TROPICAL CYCLONES IN 2014
3.2 Super Typhoon Rammasun (1409): 11 – 20 July 2014
Rammasun was the second tropical cyclone that necessitated the issuance of tropical cyclone warning signal by the Hong Kong Observatory in 2014. It was also the first tropical cyclone necessitating the issuance of Strong Wind Signal No. 3 in the year.
Rammasun formed as a tropical depression over the western North Pacific about 410 km east-southeast of Guam on the morning of 11 July. It intensified gradually and moved westwards steadily in the following few days. Rammasun developed into a severe typhoon and turned west-northwestwards on 15 and 16 July, moving across the central part of the Philippines and entering the South China Sea. After weakening over terrain, Rammasun re-organized over the South China Sea and intensified into a super typhoon on 18 July, reaching its peak intensity with an estimated sustained wind of 240 km/h near its centre. Tracking northwestwards, it made landfall near Wenchang over the northern part of Hainan Island later that day and crossed the coast of Guangxi the next morning. Rammasun weakened over land and became an area of low pressure over Yunnan on 20 July.
According to press reports, at least 98 people were killed, five were missing and 630 others were injured in the Philippines during the passage of Rammasun. There were also power blackouts over many places and the direct economic loss exceeded 10.8 billion PHP (around 1.9 billion HKD). Rammasun also wreaked havoc in Hainan Island, western Guangdong and Guangxi. At least 18 people were killed, 37 000 houses collapsed, with 7.4 million people and more than 468 500 hectares of farmland affected. Transportation services were suspended and communication in some areas was disrupted. The direct economic loss exceeded 26.5 billion RMB. Rammasun also brought rainstorms and mudslides to Yunnan where at least 14 people were killed.
In Hong Kong, the Standby Signal No. 1 was issued at 11:40 p.m. on 16 July when Rammasun was about 790 km south-southeast of the territory. With Rammasun edging closer to the south China coast, local winds strengthened gradually from the east on 17 July and the Strong Wind Signal No. 3 was issued at 4:15 p.m. when Rammasun was about 590 km south of Hong Kong. Winds in Hong Kong picked up further that night, becoming generally strong east to southeasterlies with occasionally gale force over offshore and on high grounds. At the Hong Kong Observatory Headquarters, the lowest instantaneous mean sea-level pressure of 1001.6 hPa was recorded at 4:01 a.m. on 18 July when Rammasun was at about 420 km to the south-southwest. Rammasun came closest to the territory around noon that day, skirting at around 390 km to the southwest of Hong Kong. Local winds subsided gradually as Rammasun moved away from Hong Kong. The Strong Wind Signal No. 3 was replaced by the Standby Signal No. 1 at 7:40 p.m. on 18 July. As Rammasun crossing Beibu Wan and moved further away from Hong Kong overnight, all tropical cyclone warning signals were cancelled at 3:40 a.m. on 19 July.
Under the influence of Rammasun, a maximum sea level (above chart datum) of 2.52 m was recorded at Tsim Bei Tsui, while a maximum storm surge of 0.59 m was recorded at Tai Po Kau.
Local weather was mainly fine at first on 17 July. Under the influence of the outer rainbands of Rammasun, the weather became cloudy with squally showers and thunderstorms. More than 20 millimetres of rainfall were recorded over many places in Hong Kong. Rammasun continued to bring heavy squally showers and thunderstorms to the territory on 18 July. 20 millimetres of rainfall were recorded generally over the territory, and rainfall even exceeded 50 millimetres over Sai Kung and northern part of the New Territories.
In Hong Kong, at least 51 trees were blown down and many incidents of fallen objects were reported. A lamp post in Tsuen Wan flyover fell down under strong winds on 17 July, damaging two private cars. At the Hong Kong International Airport, 57 flights were cancelled, 413 delayed and 6 aircraft were diverted.
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 Rammasun is given in Tables 3.2.1 - 3.2.4 respectively. Figures 3.2.1 - 3.2.4 show respectively the track of Rammasun, the rainfall distribution for Hong Kong, a satellite imagery and a radar imagery of Rammasun.