□ On May 31, 2013, a train of violent supercell thunderstorms erupted in the sky to the west of Oklahoma City. In the city suburb of Moore, rain began to fall over the tangled remains of homes and businesses obliterated less than two weeks earlier by a catastrophic EF5 tornado. Meteorologists at the National Weather Service recognized the tell-tale signs of a rotating mesocyclone on radar, and reports from storm chasers near the community of El Reno quickly verified the presence of a large, nebulous mass of clouds that had spun down to the ground. A rare tornado emergency was issued for the area a second time.
An unusually large number of storm chasers, both amateur and seasoned, drove down the perfect grid of county roads to the south of El Reno to film the ensuing storm. Like many large tornadoes, the El Reno storm began with a series of transient funnels beneath a rapidly rotating mesocyclone. Heavy rain left few good angles to film the storm, so most chasers concentrated near Highway 81 just northeast of the tornado. As the storm progressed slowly to the east-southeast it underwent a period of explosive strengthening. The already large tornado suddenly doubled in size in less than one minute (many say less than 30 seconds) to over two miles in width. Footage from multiple storm chasers showed a sudden increase in surface winds well away from the visible funnel. Near the intersection of Choctaw Avenue and SW 15th Street, two vehicles were engulfed by the storm, killing both drivers. One of the men killed, Richard Henderson, became the first amateur storm chaser fatality in history.
A Weather Channel vehicle driving on Highway 81 was impacted by a violent wind feature, causing it to tumble through an adjacent field (initial reports stated the car travelled 200ft while later broadcasts reported 200 yards). All of the vehicle’s passengers were injured to some degree but most were able to walk away from the wreckage. Around this time, the tornado was completing an unexpected turn to the northeast. Highly knowledgable storm chasers were caught off guard by the storm’s size and unpredictability. A motorist due east of the Weather Channel crew was killed by the tornado at the intersection of Alfadale Road and Reno Street. Along SW 10th Street, a white car carrying three professional storm chasers was swept off the road west of Radio Road. Unlike the Weather Channel vehicle, the car driven by Tim Samaras was hurled 650 yards through the air at a high rate of speed (AMS, 2013). The three chasers, likely with cameras in hand, were all killed in the “unsurvivable” wreck. Several minutes later, the tornado swept across the I-40, killing a young mother and her infant son in a car hurled from the freeway. Forty minutes after first forming, the tornado weakened and dissipated.
I surveyed the damage from the El Reno tornado and interviewed local residents on June 4th and 5th. Photographs from my survey are shown below, and my final analysis can be found at bottom.
*In August of 2013, the El Reno tornado was officially downgraded to an EF3 by the National Weather Service (Querry/NWS, 2013).
Personal Damage Survey Conclusions:
Due to my belief that the Enhanced Fujita Scale grossly underestimates winds in violent tornadoes, the wind ranges I utilize are based on my research, discussions with wind engineers and comparisons between known surface readings and adjacent damage indicators in past tornadoes. My wind estimates are significantly higher than those employed by the National Weather Service.
Peak Intensity: EF4 (≈220mph)
□ The most intense damage occurred to vegetation in a swath of varying width from an area commencing just west of the intersection of 10th Street and Radio Road and ending at the I-40. Steel fence posts were bent to the ground by winds alone and not debris impacts. Powerlines were sheared just above ground level, vehicles were thrown over 200 yards and surface crops were severely damaged and bent to the east-northeast. The most intense structural damage likely occurred to the OKC West Livestock Market just north of the I-40 and several homes west of Highway 81. The most intense structural damage was consistent with winds in the EF3 range. The scarcity of trees and buildings left few reliable damage indicators, but no EF5-level vegetation damage was noted.
□ While the tornado has been deemed the “second strongest” in recorded history due to extreme doppler velocities, this claim is completely unfounded. Few violent tornadoes are ever tracked by mobile doppler radar, so the available readings are not an objective method of classification.
□ While the tornado is being called the “widest” in history, this claim is also unfounded. The 1999 Mulhall tornado likely left a significantly wider damage path. In terms of violent tornado damage, the damage swath from the 2013 El Reno tornado was narrower than many documented tornadoes, including the 2011 Joplin tornado.
The width of EF0+ damage along Highway 81 was 2.55 miles in width, as measured by the distance between the northernmost and southernmost instances of missing shingles and downed tree branches. The southern margin was 300 yards south of SW 29th Street and northern margin was just north of 10th Street. Straight line wind damage was found in areas unaffected by the tornado, so the exact damage contours were impossible to ascertain.