385 A Radar and Warning Decision Analysis of an Anomalous Tornadic Supercell in the Texas Panhandle

Monday, 8 January 2018
Exhibit Hall 3 (ACC) (Austin, Texas)
Mark R. Conder, NOAA/NWS Forecast Office, Lubbock, TX; and S. Cobb and G. Skwira

This study examines the events leading up to and through the duration of a multi-vortex tornado that impacted mainly rural areas of Castro County in the southwest Texas Panhandle, immediately to the west and northwest of Dimmitt, Texas, on 14 April 2017. During the course of the tornado it damaged and destroyed several structures and numerous power poles and center pivot irrigation systems. The tornado incurred an EF-3 rating by the NWS damage survey team, primarily due to the destruction of a large metal building. This significant tornado was spawned by a nearly stationary supercell thunderstorm that also produced several short-lived tornadoes, baseball-sized hail and torrential rainfall during the course of the late afternoon and evening hours of the 14th.

Details regarding the atmospheric environment that supported the supercell thunderstorm and tornado will be discussed. Specifically, strong convective instability was present, though coinciding with some inhibition and minimal large-scale support. In addition, middle and upper tropospheric wind fields remained relatively weak through the event, while the low-level kinematics became stronger with time.

Once the parent supercell thunderstorm developed, it quickly began to rotate and produce large hail. The supercell then slowed to a crawl and produced its first tornado about two hours after the initial severe hail report. The significant tornado followed roughly 50 minutes later. The nearly stationary storm and long duration tornado led to a highly non-linear cyclonically curved tornado track. Creating a representative tornado warning polygon was a challenge due to the non-linear track. NWS WSR-88D radars KFDX (Cannon AFB, New Mexico), KAMA (Amarillo, Texas) and KLBB (Lubbock, Texas) are located approximately equal distances from the location of the significant tornado and provided for detailed comparison of the radar moments around the time of the tornado. We will also discuss the challenges and explore different warning methodology strategies for these conditional but potentially significant severe weather events and non-linear tornado paths.

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