Environmental Backgrounds and Radar Features of the"6·30"Severe Hail Process in Shangluo,Shaanxi Province
This study presents a comprehensive analysis of an extreme convective weather event with hail that occurred in the southeastern part of Shaanxi on June 30,2022.Hourly characteristics were analyzed by combining ground-based data,Doppler radar observations,and ERA5(0.25°×0.25°)data.The results revealed a strong potential instability stratification caused by northward airflow behind a high-altitude cold vortex,which drove dry and cold air southward in the upper layers.This stratification combined with southwest warm and humid airflow in the lower layers,which provided favorable conditions for severe convection.Several factors,including strong low-level water vapor transport and convergence,convective effective potential energy,appropriate heights of the 0℃and-20℃isotherms,and moderate vertical wind shear in the 0-6 km layer,created a conducive environment for hail weather.The occurrence of severe convection was influenced by the cold air in the middle-upper level and ground cold pools.Adequate thickness of warm and cold clouds promoted the growth of hail particles,while strong updrafts facilitated the cyclic growth of small hail particles in supercooled water.The reflectivity factor map showed areas of three-body scattering,with the strongest reflectivity factor exceeding 65 dBZ.The profile map revealed a low-level weak echo area and a middle-high level echo overhang.The position of strong echo(＞50 dBZ)exceeded the height of the-20℃layer.The velocity chart exhibited mesocyclone characteristics.The echo top height provided guidance on the development and weakening of convection.A VIL jump of over 20 kg·m-2 served as an advance warning for hail weather.
extremehailpotential instabilitythree body scatteringmesocyclone
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