Investigating Major Hurricane Joaquin Track Forecasts using the Basin-Scale HWRF

Under the Hurricane Forecast Improvement Project (HFIP), tropical cyclone (TC) track forecasts have been steadily improving in the Atlantic and East Pacific basins for the operational Hurricane Weather Research and Forecasting (HWRF) model. However, large track errors can still exist on a case-to-case basis. In a parallel and collaborative effort, the National Oceanic Atmospheric Administration's Hurricane Research Division, the National Centers for Environmental Prediction's Environmental Modeling Center, and Developmental Testbed Center have developed a research version of HWRF, called the “basin-scale HWRF”, which features multiple moving nests and a static outer domain that encompasses both the Atlantic and East Pacific basins.

For the case of Major Hurricane Joaquin (2015), the basin-scale HWRF produced more accurate track forecasts than the operational HWRF. This study aims to better understand Joaquin's complex track and its multi-scale interactions with the environment by using the basin-scale HWRF. We initialize the basin-scale HWRF from the Global Ensemble Forecast System (GEFS) to create an ensemble of forecasts for Joaquin. Sensitivity experiments quantify the relative importance of initial/lateral boundary conditions, other TCs/disturbances, synoptic upper-tropospheric troughs, and cold fronts to the track of Joaquin. This study may guide the priorities of future hurricane model development.