The Causation Analysis of Persistent Heavy Rain in Sichuan during June-July,2018

Counter the persistent heavy rain in Sichuan during June-July 2018.Analytical characteristics of circulation during continuous persistent heavy rain.the results show that South Asia High is stable and strong during heavy rain.Sichuan is located in the high level jet stream outlet area to its northeast,The Ural Blocking High and The Palestinian Lake’s low vortex are stronger and more stable than normal,Providing a favorable circulation background for the occurrence of persistent heavy rain in Sichuan.The warm moist air is continuous transported to the Sichuan basin by the south airflow on the edge of subtropical high.Dry cold air frequently moves south and southwest warm and humid air flows in Sichuan basin.At the same time,water vapor in Sichuan basin is also strong continuous convergence rise,It provides favorable power and moisture conditions for the continuous occurrence of rainstorm.The low vortex which continued to move eastward is the important heavy rain producing mesoscale convective system.