Abstract:Under the similar atmospheric circulation backgrounds, the precipitation characteristics along the coast of Guangdong on 2 and 3 June 2020 are quite different, so the mechanism is worthy of deeply exploring. Based on ERA5 reanalysis data, wind profile radar products and observation data, we comparatively analyze the differences of precipitation, atmospheric circulation and physical quantity field in the warm sector of western Guangdong coast in the two days. Besides, we also discuss the trigger and maintenance mechanism of the double low-level jets for the precipitation in the warm sector of the region. The main conclusions are as follows. The low-level southwest jet axis was located in eastern part of Guangxi, the boundary layer southerly jet over the northwest of the South China Sea strengthened at night and its front side reached the coast of western Guangdong, maintaining for a long time. Under such a condition, the dynamic convergence and uplift caused by the convergence of wind speed in the front of the boundary layer southerly jet and the blocking effect of the coastal terrain of western Guangdong on the southward flow were conducive to the occurrence of convection in this area. At the same time, the existence and maintenance of cold pool favored the development and maintenance of rainstorm in the coastal warm sector of western Guangdong. When the low-level jet was significantly strengthened, expanding to the east and retracting to the north, and the boundary layer jet turned to the southwest extending to the north of the Pearl River Delta, the condition is not beneficial to the triggering and development of convection in the west coast of Guangdong.