Plans to Evolve HWRF to a Regional FV3-based Hurricane Model within NOAA’s Unified Forecasting Strategy

NOAA is pursuing a comprehensive approach to hurricane modeling including maximizing the use of observed data, modernizing assimilation techniques, unifying the global and regional modeling systems, deriving clear, readily accessible forecaster guidance and preparing easily understood products. The approach is encapsulated in a multi-scale, multi-model system referred to as the Hurricane Analysis and Forecasting System (HAFS).

Development of HAFS begins with the current and near-term-planned operational systems progressing towards the NOAA envisioned Unified Forecast System. As such, guidance is presently generated by the current operational Global Forecast System (GFS) and Hurricane Weather Research and Forecast (HWRF) system with their respective data assimilation systems. Plans are in place to soon replace the current GFS with a superior model based on the finite-volume cubed-sphere (FV3) grid developed at GFDL taking advantage of its scalability and non-hydrostatic capabilities and including advanced physics parameterization schemes. An ensemble version of that new GFS will follow as well as a regional version at convective resolving scales. The HWRF capabilities will be incorporated into that regional version including a multiple nesting capability to track multiple tropical cyclones starting before genesis and continuing throughout their lifecycle.

Ultimately, the modeling portion of HAFS will be a fully land-ocean-waves-atmosphere coupled FV3-based GFS with movable nests to cover multiple storms at resolutions at least small enough to resolve processes in the hurricane’s inner core. That model will generate an ensemble of predictions at the highest resolution and membership allowable within the computational resources available and forecast timing constraints. This paper focuses on the near-term plans to transition from the current HWRF configuration to a regional FV3-based system at convection allowing scales.