TROPICAL CYCLONES IN 2005

Sanvu was the first tropical cyclone that necessitated the issuance of warning signals in 2005.

Sanvu developed as a tropical depression over the Pacific about 990 km east of Manila on 10 August. Moving west-northwestwards, it intensified into a tropical storm the next day. Sanvu skirted the northeastern tip of Luzon and then traversed the Luzon Strait. In the fury of Sanvu, transportation over eastern Taiwan was suspended on 12 August. Upon entering the South China Sea, Sanvu adopted a north-northwestward course and headed towards the coast of Guangdong. It intensified into a severe tropical storm on the night of 12 August. Sanvu made landfall near Shantou and weakened into a tropical storm the following day. On 14 August, Sanvu weakened further and dissipated over inland. Sanvu caused serious damages in Guangdong and Fujian where about 1.4 million and 2.1 million people were affected respectively.

In Hong Kong, the Standby Signal No. 1 was issued at 10.40 a.m. on 12 August when Sanvu was about 770 km to the east-southeast. Locally, squally showers and thunderstorms set in that evening as Hong Kong came under the influence of Sanvu. It came closest to Hong Kong at around 1 p.m. on 13 August when it was about 300 km to the east-northeast. The lowest hourly sea-level pressure of 997.0 hPa was recorded at the Hong Kong Observatory Headquarters at 3 p.m. that afternoon. All tropical cyclone warning signals were cancelled at 6.45 p.m. the same day as Sanvu gradually moved away from Hong Kong.

The rainbands of Sanvu brought heavy squally showers to Hong Kong on 13 August. More than 80 millimetres of rainfall were recorded at the Observatory Headquarters. The Amber Rainstorm Warning Signal was in force between 11.40 a.m. and 1.15 p.m. on 13 August, and between 8.45 p.m that night and 0.20 a.m. the next day.

Information on wind, rainfall and tide during the passage of Sanvu is given in Tables 3.1.1-3.1.3. Figures 3.1.1-3.1.3 show the track of Sanvu, rainfall distribution in Hong Kong and cloud imagery respectively.

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