Kinematic and Dynamic Aspects of the Harrah Tornadic Storm Analyzed from Dual-Doppler Radar Data

Abstract

Abstract The paper deals with a diagnostic study of the three-dimensional kinematic and dynamic structure of the Harrah tornadic storm. Wind fields were computed from data collected over a 28 min interval in four dual-Doppler radar volume scans during a tornado occurrence. Associated with this storm, there was a strong low-level inflow jet supplying warm, moist air to a tilted updraft, a mid-level vortex doublet, and downdrafts on both storm flanks. The left flank downdraft intensified, undercut the tilted updraft, and formed a gust front along the right rear flank. The gust front propagated cyclonically around the mesocyclone. Calculations of divergence and vorticity showed that in the middle troposphere, the updraft nearly coincided with cyclonic vorticity approximately 10−2 s−1. The low-level tornado cyclone was between the horizontally sheared inflow-outflow region. A mechanism for producing and intensifying this vorticity and downdraft structure is presented on the basis of calculations of the tiltin...