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- Title
Descending and Nondescending Tornadic Vortex Signatures Detected by WSR-88Ds.
- Authors
Trapp, R.J.; Mitchell, E.D.; Tipton, G.A.; Effertz, D.W.; Watson, A.I.; Andra Jr., D.L.; Magsig, M.A.
- Abstract
Tornadic vortex signatures (TVSs) of 52 tornadoes were identified and analyzed, then characterized as either descending or nondescending. This characterization refers to a known tendency of radar-observed tornadic vortices, namely, that of their initial detection aloft and then of their subsequent descent leading to tornadogenesis. Only 52% of the sampled TVSs descended according to this archetypal model. The remaining 48% were detected first near the ground and grew upward or appeared nearly simultaneously over a several kilometer depth; these represent primary modes of tornado development that have been explained theoretically. The descendingnondescending TVSs were stratified according to attributes of the tornado and TVS. Significantly, tornadoes within quasi-linear convective systems tended to be associated with nondescending TVSs, identification of which provided a mean tornado lead time of 5 min. Two case studies are presented for illustrative purposes. On 1 July 1997 in southern Minnesota, nondescending TVSs and associated tornadogenesis were revealed in the leading edge of a squall line, with a squall linesupercell merger, and later during that day, with the cyclonic bookend vortex of a bow echo. On 22 June 1995 in southern Colorado, a low-topped supercell storm produced a tornado that was associated with a descending TVS.
- Subjects
UNITED States; TORNADOES; DOPPLER radar
- Publication
Weather & Forecasting, 1999, Vol 14, Issue 5, p625
- ISSN
0882-8156
- Publication type
Article
- DOI
10.1175/1520-0434(1999)014<0625:DANTVS>2.0.CO;2