TROPICAL CYCLONES IN 2006

A tropical depression over the northern part of the South China Sea became the third tropical cyclone to necessitate the issuance of the Strong Wind Signal No. 3 in 2006.

The tropical depression developed over the northern part of the South China Sea about 350 km east-northeast of Xisha in the afternoon of 12 September. It moved north initially but then took a west-northwesterly track. The tropical depression weakened into an area of low pressure over coastal waters of western Guangdong the following night.

In Hong Kong, the Standby Signal No. 1 was issued at 1.40 p.m. on 12 September when the tropical depression was 470 km to the south-southeast. Under the combined influence of the northeast monsoon, winds offshore became occasionally strong. With the tropical depression edging closer to Hong Kong, the Strong Wind Signal No. 3 was issued at 10.35 a.m. the next day, when it was about 210 km to the southwest. During the tropical depression's passage, the lowest hourly sea-level pressure at the Hong Kong Observatory Headquarters was 1 006.9 hPa, recorded at 5 a.m. on 13 September. The tropical depression was closest to Hong Kong at around 2 a.m. the same day when it was centred about 180 km to the south-southwest.

As Hong Kong came under the influence of the tropical depression's outer rainbands, local weather became unstable with heavy rain and squally thunderstorms. The Amber Rainstorm Warning Signal was issued three times on 13 September. The Red Rainstorm Warning Signal and the Landslip Warning were issued at 9.30 a.m. and 11.45 a.m. respectively the same day. With the tropical depression moving away from Hong Kong and weakening, local winds gradually subsided. The No. 3 Signal was replaced by the Standby Signal No. 1 at 2.40 p.m. on 13 September. All tropical cyclone warning signals were cancelled at 4.10 p.m. the same day.

The tropical depression brought more than 200 millimetres of rainfall to many parts of Hong Kong. There were 32 reports of flooding, nine reports of landslides and 20 trees were blown down in the territory. Some roads had to be closed. A number of people were trapped by flood water in various parts of the New Territories. More than 20 villagers at Shek Wu Wai and Siu Hum Tsuen in San Tin were rescued from flood water by firemen. Service of the KCR East Rail was interrupted and ferry service to some outlying islands was suspended. At the Hong Kong International Airport, 18 flights were cancelled and another 277 delayed. In addition, one person was injured in the jetfoil bound for Shenzhen.

Information on wind, rainfall and tide during the passage of the tropical depression is given in Tables 3.6.1-3.6.3. Figures 3.6.1-3.6.4 show the track of the tropical depression, rainfall distribution in Hong Kong, cloud imagery and radar imagery respectively.

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