The European Mega-heatwave of June 2017

Trabajo presentado en el MedCLIVAR Conference: Bridging the Mediterranean Climates, celebrado en Belgrado (Serbia) del 17 al 21 de septiembre de 2018This work describes the exceptional mega-heatwave that affected western and central Europe in June 2017 as an example of summers with an earlier occurrence of record-breaking megaheatwaves. To do so, we designed a novel algorithm that monitors mega-heatwaves by tracking the spatio-temporal evolution of extreme temperature patterns. The results indicate that the spatial extension, persistence and intensity of the June 2017 event were similar to those of top European mega-heatwaves of the reanalysis period. However, it occurred earlier than other well-known mega-heatwaves, such as that of 2003. The most affected area was southwestern Europe, where the event was the longest heatwave on record, causing the warmest temperatures from daily to seasonal scales, forest fires and human casualties. The megaheatwave was associated with a record-breaking subtropical ridge in mid-June with signatures more typical of July and August, which caused an unprecedented subtropical warm air intrusion. Using the analogue method, we found that the recorded temperature anomalies were higher than those expected from past flow analogues. This was partially due to changes in circulation. However, thermodynamical changes of the last decades made a much larger contribution to the exceptionality of the event.Peer reviewe