Mesoscale Analysis of A Torrential Rain in Central Hunan

Using NCEP/NCAR,TBB and WRF mesoscale numerical weather prediction model data,the formation mechanism of mesoscale convective system was analyzed based on the persistent heavy rainfall from 1/2 July 2009 in central of Hunan Province.The results showed that process of torrential rain formation is accompanied with strong mesoscale convective motion.The rainfall in some places reach strong convective storm level.The main influencing system in the heavy rainstorm process is mesoscale convective system of front moving to the south,and the direct reason is that echo with mesoscale weather systems moves to the shear line from north to south rolling and changing.The persistent convergence plays an important role as the dynamic condition on the formation of rainstorm area.Continuous warm advection and vertical wind shear has a dominant effect on rainstorm during the development and maintenance process.