Investigation of Vegetation Discontinuities Related to the Yazoo City Tornado Scar and Enhanced Convection

Abstract

The Yazoo City tornado occurred on April 24, 2010, traveling 240 km from Tallulah, Louisiana through Yazoo City, Mississippi and ending near Starkville, Mississippi. The tornado reached a maximum wind speed of 76 m s-1 and obtained a maximum width of 2.8 km. Landsat imagery showed a distinct vegetation scar along the majority of the path of the tornado. Abrupt changes in vegetation and the related sensible and latent heat fluxes have been shown to enhance convective activity along and near the resulting land surface discontinuities. The enhancement of convection is likely related to mesoscale circulations generated along thermal and moisture discontinuities and is best identified during synoptically benign periods. This study analyzed heightened convective activity (analyzed by looking at cloudto- ground lightning data) along the Yazoo City tornado track on days of weak synoptic forcing. 2010 had the greatest percentage of convectively active synoptically benign days with 66 percent. Years prior to the Yazoo City tornado had a lower percentage of convectively active synoptically benign days with 50 percent.