Analysis of the Shelbyville, TN Anticyclonic Tornado (276)

Matthew Reagan, National Weather Service Forecast Office, Nashville, TN

 

Abstract:

On April 5, 2017, a series of supercells swept northeast across the Nashville county warning area with numerous severe hail and damaging wind reports. NWS Nashville received damage reports near the path of a left-split supercell in Shelbyville, TN. Upon completing damage surveys and reviewing video, it was determined the damage was caused by an EF-1 tornado with a path length over 5 miles. Evidence from the videos pointed to an anticyclonic tornado. Closer inspection of radar data showed low level (4000 ft AGL) anticyclonic rotation and radar echoes offset from the damage path by at least 3 miles. This study examines whether the tornado was the result of the anticyclonic mesocyclone or a landspout which developed along the flanking line of the supercell. Arguments for both possibilities will be presented using mesoscale ingredients, radar data, survey results, and video evidence.