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Super Typhoon Yutu (1826)
21 October to 2 November 2018

Yutu was the sixth tropical cyclone affecting Hong Kong in 2018 and, after Ira in 1993, necessitated the issuance of the No. 3 Strong Wind Signal in November again.

Yutu formed as a tropical depression over the western North Pacific about 1 620 km east-southeast of Guam on the afternoon of 21 October. Tracking generally northwestwards, it intensified rapidly. Yutu developed into a super typhoon on 24 October, reaching its peak intensity the next day with an estimated maximum sustained wind of 250 km/h near its centre. Yutu turned to move west to west-southwestwards on 26 and 27 October and started to weaken gradually. After moving across Luzon on 30 October, Yutu entered the central part of the South China Sea and weakened into a typhoon. Yutu further weakened into a severe tropical storm on the next day and turned to move northwestwards across the northeastern part of the South China Sea. Yutu drifted northwards slowly on 1 November and weakened into a tropical storm that night. Under the influence of the dry northeast monsoon over southern China, Yutu further weakened into a tropical depression the next day and lingered over the northeastern part of the South China Sea. It finally weakened into an area of low pressure at night.

According to press reports, Yutu left at least 2 deaths and 133 injured during its passage to Saipan. Electricity supply for many places was interrupted. The torrential rain and squalls brought by Yutu caused landslides and flooding in the northern part of the Philippines, killing at least 20 people.

In Hong Kong, the No. 1 Standby Signal was issued at 8:40 a.m. on 31 October when Yutu was about 670 km southeast of the territory. Local winds were moderate to fresh northerlies, occasionally strong offshore and on high ground. As Yutu edged closer to the coastal waters of eastern Guangdong, the No. 3 Strong Wind Signal was issued at 12:40 p.m. on 1 November when it was about 370 km southeast of Hong Kong. Under the combine effect of the northeast monsoon and Yutu, local winds were moderate to fresh northerlies, strong offshore and on high ground. The lowest instantaneous mean sea-level pressure of 1010.5 hPa was recorded at the Observatory headquarters at 3:38 p.m. on 1 November when Yutu was about 340 km southeast of Hong Kong. As Yutu’s circulation weakened significantly due to dry air intrusion, local winds subsided gradually and the No. 3 Strong Wind Signal was replaced by the No. 1 Standby Signal at 2:10 a.m. on 2 November. All tropical cyclone warning signals were cancelled at 8:10 a.m. on that day. Yutu came closest to the territory at around 11 a.m. on 2 November as it skirted past about 270 km southeast of Hong Kong.

During the passage of Yutu, a maximum sea level (above chart datum) of 2.78 m and a maximum storm surge (above astronomical tide) of 0.65 m were recorded at Tai Miu Wan.

Under the influence of the northeast monsoon, there were sunny periods on 31 October in Hong Kong. It was also very dry with the relative humidity generally staying below 40 per cent on that day. With the approach of Yutu, the weather became cloudier in Hong Kong on 1 and 2 November. There were also light rain patches in the morning and at night.

Yutu did not cause any significant damage in Hong Kong. A person was tragically drowned while surfing in Shek O on the afternoon of 31 October.