The NCEP multi-Initial Condition (multi-IC) and multi-model Short Range Ensemble Forecasting (SREF) system has been operationally running since May 2001 (Du et al. 2004). This presentation will summarize recent changes to the SREF system including increase physics diversity, scaled breeding, increased horizontal resolution and improved products. The SREF system was developed to provide a multi-regional model, short-range (0-3 days) ensemble prediction system to provide operationally relevant and useful guidance on the probability distribution of weather elements or events. The probabilistic information provided by SREF should help meet the NWS FY05 strategic goal of providing probabilistic gridded products to the NWS/WFOs, service centers and other users. The value of probabilistic products derived from the upgraded system will be evaluated with both deterministic, probabilistic verification tools as well as subjective forecaster comments. The current and potential use of SREF probabilistic products by weather forecasters for sensible weather as well as emerging will also be discussed.

The motivation for these upgrades stems from recent studies that have shown the benefits of adding physics perturbation members to an ensemble system (Stensrud et al. 2000). Also, ensemble members clustering by model in the operational SREF is a main concern of NWS field forecasters. Therefore, a new physics ensemble system was developed and evaluated.