Synthetic Analysis of a Far Distance Typhoon and Rainstorm Process in Shaanxi Province

By using routine observational data,satellite images and surface automatic observational data,a far distance typhoon and rainstorm process occurred in Shaanxi in July of 2010 was analyzed.Results show that the high pressure over the south of Baikal and west Pacific subtropical high at 500 hPa were stable,the vortex in the southern part of Gansu deepened and moved eastward,they were the main circulation characteristic of the rainstorm weather.The transportation channels of water vapor and enthalpy at the level of 700 hPa was established between the east side of typhoon and Shaanxi,which transported the warmer and wetter airflow toward Shaanxi continuously,and rainstorm occurred in the dense area of enthalpy isoline at 700 hPa.Convective instability and conditional symmetric instability were the important mechanism for development and persisting of the rainstorm.When big value area of moist potential vorticity at high level spreaded downward,the rainstorm became stronger.