Unprecedented July Rainfall in North China in 2021: Combined Effect of Atlantic Warming and Arctic Sea‐Ice Loss

Abstract Record‐breaking July‐mean precipitation hit North China in 2021, resulting in huge economic losses and human casualties. The prevailing easterlies over the southern flank of a remarkable anomalous anticyclone centered over the Kuril Islands transported sufficient water vapor into North China, resulting in persistent downpours on the windward side of the North China Plain. The anomalous anticyclone was a portion of the Eurasian Rossby wave trains. The record‐high Atlantic sea surface temperature anomalies induced the Rossby wave trains, which ended with an anomalous anticyclone over the Kuril Islands; meanwhile, the record‐low sea‐ice concentration over the Laptev–East Siberian Seas reinforced the anomalous anticyclone. Therefore, the combined effect of Atlantic and Arctic thermal forcings caused the record‐breaking July‐mean rainfall in North China in 2021. Using these two boundary layer forcings as independent predictors to run a multiple regression model produced encouraging hindcasting skills.