EF2 tornado in Custer County, Oklahoma

A television storm chaser observed this tornado develop northwest of E0930 Road and N2205 Road moving southeast crossing E0930 Road. Initially the tornado was a narrow tornado, then as it turned east-northeast quickly become a large multiple-vortex tornado as observed visually and in the damage pattern. The total damage width was about 2.7 miles along N2240 Road, including both damaging inflow winds north of the tornado and very strong damaging Rear Flank Downdraft (RFD) winds south of the tornado, but the tornado width itself was about one mile wide based on the damage survey and preliminary mobile radar data from Texas Tech University. The tornado narrowed as it approached US-183 near E0920 Road and dissipated soon afterwards.

Although tree and power pole damage was observed along the entire path, the most significant structure damage occurred along E020 Road from near N2240 Road to just east of US-183. At least two outbuildings were destroyed and two others damaged and one home had roof damage. As the tornado approached N2260 Road, a trailer and a rail car used for storage were blown a significant distance to the west, despite being on the southern periphery of the damage area, giving further evidence of the multiple-vortex tornado.

Preliminary data from a Ka-band mobile research radar from Texas Tech University showed a peak instantaneous velocity of 87.9 m/s (197 mph) at about 30 meters AGL when the tornado was approximately 6 miles west-northwest of Custer City. This was an instantaneous velocity measurement which is not directly compatible with the 3-second average wind velocity used by the EF-scale to determine intensity, but does provide indirect evidence that the tornado was likely stronger locally than the EF2 rating based on the damage survey.

Significant severe weather occurred across portions of western into central Oklahoma from the late afternoon of the 19th through early morning on the 20th. Aloft, a strong and compact upper wave moved across portions of Kansas during the afternoon. While most severe weather outcomes were expected further north of the WFO Norman area, a few supercell thunderstorms developed along a trailing dryline near the 100th meridian. This included a powerful supercell thunderstorm that moved from Hemphill County, Texas (WFO Amarillo, Texas) into portions of Roger Mills/Custer/Washita/Blaine/Canadian/Oklahoma counties during the afternoon into late evening hours. This thunderstorm was responsible for thirteen (13) tornadoes, including significant tornadoes west of Custer City and near Yukon, Oklahoma. Significant damaging wind gusts/damage and large to very large hail also occurred with this thunderstorm. Additional hail-producing supercells developed into portions of northwestern Oklahoma during the evening, with one becoming briefly tornadic during the late evening across Woods County, Oklahoma.