Extended Abstract (148K)P12.3
An Assessment of supercell and tornado forecast parameters through RUC-2 model close proximity soundings
Richard L. Thompson, NOAA/NSSL/SPC, Norman, OK; and R. Edwards and J. A. Hart
The preliminary investigation of Edwards and Thompson (2000) will be expanded to include a data set of 458 supercells that were observed across the contiguous United States from March 1999 through June 2001. Supercells were identified in base reflectivity and storm-relative velocity imagery, and an associated proximity sounding for each was interpolated spatially from hourly RUC-2 model analysis grids for each storm at the nearest surface observing site. Details regarding accuracy and representativeness of the RUC-2 analysis soundings will be presented in a companion paper by Thompson et al. (2002).
Our initial analysis of the sounding profiles confirms the findings of several previous studies, in that 0-1 km storm-relative helicity and lifted condensation level (LCL) height are the best single parameters in discriminating between significant tornadic and nontornadic supercells. We will also examine multiple combination parameters, storm-relative winds (both in fixed height and normalized to storm depth) for observed and estimated storm motions, fixed- and variable-depth shear magnitudes, and layer lapse rates and relative humidity, among numerous other parameters. A primary goal of this investigation is to aid in the operational discrimination between environments supportive of significant supercell tornadoes and nontornadic supercells. A sample of 75 proximity soundings for discrete non-supercells will also be used to quantify differences between supercells and non-supercell sounding parameters. Additionally, our findings will aid in the calibration of various supercell-related parameters as part of the hourly objective analysis scheme at the Storm Prediction Center described by Bothwell et al. (2002).
Poster Session 12, Tornado and Severe Storm Environments
Thursday, 15 August 2002, 3:00 PM-4:30 PM
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