Convective Meteorology (Mesoscale Dynamics)

Rapid-scan, polarimetric, mobile, Doppler-radar observations of the formation, evolution, and structure of the El Reno tornado of 31 May 2013

Kyle Thiem

School of Meteorology

04 March 2016, 3:00 PM

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

On 31 May 2013, the mobile, Rapid-scan, X-band, Polarimetric (RaXPol) radar collected a high spatial and temporal resolution dataset documenting the genesis, intensification, and dissipation of a tornado that caused EF-3 damage near El Reno, OK, although Doppler velocities measured by RaXPol exceeded of 135m/s near the surface. The RaXPol mobile radar was deployed three times during the tornadic phase of this storm, between 4.5-11 km from the center of the tornado, and collected 360 degree PPI scans every 2 seconds with range gate spacing between 45 to 15 meters. The evolution of the Doppler-velocity field before and after tornadogenesis was analyzed to investigate the dynamics involved in the genesis process. Reconstructed vertical cross-sections taken through the center of the tornado reveal fine-scale details about the vortex structure and how it evolves throughout the tornado’s lifecycle. The tornado then grew rapidly to an unprecedented width and underwent at least one transition from a single-vortex structure to a multiple-vortex structure with resolvable subvortices in the Doppler-velocity field. Details about the origin, path, and dissipation of at least two-dozen resolvable subvortices, some of which had translational speeds in excess of 75m/s, were also documented. Also, a rapid transition from a large, broad vortex to a small, tight vortex observed in the Doppler velocity and cross-correlation coefficient fields will be discussed along with the simultaneous existence of an anticyclone tornado and its connection to the rear-flank gust front.

Convective Meteorology (Mesoscale Dynamics) Seminar Series website