Evaluation of Hurricane Analysis and Forecast System Tropical Cyclone Quantitative Precipitation Forecasts

The National Oceanic and Atmospheric Administration (NOAA) Unified Forecast System (UFS) based Hurricane Application, Hurricane Analysis and Forecast System (HAFS), was implemented into operations in June 2023 in advance of the North Atlantic (NATL) and Eastern Pacific (EP) basin hurricane seasons. For the initial operational capability of HAFS (HAFSv1.0), two distinct configurations were selected to replace the existing regional operational hurricane forecast systems, Hurricane Weather Research and Forecast (HWRF) and Hurricanes in a Multi-scale Ocean-coupled Non-hydrostatic Model (HMON). For a new operational modeling system, it is particularly important to understand the model performance for critical fields such as precipitation. Verification of tropical cyclone quantitative precipitation forecasts (QPF) not only informs improvements in process representation within models, but also helps evaluate and improve forecasts to mitigate the risks associated with extreme rainfall and flooding from landfalling tropical cyclones. Understanding model-based QPF over the ocean also provides important information regarding the forecast biases that may impact storm characteristics at the time of landfall.

This presentation will provide a comprehensive QPF evaluation of the two operational UFS HAFSv1.0 configurations during the 2023 hurricane season in the NATL and EP basins. Performance relative to available operational models such as HWRF, which is being run in limited capacity during the 2023 season, will provide benchmarks for the HAFS QPF. The model QPF will be verified against Integrated Multi-satellitE Retrievals for GPM (IMERG) over water, and the Climatology-Calibrated Precipitation Analysis (CCPA) over land. In addition to standard QPF verification, evaluations using advanced methods such as track shifting, storm centric and object oriented verification will be shown using the enhanced Model Evaluation Tools (METplus). Differences between the HAFSv1 configurations will be explored in the context of the different physics parameterizations used (e.g. microphysics and planetary boundary layer schemes) in the configurations.