Planned Operational Implementation of the High Resolution Rapid Refresh at NCEP
In this presentation, the current HRRR configuration that will be implemented at NCEP will be described, including the WRF-ARW model formulation and the 3-km data assimilation procedure. This 3-km data assimilation procedure includes a one-hour pre-forecast period, in which four 15-min. cycles of radar reflectivity assimilation are completed, followed by application of the Global Statistical Interpolation (GSI) variational analysis package at 3-km to ensure close fit to the latest conventional observations. The WRF-ARW model formulation used for both the upgraded RAP and the HRRR utilizes a specially adapted formulation of the MYNN boundary-layer scheme and a 9-level soil model. These changes have contributed to improved near-surface forecasts. Additional work to speed up the 3-km analysis and post-processing will also be described. This work has reduced the model latency, a key factor for a guidance product such as this.
In addition to summarizing the RAPv2 and HRRR operational implementation process and challenges associated with it, we will describe ongoing developmental work toward ensemble-based, hourly updated weather guidance from the North American Rapid Refresh Ensemble (NARRE). The NARRE will be based on a six member ensemble with both WRF-ARW and NMMB dynamic core members and co-development by NOAA/ESRL and NOAA/NCEP/EMC.