Mesoscale Analysis on a Heavy Rainstorm in Jinan on 18 July 2007

A mesoscale heavy rainstorm in Jinan on 18 July 2007 is analyzed using the special observational data,including Doppler radar products,automatic meteorological station data,NCEP/NCAR reanalysis data and CloudSat satellite data.It is found that the heavy rainstorm process is generated by the interaction of westly trough,the southwest warm and wet airflow on the edge of West Pacific Subtropical High and the cold air from the north.The result shows that the mesoscale convergence center and line play important roles,which is the start mechanism for the heavy rainstorm.Furthermore,the heavy rainstorm occurres near the center of mesoscale low pressure and accompanies with them.The mesoscale convergence center develops at intersection of the boundary layer convergence line,which increase the strong wind convergence and accumulation about moisture and energy.Radar products show that convection and precipitation enhance at the junction between two strong east-west echo bands.In the vertical direction,low level convergence and high level divergence are almost vertical.This configuration shows that mesoscale convective system has strong baroclinic characteristic.This case has the typical characteristic of convective storm,accompanying with vertical tilt of updraft and obvious sink flow compensation on both sides.