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利用常规观测资料、多普勒雷达和卫星探测及反演资料、区域自动站资料及NCEP再分析资料,分析了2009年8月27日冀中南地区的突发性强风雹天气过程。结果表明,扩散南下的弱冷空气对强对流起触发作用,地面辐合线进一步促进了对流发展。雹云发展于上干下湿的环境场中,凝结潜热释放可能为雹云迅速发展提供了能量,中等偏强的深层垂直风切变为雹云的发展和维持提供了有利的动力条件。但08：00湿层低而浅薄、0℃层高度偏高（高于历史出雹的平均高度）和云顶亮温相对高等特征增加了预报难度,而相对高的云光学厚度可为午后强对流发展提供短临预报信息。雹云在雷达反射率产品上表现为线状排列的＂超级单体族＂特征,向东传播的多单体风暴使强风雹天气得以持续。“,”Effected by the hail-cloud at the end of North China though,the central and southern regions of Hebei Province occurred a sudden severe storm on 27 August 2009,and the diameter of hail exceeds 40 mm,which led to serious disaster.The event was rare in the same period of history.Based on conventional observational data,Doppler radar and satellite detection information and retrieval products,Automatic station data,NCEP reanalysis data,the environment and structure of storm were analyzed.The result showed that the southward weak cold air triggered the severe convection and the boundary on the surface promoted the development of mesoscale convective systems.The hail cloud developed in the environment of up dry and low wet air levels.The latent heat of condensation might provide the energy for the rapid development of hail cloud and the moderate deep layer vertical wind shear might provide the dynamic conditions.However,the thinner and lower moist air level,relatively high 0 ℃ layer(higher than the average height in history) at 08:00,higher TBB made it more difficult to forecast the severe convection.However,the relatively higher cloud optical thickness might give the forecast information before the severe convection developing.The hail cloud was of the supercell-cluster characterized of linear arrangement in radar reflectivity and right propagating of multi-cells made the strong storm to be sustaining.