Microphysical Insights into a Tornadic Supercell from Dual-Polarization Radar Observations in Jiangsu, China on 14 May 2021

Tornadoes are incredibly powerful and destructive natural events, yet the microphysical characteristics of the parent storm and its effects on tornadogenesis remain unclear. This study analyzed polarization radar data of a tornadic supercell that occurred in Jiangsu Province of China on 14 May 2021, in comparison with another tornadic supercell and two non-tornadic supercells that occurred in the same region in 2023. The two tornadic supercells exhibited lower differential reflectivity (ZDR) in the hook echo region compared with the non-tornadic supercells, indicating smaller median drop sizes. A distinct increase in ZDR from the melting of frozen hydrometeors, observed between 2.5- and 4.0-km altitude in the non-tornadic storms, was absent in the tornadic cases. The non-tornadic supercells also displayed substantially higher specific differential phase (KDP) below the melting level, likely aroused from enhanced melting and cooling. These findings suggest fundamental microphysical contrasts between tornadic and non-tornadic supercells. Specifically, tornadic supercells have smaller droplets and may reduce melting in hook echoes. Moreover, greater separation between the ZDR arc and the KDP foot was observed during tornadogenesis. The vertical gradient of KDP related to the cooling pool strength of the hook echo, regulating rear-flank downdraft thermodynamics. Despite the limited number of cases investigated, the findings of this study indicate that monitoring ZDR, KDP, and drop size distribution trends could assist with tornado prediction and warnings.