Development of the High-Resolution Rapid Refresh Ensemble (HRRRE)

The High Resolution Rapid Refresh (HRRR) is an hourly-updated 3-km Weather Research and Forecasting (WRF-ARW) Convective Allowing Model (CAM) developed at the Earth Systems Research Laboratory (ESRL) Global Systems Division (GSD) and run operationally at the National Center for Environmental Prediction (NCEP). The current experimental HRRR provides deterministic guidance for 0 to 36 hours over the contiguous United States as well as over Alaska. The forecasts aid in the production of severe weather outlooks and watches, prediction of aviation hazards, and provide guidance for renewable energy applications. The future of CAM systems like the HRRR will be to provide real-time ensemble analyses and forecasts, in order to produce improved skill and uncertainty information for forecast applications. A prototype HRRR Ensemble (HRRRE) is under development and it is running experimentally in real-time during the Spring and Summer of 2017. This presentation on the HRRRE will overview the system design including the data assimilation techniques, ensemble perturbations, and forecasts. The HRRRE is being evaluated during the NOAA Hazardous Weather Testbed Spring Experiment, the Flash Flood and Intense Rainfall Experiment, and the Aviation Weather Center Summer Experiment. Case studies and statistics for weeks/months will be evaluated to determine the impacts of the ensemble data assimilation. In particular, the impact of direct assimilation radar reflectivity will be investigated. In addition, examples from the real-time forecasts will be evaluated to describe strengths and weaknesses. Results will guide GSD’s continued development with a goal of an operational implementation of the HRRRE.