运城市7．29突发性大暴雨过程分析

Analysis of ‘7. 29’ Sudden Heavy Rainstorm in Yuncheng City

利用常规的天气图、物理量场、卫星云图和雷达回波等资料对2007年7月29日运城区域性大暴雨进行了诊断分析，结果表明：当西风槽后的冷空气与强经向型副热带高压西北侧的西南气流交汇时，触发对流产生，造成本次强降水的主要原因是低空急流和中低层风向切变，低空急流为本次暴雨提供了充沛的水汽和不稳定能量。物理量场表现出强的水汽辐合，低层辐合、高层辐散及强烈的上升运动；Ose、K指数和研指数对暴雨发生有较好的指示意义。卫星云图和雷达回波相结合对短时暴雨预报有很好的指导作用。

Using the data of routine weather chart, the physical quantity fields, cloud atlas and radar echoes ere, the heavy rainstorm weather process occurred on Jul 29, 2007 in Yuncheng city is analyzed. The result shows that the convection occurs when the cold air after the westerly trough combines with the southwest airflow which is at the side of northwest of the subtropical high. The main causes of the sudden weather are the low jet stream and shear line. The characteristics of water vapor convergence, low level convergence, high level divergence and strong ascending movement are especially obvious, and some rainstorm features can be found in indexes of k, SI , cloud atlas and radar echoes etc.