Typhoon "Xuan Lannuo" is coming with great force! The V-shaped path of Typhoon "Xuan Lannuo" and the interpretation of wind and rain

The fierce "Xuan Lannuo"

Between 1 and 2 a.m. today (September 2), the first super typhoon of the year finally reached the turning point of the expected deep V path, turning from the south to the north and approaching the southeast of my country.

The path of "Xuan Lan Nuo" (left: China National Meteorological Center Typhoon Network) and the infrared enhancement of Fengyun-4A at 2:00 on September 2 (right: National Satellite Meteorological Center)

At 11:00 this morning, it was about 435 kilometers east-southeast of Taitung City, Taiwan Province, and was at the strong typhoon level (level 14), having just dropped from a super typhoon. It is predicted that it will strengthen into a super typhoon in the future. The typhoon cloud shape is in the shape of a "9", that is, the main spiral cloud and rain belt is in the southeast of the typhoon.

Fengyun-4A visible light image at 11:00 on September 2, 2022 (National Satellite Meteorological Center)

Fengyun-4A infrared enhanced image at 11:00 on September 2, 2022 (National Satellite Meteorological Center)

9 goes west and 6 goes north

This is a classic experience about the relationship between typhoon path and shape. The simplest understanding of this is the literal meaning: a 9-shaped typhoon goes west, and a 6-shaped typhoon goes north. This is to predict the path based on the shape (predicting the path by shape), which is obviously not very accurate at this moment, because the typhoon is still 9-shaped but is going north.

The Central Meteorological Observatory predicted the path of "Xuan Lan Nuo" at 10:00 on September 2

Why?

Solution 1: There is no absolute, the figure 9 heading west is just a high probability, sometimes it also goes north - the fact Solution 2: The path can be changed quickly, the shape needs to change slowly - reasonable Solution 3: "9 heading west and 6 heading north" is nonsense - it is not the secret of the typhoon 9-6 shape - Feng Shui wash, cut and blow

The shape of a typhoon depends on the cloud type, and the cloud type depends on "feng shui": wind - mainly high-altitude wind, the typhoon convective cloud system will be suppressed and spread horizontally when it reaches the top of the troposphere, and then there will be more clouds on the side where the upper wind blows, which is called "blowing" water - mainly low-altitude water vapor, where there is more water vapor, there will be more convective clouds, which is called "washing". In feng shui, wind is the main and water is the auxiliary, because whether water vapor alone can form clouds depends on wind to lift. If the wind does not lift water vapor to form clouds but sinks them, the clouds will naturally disappear. The subtropical high is best at "cutting" the sinking airflow. The clouds on the side of the typhoon next to the subtropical high have all disappeared, which is called "cutting".

Visible light cloud image and wind field near the tropopause at 10:00 on September 2

The Secret of Typhoon Path——Subtropical High

The mystery of the typhoon path is simpler and more widely known than the mystery of the cloud type: the factor that affects the movement path of the typhoon the most is the subtropical high, and the simplest movement logic of the typhoon is to circle around the subtropical high. The wind direction around the subtropical high is clockwise, so most of the time, the typhoon is generated on the south side of the subtropical high, and then moves westward. When it reaches the western end of the subtropical high, it turns north, and then turns east after entering the westerly belt. In this process, if the subtropical high is strong and extends westward to the mainland, the typhoon will land. If the subtropical high is weak and does not reach the mainland, the typhoon will turn at sea. The reason for the westward movement of the figure 9 - south side of the subtropical high When the typhoon is on the south side of the subtropical high, its north side is affected by the cloud dissipation of the subtropical high, so it is naturally difficult to have the figure 6, cutting the north and blowing south - the figure 9 comes out, and because it is on the south of the subtropical high, it naturally moves westward. The reason for the figure 6 going north - when a typhoon moves to the west or north of the subtropical high, its upper wind turns to the westerly belt, so the cloud system blows northeast, and with the disappearance of clouds in the southeast subtropical high, it cuts east and blows north - the figure 6 is formed, and because it is on the west side of the subtropical high, it naturally goes north. Based on the relationship between the typhoon's position, cloud type, subtropical high, and upper wind, the typhoon's "figure 9 going west and figure 6 going north" is a high-probability event, and there is nothing wrong with this statement.

Schematic diagram of the typhoon "9 figures westward and 6 figures northward" (Tao Tao Fengyun)

"Xuanlanuo" will turn 9 into 6 in the future

"9 goes west and 6 goes north" can be used for "predicting movement by pattern" or "predicting pattern by movement": a westward typhoon turns northward, and its structure may change from 9 to 6. "Xuan Lan Nuo" has now turned from westward to northward. It used to have an asymmetric structure with strong wind and rain on the southeast side. When it moves northward and approaches my country, it may turn into strong wind and rain on the west and north sides. If this is true, it will be much more troublesome, because even if the typhoon does not land, my country's southeastern coast may encounter strong wind and rain, and it will naturally be more severe if it lands.

Schematic diagram of the potential transformation of "Xuanlanuo" 9-6 (Tao Tao Fengyun)

In a word: People in East China, especially Zhejiang, must be highly vigilant and be prepared for typhoons.

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