一次南支小槽引发的贵州南部暴雨天气过程的预报偏差分析

Forecast Deviation Analysis:A Rainstorm Process in Southern Guizhou Caused by a Small South Branch Tank

为了准确分析和精细化预报贵州暴雨的落区情况,基于NCEP 2.5°×2.5°的FNL资料和常规天气图以及数值预报等资料,对2015年6月13日发生在贵州南部及东南部的一次大范围较强暴雨过程的成因和预报偏差进行分析。结果表明:高空低涡冷槽、南支小槽、低空急流建立是此次暴雨过程的直接影响系统;假相当位温锋区的位置对强降水出现的时次和位置有一定的指示作用,并且暴雨区上空低层负涡度、高层正涡度形成抽吸结构,涡度移动的方向与天气系统的移动方向比较一致。副热带高压的缓慢加强西进是阻挡降水东移的关键,近地层西北偏北路径冷空气的补充为暴雨天气提供了触发条件,而垂直速度则为强对流天气预报中提供了很好的指示作用。EC模式对贵州暴雨预报时次和量级效果较好,但对降雨落区存在偏差。

The paper aims to accurately analyze and forecast rainstorm drop area in Guizhou.Based on FNL information NCEP 2.5°×2.5°; and conventional numerical weather maps and other information,the cause and forecast deviation of a wide range of strong rainstorm process on June 13,2015 in southern and southeastern Guizhou were analyzed.The results showed that：air vortex cooling tank,small south branch tank and the establishment of low-level jet acted as the directing impact system of the heavy rain process;the location of frontal zone of equivalent potential temperature had a certain indication on the time and location of the heavy rainfall,and lower negative vorticity and high positive vorticity over heavy rain area formed a suction structure,vorticity moving direction was more consistent with the moving direction of weather systems.Strengthening subtropical slow westward was the key blocking eastward shift of precipitation,the supplement of nearly formation north by northwest path of cold air provided trigger condition for torrential rain,while vertical speed played a good indication role in strong convective weather forecast.EC mode had good prediction time and magnitude of heavy rain in Guizhou,but there was a deviation for rain drop area.