In this paper,the analysis of two short periods of strong convection weather occurring in the northern part of Liaoning on August 8,2007 and July 16,2008 is made,which verifies that the two processes are typical severe convective weather processes of cold vortex.They agree on location of occurrence,weather background and the characteristics of radar data.
Based on the conventional meteorological data and 4 times daily NCEP reanalysis data,the causes of rain changing snowstorm in Liaoning during February 12-13 of 2009 were discussed.The low-level jet conditions,temperature conditions and coupling mechanism of water vapor and dynamics of heavy snow were diagnosed and analyzed.The low-level jet provided abundant water vapor for this process.The convergence at low level,divergence in the upper troposphere and strong ascend movement provided dynamic conditions for the snowstorm.The wedging of cold air was the chief cause of rain changing snow.The strongprecipitation area corresponded to the moist potential vorticity well.
By using NCAR/NCEP daily reanalysis data and the precipitation data in Liaoning routine automatic station during July 14-16,2008,the regional rainstorm weather process in Liaoning was done the isentropic analysis. According to the variation characteristics of isobar,isocratic specific humidity line and wind field on the isentropic surface,the rainstorm landing zone was gained and compared with the analysis results of isobaric surface. The results showed that the warm wet transportation belt on 330 K isentropic surface provided the rich water vapor condition for the rainstorm generation,and the distribution of air-pressure and wind field on the isentropic surface favored to understand the movement of airflow. Compared with the analysis of isobaric surface,the analysis of isobaric surface could better directly judge the landing zone of precipitation,and the forecast effect was better than the analysis forecast results of isobaric surface.
