The influence of Lu Mountains‐Huang Mountains topography on the formation of extreme precipitation events during the 2020 “super” Meiyu season

During the 2020 Meiyu season peak, an extreme orographic precipitation event (over 300 mm in 19 hours) struck the middle Yangtze River basin. A northwest–southeast rainband formed via interactions between the Meiyu front vortex (MYFV), Lu Mountains (LM), and Huang Mountains Branch (HB), featuring two distinct precipitation maxima: LM–HB1 (on the windward slope under southeasterly flow, Stage 1) and HB2 (on the leeward slope under southwesterly winds, Stage 2). Multisource observations and high‐resolution Weather Research and Forecasting (WRF) model simulations were employed to analyze the underlying mechanisms. In Stage 1, southeasterly winds interacted with LM downslope flow to generate strong upslope convergence, forming a deep convective core. As this core approached the HB1 ridge, orographic lifting combined with valley‐induced convergence intensified the updraft, driving the LM–HB1 rainband. In Stage 2, a southeast‐moving MYFV shifted low‐level winds to southwesterlies; the convective band propagated eastward, forming the HB2 leeward precipitation center. Northern HB2 rainfall arose via the seeder–feeder mechanism (ice particles descending, melting, and coalescing with liquid‐phase particles over the crest). Southern HB2 rainfall stemmed from terrain‐induced flow deflection: surface friction redirected airflow westward, interacting with crossmountain air to trigger strong convergence and upward motion. These findings highlight mesoscale topography's key role in modulating Meiyu front moisture and energy distribution, offering insights for forecasting of extreme rainfall in complex terrain regions.