Prediction of the U.S. Storm of 24–26 January 2000 with the ECMWF Ensemble Prediction System

Between 24 and 26 January 2000 explosive cyclogenesis along the U.S. east coast caused serious economic disruption and loss of lives. The performance of the European Centre for Medium-Range Weather Forecasts (ECMWF) high-resolution TL319 model and of the TL159 Ensemble Prediction System (EPS) in predicting the storm evolution is investigated. The most critical time period to predict was the rapid intensification of the storm between 24 and 25 January. Single deterministic forecasts based on the TL319 model gave skillful predictions only 36 h before the event. By contrast, the EPS indicated the possibility that the storm would hit the affected region 2 days before the event, consistently enhancing the indications present in forecasts issued 3 and 4 days before the event. This suggests that the ECMWF EPS, suitably used, could be a valuable support tool for critical issues as alerts for extreme winter weather. Sensitivity studies indicate that the interaction of initial perturbations and stochastic perturbations added to the model tendencies was a necessary ingredient to have some EPS members correctly predicting the storm.