Hato was the third tropical cyclone affecting Hong Kong in 2017. The highest tropical cyclone warning, No.10 Hurricane Signal, was issued for the first time since Severe Typhoon Vicente hitting Hong Kong in July 2012. Hato intensified significantly as it traversed the northern part of the South China Sea, momentarily attaining super typhoon intensity over the sea areas south of Hong Kong and the first time a super typhoon necessitating the issuance of tropical cyclone warning signals No.8 or above since Hope in 1979.
Hato formed as a tropical depression over the western North Pacific about 740 km east-southeast of Gaoxiong on the night of 20 August. It moved generally westwards across the Luzon Strait and entered the northeastern part of the South China Sea on 22 August, intensifying into a typhoon and tracking west-northwest towards the coast of Guangdong. During its approach towards the Pearl River estuary on 23 August, Hato intensified further and became a super typhoon that morning over the sea areas south of Hong Kong, reaching its peak intensity with an estimated sustained wind of 185 km/h near its centre. After making landfall over the coast near Macao and Zhuhai shortly after noon time, Hato entered western Guangdong and gradually weakened. It moved across Guangxi the next day and degenerated into an area of low pressure over Yunnan at night.
Hato brought severe storm surge to the coast of Pearl River estuary. Record-high sea levels were recorded at many places. A maximum storm surge of 2.79 m and a maximum sea level of 6.14 m were recorded at Zhuhai station. The coastal areas in Zhuhai including some underground carparks were flooded by sea water. Electricity and water supply in the city became unstable. A number of vessels ran aground about 30 km southwest of Hong Kong and 39 crew members were rescued. Hato brought damaging winds and storm surge to Macao. Extensive areas of Macao suffered damage and were seriously flooded, resulting in at least ten deaths and more than 240 injuries. The direct economic loss exceeded 8.3 billion MOP. A maximum sea level of 5.58 metres was recorded in A-Ma station, a record high in Macao since records began in 1925. Electricity and water supplies were also affected. In Guangdong, Guangxi, Fujian, Guizhou and Yannan, there were at least 15 deaths and one missing during the passage of Hato. Around 740 000 people were affected and over 6 500 houses collapsed, with direct economic loss exceeding 27.2 billion RMB.
The Hong Kong Observatory issued the No.1 Standby Signal at 8:40 a.m. on 22 August when Hato was about 660 km east-southeast of the territory. Local winds were light to moderate northerlies during the day. Squally thunderstorms triggered by high temperatures affected many places in the territory during the afternoon. As Hato edged closer to the coast of Guangdong, the No.3 Strong Wind Signal was issued at 6:20 p.m. when Hato was about 410 km east-southeast of Hong Kong. Local winds strengthened gradually in the small hours of 23 August, becoming fresh to strong northerlies, reaching gale force on high ground. The Observatory issued the No.8 Northeast Gale or Storm Signal at 5:20 a.m. when Hato was about 160 km southeast of the territory. Local winds strengthened rapidly afterwards, with northeasterly gales in many places and reaching storm force offshore and on high ground. With Hato expected to make a direct hit over the Pearl River estuary, the No.9 Increasing Gale or Storm Signal was issued at 8:10 a.m. when Hato was about 100 km south-southeast of the Hong Kong Observatory. Local winds strengthened further that morning and the No.10 Hurricane Signal was issued at 9:10 a.m. when Hato was about 70 km south of the Hong Kong Observatory. Gale to storm force winds generally affected Hong Kong, with winds persistently reaching hurricane force over the southern part of the territory and on high ground. Hato came closest to Hong Kong around 10 a.m. that morning with its centre passing only about 60 km south-southwest of the Hong Kong Observatory. As Hato made landfall to the west of Hong Kong, local winds gradually veered from northeasterly to southeasterly and started to subside. The No.8 Southeast Gale or Storm Signal was then issued at 2:10 p.m. With Hato weakening and moving away, the No.3 Strong Wind Signal and No.1 Standby Signal were issued at 5:10 p.m. and 6:20 p.m. respectively. Hato moved further inland during the night and all tropical cyclone warning signals were cancelled at 8:40 p.m.
