Abstract: Based on the mesoscale model GRAPES and WRF with multiple physical parameterization schemes and cumulus parameterization schemes, an ensemble forecast system is developed with eight combinational schemes after carrying out the sensitivity experiments. Twenty sever precipitation synoptic processes in Xinjiang in 2007 and 2008 were simulated using the ensemble forecast system, and the forecast of 24hour precipitation was tested with Ts and BS. The results reveal that the score of ensemble forecast in forecasting heavy precipitation in Xinjiang was high, the forecasted precipitation was higher than the observed precipitation, but the forecasted precipitation with ensemble forecast was lower than that with control forecast, and it was closer to the observed one. The effect of precipitation of ensemble forecast in 24 hours is superior to the others.

Key words: heavy rainfall, GRAPES model, WRF model, ensemble forecast, Ts, BS, Xinjiang