TROPICAL CYCLONES IN 2003

2.1 Review of tropical cyclones in 2003

In 2003, 23 tropical cyclones occurred over the western North Pacific and the South China Sea (i.e. the area bounded by the Equator, 45°N, 100°E and 180°), eight less than the 30-year (1961-1990) average. Throughout the year, 14 tropical cyclones attained typhoon strength, two less than the normal figure.

The first tropical cyclone of the year formed in January. The monthly frequencies of the occurrence of tropical cyclones and typhoons in the western North Pacific and the South China Sea in 2003 are shown in Figure 2.1.

During the year, seven tropical cyclones hit mainland China, and similarly for the Philippines, five affected Japan (including Ryukyu Islands), three affected Taiwan, two made landfall over Vietnam and one traversed South Korea.

The most intense tropical cyclone in 2003 was Lupit (0321). Lupit had a maximum wind speed of about 230 km/h and a minimum sea-level pressure about 905 hPa.

Parma (0318) was the tropical cyclone with the most peculiar track in 2003 (Figure 2.3.a). After strengthening into a typhoon on 22 October, Parma tracked northeastwards following the southwesterly steering flow in the northwestern quadrant of an upper-air anticyclone (Figure 2.3.b). While tropical cyclones tracking northeastwards in the mid-latitude in this season would normally became extratropical cyclone or dissipate over cooler ocean surface, Parma turned southeastwards on 25 October and then towards the west the next day along the eastern periphery of the anticyclone. On 28 October, Parma turned northwestwards under the influence of southeasterly flow to the southwest of the anticyclone. Parma repeated the northeast track on 29 October when it encountered an approaching upper-air westerly trough. Parma finally became an extratropical cyclone on 31 October after performing a large clockwise loop of over 1 000 km over the western North Pacific.

2.1.2 Tropical cyclones in Hong Kong's area of responsibility

Amongst those 23 tropical cyclones in 2003, 12 occurred inside Hong Kong's area of responsibility (i.e. the area bounded by 10°N, 30°N, 105°E and 125°E). This was about 27 % less than the 30-year (1961-90) annual average of 16.4 (Table 2.1). Three of these 12 tropical cyclones developed within Hong Kong's area of responsibility. Altogether, 342 tropical cyclone warnings to ships and vessels were issued by the Hong Kong Observatory in 2003 (Table 4.2).

2.1.3 Tropical cyclones over the South China Sea

There were eight tropical cyclones affecting the South China Sea (i.e. the area bounded by 10°N, 25°N, 105°E and 120°E) in 2003. Two of them formed over the area. Six moved into the area from the western North Pacific.

2.1.4 Tropical cyclones affecting Hong Kong

Only four tropical cyclones affected Hong Kong in 2003 (Figure 2.2), two less than the normal number (Table 2.2). These four tropical cyclones were Koni (0308), Imbudo (0307), Krovanh (0312) and Dujuan (0313). All of them originated from the western North Pacific.

The Increasing Gale or Storm Signal No. 9 was issued when Dujuan affected Hong Kong in September, the first time since 1999. Imbudo in July and Krovanh in August led to the issuance of the Gale or Storm Signal No.8 and the Strong Wind Signal No. 3 respectively. Koni in July only necessitated the issuance of the Standby Signal No. 1 in Hong Kong.

2.1.5 Tropical cyclone rainfall

Tropical cyclone rainfall (the total rainfall recorded at the Hong Kong Observatory from the time when a tropical cyclone is centred within 600 km of Hong Kong to 72 hours after it has dissipated or moved farther than 600 km away from Hong Kong) in 2003 was 365.7 mm. This is about half of the normal of 737.9 mm and accounts for some 19 % of the year's total rainfall of 1 941.9 mm.

2.2 Monthly overview

A monthly overview of tropical cyclones is given in this Section. Detailed reports on tropical cyclones affecting Hong Kong are presented in Section 3.

JANUARY

Yanyan (0301) developed as a tropical depression about 1 900 km east-southeast of Guam on 16 January and moved steadily to the west-northwest. It slowed down and turned north on 18 January. On the same day, it intensified into a tropical storm. On 19 January, it headed east-northeast and speeded up gradually. Yanyan weakened into a tropical depression on the afternoon of 20 January and dissipated over water that night.

FEBRUARY - MARCH

No tropical cyclone occurred over the western North Pacific and the South China Sea in February and March.

