2011年盛夏石家庄一次短时暴雨分析  

Case Study of a Torrential Rain in Midsummer of 2011 in Shijiazhuang

作　　者：孙云[1] 刘伟[1] 李国翠[1] 马贵东 冯洋[1] 

机构地区：[1]河北省石家庄市气象局,河北石家庄050081 [2]河北省宁晋县气象局,河北宁晋055550

出　　处：《干旱气象》2015年第1期156-161,共6页Journal of Arid Meteorology

基　　金：河北省科技计划项目(12237126D-1);灾害天气国家重点实验室开放课题(2014LASW-B02);河北省气象局重点项目(14ky04);河北省气象局预报员专项(14ky36)共同资助

摘　　要：2011年7月26日石家庄市出现一次暴雨冰雹天气,其特点是500 h Pa及以上高空强冷空气导致高空形势在12 h内发生剧变,短波槽快速南下,致使探空观测和数值预报失灵。本文对其他监测资料进行分析,发现这种剧烈变化的天气有明显特征:卫星云图上河套北部逗点云系尾长而粗壮,有向南发展趋势,云系后部的暗区表明干冷空气侵入,与低层暖湿空气形成对流云,尾部断裂表明冷空气加速南下。单站要素变化显示,石家庄地面假相当位温比正常值高了8℃,出现异常不稳定能量。强对流天气发生在假相当位温密集带内,能量中心假相当位温最高达到90℃以上,100 km内假相当位温温差超过25℃,最大降雨出现在假相当位温密集带内。雷达回波呈西南—东北带状排列,前部最大强度为65 d BZ,强回波前形成阵风锋,正负最大速度均超过20 m/s,飑线自西向东移动,它的移向和发展程度决定降雨和冰雹的路径和强度。石家庄市区风向转变和形成地面辐合线分别较降水起始时间提前21 min和30 min。A torrential rain and hail stroke Shijiazhuang on July 26,2011. The strong and cold air flow on 500 hPa and above resulted in sharp shifts of synoptic situation at high altitude in twelve hours,with short wave trough moving southward rapidly,which caused the failure of radiosonde observation and numerical forecast. Based on other monitoring data,obvious characteristics of the dramatic chan-ging weather were analyzed. Firstly,according to satellite images,the comma cloud above the Great Bend of the Huanghe River had long and stout tail,with a tendency of developing southward. The dark area at the rear part of clouds indicated the intrusion of dry cold air,which developed into convective clouds with warm and moist air at low altitude. The tail fracture suggested the acceleration of mov-ing southward of cold air. Secondly,the Shijiazhuang single station element variation showed that the surface potential pseudo equiva-lent temperature was 8 ℃ higher than the normal value,which indicated abnormal instability energy. Strong convective weather with the largest precipitation was located in the intensive zone of pseudo equivalent potential temperature,which reached 90℃ at the energy center. The difference of pseudo equivalent potential temperature within 100 km was more than 25 ℃. Finally,the radar echoes ar-ranged zonally from the southwest to the northeast with the strongest echo of 65 dBZ in the front. Gust front formed before the strong echo,its maximum positive and negative speed were both larger than 20 m/s. The squall line moved from west to east and its path and intensity ditermined the path and intensity of precipitation and hail. The transformation of wind direction and formation of surface con-vergence line were 21 min and 30 min ahead of the precipitation,respectively.

关 键 词：短时暴雨 能量锋区 短时预报 地面辐合线 

分 类 号：P458.121.1[天文地球—大气科学及气象学]