A real-time storm-scale ensemble forecast system: 2009 Spring Experiment

Funded partly by NOAA CSTAR program and in its third project year, a real-time storm-scale ensemble forecasting experiment has been planned as part of the NOAA Hazardous Weather Testbed (HWT) 2009 Spring Experiments. At 4-km horizontal grid spacing, the ensemble system based on WRF-ARW and WRF-NMM cores, developed at the Center for Analysis and Prediction of Storms (CAPS), will be run on weekdays for 30 hours from 20 April through 5 June in 2009, for a domain covering most of the continental United States. The ensemble system will have 18-20 hybrid perturbation members that consist of a combination of perturbed initial conditions and various microphysics, radiation, and PBL physics parameterization schemes. For the 2009 season, one major change from the 2007 and 2008 seasons is to include additional 6-8 members using WRF-NMM core and possibly 2 more members using ARPS model. As in 2008, daily 30 h forecasts will be initiated at 0000 UTC during weekdays using the 12 km NAM 0000 UTC analysis as background. WSR-88D radar data (both reflectivity and radial wind) will be assimilated through the improved ARPS 3DVAR and cloud analysis package.

The statistical characteristics of the ensemble system and various probabilistic QPF scores, and the comparison among different model cores will be discussed in the conference.