Dynamic Mechanism Discussion of the Continuity Storm Induced by Typhoon in the Northwest Side of Subtropical High

Using NCEP global 1 °×1 ° final-analysis data and the ground encryption unattended station material,the forms mechanism of the continuity storm in the northwest side of subtropical high is discussed with dynamic method.The results show that:It is advantage to the development of the rain storm that plus positive zone just over minus one in early period The negative value center of MPV1 and plus center of MPV2 and the surrounding compact district,is an alert area which the rainstorm produces.In later period,the negative value of MPV2 in upper air of the troposphere extended downward to the surface layer,it is advantage to enhance the barocliny of atmosphere and the vertical vorticity development,the precipitation maintained.The moisture helicity can reflect the dynamic character of weather when the rainstorm occurred,and divergence of negative vorticity on higher level matched convergence of positive vorticity and vapor rotate rising on lower leve1 is a dynamic mechanism to trigger heavy rain.Moisture helicity was superior to z-helicity for the precipitation forecast because it's increasing obviously at the time of strong precipitation.