On cold spells in North America and storminess in western Europe

International audienceWe discuss the dynamical and statistical link between cold extremes over eastern North America and storminess over Western Europe, with a focus on the mid-latitude jet stream, the North Atlantic Oscillation (NAO) and the Pacific-North American Pattern (PNA). The analysis is performed on the European Centre for Medium-Range Weather Forecasts ERA-20C reanalysis. The large-scale circulation associated with the cold spells corresponds to advection of cold air from the Arctic region into North America and to a very zonal and intense North Atlantic jet, shifted persistently south of its climatological location. These features of the Atlantic jet are conducive to destructive windstorms and intense precipitation over a large part of Southern and Continental Europe and the British Isles. The cold spells are preceded by a negative NAO and followed by a positive PNA; however, we interpret the associated circulation anomalies as being distinct from these standard modes of climate variability