Predicting Supercell Motion Using a New Hodograph Technique
FEBRUARY 2000 BUNKERS ET AL. 61 Predicting Supercell Motion Using a New Hodograph Technique MATTHEW J. BUNKERS* AND BRIAN A. KLIMOWSKI NOAA/NWS Weather Forecast Of®ce, Rapid City, South Dakota JON W. Z EITLER NOAA/NWS Houston/Galveston Weather Forecast Of®ce, Dickinson, Texas RICHARD L. THOMPSON NOAA/NWS Storm Prediction Center, Norman, Oklahoma MORRIS L. WEISMAN NCAR/Mesoscale and Microscale Meteorology Division, Boulder, Colorado (Manuscript received 16 December 1998, in ®nal form 13 September 1999) ABSTRACT A physically based, shear-relative, and Galilean invariant method for predicting supercell motion using a hodograph is presented. It is founded on numerous observational and modeling studies since the 1940s, which suggest a consistent pattern to supercell motion exists. Two components are assumed to be largely responsible for supercell motion: (i) advection of the storm by a representative mean wind, and (ii) propagation away from the mean wind either toward the right or toward the left of the vertical wind shearÐdue to internal supercell dynamics. Using 290 supercell hodographs, this new method is shown to be statistically superior to existing methods in predicting supercell motion for both right- and left-moving storms. Other external factors such as interaction with atmospheric boundaries and orography can have a pronounced effect on supercell motion, but these are dif®cult to quantify prior to storm development using only a hodograph. 1. Introduction some form of severe weather (i.e., tornadoes, ¯ash ¯ooding, hail $1.9 cm diameter, wind gusts $25 m s21, a. Background or wind damage) during their lifetime (e.g., Burgess and Although supercells1 have been given considerable Lemon 1991).
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