Abstract:The performance of three statistical post processing methods and their combinations for 3 h precipitation forecasts out to 72 h from May to September are compared in this paper. They are optimal threat score (OTS) correction, model output statistics (MOS) and MOS with prior spatial observation predictors (OMOS). The 3 h precipitation forecasts of ECMWF model output (DMO), MOS, OMOS, and their OTS correction forecasts (DMO OTS, MOS OTS, OMOS OTS) are evaluated. The results show that MOS OTS method has the best performance in the short term forecast. At the same time, for the heavy precipitation forecast, MOS OTS also obviously outperforms the operational guidance (GD) forecast which integrates subjective and objective predictions. In the first 3 h precipitation forecast, OMOS OTS is the best method. For the first 3 h precipitation forecast, the TS scores of OMOS OTS for thresholds of 0.1, 3 and 10 mm per 3 h are improved about 73%, 198% and 483% than DMO respectively. And the bias score of OMOS OTS is close to 1. In the daily variation during summer time, the first 3 h precipitation forecast from OMOS OTS outperforms both MOS OTS and GD forecast in most days evaluated by TS and Bias scores for the threshhold of 0.1 mm per 3 h.