According to Zhang Ning, chief forecaster of Henan Meteorological Observatory, the western Pacific subtropical high and continental high were maintained in the Sea of Japan and northwest China respectively, which prevented the upstream system from moving, resulting in the low-value system of westerlies being maintained in North China and Huanghuai areas for a long time. Influenced by the deep easterly jet and the stable vortex shear, combined with the strong convergence and uplift of the easterly airflow caused by the special topography of Taihang Mountain and Funiu Mountain in Henan Province, the strong precipitation centers are mainly distributed in the western and northwestern regions of Henan Province, resulting in stable and little movement and long precipitation time in Henan Province. Due to the long duration of precipitation and the concentration of heavy precipitation, the risk of geological disasters caused by mountain torrents in the western and northwestern regions has increased significantly, and the water levels of small and medium-sized rivers and reservoirs in the Yellow River Basin and Haihe River Basin have risen rapidly, which has also caused large-scale urban waterlogging and farmland waterlogging.
Let's take a look at the characteristics of heavy rain in Henan given by experts.
1. Long duration. On July 17, there was a large-scale heavy precipitation in the western and central and western regions of Henan Province for four consecutive days, and the heavy precipitation will continue.
2. The accumulated rainfall is large. The average rainfall in the whole province is 1 13.5 mm, and the average rainfall in Zhengzhou, Jiaozuo and Xinxiang is 357 mm, 2 10.6 mm and 194.5 mm respectively. The maximum precipitation occurred in Huancuiyu, Xingyang City, which was 728.0mm..
3. Large-scale heavy precipitation. There are 4,098 rainfall stations with rainfall exceeding 50 mm, 100 mm, 1923 and 606 with rainfall exceeding 250 mm. ..
4. The heavy precipitation period is concentrated. The period of heavy precipitation mainly starts from the night of 18, with heavy rain, heavy rain and local heavy rain in the northern, central and western regions.
5. extreme. Five stations, such as Songshan, Yanshi, Xinmi, Yichuan and Dengfeng, have broken through the historical extreme value of daily precipitation since the station was established. Five stations, including Songshan, Gongyi, Xinmi, Yanshi and Dengfeng, have broken through the historical extreme value of accumulated precipitation for three days since the station was established.
Has Henan experienced such a heavy rain before?
According to the data,1975 "July 8" rainstorm was the most violent. 1From August 5 to 8, 975, affected by Typhoon No.7503, the rainfall in Zhuang Lin, Biyang County, Henan Province was 830. 1mm in six hours, reaching 1060.3mm in 24 hours and 1605.3mm in three days. ..
In response to this incident, various meteorological departments acted quickly and implemented a 24-hour flood control duty system and a leadership shift system. Strengthen detection and departmental linkage, and release early warning information throughout the network.
References:
China meteorological bureau newspaper office