Abstract:In view of the prominent problems in the precipitation and model forecasts of the landfalling typhoons in South China, this paper reviews and analyzes the current researches on the asymmetry of the precipitation distribution of the landfalling typhoons and the mechanism of the persistent torrential rains in the later period of typhoons. Relevant scientific issues that need in-depth study and measures of improving numerical predictions are put forward, in order to provide references for the improvement of the forecast of heavy rainfall associated with tropical cyclone (TC) landfall in South China. The analysis reveals that the vertical shear of the ambient field, the boundary of the low-level air mass (such as the boundary of the cold pool), the intrusion of dry and cold air, mesoscale convective systems (MCSs) and the local topography are important factors causing the asymmetric distribution of precipitation of the landfalling typhoons in South China. The occurrence of persistent torrential rains in South China during the late period of landfalling typhoons is often related to the increase in summer monsoon activity. The active southwest monsoon tends to provide favorable conditions for the development of MCSs in torrential rains. Then, MCSs feed back to the large-scale circulation through latent heat heating, contributing to the maintenance of TC vortex circulation and the southwest monsoon, and cause iterative development of MCSs, resulting in persistent torrential rains. To further improve the forecast of models, it is essential to investigate and evaluate the performance of the current models, carry out in-depth research on the related scientific issues, and then propose effective improvement plans.