Extended Predictability of Tropical Cyclones in the North Indian Ocean

This analysis examines the predictability of several key forecasting parameters using the ECMWF Variable Ensemble Prediction System (VarEPS) for tropical cyclones (TCs) in the North Indian Ocean (NIO) including: tropical cyclone genesis, pre-genesis and post-genesis track and intensity projections, and regional outlooks of tropical cyclone activity for the Arabian Sea and the Bay of Bengal. Based on the evaluation period from 2007 to 2010, the VarEPS TC genesis forecasts demonstrate low false alarm rates and moderate to high probabilities of detection for lead-times of one to seven days. The VarEPS provides superior track forecasts for lead-times greater than 12 hrs when compared to other models including: UKMET, NOGAPS, and GFS, and slightly lower track errors than the Joint Typhoon Warning Center. Finally, we contrast the extended predictability of TCs in the NIO with the more limited predictability of TCs in the North Atlantic Ocean. Ultimately, this comparison demonstrates the feasibility of extended range TC forecasts in the NIO on time scales significantly greater than the three-day outlooks provided by the Indian Meteorological Department.