An analysis of a long-lived MCV observed over the Southern Plains using Potential Vorticity diagnostics.

Abstract

On the morning of 28 May 1998, a mesoscale convectively-generated vortex (MCV) was observed over the Southern Plains. This MCV was evident in the GOES-8 visual satellite imagery resulting in a spectacular picture. An analysis of this event is offered using many data sources, including products available now via the world-wide-web (WWW), the National Center for Environmental Prediction (NCEP) re-analyses, and Eta model initializations. This MCV developed out of a mesoscale convective system (MCS) that existed during 26 and 27 May over Texas. This MCV was associated with reports of severe weather and heavy precipitation over southern Arkansas. While the MCV is shown to have characteristics similar to other MCV events documented, this event is unique in that it maintained it's character, while propagating further east than other events. A dynamical analysis using potential vorticity diagnostics (PV) shows that the mid-latitude vorticity field strengthened at least partially as a result of diabatic heating. Also, the most severe weather was associated with high values of integrated 500 - 300 hPa PV values over the Southern Plains.