This paper will present an overview of the use of the NCEP Global Ensemble for tropical cyclone track forecasting, as well as mean ensemble track error statistics and selected case studies for the past two hurricane seasons, and a discussion of an ensemble-based strike probability product and its verification.

During the 2000 and 2001 hurricane seasons, the NCEP AVN model exhibited a remarkable increase in track forecasting skill for tropical cyclones in the Atlantic and eastern Pacific Ocean basins, as compared to its skill during the previous five hurricane seasons. The NCEP global ensemble, which derives its initial perturbed conditions from the AVN model, has been evaluated to determine its skill in track forecasting, and the mean ensemble track has shown considerable track forecasting skill relative to CLIPER. In addition to simple point- location track forecasts, the ensemble can provide additional useful information. Specifically, the spread of forecast solutions can suggest the sensitivity of a particular forecast to uncertainty in the initial conditions. The information from the forecast spread can be used in developing a product such as a strike probability diagram, similar to those produced operationally by the National Hurricane Center.