In the past April, the southern part of the mainland suffered a rare and continuous heavy rainfall, resulting in floods, landslides and other disasters in many places? Will such a scenario be repeated in the coming months? In fact, after the rain in the south of the mainland has weakened sharply in the past two days, the forecast of the Central Meteorological Observatory gives the answer: from May 18, the south of the mainland will usher in a round of heavy rainfall again, and heavy rainstorms will appear in large areas!
First, the amount of water vapor poured into the south
In fact, since May, the southern part of the mainland has also suffered rounds of heavy rainfall, resulting in floods, landslides and other disasters in many places. On the morning of May 13, it can be seen from the satellite cloud map that with the high pressure on the mainland controlling many places on the mainland, there are large areas of clear sky on the mainland today, and the weather in many places in the north and south is relatively clear and calm.
However, according to the supercomputer forecast, starting from May 18, with the change of the subtropical high pattern, a large number of southerly winds will drive a large amount of water vapor from the South China Sea and the western Pacific into the southern part of the continent, and at that time, the once weakened heavy rain in the southern part of the continent will strengthen again.
The subtropical high is a warm high pressure system located in the subtropical region, which plays an important role in the transport and balance of water vapor, heat and energy between the middle and high latitudes and low latitudes, and is an important system of atmospheric circulation. The shape and location of the subtropical high have an important impact on the precipitation in the southern part of the continent. When the subtropical high is in a certain position, the southern region is affected by the warm and humid airflow from the southwest, and the precipitation increases, and the weather is cloudy and rainy. According to the supercomputer's prediction, in mid-May, the change in the shape of the subtropical high will significantly strengthen the warm and humid airflow from the southwest, forming a new round of heavy precipitation.
2. Is the summer monsoon ready to break out?
For example, according to the forecast of the Central Meteorological Observatory, starting from May 18, the rainfall in the south of the Yangtze River in the south of the mainland will increase again, and the heavy rain will appear in large areas, corresponding to the substantial enhancement of the warm and humid airflow, such as the precipitation forecast on May 19, Hunan, Jiangxi, Fujian, Guangxi, and Guangdong will be intensively heavy rain and heavy rain, and local heavy rain can be reached.
For now, this may be a rehearsal for the outbreak of the summer monsoon in the South China Sea. After the outbreak of the summer monsoon in the South China Sea, South China will enter the dragon boat water stage with more violent rainstorms, and it will also further open the flood season on the mainland.
What is the South China Sea Summer Monsoon? The South China Sea summer monsoon, also known as the South China Sea monsoon, is a circulation situation in which southwest winds prevail in the lower troposphere and northeasterly winds prevail in the upper troposphere in the South China Sea during the seasonal process of atmospheric circulation in late spring and early summer. It was originally formed in the second half of May, and is actually the embodiment of the cross-equatorial airflow from the coast of East Africa in the southern hemisphere through the Indian Ocean and the Indochina Peninsula to the South China Sea, and is also a signal for the end of the continental winter monsoon and the beginning of the summer monsoon.
The South China Sea summer monsoon is an important part of the East Asian summer monsoon, which can bring a lot of water vapor and heat, and has an important impact on climate and weather. The outbreak of the summer monsoon in the South China Sea is a prerequisite for the outbreak of the summer monsoon in the South China Sea and provides conditions for convective activities in the South China Sea. The onset of the South China Sea summer monsoon is generally in mid to late May, but there are also interannual variations.
The continent is one of the most typical countries in the world with monsoon climate, and the formation of the monsoon is mainly caused by the difference in heat between land and sea. In the summer half of the year, the land heats up rapidly, the air pressure decreases, and the wind mainly blows from the sea surface to the land. Winter is the opposite. This reversal of the sea and land wind fields in winter and summer has created a situation in which northwesterly winds prevail in winter and southerly winds prevail in summer.
The summer monsoon affecting the mainland first started in the South China Sea and then gradually advanced northward. Before the outbreak of the summer monsoon in the South China Sea, the ocean east of the South China Sea and the Philippines was mainly controlled by the subtropical high, and a downdraft prevailed, with fine weather and low precipitation. However, with the outbreak of the summer monsoon in the South China Sea, the subtropical high will weaken and retreat eastward, and the southwest wind will begin to prevail in the South China Sea, with active convection and increased precipitation, marking the transition from winter circulation to summer circulation.
The early and late onset of the summer monsoon in the South China Sea indicates to a certain extent the early and late rainy season process in the mainland, especially in South China. Generally speaking, the onset of the summer monsoon in the South China Sea is early, and the rainy season process on the mainland starts earlier, and vice versa, the rainy season process starts later. After the outbreak of the summer monsoon in the South China Sea, precipitation will further increase in the southern part of the continent, and the weather will become more changeable. The South China Sea summer monsoon will also affect typhoon activity in the southern part of the mainland, and after the outbreak of the South China Sea summer monsoon, the coastal waters of the mainland will gradually begin to favor the formation and development of typhoons, bringing strong winds and heavy rains to the southern part of the mainland.
The South China Sea summer monsoon is an important feature of continental climate, which affects not only the weather in the southern part of the continent, but also the rainy season process in the central and eastern parts of the continent. Therefore, we should pay close attention to the changes in the summer monsoon in the South China Sea, keep abreast of the weather forecast, and take preventive measures to cope with possible heavy precipitation, strong convection, typhoons and other disastrous weather.