What was the name of the typhoon in July 20 12?

There are no typhoons in Beijing. . . . . .

On July 2 1 day, Beijing was hit by a torrential rain, which caused waterlogging in the city and caused mudslides and other disasters in some mountainous areas, causing casualties and property losses, which aroused widespread concern in the whole society. Why did such a major sudden rare weather suddenly attack the imperial city? Where is its "extreme"? What did the meteorological department do during the rainstorm? How should the public strengthen self-protection in rainstorm weather? With these questions, the reporter interviewed Sun Jun, chief forecaster of the Central Meteorological Observatory.

Sun Jun accepted a joint interview with China Meteorological Network and Xinhuanet. (photo by Zhuang)

1 1 The rainfall at the weather station exceeded the extreme value, and the power of "seven drops and eight liters" was fully demonstrated.

Reporter: Hello, Mr. Sun. First of all, please introduce the general situation of heavy rain.

Sun Jun: From July 2/KLOC-0 to July 22, the rainstorm affected a wide range, and large-scale heavy rainfall occurred in the central and northern parts of Beijing-Tianjin-Hebei and northwestern Shanxi. Among them, the average rainfall in Beijing is 190.3 mm, and the mouth of Shijingshan is 328 mm. The largest rainfall in the city appears in Hebei Town, Fangshan District, which is 460 mm, reaching the magnitude of rainstorm. In addition, there is a 1 1 weather station in Beijing, and the observed rainfall exceeds the historical extreme since the station was established.

This rainstorm is rare in history. Due to heavy rainfall and heavy rainfall, serious urban waterlogging occurred in Beijing, which seriously affected urban traffic and flooded some small and medium-sized rivers and reservoirs. According to the Disaster Relief Department of the Ministry of Civil Affairs, since February1,37 people have been killed and 7 people are missing in the rainstorm and flood disaster in Beijing.

Distribution map of precipitation in Beijing at 06: 00 on July 210-July 22.

Reporter: Beijing is prone to heavy rain at this time of year. What is the reason?

Sun Jun: There is a saying in meteorology called "seven drops and eight liters", that is, during the period from late July to early August, North China entered a period of concentrated rainfall, which is prone to a rainfall process with concentrated rainfall and high intensity. This is consistent with the law that the whole rain belt in China advances from south to north with the seasons, that is, from the earliest pre-flood season in South China to the rainy season in South China, and then to the rainy season in North China now.

The main reason for heavy precipitation is rich water vapor conditions. China belongs to the monsoon climate, and when the monsoon pushes north to North China, it provides sufficient water vapor supply conditions for heavy rainfall. Before it rained, the weather in Beijing was sultry, which showed that the water vapor content in the air was high. According to our estimation, the cumulative content of water vapor in the atmosphere over Beijing has reached the order of 50 mm, even if the supply of external water vapor is not counted, it is enough to reach the order of rainstorm just because the water vapor in the air falls to the ground.

The magnitude, intensity, scope and impact of this rainfall are "beyond imagination".

Reporter: 2 1 On that day, it was raining cats and dogs and there were "Wang Yang" everywhere. However, the weather in Beijing was very good on the 20th and 22nd. Some netizens don't understand why the rainfall is not relatively continuous, but this sudden heavy rainfall that changes greatly in a short period of time.

Sun Jun: Indeed, short-term heavy rainfall is one of the remarkable features of this rainstorm. According to meteorological regulations, heavy rainfall with a precipitation of more than 50 mm in 24 hours is called "rainstorm", but this time, the rainfall in some areas exceeds 50 mm in one hour, and Guajiayu in Pinggu even reaches 100 mm, and the rainfall intensity is beyond imagination.

Why is this happening? The water vapor conditions mentioned just now are sufficient, but "everything is ready, except the east wind." Before precipitation occurs, the weather system must appear to make the warm and humid airflow in this area rise. This is the case with heavy rainfall in Beijing and other places. Under the action of cold air moving eastward and southward and strong weather system, water vapor has a violent upward movement, the atmospheric stratification is extremely unstable, the upward movement is more intense, the condensation speed of water vapor is accelerated, and the air is close to saturation, resulting in extremely high rainfall efficiency.

Reporter: How many times have there been similar rainstorms in the history of Beijing in recent years? Compared with them, what are the outstanding characteristics of this rainstorm process, and where is the "extreme"?

Sun Jun: The last time was on June 23rd last year. Heavy rain also occurred in Beijing, with an average of 73 mm in the urban area, exceeding 100 mm locally and 2 15 mm at the maximum, and the local maximum rainfall intensity 128 mm even exceeded this process. However, the rainfall time is short and the rainstorm process is unevenly distributed. Only a few stations have rainfall exceeding 100 mm, which is mainly concentrated in urban areas. This time, except Yanqing, more than 90% of the administrative areas in Beijing have rainfall above 100 mm, and the average rainfall in the city is much higher than last year. In addition, in recent years, there have been several local rainfall processes in Beijing, which are more than100 mm.

