多系统影响下的一次丽江区域性暴雨分析

Analysis of a Regional Rainstorm in Lijiang under the Influence of Multiple Systems

摘要: 通过对2010年7月18日强降水天气过程的形势进行分析发现：本次大范围强降水天气过程受到多个系统的共同作用：500 hPa形势场为副热带高压与青藏高压之间形成两高间辐合区，高原东南侧有NW-SE的风向辐合，滇西地区存在南北向的切变，四川盆地西南部至滇西北形成低涡以及“康森”台风登陆。700 hPa上的系统与500 hPa对应，配合地面冷空气和充沛的水汽输送，动力和热力条件均较好，辐合抬升和不稳定对流等在此次过程中共同发挥作用。从丽江CINRAD/CC多普勒雷达回波分析，本过程是以层状云降水回波为主的积层混合降水回波变化缓慢，持续时间长而累积成的暴雨；垂直方向上的风低层顺转，高层偏北气流，这是非常有利于丽江发生降水的形势。欧洲中心形势预报稳定且具有重要参考价值，雨量量级可参考WRF预报。总结过程发现，工作中可参考云南省天气预报手册丽江部分中丽江市强降水的天气经验预报指标，但在强降水时间趋势掌握的情况下，落区的预报仍然是个难点。

Abstract: Through the analysis of the situation of the heavy rainfall weather process on July 18, 2010, it is found that this large-scale heavy rainfall weather process is affected by multiple systems: The 500 hPa situation field is a convergence zone between the subtropical high and the Qinghai Tibet high, the NW-SE wind direction convergence on the southeast side of the plateau, the north-south shear in western Yunnan, the vortex formed from the southwest of the Sichuan Basin to northwest Yun-nan, and the “Conson” typhoon landed. The system at 700 hPa corresponds to 500 hPa, with good power and thermal conditions in combination with cold air and abundant water vapor transport on the ground. Convergence and uplift, as well as unstable convection, play a combined role in this process. From the analysis of Lijiang CINRAD/CC Doppler radar echo, this process is a rainstorm ac-cumulated by the slow change and long duration of the stratified cloud precipitation echo dominated by the mixed precipitation echo; The wind in the vertical direction rotates clockwise in the lower layers and northward in the upper layers, which is very conducive to the occurrence of precipitation in Lijiang. The forecast of the central European situation is stable and has important reference value, and the rainfall magnitude can refer to the WRF forecast. It is found in the summary process that we can refer to the weather experience forecast indicators of Lijiang heavy precipita-tion in the Lijiang part of the Yunnan Weather Forecast Manual, but the forecast of the falling area is still a difficult point when the time trend of heavy precipitation is mastered.