TROPICAL CYCLONES IN 2016

3.8 Super Typhoon Sarika (1621): 13 – 19 October 2016

Sarika was the eighth tropical cyclone necessitating the issuance of tropical cyclone warning signals by the Hong Kong Observatory in 2016.

Sarika formed as a tropical depression over the western North Pacific about 1 060 km east of Manila on the morning of 13 October. Taking a west-northwesterly track towards the Philippines, it intensified into a tropical storm that night. Sarika further intensified rapidly the next day and developed into a super typhoon on the night of 15 October, reaching its peak intensity with an estimated sustained wind of 185 km/h near its centre. Sarika weakened into a typhoon while moving across Luzon in the early morning on 16 October. It re-organized after entering the South China Sea. Sarika made landfall over Hainan Island on the morning of 18 October and turned northwestwards. It moved across Beibu Wan on 19 October and dissipated over inland Guangxi later that day.

According to press reports, at least three persons were killed and three others were missing in the Philippines during the passage of Sarika. There were extensive landslides and many houses collapsed. In Guangdong, Guangxi and Hainan, at least 3.7 million people were affected with direct economic loss of around 5.5 billion RMB.

In Hong Kong, the Standby Signal No. 1 was issued at 9:20 p.m. on 16 October when Sarika was about 680 km south-southeast of the territory. Local winds were generally moderate to fresh northeasterly during the night and the next morning. As local winds were expected to strengthen gradually when Sarika moved to the southwest of Hong Kong, the Strong Wind Signal No. 3 was issued at 1:40 p.m. on 17 October when Sarika was about 550 km south-southwest of the territory. Under the combined effect of Sarika and the northeast monsoon, fresh to strong easterlies generally affected Hong Kong in the afternoon and the next day, with winds occasionally reaching gale force offshore and on high ground.

Sarika came closest to the territory around 5 a.m. on 18 October, passing at a distance of about 520 km southwest of Hong Kong. At the Observatory Headquarters, the lowest instantaneous mean sea-level pressure of 1006.3 hPa was recorded at 2:57 p.m. that day. As Sarika entered Beibu Wan and further weakened on the night of 18 October, Hong Kong came increasingly under the influence of the northeast monsoon. The Observatory cancelled all tropical cyclone warning signals at 10:10 p.m. that night and issued the Strong Monsoon Signal immediately afterwards. Under the influence of the northeast monsoon, occasional strong winds affected many places over the territory during the night. The Strong Monsoon Signal remained in force till 8:45 a.m. the next morning.

Under the influence of Sarika, a maximum sea level (above chart datum) of 3.00 m was recorded at Tsim Bei Tsui, while a maximum storm surge of 0.59 m (above astronomical tide) was recorded at Tai Po Kau.

Locally, there were sunny intervals on the morning of 17 October. Affected by Sarika, the weather became cloudy with a few squally showers in the afternoon. The convergence between the northeast monsoon and the southerly airstream associated with Sarika triggered prolonged periods of heavy rain and thunderstorms on 18 and 19 October. The rain was most intense on the afternoon of 19 October, with more than 100 millimetres of rainfall falling generally over Hong Kong and rainfall even exceeding 200 millimetres over the urban areas, Sha Tin and Tai Po, necessitating the issuance of the first ever Black Rainstorm Warning in October since the Rainstorm Warning System commenced operation in 1992. The hourly rainfall of 78.7 millimetres recorded at the Observatory Headquarters between 3 and 4 p.m. that day was also the highest in October since records began in 1884. Landslip Warning and Special Announcement on Flooding in the Northern New Territories were also in force that day.

In Hong Kong, there were many reports of fallen trees and incidents of falling objects during the passage of Sarika. A river trade vessel was overturned in the waters off Wang Chau in Sai Kung under strong winds and rough seas. Of the 13 crew members on board, 12 were rescued but one was still missing. Falling tree branches injured two persons in Wong Tai Sin and Lung Cheung Road. Scaffoldings at Tung Chau Street in Sham Shui Po collapsed, and an advertisement banner of a commercial building at Sai Yeung Choi Street South in Mong Kok was also blown down. Walls at Nam Hang Pai in Yuen Long and Chung Shan Terrace in Lai Chi Kok collapsed

During the rainstorm on the afternoon of 19 October, there were at least 14 reports of flooding and seven reports of landslide in Hong Kong. Traffic was seriously disrupted as many roads were flooded, with roads near Chai Wan and Tai Tam being the worst affected. A motorcycle was swept away and many vehicles were marooned. Flood water rushed into the stores of a shopping mall in Chai Wan. A wall at Bullock Lane in Wan Chai collapsed under the heavy rain.

Information on the maximum wind, period of strong winds, daily rainfall and maximum sea level reached in Hong Kong during the passage of Sarika is given in Tables 3.8.1 - 3.8.4 respectively. Figures 3.8.1 - 3.8.4 show respectively the track of Sarika, the rainfall distribution for Hong Kong, satellite imageries and related radar imageries of Sarika. Some damages caused by Sarika in Hong Kong are illustrated in Figures 3.8.5.