21st Conf. on Severe Local Storms and 19th Conf. on Weather Analysis and Forecasting/15th Conf. on Numerical Weather Prediction

Thursday, 15 August 2002
Initial Examination of the Tornadic and Non-Tornadic Supercells on 20 September 2000: Includes the F4 Xenia Tornado
James G. Lott, NOAA/NWS, Wilmington, OH; and J. T. DiStefano
Poster PDF (542.6 kB)
During the late afternoon and evening hours of 20 September 2000, a squall line developed across western Indiana and moved east into Ohio, where the environment was moderately unstable and strongly sheared. This squall line produced widespread, straight-line wind damage as well as two tornadoes. The first tornado, produced by a low-topped, high precipitation supercell, was responsible for generating a short-lived, but intense, F3-F4 damage track about 18 miles northwest of the Wilmington, Ohio WSR-88D. The second tornado spawned during this event was classified as an F2, and occurred approximately 65 miles northeast of the Wilmington WSR-88D. During the midst of this severe weather outbreak, two isolated, low-topped supercells developed just ahead of the squall line. Although these storms displayed a strong and persistent rotation, neither produced a tornado. This study examines, from a radar perspective, the structure of both the tornadic- and non-tornadic producing supercells, and provides some operational insight into this very difficult warning process.

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