Performance of the 2018 Real-Time HWRF-Based Ensemble Prediction System

The Hurricane Weather and Research Forecasting (HWRF) is one of the operational hurricane model systems at NCEP. It has undergone yearly upgrades and consistent improvements since its operational implementation at 2007. HWRF-based Ensemble Prediction System (HWRF-EPS) has been improved along with its deterministic version, and has been running in real time parallel for storms in the North Atlantic basin since 2014 in the support of Hurricane Forecast Improvement Project (HFIP).

The HWRF-EPS upgrades in 2018 include as follows: 1. upgrades from FY18 operational HWRF; 2. increases of model resolutions, from 27/9/3km to 18/6/2km in horizontal, L43 to L61 in vertical; 3. increase of initial and boundary resolutions from host model global ensemble forecast system (GEFS), from 1x1 degree to 0.5x0.5 degree; 4. initial sea surface temperature (SST) perturbations based on 5-years climatological GFS SST analysis; and 5. tuned stochastic perturbations for convection, PBL, and surface layer physics schemes.

In this study, the FY18 HWRF-EPS upgrades are reviewed and the ensemble performance is evaluated against best track data for 2018 real time North Atlantic hurricane season in terms of both track and intensity forecasts. The HWRF-EPS results are compared with its deterministic version and other top-flight regional models. The evaluation also includes demonstration of the improvement of statistical features of the current HWRF-EPS, such as track and intensity spread, over the previous version.

Key words: HWRF, Ensemble, Hurricane Track/Intensity