High-resolution EnKF assimilation of tornado-scale radar observations for a tornadic supercell: preliminary results

The VORTEX2 project provided unprecedented radar coverage of several tornadic supercells, including at least two in which W-band radar reflectivity and Doppler velocity data, with a radial resolution of 30 m and an average update time of 18 sec, were collected on tornadoes. These W-band radar data are assimilated into very high resolution (≤ 50 m horizontal grid spacing), Advanced Regional Prediction System (ARPS) analyses of the parent supercell storm using the EnKF technique. Data from nearby WSR-88Ds and storm-scale SMART-Rs are used to establish the storm-scale features of the storm while the W-band Doppler velocity data are assimilated to establish the tornado-vortex scale features near the surface. The impact of assimilating such high-resolution, near-surface wind data into the analyses will be assessed via a combination of RMS error statistics and subjective tracking of supercell features (e.g., rear flank gust fronts, vortex position/strength at different altitudes). To the best knowledge of the authors, this should be the first time such high-resolution radar observations of tornadoes, including tornadogenesis processes, are assimilated into a NWP model.