The Tianshan Mountains are the largest set of mountain range in middle Asia.As such,as a result of their extended zonal topography,they partially determine the distribution of the water resources in Xinjiang during the summer months,due to their capability of stimulating precipitation events.The precipitation events which are induced by the Tianshan Mountains' topography have significant benefits for the arid and sub-arid regions near Xinjiang.In this research,the aim was to explore the dynamical structures,transportation of water vapor,and microphysical mechanisms which are affected by the Tianshan Mountains' topography.A severe convective rainfall event which occurred during the summer of 2011 over the middle section of the eastern Tianshan Mountains was analyzed using the available data from ordinary observations,and automatic weather stations,along with Fengyun-2D (FY-2D) Temperature of Black Body (TBB) measurements.A Weather Research and Forecast (WRF) model with a nested domain setting was also employed in this study.When compared with the observational and satellite data,the WRF output was found to be nested in three sub-domains which had different spatial resolutions,and together,these data were found to reasonably recapture this particular precipitation event.Therefore,a more detailed analysis of the large-scale dynamics and microphysics was conducted in this study,in order to retrieve the features of this topographical-induced precipitation event over the middle section of the eastern Tianshan Mountains.The results showed that the eastern Tianshan Mountains had blocked one airflow moving towards the east,and split the flow going around the eastern Tianshan Mountains from the northern and southern slopes.On the level of 900 to 800 hPa,a northern jet stream converged following the Yili Valley,and then turned toward the southwest,before climbing Mount Poluokenu,which has a relatively low altitude in the west section of the northern Tianshan Mountains.Therefore,the northern sub-flow was determined to have originated from a clockwise turning of the northern jet stream at the right exit of the jet flow before it was forced topographically by the northern slope of the middle section of the eastern Tianshan Mountains.On the level of 750 to 650 hPa,a southwestern jet stream developed after the southern jet stream climbed the southern Tianshan Mountains to reach the Talimu Basin,and then turned to the north due to being affected by an anti-cyclonic system over the Tulufan region.It then formed a southern sub-flow which climbed up the southern slope of the northern Tianshan Mountains after reaching the Yanzhe Basin.These two sub-flows eventually merged at the top of the middle section of the eastern Tianshan Mountains,and together dynamically favored the development of local convections in which the northern sub-flow became the main source of the water vapor,which potentially caused the severe rainfall event.As can be seen from the large-scale dynamics,the high level southwestern airflow led to ice-phase cloud bodies with depths of 5 to 6 km on the northern slope of the middle section of the eastern Tianshan Mountains.These merged with the low level deep convections which have already been formed there.Then,the cloud particles in the form of super cooled water were able to be uplifted to a higher level,and co-existed with the ice particles in the ice-phase clouds.This co-existence enabled a much stronger Bergeron process,and a riming process was determined to have occurred,which accelerated the growth of the cloud particles.This in turn caused heavy rain fall processes to occur in the area.Therefore,based on both the observations and numerical simulations,this study was able to present a better understanding of the topographical effects of the Tianshan Mountain regions on heavy rainfall events.The results of this study may also potentially act as a reference for future weather forecasts and modifications in the mountainous areas of Xinjiang.