Moving Nest Advances for the Hurricane Analysis and Forecast System (HAFS)

The Hurricane Analysis and Forecast System (HAFS) is the tropical cyclone (TC) application of NOAA’s Unified Forecast System (UFS). Single storm-following high-resolution nest functionality was implemented and run operationally as HAFS v1.0 for the 2023 hurricane season. We have upgraded the code to allow multiple moving nests, each independently tracking a separate tropical cyclone. Using a regional configuration, this allows accurate forecasts of the interactions between multiple storms within a single basin. In a global configuration, we can forecast long-range interactions between storms in different basins, with nests positioned on multiple faces of the cubed sphere. Each nest runs in parallel on its own set of cores, and we will present results showing the performance efficiency of multiple moving nests.

Combinations of static and moving nests have also been enabled in the model, to permit high-resolution nesting over a static geographical area as well as a storm-following nest. Additional upgrades will allow the option of NOAH MP land surface model with the moving nest. This involves identifying the set of physics variables for that scheme that must be shifted when a nest move occurs.