Evolution of the Internal Structure of Warm-Season Precipitation Events and Its Nonlinear Response to Antecedent High Temperature: A Case Study of the Hehuang Valley in Plateau Margin Mountainous Areas

In the context of global warming, extreme precipitation on the Qinghai-Tibet Plateau has intensified significantly. Understanding the internal structure of precipitation events and their response to rising temperatures is crucial for elucidating these intensification mechanisms. Focusing on the Hehuang Valley, this study constructed an event-scale dataset using hourly observations from 15 meteorological stations (2015–2024), introducing “Inter-event Maximum Temperature” as a key thermal driver. By integrating clustering, trend tests, and logistic regression, we analyzed the spatiotemporal evolution of precipitation extremes. Results indicate that: (1) regional precipitation exhibits a pattern of fluctuating frequency but increasing intensity; (2) the proportion of uniform precipitation has decreased while non-uniform types, especially rear-peak events, have increased significantly; (3) spatial heterogeneity is strongly influenced by topography, with extreme precipitation concentrated on windward slopes and in valley contractions;(4) Inter-event maximum temperature exerts a significant non-linear positive effect, where a 1°C increase raises the odds ratio for extreme precipitation occurrence by approximately 13.4%. These results confirm that antecedent thermal accumulation enhances extremes by increasing atmospheric water-holding capacity and convective instability. While decadal-scale uncertainties remain due to the limited 10-year data span, these findings provide a scientific basis for disaster prevention and water resource management in high-altitude basins.