4.2
Some possible mechanisms for tornadogenesis failure in a supercell
David O. Blanchard, NOAA/NWS, Bellemont, AZ
A primary goal of the Verification of Rotation in Tornadoes Experiment (VORTEX) was to collect data using multiple platforms that could then be analyzed to test and possibly refute various tornadogenesis hypotheses. On June 8, 1995, VORTEX scientists were able to collect data on a strong, long-lived non-tornadic supercell which persisted for many hours and moved from the northeast Texas Panhandle into the Oklahoma Panhandle. The analysis of this storm is presented as an example of tornadogenesis failure.
Doppler radar data from the airborne NCAR Electra Doppler Radar (ELDORA) and the ground-based Doppler on Wheels (DOW), along with the surface mobile mesonet (MM) and mobile sounding systems (M-CLASS) were used to collect data while near and underneath the storm. The high spatial and temporal resolution of these data allow for a detailed analysis of the storm. An analysis of the dominant circulation features, the evolution of the rear and forward flank downdrafts, the cyclonic and anticyclonic circulation couplets, surface boundaries, and other features of the storm will attempt to determine the possible causes of tornadogenesis failure. Comparison between this non-tornadic supercell storm and other tornadic storms sampled in VORTEX clearly illustrate that many of the relevant features to the tornadogenesis process are also present in this storm and that the difference between a tornadic supercell and a non-tornadic supercell may be exceedingly subtle.
Recent work has suggested that a thermodynamic retrieval analysis can improve our understanding of the dynamic processes leading to tornadogenesis or tornadogenesis failure. We do not attempt to do a thermodynamic retrieval on this event for an important reason. The National Weather Service has no capability to do this in real time when the issuance of timely warnings is critical. One of our goals is to provide information that can be used in this “short-fuse situation” to aid in the dissemination of appropriate warnings. We present some suggestions to assist in the discrimination between these two types of storms.
Session 4, Tornadic/non-tornadic supercell discrimination
Wednesday, 12 January 2000, 2:30 PM-4:00 PM
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