Extreme precipitation events over north-western Europe: getting water from the tropics

Abstract

Our capability to adapt to extreme precipitation events is linked to our skill in predicting their magnitude and timing. Synoptic features (such as Atmospheric Rivers) developing over the North Atlantic Ocean are known as the source of the majority of water vapour transport into European mid-latitudes, and are associated with episodes of heavy and prolonged rainfall over UK and north western Europe. Thus, a better understanding of the North Atlantic atmospheric conditions prior the occurrence of extreme precipitation events over Europe could help in improving our capability to predict them. We build on atmospheric re-analyses at high spatial resolution, on a daily time scale, to highlight the anomalous path of the vertically integrated water content, transferring water from the western tropical North Atlantic to high latitudes and fuelling the storms developing in the North Atlantic sector, bound to affect Europe as responsible for the most intense precipitation events. The systematic link between anomalous north-eastward transport of vertically integrated water (precipitable water) from the western North Atlantic and anomalously high pressure patterns in the central North Atlantic, developing 5 days prior the extreme precipitation occurrence, suggest the central North Atlantic surface pressure as a potential precursor of extreme precipitation events.