The Hurricane Weather Research and Forecasting model (HWRF) is a limited-area numerical model used by the National Weather Service (NWS) to provide numerical guidance for operational tropical cyclone forecasting. The atmospheric component of HWRF employs the Non-Hydrostatic Model (NMM) dynamic core of Weather Research and Forecasting (WRF) model. The oceanic component of HWRF is the Princeton Ocean Model for Tropical Cyclones (POM-TC).

With the goal of improving the representation of cloud-radiative forcing and ultimately advancing tropical storm numerical forecasting, in 2013 the NOAA Environmental Modeling Center partnered with the Developmental Testbed Center (DTC) to evaluate an alternate configuration of HWRF with modified radiation and microphysics parameterizations.

For this test, the DTC ran retrospective forecasts for the 2012 season using two configurations of HWRF. The control (HC35) configuration is very similar to the HWRF 2013 operational implementation, except that the 2012 operational HWRF value of the boundary layer diffusivity parameter (gfs_alpha=0.7) was used instead of the 2013 operational HWRF value (gfs_alpha=0.5) in all domains.

The HDRT configuration differs from the HC35 in three aspects: the Thompson microphysics parameterization was used instead of the Ferrier one, the Rapid Radiation Transfer Model for General Circulation Models (RRTMG) radiation parameterization was used instead of the default HWRF scheme (the Geophysical Fluid Dynamics Laboratory radiation parameterization), and the radiation scheme was called every 4 hours instead of the 1 hour used in the operational HWRF.

Runs were conducted in the jet and zeus NOAA research computers, and the two configurations were always runs in the same platform for a given storm.

Contact information: Ligia Bernardet (Ligia.Bernardet@noaa.gov)