Generally speaking, the "July 21"rainstorm in Beijing has the characteristics of heavy rainfall, strong rainfall, wide range and heavy impact. The daily rainfall in some areas even reaches or exceeds the annual average rainfall, which is an "extreme" embodiment and extremely rare in Beijing history.

Heavy rain did not raise the standard of extreme weather.

Reporter: In recent years, we are always talking about "extreme weather". Under what circumstances can it be defined as "extreme weather"?

Sun Jun: Meteorology has its own standards and data processing methods for extreme weather. From the public's point of view, "extreme" is rare, and the probability of occurrence is small. Take the rainstorm as an example. For a certain area, since there are meteorological data, it will accumulate a certain time series of rainstorm observation data. If a certain rainfall is within 5% of the maximum value of historical rainstorm, it can be called extreme weather.

Reporter: Will this rare rainstorm in Beijing lead to a higher standard of extreme rainstorm in Beijing?

Sun Jun: If this kind of heavy rainfall happens frequently in the future, the standard may be raised. But only once in a while is not enough to raise the standard of "extreme weather"

It is difficult to forecast the rainstorm, and the rolling service of the meteorological department fully responds.

Reporter: What measures has the meteorological department taken to deal with this rainstorm?

Sun Jun: The Beijing Meteorological Bureau reported this forecast earlier. On the 20th, special forecasts were issued twice, pointing out that there will be heavy rain from evening to night on February1day, and there may be heavy rain in some areas. 2 1, the municipal meteorological observatory issued five early warnings a day. 18: 30, the rainstorm warning level rose to orange, and the four-level to two-level emergency response was started one after another, and the duty was strengthened, and the front command and rolling service were strengthened.

During the period, the Municipal Meteorological Observatory issued five important weather reports to the municipal party committee, the municipal government, the municipal flood control office, the traffic management bureau and other relevant departments, and released the rainfall tables of some meteorological observation stations and the 18 rainfall distribution map of the whole city, and jointly issued a three-level early warning of geological disasters with the Municipal Institute of Geology. For Fangshan District, which suffered the most, the district meteorological bureau reported the situation to the district government office by telephone every hour and updated it every three hours.

In addition, the departmental emergency linkage was also quickly launched. According to the level of forecast and early warning signals, the municipal government and county government responded in time, quickly linked, and took measures to actively respond to and deal with the various impacts brought by heavy rain.

On the afternoon of 20th, the Central Meteorological Observatory issued a blue rainstorm warning, which was upgraded to yellow at 2 1 noon. The encryption was strengthened, and the provinces and cities were consulted to remind them to issue the warning. Generally speaking, the early warning of this process was issued by the meteorological department, and the early warning level was relatively high.

Strengthen the awareness of self-prevention, and avoid luck and carelessness.

Reporter: Although the meteorological department predicted this process in advance, casualties and property losses still occurred. From the public's point of view, what do you think needs to be strengthened in severe weather?

Sun Jun: The public is the direct face of disastrous weather, so they should raise their awareness of prevention, realize the seriousness and harmfulness of extreme weather, learn more about popular science and protect themselves. For example, receive early warning information issued by the meteorological department in advance, or see that heavy rainfall has begun, try to avoid driving out. When you see a low-lying area with serious water accumulation, you should evacuate as soon as possible to avoid danger. Don't take chances and try to cross the fast-flowing water.

When threatened by flood, if there is enough time, it should be moved to hillside, highland and other places in an organized way according to the predetermined route; In the case of being caught off guard and surrounded by floods, we should use boats, rafts, door panels, wooden beds, etc. Let the water transfer as much as possible. If the flood comes too fast to transfer, you should immediately climb the roof, tall buildings, trees and high walls, take temporary shelter and wait for rescue, and don't swim alone to transfer. In mountainous areas, if it rains continuously, it is easy to have flash floods. Attention should be paid to avoid crossing the river, being washed away by mountain torrents, and preventing landslides, rolling stones and mudslides.

Reporter: What suggestions do you have for flood control in the coming period?

Sun Jun: On July 25-26, there will be another rainfall process in North China. It is predicted that there will be moderate to heavy rain in some areas, and there may be heavy rain in some areas. At present, it is still in the critical period of flood control, and there is more rainfall in the later period. There may still be heavy rain or even heavy rain in some areas. Relevant departments and the public still need to be vigilant, strengthen prevention, and not be careless. (China Meteorological Network reporter Lai Min Xinhuanet reporter Zhang Gaiping)