六盘水市2021年8月7~13日连续强降雨天气过程环流背景及模式预报效果评估
Evaluation of Circulation Background and Model Forecast Effect of Continuous Heavy Rainfall Process from 7 to 13 August 2021 in Liupanshui City

本文利用气象常规资料、区域自动站资料、卫星资料、NCEP再分析资料等对六盘水市2021年8月7~13日连续强降雨天气过程进行环流背景分析及模式预报评估。结果如下：1) 此次连续过程中亚洲中高纬环流形势稳定。雅库茨克–鄂霍次克海阻塞高压和巴尔喀什湖低压槽建立后长时间稳定维持，低压槽中不断分裂小槽东移，引导弱冷空气南下，与南方暖湿空气交汇造成连续强降雨天气。2) 西太平洋副高经历了西伸北抬–东退南落–西伸北抬–东退南落的周期过程，相应地伴有小股冷空气在副高588线北部边缘发展为小槽和东移的周期过程，这种小槽的发展和东移对贵州暖区暴雨的产生提供了有利的天气形势和触发作用。3) 过程平均(7~13日平均)的500 hPa、700 hPa、850 hPa及地面图上在贵州境内均以偏南风气流为主，贵州处于西太平洋副高附近的高能高湿环流背景下。此次过程除7日降雨以纬向水汽输送为主外，其余时段经向水汽输送更为重要，即南风暖湿气流在8日后逐渐发展强盛，为六盘水强降雨提供了充沛的水汽和能量。4) 700 hPa湿位涡的大值中心与等值线密集区对强降雨落区具有较好的预测指示意义，最大降雨通常出现在其梯度最大的区域。5) 六盘水市降雨落区(雨带)可以综合考虑EC和德国的模式预报，德国的雨带预报亦常有较好的效果。全球模式量级预报普遍偏小，所以考虑最强降雨量级时，应以中尺度模式为主，贵州WRF、CMA-MESO在此过程中预报效果更好。6) 雷达回波外推产品对六盘水市短时强降雨的预报有时成功，有时失败，外推初始时刻产品与实况的差异对外推结果影响很大。
In this paper, the circulation background analysis and model forecast evaluation of the continuous heavy rainfall process during 7~13 August 2021 in Liupanshui city were carried out by using conventional meteorological data, regional automatic station data, satellite data and NCEP reanalysis data. The results are as follows: 1) The circulation in the middle and high latitudes of Asia was stable during the continuous process. After the establishment of Yakutsk-Okhotsk blocking high and Balkhash Lake low pressure trough, they maintained stably for a long time. Small troughs in the trough kept splitting eastward, leading weak cold air to move southward, and resulting in continuous heavy rainfall when they intersected with warm and humid air in the south. 2) The western Pacific subtropical high has experienced the west and north-east retreat south, west and north-south fall back east cycle process, corresponding with the cold air on the northern edge of the subtropical high of 588 line development cycle for small trough and the east, the development of the small tanks and east areas in Guizhou warm rains provides favorable weather situation and triggering role. 3) In the process average (7~13 day average) of 500 hPa, 700 hPa, 850 hPa and the surface map, the southerly wind flow is mainly in Guizhou, and Guizhou is under the background of high energy and high humidity circulation near the Western Pacific Subtropical high. In this process, except for the zonal water vapor transport in the rainfall on the 7th, the meridional water vapor transport was more important in other periods, that is, the warm and wet air from the south gradually developed and became stronger after the 8th, providing abundant water vapor and energy for the Liupanshui heavy rainfall. 4) The large value center of 700 hPa wet potential vortex and the dense area of isolines have a good predictive significance for the heavy