Abstract: Using the surface meteorological station observations,FY-2G hourly satellite TBB (Temperature of Black Body) lightning positioning data,Xi'an CINRAD/CB-type Doppler radar,NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) 1°×1° reanalysis data in every 6 h,and conventional meteorological data,the formation mechanisms of a rare heavy snow process accompanying with an "elevated thunderstorm" occurred on November 22-23,2016 was discussed.The results show that the 500 hPa upper trough,700 hPa low-level shear line and lower troposphere jet are major systems influencing this heavy snow process.The southwest jet at 700 hPa provides sufficient water vapor,and the 850 hPa low-level jet and the inverse trough eastward airflow at the ground provide a deep cold pad.The "elevated thunderstorm" with the heavy snow is a typical "cold sector thunderstorm" which is maintained by the strong inversion layer below 700 hPa and by the wet neutral boundary layer above 700 hPa.The upflow is stronger,so the moist and deep convection is easy to form.The frontal secondary circulation circle is helpful to the development of the slantwise updraft.The vertical wind direction shear is strong.The convective echo intensity ranges from 30-50 dBz,and the echo top height is 10-12 km.The tropopause height exceeds subcooled water layer height with a temperature range of -20~0 ℃,making the thunder to form easily.The thunder and hail normally appear on the left-hand side of the low-level jet entrance region,which is close to the high concentration zone of TBB,water-vapor flux,and θ_se.

Key words: Elevated thunderstorm, Low-level jet, Thermal inversion layer, Vertical wind shear