Tropical Cyclone Nigge gradually approached the Pearl River Estuary this morning (2nd), and the Observatory issued the No. 8 Northwest Gale or Storm Signal at 1:40 pm.
However, when the Observatory issued the No. 8 typhoon warning at about 11 a.m. today, it predicted that the No. 8 northeast gale or storm signal would be issued, but in the end, "the wind direction was not as expected."
Affected by the terrain of Hong Kong, the wind blows from the northeast and the northwest when the wind blows, and the wind in Hong Kong is very different.
The Observatory explained that when the warning was issued this morning, the wind direction in Hong Kong was predicted to be northeasterly, but the actual wind field was northwesterly, and it was emphasized that Nigg was closer to Hong Kong than expected, and it was predicted that Hong Kong would gradually turn eastward to northeasterly, and it would turn 8 direction of the typhoon.
Leung Wing-wu, a meteorologist and former assistant director of the Observatory, pointed out that since Niger is currently located in the southeast of Hong Kong, it is greatly affected by the northwesterly wind. It is believed that the predicted change of wind direction is also related to the position of Niger.
According to the previous interpretation of the Observatory, since the north of Hong Kong is inland and there are mountains, if the northerly wind blows, it will be blocked by the terrain and the wind will be weak; on the contrary, if the tropical cyclone passes in the south or southwest of Hong Kong, the strong wind will be from east to northeast. Hit Hong Kong head-on.
Nigga weakened to a tropical storm on the night of November 2 and concentrated about 100 km southeast of the Hong Kong Observatory.
(Photo from the Observatory)
When the Observatory issued the No. 8 typhoon warning at 11 am, it was expected that the No. 8 northeast gale or storm signal would be issued.
(Screenshot of Observatory Facebook)
▼November 2nd, under the typhoon signal No. 8, you can see the "wind" scenery on the waterfront of Tsim Sha Tsui▼
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According to the Observatory's previous article explaining the difference between tropical cyclones "Eastern" and "Xiden", due to the tropical cyclone in the northern hemisphere, the wind flows counterclockwise to the center of the storm.
When a tropical cyclone approaches from the east of Hong Kong, it mainly blows northerly winds. However, due to the obstruction of inland mountains to the north, local winds will be relatively low.
Nigge is mainly southeast of Ben during the day, so the prevailing wind direction is northwesterly.
On the contrary, if a tropical cyclone arrives when the tropical cyclone passes from the west to the south of Hong Kong, and the wind blows from the sea in the east, since there is no natural barrier in the east to block the wind, the strong wind will hit Hong Kong head-on, and the wind will be stronger.
▼On November 2, the typhoon signal No. 8 came into effect and the situation on the waterfront in Tsim Sha Tsui▼
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Leung Wing-wu said that the wind direction in Hong Kong is mainly affected by the location of Niger. Since Niger is located in the southeast of Hong Kong during the day, it will be greatly affected by the northwesterly wind.
However, Nigg is expected to move to the northwest, so it will travel to the south of Hong Kong tonight, when the wind direction will also change.
Liang Rongwu, former assistant director of the Observatory.
(file picture)
Observatory: The direction of the No. 8 typhoon will be changed after turning northeasterly
Leung Yan-yu, Acting Senior Scientific Director of the Observatory, said that when the No. 8 typhoon warning was issued this morning, the wind direction in Hong Kong was predicted to be northeasterly, so the No. 8 northeast gale or storm signal was expected to be issued, but the Observatory issued the No. 8 northwest gale or storm signal.
She explained that the actual wind field shows that the wind direction in Hong Kong is northwesterly, so it is different from the forecast.
She also pointed out that the Observatory made predictions based on distance and local wind power at that time.
Liang Enyu also emphasized that Niger is closer to Hong Kong than expected, and it is expected to pass within 100 kilometers of Hong Kong. The Observatory also predicts that the wind direction will change, and it will gradually turn eastward to northeasterly: "Although the (current) northerly wind is not so The wind is strong, but after the northeasterly wind turns, some of the sheltered areas may become prevailing winds." She said that when the Observatory detects a change in the wind direction in Hong Kong, it will also change the direction of Typhoon No. 8.
▼On November 2nd, the swimmers took a morning swim by the Hung Hom sea under the typhoon signal No. 3▼
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