Climatic Condition and Synoptic Regimes of Two Intense Snowfall Events in Eastern China and Implications for Climate Variability

This study investigates the climatic condition and synoptic regimes of two intense snowfall events (ISEs) in central eastern China (CEC) during January 2018, focusing on the mechanisms of northerly cold advection and southerly water vapor transport. The northerly cold advections invading CEC were associated with a strengthened Siberian High, which could be partially attributed to an influence of reduced sea ice in the Kara Sea-Barents Sea during November 2017 to January 2018 on a reduced meridional temperature gradient between the midlatitudinal Eurasia and Arctic regions. The southerly water vapor transport contributing to ISEs was associated with a zonal dipole pattern in the atmosphere, which was characterized by an anomalous anticyclone over the western North Pacific and an anomalous low over the Tibetan Plateau and India. The La Nina condition provided a climatic condition for an anomalous anticyclone persisting over the western North Pacific during January 2018, which was influenced by a strengthened convection over the western tropical Pacific and influenced by the air-sea interaction over the central-northern Pacific. The anomalous low over the Tibetan Plateau and India was associated with active eastward propagating synoptic-scale waves originating from the midlatitudinal North Atlantic. The implication of aforementioned climatic conditions on climate variability was further discussed. Our results suggest that a reduced sea ice in the Kara Sea during the preceding late autumn and a concurrent La Nina-like condition may contribute to an increased frequency of ISEs in CEC during winter on the interannual time scale.