Predictability of Seasonal East Coast Winter Storm Surge Impacts with Application to New York's Long Island (running Title: Predictability of East Coast Winter Storm Surge Impacts)

The characteristics of seasons with enhanced East Coast winter storm and storm surge activity are identified from among a set of global atmospheric circulation indices and local land and sea surface temperature anomalies. Without regard for storm strength or surge potential, the most active East Coast winter storm (ECWS) seasons occur in association with El Niño events. There is also some indication that such seasons are preferred under the positive phase of the Pacific decadal oscillation. In terms of storm surge potential, forecasts of strong ECWS activity are more skillful than direct forecasts of the number of extreme surge events. In both cases, sea surface temperatures (SST) off the southeast U.S. coast and in the Gulf of Mexico differentiate high seasonal activity from relatively inactive seasons. Warmer than normal SST in both regions during summer provide a measure of storm activity in the subsequent winter. The results provide a means of anticipating seasonal East Coast winter storm activity, and to some degree impacts, that is similar to widely used forecasts of tropical storm activity. From a predictive standpoint, forecasts of active strong storm seasons and low surge activity exhibit fairly high false alarm ratios. However, the false alarm rate for forecasts of low storm activity or high surge activity is less than 10%.