The Oklahoma tornado

Deadly Oklahoma tornado widest on record, rare EF5

The weather service says EF5 twister's 2.6-mile width is the widest ever recorded

USA Today,

4 June, 2013

The National Weather Service reported Tuesday that the killer tornado that struck near Oklahoma City last Friday was a ferocious EF5 twister, which had winds that neared 295 mph.

An EF5 tornado, the highest number on the "Enhanced Fujita Scale of Tornado Intensity," is any tornado that has wind speeds of 200 mph or higher.

This beats every world wind record except the more-than 300-mph reading measured during the Moore, Okla., tornado in 1999, according to AccuWeather meteorologist Jesse Ferrell.

The weather service also said the twister's 2.6-mile width is the widest ever recorded. According to the National Severe Storm Laboratory, the tornado blew up from one mile to 2.6 miles wide in a 30-second span.

For perspective, Manhattan is 2.3 miles wide at its widest point near 14th Street.

The tornado, which carved a path 16.2 miles long near El Reno, Okla., surpasses a 2.5-mile-wide F4 tornado that hit Hallam, Neb., in 2004.

The Enhanced Fujita scale (with "EF" ratings) replaced the old Fujita scale (with "F" ratings) in 2007.

The weather service had originally rated the tornado as an EF3. But the agency upgraded the ranking Tuesday after surveying damage and reviewing measurements from a "Doppler on Wheels" vehicle that measures wind speeds remotely.

Eighteen people were killed in the tornado and flooding in the Oklahoma City metropolitan area, including four storm chasers. One of the chasers was pioneering scientist Tim Samaras and his son.

"I have heard that Tim Samaras was deploying probes in the path of the tornado before his tragic death," AccuWeather meteorologist Mike Smith notes on his blog. "I hope those probes can be recovered so we can learn more about this storm."

"Fastest winds were in the multiple suction vortices revolving about the parent tornado," writes Weather Channel severe storm expert Greg Forbes on his Facebook page. "They were travelling 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.