High-resolution Ensemble Prediction of the 31 May 2013 El Reno, Oklahoma Supercell

On 31 May 2013, an intense supercell produced a series of 8 tornadoes in central Oklahoma, including a violent tornado with a maximum path width of 4.2 km near the town of El Reno. The Multifunction Phased Array Radar (MPAR) operated by the National Severe Storms Laboratory collected nearly 4 hours of data of the El Reno supercell with a high-temporal resolution of approximately 60 s per volume. Examination of MPAR radial velocity data during the El Reno tornado reveals multiple scales of rotation, including distinct representations of the El Reno tornado cyclone and parent low-level mesocyclone.

The intensity of the El Reno supercell, coupled with the high quality of the MPAR dataset, make it an attractive case for testing storm-scale ensemble numerical weather prediction. A series of ensemble predictions produced by assimilating MPAR data using a local ensemble transform Kalman filter (LETKF) will be presented. Varying horizontal resolutions, including high-resolution ensembles with sub-500 m grid spacing, will be employed to assess the forecast skill for varying scales of rotation within the supercell, as well as the possible impact of resolving sub-mesocyclone scale circulations on the broader low-level mesocyclone track.