The environments and movement, as well as the surface characteristics of heavy rainfall (HR), were examined based on 5‐year HR episodes collected from the surface observations during the warm season (April–September) from 2015 to 2019. The results showed that the HR generally exhibited eastward movement with average moving‐speed of 59 km⋅hr⁻¹ over South China. The daytime HR exhibited more episodes and faster moving‐speed than the nocturnal HR. Both nocturnal HR and daytime HR were strongly influenced by the southerly wind during April–June over the Pearl River Delta (PRD) region. It showed a cyclonic wind pattern during the occurrence‐time of nocturnal HR and a strong early convergence belt at −3 hr of daytime HR between the southeasterly winds and the northeasterly winds over the north part of the PRD region, which might be related to the cold outflow from the upstream east‐moving convections. Another key characterization parameter of HR was the strong decrease of surface potential temperature over the PRD region, especially during July–September.

中文翻译：

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珠江三角洲温暖季节的强降雨：运动和早期信号

根据2015年至2019年温暖季节（4月至9月）从地面观测收集的5年HR事件，对环境和运动以及强降雨（HR）的表面特征进行了检查。结果表明， HR通常向东移动，平均移动速度为59 km·hr ^-1在华南。与夜间HR相比，白天HR表现出更多的发作和更快的移动速度。夜间HR和白天HR都受到珠江三角洲（PRD）地区4月至6月南风的强烈影响。在夜间HR发生期间表现为气旋风型，在白天HR的3小时之间，珠三角区域北部的东南风和东北风之间有强烈的早期收敛带。上游向东对流的冷流出。HR的另一个重要表征参数是珠三角地区的表面电势温度大幅下降，尤其是在7月至9月期间。