A case study on weather process of "8.3" heavy storm in Dalian region

A heavy storm weather process in Dalian region on Aug.3th,2004 was discussed in terms of the data from general weather map and automatic weather observation station as well as Doppler radar.The results indicated that the advantageous large-scale circulation field and the coupling of upper and lower air jets in Dalian region as well as the invasion of cold air from the northern part of North China with suitable intensity would directly result in the enhancement of vertical updraft motion.The main reason resulting in large-scale precipitation weather was the development and enhancement of the surface low pressure system,which was caused by the overlapping of upper air divergence field with high intensity and lower air convergence field with high intensity as well as continuously downward transport of the upper positive vortex.In addition,the development of vertical motion also improved the cyclonic activity with γ scale,and would strengthen the intensity of precipitation.