Why can extreme heavy rainfall continue to occur?, China Meteorological Administration: Typhoon "Haikui" is not very big
In recent days, heavy rainfall has occurred in Fujian, Guangdong, Guangxi and other areas due to the impact of Typhoon No. 11 of this year and its residual system. The cumulative coastal precipitation in these areas has generally exceeded 100 millimeters, with some areas exceeding 250 millimeters and some exceeding 500 millimeters. The precipitation in many areas has broken local historical records.
Typhoon "Haikui" is not very large and its intensity is not strong. Why can it still bring such a large amount of precipitation after weakening into a tropical depression? In this issue of "Here Comes the Chief", Zhang Tao, the chief forecaster of the Central Meteorological Observatory, is invited to interpret it one by one for everyone.
Zhang Tao, chief forecaster of the Central Weather Observatory, said that this cannot be entirely attributed to the role of "sea anemones", mainly because they are supported by a continuous stream of South China Sea monsoons. The residual system of "sea anemones" mainly plays a role in converging water vapor, gathering abundant South China Sea monsoon water vapor into its passing area. In addition, its slow pace and long retention time result in several consecutive days of heavy rainfall and accumulated rainfall in the area it passes through.
Zhang Tao said that examples of "small typhoons" having a significant impact are quite common. Compared to the two elements possessed by classic "strong typhoons", namely abundant water vapor conditions and sufficient dynamic conditions, typhoons like "sea anemones" that make landfall after landfall and make landfall with weak initial strength, or typhoons that have not yet "died", their common characteristics are small winds and insufficient dynamic conditions. However, due to their strong ability to gather water vapor, when the dynamic conditions are supplemented by releasing convective energy, they will bring about relatively strong precipitation. There are many examples of typhoons generated in the South China Sea in China. The cause is that the South China Sea is relatively close to the inland area, and typhoons make landfall before fully growing. Although the intensity is weak, they can gather the energy and water vapor of the South China Sea summer monsoon ashore, and the energy is converted into dynamic lifting water vapor through strong convection, which will bring heavy precipitation.
The entire lifecycle of a typhoon is greatly influenced by surrounding factors, such as the thermal conditions of the ocean where it originated, the transport conditions of monsoon water vapor, as well as factors such as subtropical high pressure, vertical wind shear, terrain, etc., all of which can affect the path, shape, and intensity of a typhoon. Equivalent to each typhoon having its own personality, using a "face mask" cannot encompass the characteristics of all typhoons, so it is not possible to view all typhoons with a fixed mindset towards classic strong typhoons. Zhang Tao stated that whether it is a "small typhoon" or a "large typhoon", both have the potential to cause serious disaster impacts. Therefore, in dealing with each typhoon, it is necessary to have a twelve point spirit, pay attention to and analyze its personality, and then take the most appropriate preventive measures.
It is reported that the residual circulation of Typhoon "Haikui" will end on September 12th. In the coming days, due to the combined influence of cold air moving south and the South China Sea monsoon moving north, precipitation will also occur in the Jiangnan and South China regions, and attention should be paid to preventing the combined effects.
Author: Zhang Juan
