What is the phenomenon of continuous rainy weather with frequent precipitation called?

In the Jianghuai River Basin of my country, there is often a period of continuous rainy weather with heavy rainfall and frequent rainfall in early summer every year. This phenomenon is called (Meiyu).

Meiyu refers to the weather and climate phenomenon that occurs in a certain area and in a certain season. Meiyu is a unique weather and climate phenomenon in East Asia. In China, it is a unique weather and climate phenomenon in the middle and lower reaches of the Yangtze River.

Meiyu refers to the period from mid-June to early to mid-July every year. The middle and lower reaches of the Yangtze River in China refer to the 28-34°N range east of Yichang, or the Jianghuai River Basin, to the narrow area in southern Japan. A period of continuous rainy weather occurred.

Formation conditions

1. In the high latitudes of Asia, there is blocking high pressure or a stable high pressure ridge in the middle of the troposphere, and the atmospheric circulation is relatively stable and less changeable.

2. The westerly circulation in mid-latitudes is flat, and frequent shortwave activities provide cold air conditions for the Jianghuai region.

3. The western Pacific subtropical high has an obvious westward and northward jump process. The 500hPa subtropical high ridge is stable between 20 degrees and 25 degrees north latitude, and warm and moist air flows from the edge of the subtropical high to the Yangtze-Huaihe River Basin.

Under such circulation conditions, the Meiyu front lingers in the Yangtze-Huaihe River Basin, often accompanied by southwest vortices and shear lines, and mesoscale systems are active above the Meiyu front. It not only maintains continuous rainfall during the Meiyu period, but also provides abundant water vapor for heavy rains.