Abstract:Recently, an extended range (10-30 days) forecast method, namely the spatial temporal projection model (STPM) has been applied in predicting the low frequency precipitation in tropics and shows comparable skills. Based on the daily precipitation data from 11 weather stations in Shanghai, and the daily MJO index (RMM1 and RMM2) provided by Australian Meteorological Bureau during 2011-2010, the STPM model for the extended range forecast of precipitation during Meiyu season in Shanghai was constructed. Depending on the relationship between the quasi period MJO activities and the precipitation, the coupled patterns between temporal varying real time multivariate MJO (RMM) index and regional low frequency precipitation during Meiyu season is derived based on the singular value decomposition (SVD). Therefore, using the MJO index as predictor and projecting it onto the spatial temporal coupled patterns, the forecast of regional low frequency precipitation is obtained. The STPM model is then used in the precipitation prediction during 2011-2016. The evaluation demonstrates that the prediction of the STPM model achieves a useful skill at a lead time of 25 days. Three quarters of precipitation occurrences and intensity during Meiyu season can usually be predicted. Among them, the STPM model attains a higher skill in the prediction of 10-20 d lead time. Generally, the STPM model provides a useful method in the extended range forecast during Meiyu season in Shanghai.