From June 6 to 7, heavy rainfall fell in the urban area of Beihai City and Hepu County of Guangxi Zhuang Autonomous Region, and some sections of Beihai City were seriously flooded.

Meteorological monitoring shows that from 7 o'clock on the 18th to 8 o'clock on the 18th, the precipitation of the Beihai National Basic Weather Station in 24 hours reached 453 mm. According to the query of Tianqing system, this data not only broke the local record of the largest precipitation in a single day in June, but also refreshed the highest daily precipitation of China's national basic weather station after the heavy rainstorm in Zhengzhou in 6!

So, where is the extreme nature of this rainfall? What causes heavy rainfall in the North Sea? How long will the rains continue in the future? Liang Baorong, director of the Science and Technology Service Center of Beihai Meteorological Bureau, interpreted this.

Q1: Where is the extreme nature of this rainfall?

A: From June 6 to 7, there was heavy rain to exceptionally heavy rainfall in Beihai City, and the center of heavy rainfall was located at the Beihai National Basic Meteorological Station (located near the mouth of the sea, the terrain is flat). The station measured 8 mm of precipitation from 7:18 on the 8th to 18:453 on the 51th, which is almost equivalent to 7% of Beijing's average annual precipitation! At the same time, the rainfall is relatively concentrated and violent, with a maximum hourly rainfall intensity of 30.<> mm. The heaviest precipitation occurred in the urban area of Beihai City and its suburbs, and the urban area had multiple flooding points due to poor drainage, and the stage flooding reached <> cm.

Overall, this rainfall is characterized by a wide range of heavy and extra-heavy rainfall.

To this end, from the afternoon to the evening of the 7th, Hepu and Beihai issued yellow warning signals for heavy rain, and timely updated and issued orange and red warning signals for heavy rain according to the development of rain. Beihai City and Hepu County launched a four-level emergency response for flood control.

Rainfall from 6 a.m. on June 7 to 08 a.m. on June 6

Q2: What is the cause of this heavy rainfall in the North Sea?

A: The reason for this heavy rainfall is mainly due to the impact of the South China Sea monsoon low into the North Sea northward, and this South China Sea monsoon low has been hovering near the North Sea, with little change in location and longer duration, resulting in a large cumulative rainfall and a wide range of rainfall.

Many scholars also compare the "monsoon depression" to a small "small typhoon" because it also has a circulation structure. If its power is not strong enough, it will bring continuous precipitation to a certain place at the time of "dilemma".

It is worth mentioning that every year around the Dragon Boat Festival, the warm and humid air flow in the south is active, which meets the cold air from the north and south in Guangdong, Guangxi, Fujian and Hainan, and there will often be continuous, large-scale heavy precipitation, which is often called "dragon boat water".

Q3: What are the pros and cons of this heavy rainfall?

A: Due to the wide area and long duration of rainfall in this process, it brings a greater risk of urban and rural waterlogging, which has a certain negative impact on transportation. In agriculture, precipitation objectively alleviates the previous drought, but it is necessary to pay attention to the risk of turning from drought to flood.

Q4: Will there be any rainfall in the next few days in Guangxi Beihai?

A: In the coming week, Beihai City will continue to have obvious rainy weather, and for areas such as small and medium-sized rivers, it is necessary to guard against the impact of process superposition. The public needs to pay close attention to the forecast and warning information issued by the meteorological department and pay attention to traffic safety.

Author: Liu Jia Han Jiale

Expert consultant: Liang Baorong, director of the Science and Technology Service Center of Beihai Meteorological Bureau

Data support: National Meteorological Information Center

Editor: Liu Jia

Review: Duan Haoshu

(China Meteorological Administration WeChat public account)