APRIL

Kujira (0302) developed as a tropical depression over the Pacific, about 2 000 km east-southeast of Guam on 9 April. Tracking mainly to the west-northwest, it intensified into a tropical storm in the early morning of 11 April. Kujira became a severe tropical storm on 13 April and strengthened further into a typhoon the next day. It attained a maximum sustained wind speed of about 210 km/h on 16 April. Kujira turned towards the northwest over the seas east of the Philippines on 19 April. It weakened into a severe tropical storm on 22 April and further weakened into a tropical storm in the early morning of the following day. Kujira accelerated towards the northeast over the seas east of Taiwan on 24 April. It became an extratropical cyclone near Kyushu in Japan in the morning of 25 April.

MAY

On the early morning of 18 May, a tropical depression was formed over the Pacific, about 1 100 km southeast of Manila. It tracked towards the northeast at first and then turned to the north-northwest on 19 May. It started to slow down on 21 May and dissipated over the Pacific east of Luzon the following day.

Chan-hom (0303) developed as a tropical depression about 900 km southeast of Guam on 19 May. It moved slowly at first and strengthened into a tropical storm on 20 May. Chan-hom intensified into a severe tropical storm on 21 May and tracked northwards for the next few days. It attained typhoon strength on 23 May and started to accelerate towards the northeast the following day. Chan-hom weakened into a severe tropical storm on 26 May. It weakened further into a tropical storm on the early morning of 27 May and became an extratropical cyclone the same day.

On the night of 25 May, Linfa (0304) developed as a tropical depression over the northern part of the South China Sea, about 380 km northwest of Manila. It moved slowly towards the east and intensified into a tropical storm the next day. Linfa intensified into a severe tropical storm on 27 May, but weakened to a tropical storm again while moving across Luzon. During the passage of Linfa, 41 were killed, nine were missing and thousands were displaced in Luzon. Heavy rain associated with Linfa also triggered widespread flooding and landslides. Damage to crops and infrastructure was estimated to be over USD 2 millions. It entered the seas east of Luzon on 28 May and then tracked towards the northeast. Linfa intensified into a severe tropical storm again and accelerated towards Japan on 30 May. Linfa weakened into a tropical storm on the early morning of 31 May and became an extratropical cyclone in southern Japan the same day.

JUNE

On 1 June, Nangka (0305) developed as a tropical depression over the South China Sea, about 400 km south of Dongsha Dao. It rapidly intensified into a tropical storm the same day and then tracked mainly to the northeast in the next few days. While moving across the Luzon Strait, Nangka strengthened into a severe tropical storm on 2 June. On the early morning of 3 June, it weakened into a tropical storm over the seas east of Taiwan and then accelerated towards the seas south of Japan. Nangka became an extratropical cyclone on the morning of 4 June.

On the morning of 13 June, Soudelor (0306) formed as a tropical depression over the Pacific, about 1 300 km east-southeast of Manila. It strengthened into a tropical storm that night and moved northwestwards in the next few days. Soudelor intensified into a severe tropical storm on the early morning of 16 June over the seas east of Luzon. On the next day, Soudelor turned northwards and attained typhoon strength near Luzon Strait. In the Philippines, Soudelor caused 11 deaths, three people injured and two missing. Widespread floods also caused more than 3 000 people to be displaced. Soudelor accelerated to the northeast and crossed the East China Sea on 18 June. It weakened rapidly into a tropical storm on the night of 19 June and became an extratropical cyclone over the Sea of Japan on the early morning of 20 June. In Japan, 21 people were injured and 26 houses were damaged in Kyushu during the approach of Soudelor. More than 250 domestic flights were canceled.

JULY

Koni (0308) developed as a tropical depression about 1 000 km east-southeast of Manila on 16 July. Tracking to the west-northwest, it moved across the central part of the Philippines on 17 July. In the Philippines, Koni caused two deaths and two others missing during its passage. Koni entered the South China Sea and intensified into a tropical storm on 18 July. An aircraft enroute from Kota Kinabalu of Malaysia to Hong Kong encountered severe turbulence that afternoon the same day when it passed about 300 km west-northwest of Koni. Fifteen persons were injuried. On 19 July, it turned to the northwest. Koni intensified further into a severe tropical storm and attained a maximum wind speed of about 100 km/h near the centre on 20 July. On 21 July, it moved towards west-northwest and traversed Hainan that night. Koni entered Beibu Wan on 22 July and then weakened into a tropical storm after making landfall in northern Vietnam that night. Over land, Koni further weakened into a tropical depression in the early morning of 23 July and dissipated about 100 km west of Hanoi the same day. In northern Vietnam, three people were killed and 18 were injured. The torrential rains and high winds damaged more than 1 000 houses and thousands of hectares of crops.

