12.5 High-Temporal Resolution Observations of the 27 May 2015 Canadian, Texas, Tornado Using the Atmospheric Imaging Radar

Thursday, 11 January 2018: 2:30 PM
Room 17B (ACC) (Austin, Texas)
Casey B. Griffin, Univ. of Oklahoma, Norman, OK; and D. J. Bodine, J. M. Kurdzo, A. Mahre, and R. D. Palmer

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 resolution 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 associated with a decreasing tornado core diameter and the transition from a two-cell to a one-cell vortex flow. Additionally, a time-height investigation of Delta-V and a high-temporal resolution angular momentum budget will be presented. Finally, the temporal evolution of circulation over a range of areal extents will be studied to understand how the spatial distribution of vorticity changes in time.

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