The Basin Centric HAFS Modeling System

The Hurricane Analysis and Forecasting System (HAFS) is NOAA’s next-generation, ocean-atmosphere-coupled multi-scale numerical model and data assimilation system. An integral part of Hurricane Forecast Improvement Program’s strategic plan to address the weather act, two regional versions of HAFS with uniform resolution of 6-km and embedded storm following nest at about 2-km horizontal resolution to cover the core of the Tropical Cyclone and its immediate surrounding were implemented in operations in 2023. HAFS consistently showed improvements on the order of 10-15% for tracks and about 2-5% for intensity predictions during pre-implementation testing as well as during the 2023 over the legacy HWRF system. The “Basin-Scale” HAFS is a more flexible and multi-scale modeling configuration than the operational HAFS and represents a pathway forward for hurricane forecasting. While the operational HAFS configuration is storm centric and single nested, not ideal for representing multi-storm interactions or for post landfall applications the basin scale HAFS spawns a static domain covering the North Atlantic Basin and supports high-resolution moving nests around any number of tropical cyclones in the domain, key for improving storm-storm and land-storm interactions. In addition the basin centric HAFS may be a more viable path-way for several down-stream developments, applications and products and an evolutionary development towards our eventual goal of producing global HAFS. In this work we will report on the developments of this next generation HAFS capacity and run some of the cases in the 2022-23 hurricane season to illustrate the importance of multi-scale interactions for further improving intensity predictions. We plan to run this basic centric HAFS configuration under the HFIP real-time Experiments (HREx) for the 2024 season.