Limited observations have resulted in few studies examining mesovortices within quasi-linear convective systems (QLCSs) in China, especially in Northeast China, where the polarimetric signatures of tornadic versus nontornadic vortices remain unclear. This study examined 12 mesovortices (including one that produced a tornado) within a QLCS that occurred on 18 August 2020 over the Liaohe Plain, Northeast China, using conventional observations, reanalysis data, and Doppler weather radar observations. The QLCS was associated with notable conditional instability and moderate-to-strong low-level shear under the influence of a cold vortex. Observed extreme winds, reaching up to 41.5 m s⁻¹, were located north of the rear-inflow jet (RIJ) core, a pattern consistent with mesovortices along the gust front rather than those at the bow echo apex. The tornadic mesovortex exhibited faster propagation speeds and stronger low-level rotation compared to its nontornadic counterparts. Notably, dual-polarization radar parameters indicated a marked increase in mid-level specific differential phase (K_DP) and lower average differential reflectivity (Z_DR) for the tornadic mesovortex. Hydrometeor identification (HID) analysis further revealed that above the wet-bulb zero (WBZ) level, the tornadic mesovortex contained a higher proportion of hail, whereas below the WBZ, it exhibited a greater concentration of smaller raindrop particles. The Eulerian vorticity budget analysis identified the stretching term as the largest contributor to vortex intensification, especially in its initial stage. The tornadic mesovortex originated as a bookend vortex at the intersection of two QLCS segments, with a transient northern anticyclonic vortex observed in its immediate vicinity during the convective merger process. These findings provide valuable observational context and conceptual models on the structure and evolution of mesovortices within QLCSs, offering guidance for improving the forecasting of tornadic and nontornadic mesovortices in QLCSs over Northeast China.

An EF1 tornado occurred in the northern coast of the Bohai under the background of cold vortex on 16 August 2019. Using the Yingkou S-band dual-polarization Doppler weather radar data, surface automatic weather station (AWS) observations at 5 min interval, the Panjin wind profile radar data and ERA5 reanalysis data, the environmental background, the structure and formation of the tornadic storm and the tornadogenesis are studied. The results show that the tornado occurred under the background of a cold vortex at 500 hPa, and it was located in the water vapor conveyor belt on the west side of the residual vortex of typhoon "Lekima". The environmental condition is characterized by weak vertical wind shear and strong low-level thermal instability. The Yingkou dual-polarization radar is located 15 km away from where the tornado originated. The hook echo, the descending reflectivity core (DRC), the weak echo hole (WEH), and the tornadic debris signature (TDS) in mini supercell are detected by the radar. The outflow of the decaying thunderstorm gust front moved westward, while the sea breeze front near Yingkou slowly moved eastward. The two boundary layer convergence lines merged, leading to the forming of γ-mesoscale vortex under the influence of horizontal shear instability. The intersection of outflow boundaries, the large positive ambient buoyancy and the vertical perturbation pressure gradient associated with the low pressure induced by the middle level mesocyclone jointly produced strong updrafts. The collocation of the updrafts and the γ-mesoscale vortex played a critical role for the genesis of misocyclone by strong stretching. The combination of the maximum rotation velocity and the minimum diameter of the misocyclone corresponded to the tornadogenesis, and the separation of the misocyclone and the mesocyclone in the middle level led to the dissipation of the tornado.

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 (Z_DR) in the hook echo region compared with the non-tornadic supercells, indicating smaller median drop sizes. A distinct increase in Z_DR 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 (K_DP) 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 Z_DR arc and the K_DP foot was observed during tornadogenesis. The vertical gradient of K_DP 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 Z_DR, K_DP, and drop size distribution trends could assist with tornado prediction and warnings.