The Basin-Scale HWRF: Developments and Evaluation of 2018 Real-Time Forecasts

The Hurricane Weather Research and Forecasting (HWRF) Model has provided increasingly valuable guidance for tropical cyclone (TC) forecasts issued by operational centers around the world. Under the Hurricane Forecast Improvement Project (HFIP), research communities have developed new capabilities for the HWRF system. To facilitate transitions from research into operations, an experimental version of HWRF, called the "Basin-Scale" HWRF (HWRF-B), was developed at AOML/HRD. HWRF-B was configured with two key upgrades to improve forecast skill: 1) a large, fixed outermost domain and 2) multiple sets of movable multi-level nests that follow each TC. Several aspects of the HWRF-B configuration were upgraded in 2018, including increased resolution over the TC inner core at 1.5 km and ocean coupling to the outermost model domain. HWRF-B was operated as an HFIP real-time demonstration project during the 2018 hurricane season, and we evaluated its forecast performance in the North Atlantic and Northeast Pacific basins. In particular, we identified strengths and weaknesses of the HWRF-B system and analyzed new capacities of this model, including ocean coupling and ensemble forecasts. The ensemble prediction system of HWRF-B can be a tool for research into data assimilation and probabilistic guidance.