Impacts of operational vortex initializations on 2009 hurricane forecast with the HWRFx model

Initial conditions of the NOAA operational models for hurricane forecast are investigated for their effect on intensity change with the Hurricane Weather Research and Forecasting Experimental (HWRFx) model during the 2009 hurricane season. The HWRFx model is a high-resolution version of the Hurricane Weather Research and Forecasting (HWRF) model, using moving nests to enhance the model resolution in the vicinity of the storms. Real-time experiments have been conducted with the HWRFx model at 3-km resolution for a 6x6 degree window moving in a regional domain of 9-km resolution with two-way interaction, using the HWRF initial conditions. Retroactive experiments are also conducted with the initial conditions of the Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model, and with those of the Global Forecast System (GFS), which does not have small-scale vortex initialization. Verification against the best tracks suggests that the dynamical consistency between the model and the initial condition is essential to accurate hurricane intensity forecast, through effective spinup in the early period of forecast.