TROPICAL CYCLONES IN 2012

3.5 Severe Typhoon Tembin (1214): 18 – 30 August 2012

Tembin was the fifth tropical cyclone that necessitated the issuance of a tropical cyclone warning signal by the Hong Kong Observatory in 2012.

Tembin formed as a tropical depression over the western North Pacific about 660 km northeast of Manila on 18 August and moved south-southwestwards. It became slow moving on the following day and intensified gradually into a severe tropical storm. On 20 August, Tembin took on a northerly track and continued to intensify gradually and became a severe typhoon over the Pacific about 590 km north-northeast of Manila in the afternoon. It reached its peak intensity that night with an estimated maximum sustained wind of 175 km/h near its centre. Tembin turned to move westwards towards Taiwan and weakened into a typhoon on 22 August, but strengthened again into a severe typhoon over the Pacific to the east of Taiwan on the next day. It crossed the southern part of Taiwan in the morning on 24 August, weakened into a typhoon and entered the northeastern part of the South China Sea that afternoon. Tembin looped over the northeastern part of the South China Sea on the following two days, passing close to Dongsha from north to south on 26 August, where a mean sea level pressure of 968.5 hPa was recorded at 2 p.m. Under the influence of another tropical cyclone Bolaven over the western North Pacific, Tembin turned to move east-northeastwards on 27 August, accelerated northeastwards across the seas east of Taiwan, weakening into a severe tropical storm on 28 August. Tembin then moved north-northeastwards across the East China Sea on 29 August and made landfall over the Republic of Korea in the morning on 30 August. It weakened into a tropical storm that afternoon and became an extratropical cyclone over the eastern part of the country that evening.

The track of Tembin was quite erratic. It passed close to Taiwan twice during its life history. According to press reports, Tembin brought rainstorms to Taiwan during its first passage where at least one person was killed, five people injured and about 130 000 households left without electricity. Tembin came close to Taiwan again on 28 August. Another person was killed, one missing and 11 people injured during its second passage. Tembin also caused the death of two people, injured three others and left 4 000 households without electricity in the Republic of Korea.

In Hong Kong, the Standby Signal No. 1 was issued at 10:40 p.m. on 24 August when Tembin was over the northeastern part of the South China Sea about 540 km east of the territory. Local winds were moderate to fresh north to northwesterly winds, occasionally strong on high ground. Tembin moved slowly closer to the south China coast on 25 August and was closest to Hong Kong at around 1 a.m. on 26 August when it was passing about 290 km to the east-southeast. It started to move slowly away from Hong Kong that day. At the Hong Kong Observatory Headquarters, the lowest instantaneous mean sea-level pressure of 999.6 hPa was recorded at 4:26 p.m. on 26 August when Tembin was about 330 km to the east-southeast. Tembin moved further away from Hong Kong that afternoon and all tropical cyclone warning signals were cancelled at 4:40 p.m.

During the passage of Tembin, a maximum hourly mean wind of 47 km/h was recorded at Tai Mo Shan, while gust of 70 km/h was recorded at Tate's Cairn. A maximum sea level (above chart datum) and maximum storm surge of 2.52 m and 0.49 m was recorded at Waglan Island respectively.

Affected by the subsiding northerly airstream associated with Tembin, it was very hot in Hong Kong from 24 to 26 August. There were a few isolated showers on 25 August, bringing a couple of millimetres of rainfall.

In Hong Kong, two people were swept away by waves in the sea front at Sai Kung. One person was killed while another was injured.

Information on the maximum wind, daily rainfall and maximum sea level reached in Hong Kong during the passage of Tembin is given in Tables 3.5.1 - 3.5.3 respectively. Figures 3.5.1 - 3.5.3 show respectively the track of Tembin, a satellite imagery of Tembin and the radar imagery of the outer rainbands of Tembin.

 

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