Thursday, 7 October 2004: 11:00 AM
In the past, observational studies of supercell storms primarily focused on the tornadic phase and tornadogenesis. These studies have indicated an important relationship between the rear-flank downdraft (RFD) and tornadogenesis. However, to better understand the processes that lead to tornadogenesis, it is necessary also to study cases with genesis failure. High-resolution dual-Doppler radar data provides an opportunity to document the evolution of these processes. On May 29th, 2001, two 3-cm Doppler on Wheels (DOW) radars intercepted a cyclic supercell located near Kress, TX. The deployment occurred as the storm matured and showed a very strong mesocyclonic signature. It later transitioned to a tornadic high-precipitation (HP) supercell. The dual-Doppler synthesis of this case utilized 15 minutes of data including two cycles of the mesocyclone. Analysis of the data focused primarily on the rear-flank of the storm, with areas of interest including multiple mesocyclones and associated rear-flank downdrafts. An attempt was made to resolve the 4-D structure of these features to document their genesis, growth/evolution, and decay. Specifically, the dimensional extent and magnitude of negative vertical velocity (corresponding to RFD regions) were analyzed along with their relation to reflectivity and mesocyclone signatures. Possible reasons for the failure of the strong mesocyclone to produce a tornado will be explored.
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