Basic characteristics and preliminary causes of the extreme rainstorm over North China in late July 2025

This study investigates the extreme rainstorm over North China during 23–29 July 2025 using surface and upper-air observations, FY-4B satellite data, radar data, and ERA5 reanalysis data. The event was characterized by a long duration, high intensity, and large accumulated precipitation, exhibiting a spatial pattern of “double rainbands with multiple centers” and marked warm-sector features. A stable synoptic background formed by a mid–high-latitude straight frontal zone, the northward extension of the western North Pacific subtropical high, and multiple typhoons favored the prolonged rainfall. Relayed moisture transport along typhoon peripheries provided abundant water vapor. Warm-sector rainstorms on 26–27 July were sustained by mesoscale β convective systems.The “train effect”, associated with the backward propagation of convective cells and the strong alignment between the orientation and movement direction of the convective system, was a key factor contributing to the longevity of short-term heavy precipitation. Mesoscale processes, including the interactions beteween the cold pool and warm-moist tongue, mesoscale front maintenance, and low-level southerly convergence along the mountain front, further promoted convective initiation and organization.