Characteristics of Major Flow Patterns and Environmental Parameters of Strong Convective Weather in the Hetao Irrigation Area from 1991 to 2020
This paper analyzed the primary flow patterns and environmental parameter characteristics of 542 hail cases and 281 short-term heavy precipitation cases in the Hetao Irrigation Area from 1991 to 2020,using conventional meteorological observation data,regional automatic station observation data,and ERA5 reanalysis data.The results showed that:(1)The weather associated with short-term heavy precipitation is primarily characterized by four types of influencing systems,Xinjiang low trough(vortex),northeast cold vortex,Mongolia cold vortex,and southwest airflow.In contrast,hail weather is primarily associated with four types:Mongolia cold vortex,northwest airflow,northeast cold vortex,and Balkhash Lake cold vortex.(2)Variations exist in the forecasting thresholds for key parameters of short-term heavy precipitation and hailstorms in the Hetao Irrigation Area.The suggested lowest thresholds are determined based on the 25 th percentile values from box-and-line diagrams.The mean values of △T850-500 are 26 and 33 ℃,the mean values of the K-index are 27 and 35 ℃,the mean values of CAPE are 515 and 405 J·kg-1,the vertical wind shear from 0 to 6 km is 7×10-3 s-1,the mean values of the 0 ℃ layer heights are 4 656 and 4 069 m,and the mean values of the-20 ℃ layer heights are 8 070 and 7 054 m,respectively.(3)Hailstorms require larger K-index values,greater △T850-500,and stronger low-level warm air for development.Furthermore,hailstorms are associated with lower 0 ℃ and-20 ℃ layer heights,as the lower 0 ℃ layer heights can prevent hailstones from melting during the descent.Moreover,the impact of subsurface factors on different severe convective weather events varies,with altitude being the primary factor influencing the distribution of hailstorms in the Hetao Irrigation Area.
convective weathershort-term heavy precipitationhailstormphysical quantities
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