Abstract:The track and intensity forecast errors of super Typhoon Muifa (No.1109) and the rapid intensification of severe typhoon Roke (No.1115) over south of Japan are analyzed in this paper and some practical forecasting points are obtained. The results show that the combination of NW Pacific Ocean subtropical high and equatorial high located between the two typhoons which row from east to west is an obvious signal for the typhoon in the west to move northward. The high over China mainland at the west of the typhoon and the equatorial high located southeastward of the typhoon should also be focused on in the forecasting process. In terms of the typhoon intensity forecast, upper level trough to its northwest approaching typhoon with southwesterly jet which is at the speed of more than 40 m·s-1 is a favorable condition for the intensifying process. In addition, in the synoptic situation unfavorable for the intensification of typhoon, the mutual effect between thermal status of tropical ocean and the typhoon is another key point in the operational intensity forecasting.