CAUSE ANALYSIS OF A FLOOD-CAUSING RAINSTORM PROCESS IN THE MIDDLE REACHES OF THE YANGTZE RIVER

Conventional meteorological observation and 6-hour re-analysis data of NCEP1°×1° were used to analyze the cause of the process from July 18 to 19, 2020. The results showed that the "07.18" process had the characteristics of mixed precipitation, the circulation pattern was double resistance, and the southwest and northeast winds were strongly converging in the middle and low levels, which was conducive to the generation of systematic heavy precipitation. The middle-scale convergence system is at least 3h earlier than the occurrence of heavy precipitation, which can be used as a reference for this kind of weather forecast. The water vapor condition and dynamic condition are good, but the energy condition is general, which is not conducive to the occurrence of short-term heavy precipitation with heavy rain intensity. The rise of the cold air in the boundary layer and its above strong convergence and high altitude strong divergence are one of the main reasons for the occurrence of this heavy precipitation. In addition, the MPV center has a good indication of the rainstorm center.