Convective Meteorology (Mesoscale Dynamics)

Dual-Doppler and polarimetric observations of two tornadic supercells in central Oklahoma on

Zach Wienhoff

School of Meteorology

06 November 2015, 3:00 PM

National Weather Center, Room 5600
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

On 19 May 2013, two supercells moved through central Oklahoma and produced seven tornadoes, including one of EF-3 and one of EF-4 intensity. High temporal and spatial resolution observations were collected in both strong tornadoes by a mobile, rapid-scan, X-band, polarimetric radar (RaXPol). In conjunction with the nearby WSR-88D Twin Lakes radar, dual-Doppler analyses were synthesized to produce the three-dimensional wind field and vertical vorticity throughout the tornadoes’ lifecycles. In order to account for significant differences in the temporal resolutions of the two radars, a reflectivity-tracking scheme was employed to interpolate linearly (in a Lagrangian sense) between two radar volumes through a variational algorithm. These analyses are unique because they are one of the first, to the authors’ knowledge, to make use of data from both an operational, S-band radar and a mobile, rapid-scan, X-band radar.

This work will focus on the methodology used to combine both RaXPol and KTLX datasets, including discussion regarding the strengths and weaknesses of this technique. Analyses will be presented on the both the Edmond-Carney and Norman-Shawnee tornadoes, examining the characteristics of the wind field associated with the intensification, maturity, and demise of the tornado. The 3-D wind fields of the tornado and mesocyclone will be examined to see how they evolved in time, and especially how vertical vorticity and vertical velocity changed as the tornado intensified. Differential reflectivity (ZDR) from the WSR-88D will be compared to the vertical velocity field estimated from dual-Doppler analyses to examine how the characteristics of a ZDR column varied with respect to changes in the updraft intensity. Results from both cases will be compared, and some thoughts on future improvement to this technique will be presented.

Convective Meteorology (Mesoscale Dynamics) Seminar Series website