Abstract

The NAO is the single most important pattern of variability for year to year changes in UK and Northern European winter climate. However, recent forecast systems have shown only low levels of skill in predicting the NAO and European and North American surface winter climate at seasonal lead times. In this talk we will examine teleconnections to the NAO from a variety of predictable drivers and reassess the seasonal predictability of the NAO and winter north Atlantic climate using a new long range forecast system. We will demonstrate that the surface North Atlantic Oscillation and key aspects of European and North American winter climate were in fact highly predictable in recent decades. Unprecedented levels of skill in retrospective winter forecasts of the surface North Atlantic Oscillation, near surface temperature, wind speed and storminess imply that these seasonal winter forecasts also have high potential value for planning and adaptation to climate variability. Further analysis of forecast ensembles suggests that while we have now achieved useful levels of seasonal forecast skill, key sources of predictability for the NAO are still only partially represented and there is further untapped predictability.