高空西北气流下特大暴雨的预报误差分析及思考

Forecast Error Analysis of Extremely Heavy Rain Under High-Level Northwest Flow

利用常规及非常规气象资料、业务数值预报模式、GFS再分析资料(0.5°×0.5°),分析了2016年6月19日江西北部高空西北气流下特大暴雨环境场特征和数值模式误差,对比了相似形势的暴雨过程,找出业务预报误差较大的可能原因是对高空"干冷"西北气流南移、副热带高压北抬的速度、低空西南急流加强及前端辐合、上游移来短波槽、异常水汽条件的综合作用分析不到位,各类数值模式产品对降水落区预报偏北、强度预报偏弱也影响了预报员对暴雨的综合判断;给出了预报这类特大暴雨着眼点和预报概念模型以及订正模式降水的思路。

By using conventional and non-conventional meteorological data,numerical prediction model,GFS reanalysis data（0.5°×0.5°）,the environment features and model errors of extremely heavy rain under northwest flow which happened on 19 June 2016 in northern Jiangxi are analyzed.Compared with the similar situation,some possible causes of the prediction error are found out,such as the deviation of southward northwest dry-and-cold air,the speed of the subtropical high,the strengthening and convergence of the southwest low-level-jet,short-wave trough from upstream and abnormal moisture conditions.Even more,the prediction of rain belt by ECMWF was northward and much lighter than observation.Finally the forecasting methods of severe heavy rain are given.