The Kellerville Tornado during VORTEX: Damage Survey and Doppler Radar Analyses

A detailed aerial and ground survey of a long-track (50 km) F5 tornado is presented. The survey revealed that the tornado exhibited unusual nonlinear movements at two different locations. One portion of the track was associated with a pronounced sinusoidal pattern while another location was characterized by a cusplike pattern. For the first time, high-resolution dual-Doppler wind measurements can be used to evaluate mechanisms for such deviations from a linear tornado path. The analyses of data collected with Electra Doppler Radar (ELDORA) suggest that these departures are trochoidal marks produced as the tornado was revolving within the larger-scale mesocyclone. Retrieved perturbation pressures indicate that the mesocyclone departed significantly from a cyclostrophically balanced state during these deviations. The maximum vorticity associated with the mesocyclone at low levels was shown to be an unreliable indicator of the tornado's intensity.