Abstract:By using the object-oriented method of contiguous rain area (CRA), this paper investigates sources of the rainfall forecast error in deterministic forecasts by the ECMWF, and their changes with different rainfall levels and forecast periods when typhoons influenced China in 2019. Then, the correlations between typhoon track errors and displacement errors of rainfall events are analyzed and the performance improvements of rainfall forecasts calculated with track correction or CRA shifting are compared. Finally, forecast errors of rainfall probability distribution, radial and asymmetric rainfall distribution are verified and analyzed. The results are as follows. In general, the main forecast errors come from displacement error and shape error. Except for enormous amount of rainfall, track error is significantly correlated to the displacement error of CRA rainfall events. The improvement of rainfall forecasts made by track error correction is less than that made by CRA shifting correction. The shape of probability density distribution for rainfall forecasts resembles the observed one， but the forecasted rainfall intensity in typhoon core area is stronger than the observed one. Before and after typhoons’ making landfall or approaching the coast, the forecasted rainfall is much closer to typhoon center than the observed one, and it lags behind the observation. The asymmetric structure of forecasted rainfall is significantly weaker than the observed one.