TROPICAL CYCLONES IN 2006

Bopha was the fourth tropical cyclone to necessitate the issuance of tropical cyclone warning signal in 2006.

Bopha developed as a tropical depression over the western North Pacific about 590 km southeast of Naha, Okinawa in the afternoon of 6 August and moved west-northwest. Bopha once attained the strength of a severe tropical storm during the day on 7 August. However, it weakened into a tropical storm that night and took a westerly track heading towards southern Taiwan.

After skirting southern Taiwan, Bopha edged towards the coastal waters of eastern Guangdong. It weakened further into a tropical depression in the night of 9 August. Under the influence of another tropical cyclone Saomai, Bopha's movement was slow and erratic on 10 August. Bopha weakened into an area of low pressure that night.

In Hong Kong, the Standby Signal No. 1 was issued at 8.40 a.m. on 9 August when Bopha was 590 km to the east. Under the influence of Bopha's outer rainbands, heavy rain with thunderstorms affected the territory in the small hours on 10 August. The Amber Rainstorm Warning Signal was issued at 0.10 a.m. and cancelled at 1.40 a.m. During the passage of Bopha, the lowest hourly sea-level pressure of 998.5 hPa was recorded at the Hong Kong Observatory Headquarters at 6 p.m. on 10 August. Bopha was closest to Hong Kong at around 8 p.m. the same day when it was centred about 180 km to the east-southeast. As Bopha weakened into an area of low pressure that night, all tropical cyclone warning signals were cancelled at 10.10 p.m.

During the passage of Bopha, 10 flights were cancelled and another 19 delayed at the Hong Kong International Airport. In addition, an elevated high voltage electric cable running between Shatin and Tai Po was struck by lightning in the early morning of 10 August. This led to a sudden voltage drop being experienced in some locations in Kowloon and the New Territories. A total of 17 incidents of passengers being trapped in elevators were reported.

Information on wind, rainfall and tide during the passage of Bopha is given in Tables 3.4.1-3.4.3. Figures 3.4.1-3.4.3 show the track of Bopha, rainfall distribution in Hong Kong and cloud imagery respectively.

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