Spatiotemporal Evolution of Landfalling Tropical Cyclone Rainfall and Its Synoptic Associations

Accurately characterizing the spatiotemporal distribution of tropical cyclone rainfall is fundamental to enhancing coastal flood defense capabilities. Taking western Guangdong Province as the study case and utilizing hourly rainfall data from 2005 to 2025, this paper employs the Locally Linear Embedding algorithm, K-means clustering, and composite analysis to classify the spatiotemporal patterns of tropical cyclone rainfall and to explore the linkage mechanisms between each pattern and the synoptic fields. The results indicate that, during 2005–2025, a total of 49 tropical cyclones made landfall in western Guangdong, predominantly during the period from June to October. The tropical cyclone rainfall can be categorized into three spatiotemporal patterns: Pattern 1 is a bimodal migrating type, characterized by a southwest-to-northeast migration of the rainfall center and the strongest spatial variability; Pattern 2 is a unimodal balanced type, featuring the most spatially uniform distribution and a broad areal influence; Pattern 3 is a bimodal locked type, with the rainstorm center persistently anchored over the Yangjiang, the highest mean rainfall intensity, and the strongest spatial concentration. For Pattern 1, tropical cyclones with northwest and northward tracks allow the right-front quadrant of heavy precipitation to dominate the migration of the rainstorm center. For Pattern 2, the dispersed low-level wind field jointly suppress the migration and concentration of the rainstorm center. For Pattern 3, the superposition of high-value moisture transport and funnel-shaped topographic forced lifting appears to be a primary contributing factor to the stable maintenance of the rainstorm center. The findings of this paper can provide scientific evidence for tropical cyclone rainfall forecasting and flood defense in western Guangdong.