Abstract:By using the besttrack datasets of tropical cyclones (TCs) provided by the China Meteorological Administration (CMA) and the ERA interim reanalysis data provided by the European Centre for MediumRange Weather Forecasts (ECMWF), the reasons for the difference between the tracks of typhoons Yagi and Rumbia that influenced Shandong when moving northward in 2018 are analyzed. It is found that: The differences between the tracks of typhoons Yagi and Rumbia are mainly related to the different distributions of the weather systems. Both typhoons were affected by the subtropical high and continental high successively, and Rumbia was also influenced by the upper trough that made a big angle change of the move direction. The steering airflow formed by the interaction between typhoon and highpressure systems were the main factors influencing the tracks of the two typhoons. The radiuses of the best steering airflow were within 5 latitudes of the TC center in both Yagi and Rumbia, but the height was different in different stages. The indicative function of the airflow at the middlelow levels was superior to that at the high levels before landing. After landing and before turning, the zonal airflow was better than the meridional, but the stability was little worse. After turning, without the meridional airflow of Rumbia, both the meridional and zonal airflow of Yagi and the zonal airflow of Rumbia had significant correlation across the whole level, and the middleupper levels were slightly better than the low levels. The airflow from 300 to 200 hPa can be used to forecast the turning of the typhoon 12 hours in advance. In addition, typhoons always move towards the direction of the positive vorticity advection nearby, and the stronger the positive vorticity advection is, the faster the typhoon moves.