从一次冰雹过程看冰雹快速预警的有效方法

The Effective Way for Rapid Hail Warning Concluded from the Hail Weather Process

大冰雹(直径≥2 cm)为强致灾性天气,目前冰雹预警时效普遍偏短,与社会防灾需求存在一定差距。通过对2016年6月8日长三角地区较为典型的冰雹过程分析,结合实际预警业务经验提出快速冰雹预警流程:首先掌握属地及周边冰雹生消时空规律,提高冰雹易发季节预警敏感度;其次于中短期预报中分析对流种类和强度,判断适合冰雹产生的强对流潜势大小,并检验冰雹特征指标,即0℃层高度、对流有效位能和垂直切变等是否符合经验指标;最后于短临预报中着重监测雷达回波的生成和动态,当初生对流发展迅速、将继续加强并影响责任区时,回波强度达50 dBz、回波顶高达12 km时,即可提前发布冰雹预警。

Large hails(diameter≥2 cm)usually cause disasters,hail warning time is usually short at present,which has a certain gap with the social demand for disaster prevention.Based on the analysis of the typical hail process in the Yangtze River Delta region on June 8,2016,combined with the warning business experience,the rapid hail early-warning process was proposed:Firstly,the time-space regulations of hail generation and extinction in the responsibility area and surrounding areas should be mastered to improve the early-warning sensitivity in the prone season;Secondly,the type and intensity of convection are analyzed in short-medium term forecast to judge the potential of strong convection which is suitable for hail generation,and the characteristic indicators of hail should be tested,including height of 0℃layer,CAPE and vertical shear whether they conform to empirical indicators or not.Finally,the generation and dynamics of radar echo should be monitored in the short term forecast,when the initial convection develops rapidly,and it is judged that the echo will continue to strengthen and affect the responsibility area,the hail alert can be issued in advance when the echo intensity reaches 50 dBz and the tops reaches 12 km.