OKLAHOMA CITY (AP) -- The deadly tornado that struck near Oklahoma City late last week had a record-breaking width of 2.6 miles and was the second top-of-the-scale EF5 twister to hit the area in less than two weeks, the National Weather Service reported Tuesday.
The weather service initially rated the tornado that hit El Reno on Friday as an EF3. But the agency upgraded the ranking after surveying damage, and determined the storm packed winds reaching 295 mph. Eighteen people died in the storm, including three storm chasers, and its subsequent flooding.
Deep in the heart of Tornado Alley, the Oklahoma City area also saw an EF5 tornado on May 20. That one raked Moore, a suburb that's 25 miles away from El Reno, and killed 24 people. In 1999, Moore was hit by another EF5 with the strongest winds ever measured on earth: 302 mph.
Friday's massive tornado avoided highly populated metro areas, a fact forecasters said likely saved lives. Winds were at their most powerful in areas devoid of structures, said Rick Smith, chief warning coordination meteorologist for the weather service's office in Norman.
"Any house would have been completely swept clean on the foundation. That's just my speculation," Smith said. "We're looking at extremes ... in the rare EF5 category. This in the super rare category because we don't deal with things like this often."
The stretch between El Reno and Union City that the twister spun through is mostly rural farm and grazing land. Most of the destruction came toward the end of the tornado's 16.2-mile path along Interstate 40, where several motorists were killed when their vehicles were tossed around.
Like many Midwestern cities, the Oklahoma City metropolitan area continues to expand thanks to the suburbs, but the rapid growth hasn't quite reached as far west as where Friday's tornado tracked.
William Hooke, a senior policy fellow of the American Meteorological Society, said the continued expansion of cities in the most tornado-prone areas makes it only a matter of time before one hits a heavily populated area.
"You dodged a bullet," Hooke said. "You lay that path over Oklahoma City, and you have devastation of biblical proportions.
"It's only a matter of time."
El Reno Mayor Matt White said that while his 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 -- he said it could have been much worse had the violent twister tracked to the north.
"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."
The EF5 storm that hit Moore decimated neighborhoods.
"It's very scary ... I don't think a normal person can fathom just how scary," White said." I don't think they realize how lucky El Reno was."
Smith said the storm's 2.6-mile-wide path -- besting a record set in 2004 in Hallam, Neb. -- would have made the storm hard to recognize up close.
"A two-and-a-half mile wide tornado would not look like a tornado to a lot of people," Smith said.
Greg Carbin, a meteorologist for the National Oceanic and Atmospheric Administration's Storm Prediction Center in Norman, said May in Oklahoma is a time of transition, offering the perfect fuel for violent thunderstorms that can produce tornadoes -- a combination of warm, moist air combined with cooler jet stream energy that causes massive instability in the atmosphere.
"In these past two events, we've had a lot of unstable air sitting around, a lot of moisture and warm air," Carbin said. "That provides the fuel for thunderstorm development."
Associated Press writer Jill Bleed in Little Rock, Ark., contributed to this report.
Sean Murphy can be reached at www.twitter.com/apseanmurphy