Report on Typhoon Trami (2420)

Typhoon Trami (2420)
21 – 28 October 2024

Trami was the fourth tropical cyclone affecting Hong Kong in 2024.

Trami formed as a tropical depression over the western North Pacific about 1 370 km east of Manila in the small hours of 21 October, moved westwards towards the seas east of the Philippines, and intensified gradually. It intensified into a tropical storm in the small hours of the next day and then turned to move west-northwestwards or northwestwards towards Luzon. Trami moved across Luzon on 24 October and entered the central part of the South China Sea that afternoon. Trami intensified into a typhoon on the morning of 26 October and attained its peak intensity with an estimated maximum sustained wind of 120 km/h near its centre. Under the influence of the relatively high vertical wind shear over the central part of the South China Sea, Trami weakened gradually afterwards. It turned to track south-southwestwards the next morning and made landfall over the central part of Vietnam around noon. With a relatively weak steering flow, Trami then lingered over the coastal areas and finally degenerated into an area of low pressure on the morning of 28 October.

According to press reports, Trami brought torrential rain and squalls to the Philippines, leading to flooding and landslides, resulting in many casualties and significant economic loss. Under the influence of Trami and its remnant, torrential rain occurred in Hainan on 26 – 31 October, with a maximum cumulative rainfall of 1243.1 millimetres recorded in Qionghai during the period. Flooding and landslides triggered by torrential rain led to ten deaths, more than 550 000 people affected and an economic loss of about RMB 230 million. Trami also brought very heavy rain to Vietnam, causing at least three deaths, one missing and more than 290 houses damaged.

The Standby Signal No. 1 was issued at 1:40 a.m. on 25 October, when Trami was about 800 km southeast of Hong Kong. Local winds were moderate to fresh northerlies, occasionally strong offshore and on high ground that day. Trami came closest to Hong Kong at around 2 a.m. on 26 October, skirting past about 550 km south of the territory. As Trami continued to move westwards, winds over Hong Kong would veer to the east gradually and some places which had been sheltered before would become exposed. In addition, under the combined effect of Trami and northeast monsoon, strong winds were expected to affect the vicinity of the Pearl River Estuary. Thus, the No. 3 Strong Wind Signal was issued at 10:40 a.m. on 26 October when Trami was about 600 km south-southwest of Hong Kong. Locally, strong east to northeasterlies prevailed over many places during the day that day, with gale force winds occasionally affecting high ground. As Trami continued to depart from Hong Kong and weaken, local winds moderated gradually that night. The No. 3 Strong Wind Signal was replaced by the Standby Signal No. 1 at 10:20 p.m. on 26 October and all tropical cyclone warning signals were cancelled at 12:20 a.m. on 27 October.

Trami did not cause any significant damage in Hong Kong during its passage. Under the influence of Trami, a maximum sea level (above chart datum) of 2.86 m and a maximum storm surge (above astronomical tide) of 0.72 m were recorded at Tai Po Kau. At the Observatory Headquarters, the lowest instantaneous mean sea-level pressure of 1004.2 hPa was recorded at 3:17 p.m. on 25 October.

While it was mainly fine in Hong Kong during the day on 25 October, the weather turned cloudy at night with the approach of Trami. Affected by the outer rainbands of Trami, the weather of Hong Kong was mainly cloudy with a few showers on 26 October.