Tornadic Debris Signature and Debris Fallout Analysis of the 10-11 December 2021 EF4 Tornado

The late-season tornado outbreak of 10 – 11 December 2021 left an unprecedented impact across the south-central United States. With ample shear, instability, and moisture present, the environment was primed for potentially significant, long-lived tornadoes and resulted in being the deadliest outbreak on record for the month of December. By utilizing data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) network, the evolution of tornadic supercells can be observed from polarimetric signatures throughout a tornado’s lifecycle. In the case of the Mayfield, Kentucky tornado, observations made by WSR-88D in Paducah (KPAH) presented various debris-related signatures as a result of the ongoing EF4 tornado. In particular, debris-related signatures included a well-pronounced and long-lived tornadic debris signature (TDS), a debris-induced three body scatter spike (TBSS), and a debris fallout signature (DFS) collocated within the forward-flank downdraft (FFD). This study primarily assesses the similarities and differences in the TDS and DFS over time before and after the tornado impacted Mayfield, KY. The values of polarimetric variables such as ρ_HV related to the TDS area and areal extent of the DFS will be examined as a function of time and height. These signatures can greatly vary throughout the progression of the tornado’s lifecycle. For instance, the TDS area is observed to increase with height with fluctuations in the vertical profile of ρ_HV. Near the surface, debris fallout tends to first remain localized near the forward-flank downdraft’s southern edge before advecting northeastward throughout the supercell over time. The knowledge resulting from this study aim to be useful within operational settings, providing insight regarding ongoing damage that can be communicated in operational warning messages.