Connecting North American and European Weather Regimes

Weather regimes are recurrent and quasi-stationary atmospheric circulation patterns, typically linking to surface weather and extremes. Despite their widespread use, little is known on whether or how regimes defined in different regions relate to each other and reflect long-distance teleconnection patterns. Here, we shed light on this knowledge gap, focussing on North American and Euro-Atlantic regimes. The selection of these two regions is motivated by recent evidence pointing to a systematic connection between winter weather in North America and Europe. We find that specific pairs of North American and Euro-Atlantic regimes show a close statistical correspondence and that their joint analysis can provide medium-range statistical predictability for anomalies in their occurrence frequencies. Conditioning on North American weather regimes also results in anomalies in both the large-scale circulation during specific Euro-Atlantic regimes, and the associated European surface weather. We conclude that there is a benefit in conducting joint analyses of North American and European weather regimes, as opposed to considering the two in isolation.