North American Rapid Refresh Ensemble (NARRE)-Preliminary Configuration

The focus of the pre-NARRE effort is to work toward the development and implementation of the hourly updated North American Rapid Refresh Ensemble (NARRE) forecasting system. This new system is planned for implementation into NCEP operations as an extension of the Short Range Ensemble Forecasting (SREF) system in 2017. This new system will provide improved probabilistic forecasts for aviation and other short-range applications. The work is conducted collaboratively by the GSD, EMC, and DTC staff. For initial testing, the Rapid Refresh (RAP) domain is being used, but in a later phase, the domain will be slightly enlarged. Configuration tests have been performed in retrospective mode. The tests included eight ensemble members, four using the Advanced Research WRF dynamic core and four using the Nonhydrostatic Multiscale Model on the B grid (NMMB) dynamic core. The ARW core members employed variations in physics and initial and lateral boundary conditions, while the NMMB members differed only in initial and lateral boundary conditions. The chosen baseline pre-NARRE configuration is illustrated in Table 1. This configuration has been running in real time since November 15, 2014 to supply datasets for the HMT-WPC WWE. As a part of the WWE, pre-NARRE has been evaluated along side operational and experimental versions of SREF. More details about the configuration testing and a summary of the WWE findings will be presented at the workshop.