Using conventional upper-air and surface observation data, along with satellite and radar detection data, the regional heavy rain weather event that occurred in Yibin City on June 22, 2022 is analyzed. The results indicate that the event was caused by the eastward movement of an upper-level trough and a low-level shear line. Under the combined effects of dynamic instability and topographic forced uplift, short-duration heavy rainfall, thunderstorms, and other severe convective weather were formed. The first half of the event was local warm and moist convection, while the latter half transitioned into stable precipitation. During the event, the low-level southwestern jet stream moved northward along the periphery of the subtropical high, ensuring unobstructed water vapor transport in the lower atmosphere. Additionally, the initially high atmospheric temperature contributed to atmospheric instability, providing favorable conditions for the interaction between cold air from the north and local warm, moist air, which triggered the heavy rainfall. Furthermore, the weak upper-level vertical wind shear, slow system movement, prolonged duration, and the westward and northward shift of the main system increased the difficulty of forecasting the event.