How long will it take for the first "extreme" heavy rainfall in the north
On the evening of July 11, the Central Meteorological Observatory issued the first orange warning of heavy rain this year. The Beijing-Tianjin-Hebei region encountered heavy rainfall, and precipitation in many places exceeded the historical extreme value of July.
This is the first "extreme" heavy rainfall in northern my country this year.
On the morning of July 12, the Central Meteorological Observatory continued to issue yellow warnings for heavy rain and severe convective weather.
Why did this torrential rain in the north come so fast?
How long will it be next?
How should the public respond?
The reporter interviewed Zhang Fanghua, chief forecaster of the Central Meteorological Observatory, to give a professional interpretation of the rainstorm.
This heavy rain is slightly earlier than in previous years
Reporter: Does this round of heavy rainfall in the Beijing-Tianjin-Hebei region mean the official start of the rainy season in North China?
Zhang Fanghua:
According to the monitoring and analysis of the Central Meteorological Observatory, the precipitation process that began on July 11 means that the rainy season in North China has officially kicked off this year, slightly earlier than the average start time of normal years (July 18).
However, it is not uncommon to see heavy rainfall at this stage in previous years.
Reporter: Why is it "extreme" directly mentioned in this round of heavy rainfall forecasts? So far, which sites have broken through historical extremes? What is the scope of influence?
Zhang Fanghua:
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, etc. Heavy rains or extreme rains (precipitation above 250 mm) occurred in parts of northern Henan, northwestern mountains, etc., 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 historical extreme value in July, among which Jize, Hebei (206.4 mm) and Huaxian, Henan (211.7 mm) exceeded the historical extreme values since the meteorological record.
From July 14th to July 20th, there is still a lot of rain in North China
Reporter: What are the characteristics of this heavy rainfall process?
Zhang Fanghua:
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.
We have paid close attention to the process of heavy rainfall in the north. The large-scale precipitation echoes caused by the low vortex in Hebei, Tianjin, and Shandong are still relatively strong.
From the point of view of causes, the heavy rainfall process was affected by the deep low vortex system. The east side of the low vortex was accompanied by strong low-level jets, which brought abundant water vapor and unstable energy, which was very conducive to the production of heavy rainfall.
Due to the slow movement of the low vortex system this time, the precipitation time is longer and the accumulated precipitation is large.
In addition, the low-level jet stream converges and rises on the windward slopes of Taihang Mountain, resulting in strong local rainfall.
Reporter: In addition to heavy rains, why did many places in Beijing, Tianjin and Hebei still encounter strong winds of magnitude 8 to 10?
Zhang Fanghua:
During this process, strong winds mainly appeared on the east and north sides of the low vortex system, with southerly winds and easterly winds mainly.
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.
Reporter: How long will this rain last?
Zhang Fanghua:
As of 12:00 on July 12, the heavy rainfall in North China has moved to the northeast, and the intensity has also weakened.
It is expected that from July 12 to July 13, some areas in Beijing, Tianjin, Hebei, Shandong, Liaoning, Inner Mongolia and other places will experience strong rainfall, strong convection and strong winds.
The rainfall on the 12th was mainly located in northern China and eastern Huanghuai, and 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 from July 14th to July 20th, there will be a lot of rainfall in North China, Huanghuai and other places, with strong rainfall around the 18th.
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.
Precipitation weather in Northeast China shows an increasing trend
Reporter: In the face of extremely heavy rainfall, what defensive measures should the public take?
Zhang Fanghua:
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
upcoming
weather forecast.
From July 12th to July 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 wind 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.
Heavy rainfall causes slippery roads, reduced visibility, and water accumulation in low-lying sections, which will have a greater impact on urban operation security 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 of preventing trees from falling to the ground, 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.
(Our newspaper, Beijing, July 12th, by our reporter Yuan Yufei)