Contrast Analysis on Two Continuous Hail Weather Processes Triggered by Cold Air in Tongren of Guizhou Province
Based on weather observation data from ground intensive stations,observation data of Tongren Doppler radar and NCEP/NCAR reanalysis data,the weather system development,structure characteristics and forming reasons of two continuous hail processes on 19 March and 22 March 2013 in Tongren were analyzed.The results are as follows:(1)The upper dry air being superimposed on the low layer warm air resulted in unstable stratification,which was the favorable circulation background of two hail processes,mean-while,the warm and moist air flow accumulated in the middle and low layer caused heavy rainfall.(2)Strong geopotential instability caused by cold and dry air in the mid-layer and intrusion of cold air from surface was the important environmental condition for the se-vere convective weathers such as hail in Tongren.(3)The K index≥38 ℃,SI≤-1 ℃,SWEAT≥310,CAPE≥300 J/kg could be used as favorable indexes for hail weather forecast,and when the vertical wind shear from ground to 400 hPa was 5 ×10 -3 s-1 above, it was conducive to developing and strengthening of hailstorm system.(4)Radar echo analysis showed that the strong echo with reflec-tivity more than 50 dBZ developed and stretched to the height more than -20 ℃ layer,and there was weak echo region or boundary weak echo region,and the radial velocity field was often accompanied by dead wind or secondary vortex,the above mentioned were all typical characteristics of hail weather.(5 )When the vertical liquid water content increased to more than 25 kg/m2 ,it indicated that there was a hail ocurrence,and combined the hail index,they could be used as an important reference for hail warning.
NETL
NSTL
万方数据
维普
