The 2013 El Reno tornado was a very large and intense EF3 tornado that occurred over rural areas of Central Oklahoma during the early evening of May 31, 2013.
The widest tornado in recorded history, it was part of a larger weather system that produced dozens of tornadoes over the preceding days. The tornado initially touched down at 6:03 p.m. Central Daylight Time (2303 UTC) about 8.3 miles (13.4 km) west-southwest of El Reno, rapidly growing in size and becoming more violent as it tracked through central portions of Canadian County.
Remaining over mostly open terrain, the tornado did not impact many structures; however, measurements from mobile weather radars revealed extreme winds in excess of 295 mph (475 km/h) within the vortex. As it crossed Highway 81, it had grown to a record-breaking width of 2.6 miles (4.2 km). Turning northeastward, the tornado soon weakened. Upon crossing Interstate 40, the tornado dissipated around 6:43 p.m. CDT (2343 UTC), after tracking for 16.2 miles (26.1 km), avoiding affecting more densely populated areas near and within the Oklahoma City metropolitan area.
The tornado killed four storm chasers, the first known deaths in the history of storm chasing. Although the tornado remained over mostly open terrain, dozens of storm chasers unaware of its immense size and erratic movement were caught off-guard. Near U.S. Highway 81, TWISTEX scientist and engineer Tim Samaras, along with his son Paul and research partner Carl Young died in the tornado. Paul and Young were ejected from their Chevrolet Cobalt by the storm’s sub-vortex, while Tim was still buckled in the passenger’s seat next to Young’s driving seat.
Local resident Richard Henderson, who decided to follow the storm, lost his life in that same area. He snapped a picture of the tornado from his cellular phone before it struck him. Other chasers, including Mike Bettes of The Weather Channel and Reed Timmer, were either injured or had their vehicles damaged. A Doppler on Wheels-based analysis of how the tornado impacted these teams revealed that they were hit by an intense internal sub-vortex. Overall, the tornado was responsible for eight fatalities and 151 injuries. The National Weather Service referred to the tornado as “the most dangerous tornado in storm observing history.”
Alongside rush hour traffic, thousands of residents in Oklahoma City attempted to outrun the storm by taking to the roads in an attempt to drive out of the tornado’s projected path. By attempting to escape the storm by vehicle, in direct contrast to the recommended plan of action, residents put themselves at great risk from the storm; had the tornado maintained itself and passed over the congested freeways, more than 500 lives could have been lost.
The intensity of the tornado has been a subject of internal debate within the National Oceanic and Atmospheric Administration. The agency utilizes the Enhanced Fujita Scale to rate and assess tornado intensity based on the damage left behind. This excludes the use of supplementary measurements, such as those from mobile radar, in concluding a tornado’s intensity. Initially receiving an official EF3 rating based on damage, the El Reno tornado was subsequently upgraded to a radar-estimated EF5 rating, the highest on the scale, based on data from a mobile radar. The University of Oklahoma’s RaXPol mobile Doppler weather radar, positioned at a nearby overpass, measured winds preliminarily analyzed as in excess of 295 mph (475 km/h).