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Why has Henan become the center of heavy rainfall in China? How long will it take?

via:驱动之家     time:2021/7/21 2:17:10     readed:161

Since the 17th, Henan has been experiencing persistent heavy rainfall, with heavy rain and torrential rain in many places and torrential rain in some areas.

So, why is the rain so fierce in Henan? How long will it last?

1. How heavy is the rain?

The heavy rainfall was mainly concentrated in the western, northern and central areas of Henan Province, and heavy rain occurred in Zhengzhou, Jiaozuo, Xinxiang, Luoyang, Nanyang, Pingdingshan, Jiyuan, Anyang, Hebi and Xuchang.

During the heavy rainfall,It has the characteristics of long duration, large accumulated rainfall, wide range of heavy rainfall, concentrated period of heavy rainfall and extreme.

The average rainfall of the whole province is 113.5 mm, and that of Zhengzhou, Jiaozuo and Xinxiang are 357 mm, 210.6 mm and 194.5 mm respectively.The maximum precipitation occurred at 728.0 mm in huancuiyu, Xingyang city.

There are 4098 rainfall stations in the whole province, with precipitation exceeding 50 mm, 1923 stations exceeding 100 mm and 606 stations exceeding 250 mm.

From 8:00 on the 19th to 8:00 on the 20th,Songshan 364.6 mm, Xinmi 254.9 mm are the first local heavy rainSeveral stations broke the single day precipitation record in July.

The hourly rainfall in Zhengzhou is 201.9 mm from 16:00 to 17:00 on the 20th, and the daily rainfall is 552.5 mm from 20:00 on the 19th to 20:00 on the 20th, which is the highest since the establishment of Zhengzhou station in 1951. From the perspective of climatology, it belongs to the level of once in a thousand years.


2. Why such extreme heavy rainfall?

Zhang Ning, chief forecaster of Henan Meteorological Observatory, analyzed that the Western Pacific subtropical high and the continental high were respectively stable in the sea of Japan and Northwest China, blocking the movement of the upstream system, resulting in the long-term maintenance of the low value system of the westerly belt in North China and Huang Huai Region.

Influenced by the deep easterly jet and the stable vortex shear, combined with the strong convergence and uplift effect of the special topography of Taihang Mountain and Funiu Mountain in Henan Province on the easterly flow, the heavy precipitation centers are mainly distributed in the western and northwestern mountain areas of Henan Province, which is stable and less dynamic, resulting in the long-term precipitation in Henan Province.

Due to the long duration of precipitation and the concentrated area of heavy precipitation, the risk of mountain torrents and geological disasters in the western and northwestern mountainous areas has increased significantly. The water level of small and medium rivers and reservoirs in the Yellow River Basin and Haihe River Basin has risen rapidly. In addition, it has also caused large-scale urban waterlogging and farmland waterlogging.


3. When will it end?

In the first half of the 20th, the rain will weaken slightly, and increase again from the second half of the night, but it is not as strong as that from the evening of the 19th to the morning of the 20th, because the trend of the whole rainfall is gradually weakening.

It is expected that the heavy rainfall will last until the night of the 21st, and the heavy rainfall concentrated area is still in the northwest and central areas of Henan, with the precipitation of 100-250 mm and 300-400 mm in some parts.

22 to 26, Henan Province, no obvious large-scale heavy rainfall weather, scattered thunderstorm weather.

Henan meteorological observatory predicted that there will be light to moderate showers and thunderstorms on cloudy days in the whole province this night. There will be heavy to moderate rainstorms in the north of the Yellow River, Luoyang, Zhengzhou, Kaifeng, Pingdingshan, Xuchang, Luohe, the west of Shangqiu and Zhoukou, and some parts of the North of Sanmenxia and Nanyang, accompanied by short-term heavy rainfall Strong convective weather such as short-term gale.

In the daytime tomorrow, there will be light to moderate showers and thunderstorms in the whole province. In the north of the Yellow River, Luoyang, Zhengzhou, Kaifeng, Pingdingshan, Xuchang and some areas in the north of Nanyang, there will be heavy rain, local heavy rain, short-term heavy rainfall, short-term strong wind and other strong convective weather.

Tomorrow night, there will be showers and thunderstorms on cloudy days in the whole province. There will be moderate to heavy rain in the north and some parts of the central and western regions, local rainstorms or torrential rain, accompanied by short-term heavy rainfall and other severe convective weather.

It should be noted that today and tomorrow, the heavy rainfall areas in Henan will be highly overlapped with the previous ones, and the risks of mountain torrents and geological disasters will be further aggravated. Relevant departments and the public should pay special attention to the secondary disasters and urban waterlogging caused by heavy rainfall.

PS: there are more severe rainstorms in Henan history, which occurred from August 5 to 8, 1975. Affected by typhoon 7503, linzhuang, Biyang County, Henan rainstorm center, has 6-hour rainfall of 830.1 mm, 24-hour rainfall of 1060.3 mm and 3-day rainfall of 1605.3 mm.


Real shot of Lukou in Zhengzhou, Henan Province


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