Why are there fewer typhoons in July this year or in the year when Mei Yu is strong for the first time in 71 years?

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 Why are there fewer typhoons in July this year or in the year when Mei Yu is strong for the first time in 71 years?


Due to the rare appearance of typhoons this year, the appearance of Tropical Disturbances far away at sea has attracted a lot of attention. But because of the lack of energy, the tropical disturbance soon dissipated at sea.

According to the Medium-term Forecast of the central meteorological station, there will be no typhoon in the Northwest Pacific and South China Sea before the end of July. This means that there may not be a typhoon in July this year.

Hu Xiao, chief meteorological analyst of China Weather Network, said that similar abnormal conditions also occurred in the Northwest Pacific and the South China Sea in the midsummer of 2014. No typhoon (Northwest Pacific and South China Sea) was generated, setting a precedent of no typhoon in August in history. In July, there are at most eight typhoons and at least one typhoon. If no typhoon appears in July this year, it will become the first empty typhoon phenomenon in July since 1949, which is very rare for the month with abundant typhoons.

However, the low number of typhoons does not mean that the threat of typhoons will decrease this year, Hu added. From the current situation, the sea surface temperature in the Western Pacific and South China Sea is significantly higher than that in the whole year, which is about 30 u2103, and the annual sea surface temperature is about 27-28 u2103. If Typhoon occurs, it will be conducive to its development. Therefore, with the increasing number of typhoons from August to September, the possibility of concentrated generation or outbreak of typhoons cannot be ruled out. .

Since the beginning of summer, the subtropical high continued to be strong and southward, which greatly inhibited the convective activities in the tropical western Pacific region, the source of typhoon formation, and made it lack of the most critical environmental conditions, squeezing the survival space of typhoons. This is one of the important reasons for the lack of typhoon generation and landing since this year.

The subtropical high in flood season plays an important role in the transportation and balance of water vapor, heat and energy in China. Its strength, advance and retreat and movement are closely related to the generation of typhoon and drought and flood in eastern China. It is the main weather system that affects the weather in flood season in China. This year, the subtropical high is stronger and southward for a long time, which not only makes the typhoon in its control center less, but also makes the plum rains in Jiangnan and other places earlier and violent.

From the perspective of space, the water area of Poyang Lake has increased significantly. Photo source: National Satellite Meteorological Center

Since June, there have been nine rounds of heavy rainfall in the south, and violent plum blossom in the middle and lower reaches of the Yangtze River, which is the first in the same period since 1961. The area of the main body of Poyang Lake and its nearby waters is the largest in recent 10 years.

Hu Xiao said that the strength of the subtropical high is closely related to El Nino. In the autumn of 2019, a weak El Nino event was experienced, and the northern Indian Ocean sea surface temperature was warmer, which led to the subtropical high being stronger, and the water vapor transported by the subtropical high to the middle and lower reaches of the Yangtze River was obviously stronger.

At present, plum blossom has been produced in Zhejiang, Shanghai, Jiangsu and other places, which means that this years plum rainy season is coming to an end. However, the rainfall will not stop in the future. The relevant departments and the public still need to pay close attention to the changes of rainfall and flood conditions, and their vigilance should not be relaxed.

(function(){( window.slotbydup=window .slotbydup||[]).push({id:u5811557,container:ssp_ 5811557, async:true }South China is in urgent need of typhoons to put out the fire. Since June, many places in South China have become dizzy due to the strong subtropical high and basically stable control of the region. For example, Fuzhou is the most fierce heat. As of July 23, there have been 33 high temperature days, and Haikou has been hot for 40 days. Hu Xiao analysis, until the end of July, South Chinas high temperature and muggy weather will continue. Although the subtropical high may weaken and retreat in stages, it has little effect on relieving the high temperature in South China. If you want to put out the fire, you can only expect a typhoon or a proper soaking rain. In the future, we need to pay attention to cooling in South China. (planning / Yang Xing design / Li Yiyu data support / Zhang Juan review / Zhang Fangli, Liu Wenjing, Hu Xiao, Liu Hongxin) extended reading: the Yellow rainstorm warning issued by the Central Meteorological Station: Henan, Jiangsu, Sichuan and other places have reached the rainstorm warning again! The landslide of Enshi mountain in Hubei has formed a barrier lake, and the central meteorological station has issued rainstorm warning big data for 41 consecutive days to tell you where the rain has gone Sun Jili, editor in charge of China Weather Network_ NN3563

South China needs typhoon to put out the fire

Since June, many places in South China have become dizzy due to the strong subtropical high, which basically controls South China. For example, Fuzhou is the most fierce heat. As of July 23, there have been 33 high temperature days, and Haikou has been hot for 40 days.

Hu Xiao analysis, until the end of July, South Chinas high temperature and muggy weather will continue. Although the subtropical high may weaken and retreat in stages, it has little effect on relieving the high temperature in South China. If you want to put out the fire, you can only expect a typhoon or a proper soaking rain. In the future, we need to pay attention to cooling in South China. (planning / Yang Xing design / Li Yiyu data support / Zhang Juan review / Zhang Fangli, Liu Wenjing, Hu Xiao, Liu Hongxin)