Southern Caribbean Hurricane Case Study: Observations and WRF Simulation

Abstract

The meteorological conditions of three hurricanes passing through the southern Caribbean are analyzed using Hurdat, atmosphere - ocean reanalysis, satellite rainfall and SST fields, and buoy observations. The cases are Ivan 2004, Emily 2005 and Dean 2007, each traced to an African easterly wave moving zonally beneath an atmospheric ridge over the North Atlantic. SST were > 29 o C west of the Antilles Islands due to +40 W/m 2 surplus net heat flux and weak upper ocean currents. The analysis results suggested that the warm sea temperatures enhanced moisture fluxes, rain rates and convective heating, which affected these hurricanes significantly. WRF model simulations at 3 km resolution are evaluated for ability to forecast intensification up to 48 h lead time. In Emily (2005), the simulation results showed that upper winds disrupt the outflow. As the result, the model recovers the vortex too slowly. Overall, the WRF forecast decrease in central pressure was close to observed in Ivan (2004), but less than half of the observed in Dean (2007). Although the WRF model simulations gave evidence of initialization and intensification errors in comparison with NHC observations, the WRF 3 km resolution domain is essential for improving hurricane wind simulations. Nevertheless, significant improvements still depended on the initialization and data assimilation.