Airborne Pseudo-Dual-Doppler Analysis of a Rear-Inflow Jet and Deep Convergence Zone within a Supercell

Abstract

On 22 May 1995, numerous thunderstorms, several of which produced large hail and small tornadoes, formed along a dryline in the central and northern Texas Panhandle. The only long-lasting, daytime, severe storms developed later, south of the earlier storms. By late afternoon, new cells merged and evolved into two large supercells. The northern supercell produced three weak tornadoes and hail; the southern supercell did not produce a tornado, but did produce very large hail for an extended period of time. Verification of the Origins of Rotation in Tornadoes Experiment crews collected data in the southern supercell from its early stage through much of its mature stage. The National Center for Atmospheric Research Electra Doppler Radar collected pseudo-dual-Doppler radar data on this storm continuously for well over an hour. Detailed analyses of this high-resolution dataset revealed several unusual features, most notably an intense elevated rear-inflow jet at midlevels having maximum wind speeds approaching 60 m s?1. Flanking this jet was a strong cyclone?anticyclone couplet. Moreover, a deep convergence zone (DCZ) that extended from the surface up through midlevels was present at the interface between the rear-inflow jet and the strong southeasterly inflow (over 40 m s?1 just above the ground) to the storm. The formation and potential importance of the rear-inflow jet, vorticity couplet, and DCZ are analyzed in detail, with emphasis on comparisons to similar features often found within mesoscale convective systems.