The storm surge brought by Hato raised the water level in Hong Kong generally by about one to two metres. Coinciding with the high water of the astronomical tide (the astronomical high tide was about 2.4 m at Quarry Bay in the Victoria Harbour that morning), the aggregated effect resulted in the inundation of many low-lying areas in Hong Kong by sea water. The water level at Quarry Bay reached a maximum of 3.57 mCD (metres above Chart Datum), the second highest since records began in 1954 and only lower than the record high of 3.96 mCD set by Super Typhoon Wanda in 1962. A maximum water level of 4.56 mCD was recorded in Tsim Bei Tsui, the highest since records began in 1974. For the maximum sea levels recorded at various tide stations in Hong Kong during the passage of Hato, please refer to this figure.
As Hato battered Hong Kong on 23 August, maximum hourly mean winds of 130, 124, 94 and 85 km/h and maximum gusts of 193, 171, 140 and 137 km/h were recorded at Waglan Island, Cheung Chau, Tai Mei Tuk and North Point respectively. The lowest instantaneous mean sea-level pressures recorded at some selected stations are as follows:
The subsidence effect ahead of Hato’s circulation brought hazy skies and oppressive heat to Hong Kong on 22 August, with temperatures in many places reaching 37 degrees or above. Temperature at the Hong Kong Observatory soared to an all-time record-breaking high of 36.6 degrees around 2 p.m. that day. Intense convection triggered by high temperatures brought heavy showers and squally thunderstorms to the territory later in the afternoon. Under the influence of Hato’s circulation, there were heavy squally showers and thunderstorms on 23 August, and Amber Rainstorm Warning was issued by the Observatory that morning. The weather improved with sunny periods during the day on 24 August. More than 60 mm of rainfall were recorded generally over Hong Kong during the 3-day period.
In Hong Kong, at least 129 people were injured during the passage of Hato. There were over 5,300 reports of fallen trees, many incidents of falling objects, one report of landslide as well as a number of flooding reports. Two police officers were hit on the head by falling branches near San Po Kong when clearing the fallen trees. One person was injured by a falling clothes-hanging pole in Kwun Tong. A suspended work platform at an apartment block in Hung Hom came loose under strong winds and rammed into the windows of several units of the building. Glass curtain walls of several commercial buildings in Wan Chai and Central were shattered. Some scaffolding in Kwun Tong and Tsueu Wan collapsed. A vessel ran aground near Discovery Bay in Lantau Island and ten crew members on board were taken to safety.
Storm surge induced by Hato resulted in serious flooding and damages in a number of coastal areas in Hong Kong, including Tai O, Shek Pik, Mui Wo, Cheung Chau, Heng Fa Chuen, Siu Sai Wan, Lei Yue Mun, Tseung Kwan O, Sha Tin, Tai Po, Sai Kung, Yuen Long and Lau Fau Shan. The flooding in Tai O was reported to be more damaging than that of Hagupit in 2008. The flood alert system for Tai O was activated and many residents were evacuated. Serious flooding also occurred in Lei Yue Mun, with sea water flowing into a number of village houses and shops, trapping many residents who had to be helped to safety by firemen. The Heng Fa Chuen promenade was inundated, with sea water flowing into the estate and its underground car park. Siu Sai Wan Sports Ground was also flooded by sea water. The cycle tracks and subways near Shing Mun River in Sha Tin, coastal area of Tolo Harbour, Lam Tsuen River in Tai Po were flooded, as well as a number of village houses in Sai Kung, Lau Fau Shan and Tai Po. Electricity supply to many village houses in Tai Po was interrupted. The waterfront at Tseung Kwan O was damaged by sea waves. The surge of water level in Yuen Long nullah and Shan Pui River resulted in flooding nearby. Shek Pik Prison Staff Quarters was also seriously flooded, with vehicles swept away by sea waters. External communication services in Cheung Chau and Peng Chau were affected as a result of damaged optical fibre cables.
Transportation services in Hong Kong were seriously affected by Hato. Train services along the open sections of MTR were once suspended. Many roads were closed due to strong winds, fallen trees or flooding. Resumption of ferry services was affected due to the damage of facilities at a number of ferry terminals. More than 480 flights were cancelled and nine flights were diverted at the Hong Kong International Airport.