石家庄盛夏一次暴雨空报诊断分析

Diagnostic Analysis on a False Rainstorm Prediction in Midsummer in Shijiazhuang of Hebei Province

实时天气系统的时空分布、多个物理量要素都表明2007年7月18日河北省石家庄市东、南和北部将有暴雨天气发生的可能,结果暴雨并没有发生。为了找到暴雨空报的原因,对常规资料和各种数值预报产品进行诊断分析。结果表明:(1)石家庄地区处于2条切变线的中间区域,导致缺少强降水的垂直条件(中、低层的切变线),这是暴雨空报的最主要原因;(2)利用离石家庄最近的邢台探空站的物理量特征来判断石家庄对流发展程度效果较差,这和探空站空间尺度较大有关,这是空报原因之二;(3)缺少有效的数值预报产品是预报失误原因之三:(4)这次邢台、邯郸的暴雨天气系统可定为西南涡类暴雨。利用卫星水汽云图和雷达、国家级自动站要素资料相结合可以大大提高灾害性天气预警能力。

It was proved a false prediction that the heavy rain would occur in Shijiazhuang on July 18,2007, though the temporal -spatial distribution of synoptic systems and physics factors all indicated a hint of the rainfall. In order to find the reasons, some factors were diagnosed by using the conventional material and numerical prediction products. Results are as follows： （ 1 ） It is the main cause for false forecast that Shijiazhuang was on the intermediate region of two shear lines, which resulted in a lack of vertical condition （ middle - low shear line） ; （2）The estimation effect of convection development over Shijiazhuang by using physical quantities from Xingtai station is not well; （3） A lack of the effective numerical forecasting products resulted in this false prediction; （4） The rainstorm occurred in Xingtai and Handan should fall into southwest vortex rainstorm ; （5） The early warning ability of severe weather can be greatly improved using satellite cloud images, radar data and meteorological factors from national automatic station.