Revisiting Extreme Precipitation of European Summer 2012: The Role of Atlantic Tropical Storm Debby

The summer of 2012 in Europe was characterized by sharp contrasts in precipitation. The United Kingdom recorded its wettest summer season (June–August) since 1912. Spain faced drought and wildfires, as summer precipitation levels there were the second lowest in the last 60 years. These anomalies demonstrate an unexpectedly rapid northward shift of the precipitation zone across Europe. The shift contradicted, however, prevailing climate change projections, according to which severe summer drying across the continent and a slower trend toward increased wetting of northern Europe have been expected. The physical mechanisms responsible for the extreme trend remain not clear. It is worth noting that a significant part of 2012 summer precipitation occurred from mid-June to mid-July. Hurricane Chris and Tropical Storm Debby also formed in the North Atlantic in June of that year. This paper presents evidence that the extreme climate behavior of the summer of 2012 and the anomalous summer precipitation distribution in Europe could have been largely determined by the intense transport of moist air from the tropical Atlantic associated with the formation of Tropical Storm Debby, which should be considered among the main drivers of intense flooding events over northwestern and southeastern Europe during the 2012 summer season.