The El Reno Tornado: The Widest Ever Recorded

Less than 36 hours after it dissipated, the NWS office in Norman rated El Reno an EF5 — the first time a US tornado had been rated on mobile-radar wind measurements alone. The RaXPol research radar had clocked winds near 296 mph aloft, with instantaneous readings in small sub-vortices estimated even higher. On the Enhanced Fujita scale, anything at or above 200 mph is EF5 territory.

Then came the damage survey. The Enhanced Fujita scale rates tornadoes on the damage they leave, not the winds a radar sees — and El Reno spent almost its entire life over open farmland. Surveyors could not find a single structure hit hard enough to justify an EF5, or even an EF4. On August 30, 2013, the NWS downgraded it to EF3, the rating our SPC data still carries. The decision divided meteorologists: some argued the radar winds were real and the scale is simply blind to tornadoes over empty land; others held that the EF scale must stay tied to observable damage to mean anything.

Either way, the width is not in dispute. A 2.6-mile-wide circulation is roughly the distance across all of Manhattan at its widest — and El Reno’s did not move in a straight, predictable line. It expanded from about a mile to its full 2.6 miles in seconds, changed direction, and accelerated. That erratic, rain-wrapped behavior is what turned it into the deadliest day in storm-research history.

Eight people were killed by the El Reno tornado, according to the SPC record. Four of them were chasers. The TWISTEX team — veteran engineer and researcher Tim Samaras, his son and photographer Paul Samaras, and meteorologist Carl Young — were overtaken in their vehicle as the tornado ballooned and lunged unexpectedly to the northeast. Tim Samaras was among the most safety-conscious figures in the field, famous for deploying probes into tornado paths and then getting clear. They were the first storm researchers ever killed by a tornado they were intercepting. Amateur chaser Richard Henderson, who had texted a photo of the funnel minutes earlier, was also killed.

The rest of the deaths were people caught in the open — some in cars on the clogged highways west of Oklahoma City, where a televised warning to “drive south” during the 1999 and 2013 Moore tornadoes had trained residents to flee by car. On this night the flight itself was deadly. The tornado missed the packed interstates by a narrow margin; had it tracked a few miles east into the metro, the toll would have been catastrophic.

For the chase and forecasting community, El Reno became a permanent cautionary tale about fast, wide, rain-wrapped tornadoes — the ones you cannot see coming and cannot outrun on a grid of section roads. It is a very different lesson from the slow, visible, plains “textbook” tornado, and it is why chasers now give storms like the ones in the 2011 Super Outbreak a far wider berth.

El Reno did not happen in isolation. Our SPC data records 36 tornadoes across the country on May 31, 2013, and 134 tornadoes over the broader May 26–31 outbreak that stretched from the Plains to the Northeast. El Reno was by far the most extreme of them — all eight of that day’s tornado deaths came from this single storm.

The same supercell system dumped extraordinary rain on the Oklahoma City metro that evening. Flash flooding on top of the tornado threat killed additional people across the region that night, which is why the total May 31, 2013 death toll runs higher than the tornado’s eight in most accounts. You can pull the daily conditions for that date — or any date since 1970 — on our historical weather lookup, and browse Oklahoma’s wider tornado record on its state tornado page.