Abstract: Initialized with FGGE-Ⅱ b data at 1 2 0 0 GMT on June 1 4, 1 9 7 9, a quasi-operational medium-term NWP model (T 4 2 L 9), introduced from ECMWF and with its cloud-radiation scheme modified, was used to investigate into the relative contribution by thermodynamic and dynamic forcings and cloud-radiative effects for the Tibetan Plateau during the northward advancement and enhancement of the South Asian High from June 14-19,1979.The 5-day.experiment was done under the conditions of diabatic or adiabatic heatingg with or without topographic effects and in the absence of cloud-radiation feedback.The resu It shows that the thermodynamic forcing south of the Plateau is the main cause behind the northward advancement and enhancement while the dynamic forcing acts as an unfavourable factor, both contributing to the medium-term oscillation of the High.Cloud-radiation interaction is another favourable factor.