Structure of a Tornado Based on an Analysis of Lofted Debris Speeds, Debris Orientation, and Mobile Radar Data

An EF1 tornado was documented using photographs, a high-resolution video, and a mobile radar as it entered Selden, Kansas, on 24 May 2021. The kinematic structure of the tornadic wind field was presented by tracking lofted debris and analyzing single-Doppler velocities. Tracking of debris on the side of the tornado farthest from the observer was possible due to the transparent nature of the debris cloud. The analysis suggests that the circulation was axisymmetric with the maximum horizontal velocities located at low levels. The positive vertical velocities were strongest on the forward side of the tornado. The maximum vertical velocities were associated with a secondary vortex. For the first time, the dataset provided an opportunity to assess the orientation of a large, lofted debris based on the images recorded by a movie and compare these observations with the differential radar reflectivity (Z_DR) recorded by a mobile polarimetric radar. The T-matrix calculations of wood boards yielded a mean Z_DR that was negative and was also observed in the Z_DR analysis suggesting a preference for lofted debris to be vertically oriented.