Casey B. Griffin-February 16

High-temporal Resolution Observations of the 27 May 2015 Canadian, Texas, Tornado using the Atmospheric Imaging Radar

On 27 May 2015, the Atmospheric Imaging Radar (AIR) collected high-temporal resolution radar observations of an EF-2 tornado near Canadian, Texas.  The AIR is a mobile, X-band, imaging radar that uses digital beamforming to collect simultaneous RHI scans while steering mechanically in azimuth to obtain high-temporal weather data.  During this deployment, 20º-by-80º sector volumes were collected every 5.5 s at ranges as close as 6 km.  The AIR captured the late-mature and decaying stages of the tornado.  Early in the deployment, the tornado was 1 km in diameter and exhibited maximum Doppler velocities near 65 m/s.

This study documents the rapid vortex structure changes associated with the dissipation stages of the tornado.  Axisymmetric analyses are used to interrogate changes in tangential flow and reflectivity structure associated with a decreasing tornado core diameter and a transition from a two-cell to a one-cell vortex flow.  Additionally, a time-height investigation of Delta-V is presented and illustrates an instance of upward vortex intensification as well as downward tornado dissipation.  Vortex tilt is also interrogated in a time-height perspective and a persistent region of enhanced vortex tilt is discussed.  Finally, a high-temporal resolution angular momentum budget and a time sensitivity analysis of the angular momentum budget will be presented.