Tropical Cyclones in 2018 > Report on Severe Tropical Storm Bebinca (1816): 9 – 17 August 2018

3.3 Severe Tropical Storm Bebinca (1816): 9 – 17 August 2018

Bebinca was the third tropical cyclone affecting Hong Kong in 2018. Under the influence of weak steering flow, it exhibited an erratic movement and lingered over the seas off the coast of western Guangdong for a rather long time. The tropical cyclone warning signals had been in force for 132 hours and 5 minutes, making it the third longest since 1946, just after 161 hours for Tilda in 1964 and 139 hours 10 minutes for Dinah in 1977.

Bebinca formed as a tropical depression over the northern part of the South China Sea about 540 km southwest of Hong Kong. Moving slowly northwards, it made landfall near Yangjiang of western Guangdong around noon on 11 August. Bebinca then made an anti-clockwise loop over the coastal region of western Guangdong and moved back to the coastal waters that night. After drifting southeastwards on 12 August, Bebinca intensified into a tropical storm and looped slowly in anti-clockwise direction off the coast of western Guangdong on 13 and 14 August. Bebinca picked up speed to move west-southwestwards and intensified into a severe tropical storm on 15 August, reaching its peak intensity with an estimated sustained wind of 90 km/hr near its centre. It moved across Beibu Wan the next day. Bebinca made landfall over the northern part of Vietnam and weakened into an area of low pressure inland on 17 August.

According to press reports, Bebinca brought torrential rain and squalls to Guangdong, Guangxi and Hainan. At least three people were killed and 2 were reported missing. Bebinca also caused extensive flooding and landslides in Vietnam during its passage, killing 10 people with another three missing.

In Hong Kong, the No. 1 Standby Signal was issued at 5:15 p.m. on 9 August when Bebinca was about 540 km southwest of the territory. Local winds were moderate to fresh east to southeasterlies on 9 - 13 August, and occasionally reaching strong force offshore and on high ground. As Bebinca started to move slowly northwards on 14 August, edging slightly closer to the Pearl River Estuary, the No. 3 Strong Wind Signal was issued at 5:20 a.m. on 14 August when it was about 190 km south-southwest of Hong Kong. As the circulation of Bebinca was relatively small, local winds were only moderate to fresh east to southeasterlies during the day, and occasionally reaching strong force offshore and on high ground. Bebinca came closest to the territory at around 2 p.m. on that day as it skirted past about 150 km south-southwest of Hong Kong. As it tracked westwards and departed from Hong Kong at night, the No. 3 Strong Wind Signal was replaced by the No. 1 Standby Signal at 2:20 a.m. on 15 August, and all tropical cyclone warning signals were cancelled at 5:20 a.m. on that day.

During the passage of Bebinca, a maximum sea level (above chart datum) of 3.33 m was recorded at Tsim Bei Tsui and a maximum storm surge (above astronomical tide) of 0.43 m was recorded at Tai Po Kau. The lowest instantaneous mean sea-level pressure of 994.7 hPa was recorded at the Observatory headquarters at 5:34 p.m. on 12 August when Bebinca was about 260 km southwest of Hong Kong.

Under the influence of an anticyclone aloft over southern China, there were sunny periods and isolated showers in Hong Kong on 9 August. It was very hot during the day. The outer rainbands associated with Bebinca brought occasional heavy squally showers and thunderstorms to Hong Kong on 10 – 15 August. Amber Rainstorm Warning Signals were issued on 10, 11 and 12 August. More than 150 millimetres of rainfall were generally recorded over the territory during 9 – 15 August, with rainfall over parts of the New Territories exceeding 250 millimetres.

In Hong Kong, there were at least 18 reports of fallen trees during the passage of Bebinca. A tree collapsed at San Tin Highway near Yuen Long and damaged a private car and a container truck passing by. One of the drivers suffered a minor injury.