Examining the structure and evolution of the 31 May 2013 El Reno tornado observed with rapid-scan, polarimetric, mobile, Doppler-radar observations

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 at least EF-3 damage near El Reno, OK. 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 from 0-20 degrees at 30 meter range gate spacing before and during tornadogenesis, and 0-5 degree scans at 15 meter range gate spacing afterwards. Reconstructed vertical cross–sections taken through the center of the tornado reveal fine scale details about the wind field structure. By examining cross-sections at different times we investigate how the structure of the tornado evolves throughout its lifecycle. Observations also show that the tornado grew rapidly to an unprecedented width, and that the tornado appeared to undergo at least one transition from being characterized by primarily a single vortex structure to a multiple vortex structure with subvortices clearly resolved in the data. As many as six vortices co-existed simultaneously; some having translational speeds in excess of 75 m/s. Doppler velocities observed within one of the subvortices was measured to be at least 135 m/s. By tracking these vortices through space and time we can also examine how the behavior of the multiple vortex structure evolves.