Impact of Differences in Initial Conditions on Rapid Intensification Forecasting for NCEP Hurricane Models

Although there are some hypotheses and theories for Rapid Intensification (RI) of tropical cyclones (TCs), RI forecast remains a challenge for operational hurricane models, including the NCEP’s hurricane forecast guidance models, Hurricane Weather Research and Forecasting Model (HWRF) and Hurricanes in a Multi-scale Ocean-coupled Non-hydrostatic model (HMON). Previous studies have demonstrated the roles of environmental factors and inner-core processes in RI of TCs. In this study, RI of TCs is examined from another perspective, i.e. through model initial conditions. Initial condition used by a hurricane model is found to be one of the key factors affecting RI forecast. This study will focus on the operational HWRF/HMON forecasts for the 2017 North Atlantic major storms. The 2017 hurricane season in the North Atlantic was very active, and there were several intense storms that exhibited RI. HWRF/HMON predicted RI very well for some forecast cycles but not consistently. Since the model setup was not changed during these forecasts, comparisons of these cycles indicate that the model initial conditions are very important for successful RI forecasts. A discussion on the impact of differences in initial conditions on RI forecast cycles by analyzing factors which may lead to successful RI will be presented.