Initial Analysis and Forecasts of the 31 May 2013 El Reno Tornadic Storm: Impact from Rapid-Scan Phased Array Radar (PAR)

The National Weather Radar Testbed (NWRT) Phased Array Radar (PAR) continuously sampled a tornadic supercell in central Oklahoma on 31 May 2013. The 10-cm radar collected volumetric data in a 90 degree sector approximately every 60 seconds from prior to convection initiation through storm passage over the radar location. During sampling by the PAR, the supercell produced a total of 8 tornadoes, including one near the city of El Reno, Oklahoma that persisted for 40 minutes, had a maximum path width of 4.2 km, and was rated EF-5. The well sampled, significant tornado coupled with the proximity of the supercell to the PAR (less than 75 km throughout the dataset) makes this an attractive dataset to test the impact of assimilating rapid-scan radar data for convective-scale numerical weather prediction.

Data assimilation experiments using an ensemble Kalman filter (EnKF) will be carried out with the National Severe Storms Laboratory Collaborative Model for Multiscale Atmospheric Simulation (NCOMMAS). Ensemble analyses and forecasts for different periods during the evolution of the storm will be produced from experiments assimilating data from both the PAR and WSR-88D radars and experiments where only WSR-88D data are assimilated. The resulting analyses and forecasts will be compared to assess the impact of assimilating rapid-scan PAR data on convective-scale forecasts at different points during the evolution of the storm with an emphasis on an ability to accurately analyze and forecast the development and track of the El Reno tornado.