The kinematic and cloud-to-ground lightning structure of the 9-10, June 1998 Red River Mesoscale Convective System

Abstract

An investigation of the kinematic and electrical properties of the 9-10 June, 1998 Red River Mesoscale Convective System (MCS), as observed by the NOAA P3 Tail Radar and the National Lightning Detection Network, is presented. This system exhibits both bow echo and supercell-like features. Wind and vorticity retrievals show distinct kinematic features which agree well with current conceptual models for both systems. During the course of the observations the two features which begin as distinct systems merge. During this merger the strength of both the low and mid-level mesocyclone, and the northern cyclonic bookend vortex are enhanced, while the anticyclonic vorticity of the bookend on the southwest end of the bow is greatly reduced. The Cloud-to-Ground (CG) lightning associated with the supercell updraft is also studied. Recent hypothesis suggest that strong updrafts, such as the ones observed in this system may elevate the lower main charge center so that CG lightning is reduced. Observations of updraft speed and lightning frequency indicate that as updraft speed increases the overall frequency of lightning strikes is decreased. This agrees with the hypothesis and other similar observations. A decrease in the percentage of positive lightning flashes with increasing vertical velocity is also observed. Given the dominance of positive lightning in this storm and other microphysical considerations, this suggests a process which may be responsible for the enhancement of positive flash frequency in this storm.