Causality and predictability of the Pan Atlantic compound extremes

The co-occurrence of wintertime cold spells in North America and wet, windy extremes in Europe, known as the Pan-Atlantic compound extremes, is linked to distinct dynamical pathways. One of those dynamical pathways involves the presence of a persistent high-pressure system west of Greenland. This high-pressure anomaly tends to simultaneously induce a southward displacement of a trough over the eastern United States and sustain an upper-level trough over southwestern Europe, creating conditions that induce both cold spells in North America and extreme precipitation in Europe. The co-occurrence of the Pan-Atlantic compound extremes has been investigated in previous studies. However, the causal association between extremes on both sides of the Atlantic has yet to be verified. In this study, we aim to assess the relationship between these compound extremes and to uncover the causal mechanisms driving their co-occurrence. Preliminary findings indicate that high-pressure anomalies over Greenland are a main driver of both phenomena, providing a coherent dynamical link that bridges these geographically distinct extreme events. The study further seeks to clarify the underlying dynamics and improve predictability for such interconnected extreme weather events, which can help to better manage and mitigate their impacts.