReno_PNS_graphic_final

The “OU RaXPol” (Rapid-scan X-band Polarimetric Radar), led by University of Oklahoma tornado researcher Howard Bluestein, in combination with survey teams from the National Weather Service in Norman, OK concluded the tornado was, at its widest, 2.6 miles across. This is a new record-wide tornado for the U.S. The previous record-widest tornado was at Wilber–Hallam, NE on May 22, 2004 at a maximum width of 2.5 miles.

To give you some perspective, 2.6 miles is the distance along Broad Street in-between the WTVR CBS 6 Tower to the City Center of Downtown Richmond (at North 4th Street near the Convention Center). That’s how wide this tornado was!

The OU RaXPol is operated by the University of Oklahoma’s Atmospheric Radar Research Center (ARRC), which says, “RaXpol boasts extremely rapid pedestal speeds, which enable a volume scan to be completed in as little as 20 seconds. The truck-based platform can quickly maneuver to a target area, deploy, operate, and depart with minimal preparation.”  Here is what the OU RaXPol vehicle and radar look like:
raxpol_left

And this is the research video taken simultaneously while scanning the storm by the team (Gabe Garfield, Tim Marquis, Amy Edmonds and Logan Karsten):

http://youtu.be/rmK1zm66RXM

Velocity data gathered by OU RaXPol measured wind speeds just 500 feet above the surface of the ground at a staggering 296 mph. That isn’t the fastest wind speed ever measured, but it’s close. The record for the fastest wind speed in a tornado (as measured by an earlier generation of Doppler On Wheels) still stands with the May 3, 1999 Moore, OK tornado. Wind speeds then were radar-estimated by another tornado researcher Joshua Wurman, who leads the Center for Severe Weather Research. His team recorded 301 mph winds in that tornado near Moore, OK on May 3, 1999.

Wurman was part of another doppler radar research team tracking the El Reno tornado Friday at a different location than Bluestein’s group. Their two mobile doppler radars (called Doppler On Wheels) measured speeds of 246-258 mph.

With both of those teams providing those radar-estimated wind speeds, the National Weather Service was able to, with full confidence, upgrade the tornado to an EF-5 with winds surpassing 200 mph. (It was previously surveyed as an EF-3).

It is worth noting that the Enhanced Fujita Scale, which is used to rate tornadoes, is a damage-indicator-driven scale. However, there weren’t higher-level “damage indicators” (i.e., sturdy structures) in much of the path of this tornado. Therefore, this radar data is crucial in determining just how strong and just how wide the tornado was.

Meteorologist Carrie Rose



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