Polarimetric and Dual-Doppler Radar Observations of the Lipscomb County, Texas, Supercell Thunderstorm on 23 May 2002

Abstract

Polarimetric and dual-Doppler observations of a supercell observed by the National Center for Atmospheric Research (NCAR) S-band Polarimetric (SPOL) radar, two Doppler-On-Wheels (DOW) radars, and the Greek XPOL radar on 23 May 2002 during the International H2O Project (IHOP) are presented. The polarimetric radar observations began as the storm organized into a supercell and continued for over an hour while the storm was in its mature phase. The hydrometeor distribution within the mature storm was retrieved using a fuzzy logic hydrometeor classification algorithm. The dual-Doppler radar observations began around the time that the polarimetric radar observations concluded, and they covered the end of the mature phase and much of the dissipation phase of the storm. The dual-Doppler wind syntheses are used to evaluate the importance of the forward-flank outflow in augmenting the horizontal vorticity field near the storm above 400 m. In this case, having a relatively weak low-level mesocyclone, the parcel trajectories and the horizontal vorticity field observed within the forward-flank outflow are not what one would likely expect based on prior numerical studies (having generally stronger low-level mesocyclones) that have emphasized an important dynamical role for forward-flank downdrafts in terms of their horizontal vorticity generation. Instead, the observed trajectories could not be traced from the forward-flank outflow toward the storm?s updraft and the horizontal vorticity vectors within the forward-flank outflow generally did not point (westward) toward the storm?s updraft.