利用气象卫星、多普勒天气雷达、区域自动气象观测站及常规气象观测资料，结合NCEP/NCAR逐日6 h再分析资料（0.25°×0.25°），对2018年18号台风“温比亚”及其残骸长时间影响山东引发特大暴雨的成因进行分析发现：1）此次极端降水可分为三个阶段，分别受台风外围螺旋云系、倒槽和变性后温带气旋冷锋影响，其中弱冷空气与台风倒槽相互作用对强降水的产生和维持起到了重要作用。2）“温比亚”缓慢北上过程中，强降水落区从台风东侧逆时针转至其北部倒槽附近，并逐渐远离台风中心，台风强度逐渐减弱。3）冷空气在对流层中层与台风倒槽相互作用，中层冷暖平流增强形成锋区，斜压不稳定能量增强，暖湿空气在锋区附近上升，并与低层倒槽辐合上升运动相配合，引发了倒槽附近特大暴雨的发生。4）此次过程中，低空急流稳定维持，源源不断地将水汽自东海输送至台风倒槽附近，水汽输送集中在800 hPa以下，850 hPa水汽通量辐合强度大于8×10-6 g·cm-2·hPa-1·s-1区域与暴雨落区的形态和位置对应良好。5）对流层中层的弱冷空气和低层的强暖湿气流促进了对流不稳定层结的发展和维持，低层强风速带在鲁中山区迎风坡强迫抬升不断触发中尺度对流系统，在中高层气流引导和地形作用下产生“列车效应”，也是此次过程中局地特大暴雨产生的重要因素。
Based on data of satellite, Doppler weather radar, regional automatic observation stations, and conventional observation, combined with NCEP/NCAR 6-h reanalysis data (0.25°×0.25°), the causes of the extraordinary rainstorm in Shandong Province produced by Typhoon RUMBIA (1818) and its aftermath, which affect the region for a long time, are analyzed. The findings are as follows. 1) The extreme precipitation can be divided into three stages, in which the rain areas are affected by the spiral cloud system around the typhoon, the inverted trough, and the cold front of a denatured extratropical cyclone, respectively. The interaction between the weak cold air and the typhoon inverted trough plays an important role in the generation and maintenance of heavy precipitation. 2) During the slow northward movement of Typhoon RUMBIA, the heavy precipitation area contrarotates from the east side of the typhoon to the northern inverted trough of it and gradually moves away from the typhoon center. Furthermore, the intensity of the typhoon is gradually weakened. 3) The cold air interacts with the typhoon inverted trough in the middle troposphere, where the cold and warm advection are strengthened, the frontal zone is formed, and baroclinic instability is intensified. The lifting of warm and wet air near the frontal zone, combined with the convergence and upward movement of the inverted trough at the lower layer, generates the extraordinary rainstorm near the inverted trough. 4) In this process, the stable low-level jet stream continuously carries water vapor from the East China Sea to the typhoon inverted trough and the transfer of water vapor is concentrated below 800 hPa. The region where the intensity of water vapor flux convergence at 850 hPa is greater than 8×10-6 g·cm-2·hPa-1·s-1 corresponds well with the shape and location of the rainstorm area. 5) The weak cold air in the middle troposphere and warm and wet air at the lower layer promote the development and maintenance of instable convective stratification. Under the guidance of middle and upper airflow and the impact of topography, mesoscale convective system is constantly triggered by the forced uplift of the strong wind belt at the lower layer in the windward slope of central mountainous areas in Shandong Province, producing train-effect, which is also an important factor for the occurrence of local extraordinary rainstorm in this process.