Abstract:This paper reviews the predictive information provided by dynamic models and precursors consi-dered in the operational monthly prediction of precipitation in October 2016. The average amount of precipitation over China in October 2016 is the largest compared to the precipitation in the corresponding period since 1951, and the spatio-temporal characteristics of precipitation distributions and atmospheric circulation changes significantly during the month. There exists considerable difference between operational forecasts of precipitation anomalies issued in late September and observational results in the south of North China, Huanghuai, Jianghuai and Jianghan regions. Meanwhile, the forecasts underestimate the adjustment of general circulation within month and the transition of precipitation anomaly distributions. Analysis of model output and the impact of external forcing signals indicate that the estimation of general atmospheric circulation is basically consistent with observation, while significant difference remains between the forecast and observation results of the intensity, position of ridge line of West Pacific subtropical high (WPSH), etc. Lagged and simultaneous correlation analysis between atmosphere and sea surface temperature (SST) indicates that, the WPSH tends to be intensified and northward in the autumn of decay years of medium and strong El Nino events. In addition, the anomalous meridional circulation induced by active convection in the West Pacific warm pool, which leads to the anticyclonic circulation anomaly around Japan, also contributes the intensification and northward of WPSH. The significant negative phase of tropical Indian Ocean dipole (TIOD) in September and October, which is in favor of strong Indian-Myanmar trough and vapor transport, combined with cold air from north, resulting in more precipitation in east and north China. Moreover, the active convection of tropical West Pacific, and increased number of generated and landed typhoons, is the main reason for heavy rains in the southeast coastal regions of China.