Multiple Doppler Analysis for 20 May 2013 tornadic supercell using a 3DVAR Method

In this study, we will present preliminary analysis results from assimilating WSR-88D observations of reflectivity and radial velocity for the 20 May 2013 tornadic supercell case using the 3DVAR technique developed for Advanced Regional Prediction System (ARPS) as the data assimilation tool. The 2013 Moore tornado was an EF5 tornado that struck Moore, Oklahoma, and adjacent areas on the afternoon of May 20, 2013, with peak winds estimated at 210 miles per hour (340 km/h), killing 23 people and injuring 377 others. The tornado touched down west of Newcastle at 2:56 pm central local time (19:56 Z), staying on the ground for 39 minutes over a 17 miles path. The tornado was 1.3 miles wide at its peak. For this particular case, the ARPS 3DVAR with a 200km x 200km domain size was running in near real-time during the tornado outbreak. A supercell with a very strong mesocyclone was automatically detected from a floating domain analysis whose location was determined using an automatic domain position system (Gao et al. 2013), though this year our system is not evaluated by the NWS forecasters. The supercell related to this particular storm developed very quickly. The analysis at 2:00 pm only showed a little sign of a mesocyclone at 3km above the ground level. However, at 2:56 pm, the tornado was already touched down at west of Newcastle, Oklahoma. The maximum vertical velocities during tornado touched down time are close to 30 m/s, and maximum vertical vorticity is close to 0.015 s-1 with 1km grid resolution. The storm track derived from these analyses will be used to explore the value of the 3DVAR to identify mesocyclones within this supercell and will be used to verify the forecast results carried out in NOAA's Hazardous Weather Testbed. The detail of the analyses will be presented in the conference for this particular event.