A Multi-Scale Modeling System for Improved Hurricane Prediction

Global non-hydrostatic models are being envisioned by the National Weather Service (NWS) to be run at higher resolutions by the end of this decade. However, it remains to be seen whether these models can routinely operate at a 1-3 km resolution, critical for providing reliable tropical cyclone intensity guidance, with the refreshing frequency needed to support a range of operational forecast products. In the absence of a very high-resolution global model in all basins, grid nesting over individual storms could be a practical approach for the hurricane-forecasting problem, both at the regional and global scales. To investigate the technical and scientific challenges and merits of a multi-storm configuration, NOAA's Hurricane Forecast Improvement Project (HFIP) supported HRD/AOML, along with its partners at NCEP/EMC and the Developmental Testbed Center (DTC), to create a basin scale configuration of HWRF that operates with multiple moving nests. This configuration, which is now an option in the centralized HWRF code, was run for the 2015 hurricane season and also in retrospective mode for the 2011-2014 seasons. Results from the basin scale HWRF will be presented to show that an extension of the multi nested basin scale paradigm to global models could be considered for NOAA's Next Generation Global Prediction System (NGGPS). The talk will especially emphasize the value of nesting in providing the key multi-scale interactions required for intensity predictions.