Towards Initial Operational Capability of Hurricane Analysis and Forecast System : Plan, Configuration, and Real-time Experiments

Hurricane Analysis and Forecast System (HAFS), a Unified Forecast System (UFS) based tropical cyclone (TC) modeling application, is under active development at NOAA. HAFS is an atmosphere-ocean-wave coupled, multi-scale high resolution regional model system with TC-following moving nests, and TC inner-core data assimilation. It is capable of providing analyses and forecasts of the TC track and intensity forecast guidance, as well as the inner core structure of TC for all global oceanic basins. The Initial Operational Capability (IOC) of HAFS is planned for the 2023 hurricane season, replacing NOAAs current operational TC forecast systems, HWRF and HMON. Supported by the Hurricane Forecast Improvement Program (HFIP), HAFS aims to be a community-based coupled earth modeling system, promoting research to operation to research (R2O2R) transitions and provide improved forecasts to forecasters with reliable, robust and skillful guidance on TC track and intensity, rapid intensification (RI) events, storm size, genesis, storm surge, rainfall and tornadoes associated with TCs. It will also provide an advanced analysis and forecast system for cutting-edge research on modeling, physics, data assimilation, and coupling to earth system components for high-resolution TC predictions To demonstrate HAFS performance and prepare its IOC for FY23, various HAFS configurations have been developed for real time experiments since 2019. The standalone atmospheric regional configuration (HAFS-A) serves as the baseline for all other configurations. The global-nest configuration (HAFS-B) is designed to examine the impact of nest feedbacks to the global large-scale system for TC track and intensity forecasts. All observed data used in the current HWRF DA system are assimilated in HAFS data assimilation experiment (HAFS-D) to demonstrate the DA impact and test the effectiveness of DA on forecast skill. HAFS based ensemble configuration (HAFS-E) provides probabilistic forecast guidance. The details of each configuration will be presented, and the results will be analyzed and verified with comparisons to each other, and to the forecast guidance provided by operational forecast models. Possible options and timelines for development of HAFS IOC will also be discussed.