Chinanews client, Beijing, July 13th (Reporter Zhang Nilanglang) On the evening of the 11th, the Central Meteorological Observatory issued the first orange rainstorm warning of this year. The Beijing-Tianjin-Hebei region encountered heavy precipitation, and precipitation in many places exceeded the extreme value of July.
On the morning of the 12th, the Central Meteorological Observatory continued to issue yellow warnings for heavy rain and severe convective weather.
Why is this rain coming so fast?
How long will it be next?
Zhang Fanghua, chief forecaster of the Central Meteorological Observatory, gave a comprehensive interpretation of the issues of public concern.
FY-4B satellite monitoring cloud map: North China heavy rain map/National Satellite Meteorological Center
Why is this rainfall called "extreme"?
——Daily rainfall at multiple sites breaks through the historical extreme value of meteorological records
Zhang Fanghua said that according to the monitoring and analysis of the Central Meteorological Observatory, the precipitation process that began on July 11 can be counted as the beginning of the rainy season in North China this year, which is slightly earlier than the average start time of normal years (July 18).
Overall, as of 9 o'clock on the 12th, heavy rains occurred in Beijing, northern and central Tianjin, central and southern Hebei, southwestern Shanxi, northern Henan, and northwestern Shanxi. Among them, southern Beijing, central and southern Hebei, southeastern Shanxi, and northern Henan Heavy rains or extreme rains (precipitation above 250 mm) occurred in parts of the north, east, west and north of the mountains, accompanied by thunderstorms of magnitude 8 to 10, and hail occurred locally in Hebei and Beijing.
From an extreme point of view, local rainfall in Handan, Hebei, Jincheng and Changzhi in Shanxi, Jiyuan, Anyang and Hebi in Henan, etc. local rainfall is 220-342 mm (the maximum hourly rainfall is 102-125 mm); there are 7 countries in central and southern Hebei and northern Henan. The daily rainfall at the station exceeded the extreme value in July, among which Jize, Hebei (206.4mm) and Huaxian, Henan (211.7mm) exceeded the historical extreme since the meteorological record.
Heavy rains occurred in most areas of Beijing, affecting the morning peak.
The picture shows the Xizhimen area in the rain.
Image source: Visual China
Why does the heavy rainfall process come so fast?
——The rainfall process is affected by the deep vortex system
What is the special reason behind this heavy rain?
In this regard, Zhang Fanghua analyzed that this round of heavy rainfall has the characteristics of wide impact, high rainfall intensity, long duration, large accumulated rainfall, accompanied by strong convection and windy weather, and high disaster risk.
From the point of view of causes, this heavy rainfall process was affected by a deep low vortex system. The east side of the low vortex is accompanied by a strong low-level jet, which brings abundant water vapor and unstable energy, which is very conducive to the production of heavy precipitation.
The low vortex system moves slowly and the precipitation time is longer, which is conducive to the increase of accumulated precipitation.
In addition, the low-level jet stream converges and rises on the windward slope of Taihang Mountain, which is also conducive to local production of stronger precipitation.
The picture shows that Chaoyang Fire Department decomposes and disposes of dead trees on site.
Photo courtesy of Beijing Chaoyang Fire
Why in addition to heavy rains in Beijing-Tianjin-Hebei, there are still gales?
——The superposition of two factors leads to obvious windy weather
Experts analyzed that during this process, windy weather mainly appeared on the east and north sides of the low vortex system, with southerly winds and easterly winds dominating.
Corresponding to the low vortex, there is a cyclone system on the ground, with a large pressure gradient on the east side, which is conducive to generating strong ground wind.
At the same time, this process was accompanied by convective thunderstorms.
The two reasons are superimposed, and the windy weather in this process is also very obvious.
Source: Official website of the Central Meteorological Observatory
How long will this rain last?
——The precipitation area will move east to north on the 13th
Zhang Fanghua said that as of 12:00 on the 12th, the heavy rainfall in North China has moved to the northeast and its intensity has also weakened.
It is expected that from the 12th to the 13th, there will be heavy rainfall, strong convection and strong winds in parts of Beijing, Tianjin, Hebei, Shandong, Liaoning, Inner Mongolia and other places.
The rainfall on the 12th was mainly located in northern China and eastern Huanghuai. Some areas were accompanied by thunder and lightning, short-term heavy rainfall and strong winds. The maximum hourly rainfall was 30-50 mm, and the local area could exceed 80 mm; gusts were around 8 , Up to 10 to 11 levels.
On the 13th, the precipitation area will further move east to north, mainly affecting Liaoning, Heilongjiang and eastern Inner Mongolia, and the intensity will be further weakened.
It is expected that there will be heavy rainfall in North China, Huanghuai and other places from the 14th to the 20th, with strong rainfall around the 18th; in addition, there will be heavy rainfall in the Sichuan Basin from the 14th to the 16th.
In the coming week, my country's main precipitation belts will be concentrated in the east of Southwest China to North China, Huanghuai, and Northeast China, with a southwest-northeast trend.
The weather in the southern region, especially the Jianghuai, Jiangnan, and South China areas will be dominated by high temperature and little rain.
The picture shows the Baoding City Public Security Traffic Police diverting traffic in heavy rain.
Photo courtesy of Baoding Traffic Police Detachment
What should be paid attention to during the "seven down and eight up" stage?
——Do not go to mountainous areas, rivers, and areas with hidden geological hazards
Experts reminded that immediately entering the "seven lower and eight upper" stage, the precipitation weather in North China and Northeast China is showing an increasing trend, and the public should pay attention to the approaching weather forecast.
From the 12th to the 13th, some areas of Beijing, Tianjin, Hebei, Shandong, Liaoning, Inner Mongolia and other places will have heavy rainfall, accompanied by thunder and lightning, short-term heavy rainfall, strong winds and hail.
Among them, the southwest and north of Beijing, the north of Tianjin, the south and northeast of Hebei, the north of Henan, the southeast of Shanxi, and the southeast of Liaoning have high meteorological risks for mountain torrents, geological disasters, and the northeast of Hebei, northern Henan, and southeast Shanxi The meteorological risk of flooding in small and medium-sized rivers is high. It is necessary to strengthen the inspection and elimination of hidden danger points, especially in mountainous areas, and pay attention to the transfer of people in dangerous areas in advance.
The public should minimize unnecessary trips and do not go to mountainous areas, rivers, and areas with hidden geological hazards.
In addition, heavy rainfall causes slippery roads, reduced visibility, and water accumulation in low-lying sections, which will have a greater impact on urban operations such as traffic and drainage, and countermeasures must be taken in advance.
This process is accompanied by thunderstorms and windy weather, and it is necessary to do a good job in preventing tree lodging, reinforcing outdoor structures and billboards, and safety protection for outdoor high-altitude operations.
Agricultural production needs to take measures such as drainage and waterlogging prevention, wind prevention and reinforcement to reduce disaster losses.
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