Hurricane deflection by sea surface temperature anomalies

Accurate forecasts of hurricane tracks and landfall are important for emergency planning. In order to determine whether these forecasts can be improved using higher-resolution sea surface temperature (SST) data, we hindcast the 2005 hurricanes: Dennis, Katrina, Rita and Wilma using the Met Office's NWP model with 40 km and 6 km resolution SST analyses, the latter called OSTIA. The use of OSTIA had little effect on the forecasts of Katrina and Wilma, but slightly improved those of Dennis and Rita. For Rita the improvement disappeared when a warm eddy captured only by the OSTIA SST was deleted from OSTIA by reducing the SST by 0.25K over an area of 36,000 km², showing that in this case the warm eddy deflected the hurricane. However, an analysis of all the hurricanes' trajectories and their local SST gradients showed no significant correlation.