Linfa was the second tropical cyclone necessitating the issuance of tropical cyclone warning signal by the Hong Kong Observatory in 2015. It was also the only tropical cyclone requiring the issuance of the Gale or Storm Signal No. 8 in the year.
Linfa formed as a tropical depression over the western North Pacific about 830 km east of Manila on the afternoon of 2 July. It moved generally westwards and intensified into a tropical storm the next morning. Moving northwestwards, Linfa headed towards the northern part of Luzon and developed into a severe tropical storm on 4 July. Linfa moved across the northern part of Luzon on 5 July and entered the South China Sea. It weakened into a tropical storm the next day. With a weaker steering flow, Linfa slowly drifted northwards on 6 and 7 July and re-intensified into a severe tropical storm. It started to take on a more westerly track and edged closer to the coast of eastern Guangdong on the afternoon of 8 July. Linfa intensified into a typhoon that night, reaching its peak intensity the next morning with an estimated sustained wind of 140 km/h near its centre. Linfa made landfall near Lufeng in Guangdong around noon and continued to track westwards across the coastal areas of Guangdong towards the Pearl River Estuary in the afternoon. Affected by relatively dry air from the north, Linfa weakened rapidly into a tropical depression. It finally degenerated into an area of low pressure on the morning of 10 July over western Guangdong.
According to press reports, at least 700 000 people were affected and 6 700 houses were damaged in eastern Guangdong during the passage of Linfa. Transportation services were suspended and there were power outage in many places.
As Linfa was expected to turn west towards the coastal areas of eastern Guangdong, the Standby Signal No. 1 was issued at 7:40 a.m. on 8 July when Linfa was about 480 km east of Hong Kong. As Linfa continued to move closer to the coast of Guangdong, the Strong Wind Signal No. 3 was issued at 8:40 am on 9 July when Linfa was about 260 km east-northeast of the territory. Wind strengthened generally over Hong Kong in the afternoon, with strong winds recorded over many places and winds reaching gale force occasionally on high ground.
As Linfa was expected to turn west or west-southwestward, getting very close to the territory in the evening, the No. 8 Northwest Gale or Storm Signal was issued at 4:40 p.m. on 9 July when Linfa was about 110 km northeast of the territory. Subsequently, Linfa weakened rapidly and its circulation and gale extent also shrunk significantly. Linfa was closest to Hong Kong at around 9 p.m. on 9 July when it was about 50 km north of the Hong Kong Observatory Headquarters. With Linfa gradually moving away from Hong Kong and weakening, the threat of gales subsided. The Strong Wind Signal No. 3 was issued at 10:10 p.m. on 9 July. As Linfa degenerated further into an area of low pressure, all tropical cyclone warning signals were cancelled at 5:50 a.m. on 10 July.
Under the influence of Linfa, a maximum sea level (above chart datum) of 2.37 m and a maximum storm surge of 0.48 m (above astronomical tide) were recorded at Waglan Island. The lowest instantaneous mean sea-level pressures recorded at some selected stations are as follows:-
Station
Lowest instantaneous mean sea-level pressure (hPa)
Date/Month
Time
Hong Kong Observatory Headquarters
993.8
9/7
4:21 p.m.
Cheung Chau
993.8
9/7
4:40 p.m.
Hong Kong International Airport
994.9
9/7
4:36 p.m.
King’s Park
993.5
9/7
4:32 p.m.
Lau Fau Shan
994.1
9/7
5:05 p.m.
Waglan Island
993.1
9/7
3:59 p.m.
There were sunny intervals in Hong Kong on 8 July. Rainbands associated with Linfa and its remnant affected the territory from the afternoon of 9 July to the morning of 10 July. More than 20 millimetres of rainfall were generally recorded, with rainfall amounts exceeding 40 millimetres over Hong Kong Island, Lantau Island, Cheung Chau and Lamma Island.
Linfa did not cause any significant damage in Hong Kong and there were a few reports of fallen trees. There were 520 flights re-scheduled at the Hong Kong International Airport.
Information on the maximum wind, period of strong and gale force winds, daily rainfall and maximum sea level reached in Hong Kong during the passage of Linfa is given in Tables 3.2.1 - 3.2.4 respectively. Figures 3.2.1 - 3.2.5 show respectively the track of Linfa, the rainfall distribution for Hong Kong, aircraft observation, satellite imageries and radar imageries of Linfa.
