A BIT OF BACKGROUND ON THE HWRF
The Weather Research and Forecast system for hurricane prediction, or the HWRFTM, became operational at NCEP in 2007. This advanced hurricane prediction system was developed at EMC, beginning in 2002, in collaboration with NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) scientists and the University of Rhode Island (URI). To meet operational implementation requirements, it was necessary that the skill of the track forecasts from the HWRFTM and GFDL hurricane models be comparable. Additionally, features of the GFDL hurricane model that led to demonstrated skill for intensity forecasts, such as ocean coupling, upgraded air-sea physics and improvements to microphysics, were also captured in the newly developed HWRFTM system.
The HWRFTM system is composed of the WRF model software infrastructure, the Non-Hydrostatic Mesoscale Model (NMM) dynamic core, the three-dimensional Princeton Ocean Model (POM), the NCEP coupler, and a physics suite tailored to the tropics, including air-sea interactions over warm water and under high wind conditions, and boundary layer and cloud physics developed for hurricane forecasts. It should be noted that, although the HWRFTM uses the same dynamic core as the NCEP North American Mesoscale (NAM) model, the NMM, the HWRFTM is a very different forecast system from the NAM and was developed specifically for hurricane/tropical forecast applications. The HWRFTM is configured with a parent grid and a high-resolution movable 2-way nested grid that follows the storm, is coupled to a three-dimensional ocean model and also differs from the NAM in its physics suite and diffusion treatment. The HWRFTM also contains a sophisticated initialization of both the ocean and the storm scale circulation.