Zhaoming Li, Lanqiang Bai, P. W. Chan, Peiling Fu. 2024: Fine-scale Phased-array Radar Observations of an EF2 Tornadic Supercell near Mountain Lees. Adv. Atmos. Sci., https://doi.org/10.1007/s00376-024-4094-x
Citation: Zhaoming Li, Lanqiang Bai, P. W. Chan, Peiling Fu. 2024: Fine-scale Phased-array Radar Observations of an EF2 Tornadic Supercell near Mountain Lees. Adv. Atmos. Sci., https://doi.org/10.1007/s00376-024-4094-x

Fine-scale Phased-array Radar Observations of an EF2 Tornadic Supercell near Mountain Lees

  • This study presents finely resolved radar signatures of multiple cyclonic vortices associated with an EF2 tornadic supercell that occurred in Guangzhou on 16 June 2022 and elucidates how the shallow tornadic mesocyclone formed on mountain lees. A nearby X-band phased-array radar provides evidence that the mesocyclone was shallow, with a depth generally under 3 km. The mesocyclone was observed to develop from ground level due to the interaction between intensifying cold pool surges and shallow lee-side ambient flows. It was first recognized shortly after the presence of near-ground cyclonic convergence signatures over the leading edges of cold pool outflows. Within the next 17 min, the mesocyclone developed upward and spawned a tornado 8 min later. Almost at the time of tornadogenesis, a noticeable separation of low-level tornado cyclone from the midlevel mesocyclone was identified. This shift in the vertically oriented vortex tube was likely caused by modifications to the low-level flow due to the complex hilly terrain or by occlusions associated with rear-flank downdrafts. After tornadogenesis, high-resolution X-PAR observations revealed that the lowest-level mesocyclonic signature contracted into a gate-to-gate tornado vortex signature (TVS) at the tip of the hook echo. Compared to traditional S-band weather radars, rapid-scan X-PAR observations suggest that to extend the lead time for Doppler-based tornado warnings, a core diameter threshold of 1.5–2 km could be used to identify a cyclonically-sheared radial velocity couplet as a TVS.
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