When will Guangzhou Dragon Boat Water go down?

During the first flood season in Guangdong, there was a period of relatively concentrated precipitation, and there were frequent rainstorms, heavy rainstorms and even heavy rainstorms for several days. Because it is the time of dragon boat race, people call it "dragon boat water", which is the "last madness" in the first flood season in South China.

For the convenience of statistics, "dragon boat water" generally refers to the precipitation from May 2 1 day to June 20.

It is understood that the cause of "Dragon Boat Water" is related to summer monsoon and cold air, and the weather change in South China is the most complicated period before and after the Dragon Boat Festival. The cause of dragon boat water is closely related to the alternating changes of winter and summer monsoon in the South China Sea. The South China Sea summer monsoon usually breaks out in May. After the monsoon broke out, it pushed to South China, producing monsoon convective precipitation. At the same time, the cold air in the north is reluctant to part with South China.

Although after May every year, the influence of warm and humid air from the tropical ocean has been continuously strengthened, and the temperature in the area south of Nanling Mountains has gradually increased, and the weather has turned hot, but the cold air has always refused to "retreat northward", and the convergence of cold and warm air has caused frontal precipitation. Therefore, under the combined influence of monsoon precipitation and frontal precipitation, large-scale concentrated precipitation often occurs in Guangdong from late May to mid-June, that is, "Dragon Boat Water".

The formation mechanism of rainstorm is quite complicated, but there are two important macro conditions:

First, there must be a rich source of water vapor; Second, there must be a strong updraft and a favorable atmospheric circulation situation to make the intensity of precipitation large enough and last long enough.