Tornadogenesis and Associated Phenomena

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9617318 Rasmussen During the Springs of 1994 and 95, a field program entitled the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX) was executed by a combination of NSF and National Oceanic and Atmospheric Administrations sponsored scientists. The primary objective of VORTEX was to evaluate several hypotheses pertaining to low-level mesocyclone intensification, and tornado formation, maintenance, and demise. The observations collected include ground-based (mobile and stationary) and airborne Doppler radars, mobile surface and balloon borne meteorological instruments. Eight of the VORTEX cases are of primary interest in the investigations supported under this award. First, several cases of tornadogenesis will be examined. The Dimmitt and Friona, TX, tornadic cases of 2 June 1995 were particularly well sampled by the suite of VORTEX sensors. Observations made near the Hanston, KS tornado (16 May 1995), Kellerville and Allison, TX (8 June, 1995), and Temple, OK (17 April 1995) also will be analyzed. These cases span a large variety of tornadoes, from a brief, weak tornado in an unexpected location to one of the most severe tornadoes ever observed (in terms of the combination of damage path width and intensity). In order to begin to adequately evaluate hypotheses concerning tornadogenesis and low-level mesocyclone intensification, the Principal Investigators will compare the tornadic cases described above with several well-sample non- tornadic supercells. All of these storms will be studied using a combination of airborne Doppler radar, the newly developed "Doppler-on-Wheels" (DOW), mobile mesonetwork, upper air soundings, and stereo photogrammetric cloud mapping. The synthesis of all of these data sources is considered vital to any comprehensive understanding of the dynamics of the processes being investigated. The proposed work is of vital importance to progress in understanding supercell dynamics and issues of t ornado formation and demise. If proposed hypothesis regarding tornadogenesis are verified, then it is possible that a new radar tornado signature could be developed with the potential of significantly reducing false alarms and increasing the probability of detection of tornadoes. ***