Analysis on the Track Deflection of Hurricane Florence (2018) Using HWRF Modeling and Vorticity Budget Analysis

As the ninth most destructive hurricane ever to hit the United States, in September 2018, Hurricane Florence made landfall in North Carolina as a weakening Category One storm. Studies suggested that the Florence (2018) caused a record-breaking storm surge of eight to eleven feet and catastrophic flooding due its slow-movement in combination with the “L-shaped” track. In this study, we examine the causes and major factors of track deflection. We utilize the operational Hurricane Weather Research and Forecast (HWRF) model with a parent domain (spatial interval of 11km) and two moving nested domains (spatial interval of 3.67km and 1.22km). The model is initialized by the forecast data from the Global Forecast System (GFS). With various settings and scheme options, we conduct numerous simulations in HWRF to obtain a control case with the storm track that captures all the major track deflections with the minimum error. The vorticity budget analysis indicates that the storm’s movement can be predicted by the maximum vorticity tendency (VT). Further analysis of the vorticity budget shall reveal the specific vorticity components that have an impact on the storm's track through steering. This research is important because it will help the meteorology community make more accurate predictions of hurricanes, which is essential to community preparedness for hurricane evacuations and lessen damages caused by natural disasters.