20 Diagnosis of Conditional Maximum Tornado Damage Probabilities

Monday, 5 November 2012
Symphony III and Foyer (Loews Vanderbilt Hotel)
Bryan T. Smith, NOAA/NWS/NCEP/SPC, Norman, OK; and R. L. Thompson, H. E. Brooks, A. R. Dean, and K. L. Elmore
Manuscript (4.0 MB)

Radar-based convective modes, peak low-level rotational velocities, and near-storm environment data were assigned to a sample of tornadoes (e.g., EF2 > 2009-2010, EF0 > 2011) reported in the contiguous United States (CONUS) during 2009-2011. The tornado segment data were filtered by the maximum EF-scale tornado event per hour on a 40 km Rapid Update Cycle model horizontal grid. Convective mode was assigned to each tornado event via manual examination of full volumetric WSR-88D data at the beginning time of each event, and peak low-level rotational velocity was calculated during the life span of each tornado event. Environmental information, consisting primarily of supercell-related convective parameters from the hourly objective mesoscale analyses calculated and archived at the Storm Prediction Center (SPC), accompanied each grid-hour event. Preliminary results suggest that a simplified 2-D near-storm environment – radar product relationship, featuring the Significant Tornado Parameter (STP) and peak rotational velocity (Vrot) data using lowest elevation tilt (i.e., 0.5 degree elevation scan), exhibits an increasing probability for greater EF-scale damage as both STP and Vrot increase. The findings also indicate that inclusion of convective mode information with Vrot and STP further improves identification of potentially intense tornadoes. Possible applications include the development of conditional tornado intensity guidance for real-time, semi-automated tornado identification and short term forecasts, and some post-event utility in assessing a range of expected damage intensity in a damage survey setting.
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