Seasonal Predictability of the East Atlantic Pattern in Late Autumn and Early Winter

The North Atlantic Oscillation ("NAO") and the East Atlantic Pattern ("EAP") dominate winter atmospheric variability over the North Atlantic. Unlike the NAO, seasonal predictability of the EAP has remained elusive. A multi-model ensemble of seasonal predictions yields skillful forecasts of the EAP in late autumn and early winter, complementing NAO prediction skill in winter. The shift in prediction skill from EAP to NAO reflects the ability of the ensemble to forecast the evolving influence of the El Nino South Oscillation on the North Atlantic region. In early winter, the ensemble correctly forecasts the key tropical-extratropical teleconnections, resulting in skillful predictions of the EAP and western European temperatures and rainfall. However, the modeled tropical-extratropical teleconnections are weak compared to observations, contributing to a signal to noise error in predictions of the EAP. Improving the strength of such teleconnections would improve predictions of the EAP and associated surface climate.