What is the reason for the frequent rainfall in Henan?

The reasons for frequent rainfall in Henan are:

First, the atmospheric circulation situation is stable. The western Pacific subtropical high and continental high are maintained in the Sea of Japan and the northwest of China, respectively, which leads to the stagnation of the low-value weather system between them in Huanghuai area, resulting in long-term precipitation in the central and western Henan.

Second, rich water vapor conditions. In mid-July, Henan is on the edge of the subtropical high, and the convective instability energy is sufficient. /kloc-on 0/8, the typhoon "fireworks" was generated in the western Pacific and approached China. Under the guidance of the airflow around the typhoon and east of the subtropical high, a large amount of water vapor is transported to the inland areas of China, and the precipitation efficiency is high.

Third, the effect of topographic precipitation is remarkable. Influenced by the deep easterly jet and low vortex shear weather system, and the special topography of Taihang Mountain and Funiu Mountain in Henan Province, the easterly airflow has the function of convergence and uplift. The heavy precipitation areas in the western and northwestern regions of Henan Province are stable and less moving, and the precipitation before the windward slope increases obviously.

Fourth, the convection "train effect" is obvious. Under the stable weather situation, the mesoscale convection in front of Funiu Mountain develops repeatedly and moves to Zhengzhou, forming a "train effect", which leads to a large precipitation intensity and a long duration, resulting in extremely strong local precipitation.