The deadly cyclone that struck on Friday in El Reno, Oklahoma, was the second EF5 tornado in less than two weeks to wreak devastation on the state. It was also the largest twister ever recorded in the United States. According to the National Weather Service, the May 31 tornado that killed 18 people grew to 2.6 miles wide, achieving a top speed of 295 miles per hour. The second-widest funnel, which devastated parts of Hallam, Nebraska, in 2004, spanned only 2.5 miles. The record only underscores the distressing frequency of tornados touching down in Oklahoma, which saw 24 people die, hundreds more injured, and millions of dollars in property blown apart, when a a 1.3 mile-wide tornado tore through Moore, Oklahoma, located 31 miles southeast of El Reno and 10 miles south of Oklahoma City, on May 20.
NWS officials told NBC News that the tornado's diameter was measured with a "mobile radar unit" stationed on a stretch of U.S. Route 81 just south of El Reno, near where the twister passed through the town of 16,729 residents. The radar unit was, presumably, luckier than the Weather Channel car that was upended by the very tornado it was designed to chase — and the storm chasers who, miraculously, made it out of the car alive. Some weren't so lucky.