A number of meteorological factors contribute to the genesis and development of low pressure systems in this area in the spring. When the Southwest monsoon season starts in April, warm moist air begins its invasion from the Indian Ocean northward into South China. Storms usually develop as the warm moist air encounters the cold, dry air mass from the north. Topography also plays a great role in cyclone development. China's high plateau to its west and complex terrain to the south complicates the circulation. Our study stresses the thermo-hydrodynamics of cyclonic circulations. A number of cyclogenetic cases were selected; maps at different levels for each case were analyzed. Based on the equations of our theoretical model, each term in the equations was measured from the maps and tabulated. Statistical analysis and interpretation of these data show that the most important contribution factors are the baroclinic and the condensational heating effects. An analytical and theoretical model was developed in order to determine how the presence of the Tibetan Plateau and other factors affect the cyclogenesis. Solution under linearized conditions was obtained and the 500 mb trough position was in general agreement with observations.