Impacts of Distinct Synoptic Patterns on Fine‐Scale Precipitation Characteristics in Complex Terrain of S outhwestern C hina

ABSTRACT Due to the effects of large‐scale topography of the Tibetan Plateau (TP), Yunnan‐Guizhou Plateau and Sichuan Basin (SCB), Southwest China (SWC) is characterised by complex synoptic patterns and variable precipitation features. However, the impacts of different synoptic patterns on fine‐scale daily and sub‐daily precipitation in SWC remain poorly understood. To address this issue, this study employs the Self‐Organising Map method to classify summertime synoptic patterns based on rainy‐day circulation fields over SWC into three distinct types. These types are primarily distinguished by the position of the western Pacific subtropical high (WPSH). In the northward‐shifted and inland‐extended pattern (Type 2, 31%), strong afternoon radiative forcing over SWC enhances nocturnal southerly advection, which transports moisture from the South China Sea northward into the SCB, enhancing CAPE and facilitating rapid convective development along the eastern slope of the TP. Under the eastward‐displaced pattern (Type 3, 30%), both radiative forcing and southerly advection weaken. South‐westerly moisture transport from the Bay of Bengal converges with cold air over southern Guizhou (GZ) and South China, creating a high‐CAPE zone conducive to precipitation initiation and subsequent eastward propagation. When the WPSH is located near its climatological position (Type 1, 39%), the lower troposphere over SWC is simultaneously influenced by warm‐moist flows from both the Bay of Bengal and the South China Sea. This configuration leads to pronounced and long‐lasting nocturnal precipitation peaks in both the SCB and GZ, with SCB precipitation primarily associated with a low‐level vortex. The findings of this study provide a new perspective for understanding fine‐scale precipitation characteristics over SWC.