Imbudo (0307) developed as a tropical depression about 730 km southwest of Guam on 17 July. Tracking towards the west-northwest, it intensified into a tropical storm the same night. Imbudo became a severe tropical storm on 19 July and further strengthened into a typhoon the next day with a maximum wind speed reaching about 185 km/h near its centre on 21 July. Imbudo swept through Luzon on 22 July, killing 22 people and injuring hundreds. More than 14 000 people were evacuated and over USD 35 million worth of crops were destroyed. Imbudo entered the South China Sea on the night of 22 July and continued to move west-northwestwards towards the South China coast. On the morning of 24 July, it made landfall near Yangjiang of western Guangdong and then weakened into a severe tropical storm. Imbudo weakened into a tropical storm over land on the morning of 25 July and dissipated in Guangxi the same day. During the approach of Imbudo, one person was killed and 45 others were injuries in Hong Kong. In Guangdong and Guangxi, the death toll due to Imbudo reached 20, with three people missing. Near 6 000 houses collapsed and more than 10 millions hectares of crops were damaged. The estimated economic loss was over 1.9 billion RMB.

AUGUST

On 2 August, Morakot (0309) developed as a tropical depression over seas east of Luzon, about 640 km northeast of Manila. It moved towards the northwest and intensified rapidly into a tropical storm the same day. Maintaining a northwest track in the next two days, Morakot moved across Luzon Strait on 3 August and skirted the southern part of Taiwan the same night. Morakot brought heavy rain to Taiwan and resulted in a loss of over NT$ 70 million in crops. On 4 August, Morakot made landfall near Xiamen and dissipated that night.

On 3 August, Etau (0310) formed as a tropical depression over the Pacific, about 600 km west of Guam. It headed northwest and strengthened into a tropical storm the same night. Etau intensified into a severe tropical storm on 4 August and further intensified into a typhoon on 5 August. Etau turned towards the north on 6 August. After crossing the Ryukyu Islands on 7 August, it moved towards the northeast the same day and headed towards Japan. On the night of 8 August, Etau skirted Shikoku, Japan. While traversing Honshu on 9 August, Etau weakened into a severe tropical storm in the morning and further into a tropical storm that night. Etau transformed into an extratropical cyclone in Hokkaido on the early morning of 10 August. During the passage of Etau in Japan, 11 people were killed, 10 reported missing and about 80 were injured. The torrential rains and high winds damaged at least 20 houses and caused 106 cases of landslides. More than 1 000 houses were flooded. In addition to suspension of train service, more than 450 flights were cancelled.

Krovanh (0312) developed as a tropical depression about 110 km south-southwest of Guam on 17 August. It tracked northwestwards in the first two days and turned westwards on 19 August. Krovanh intensified into a tropical storm on the night of 20 August and further intensified into a severe tropical storm the next night. It reached typhoon strength on 22 August and moved across Luzon that night. In the Philippines, the heavy rain brought by Krovanh killed a girl and caused over 1000 families to be displaced. Adopting a west-northwest track, Krovanh entered the South China Sea on 23 August morning and moved across the northern part of the South China Sea the next day. After skirting the northeastern part of Hainan, Krovanh entered Beibu Wan on 25 August. The approach of Krovanh resulted in 11 people injured in Hong Kong. In Guangdong, Guangxi and Hainan, at least two people were killed and five were injured during the approach of Krovanh. About 13 000 houses collapsed and 140 thousands hectares of crops were affected. The estimated economic loss was over 2.1 billions RMB. Krovanh weakened into a severe tropical storm on the early morning on 26 August after making landfall over northern Vietnam. It further weakened into a tropical storm the same day and dissipated over inland that night. In northern Vietnam, one person was found dead and five were hurt during the passage of Krovanh. Krovanh also flattened about 1 000 houses.

On 19 August, Vamco (0311) formed as a tropical depression about 440 km southeast of Taibei. Tracking northwestwards, it intensified into a tropical storm the same night. Vamco weakened into a tropical depression shortly before it made landfall near Wenzhou in Zhejiang on the morning of 20 August. Moving further inland towards the northwest, it weakened into an area of low pressure the same day. Near 1 000 houses were damaged during the passage of Vamco in Zhejiang.

Dujuan (0313) developed as a tropical depression about 990 km west-northwest of Guam over the Pacific on the early morning of 29 August and was slow-moving. It intensified into a tropical storm on the early morning of 30 August and strengthened further into a severe tropical storm the same day. Accelerating towards the west-northwest on 31 August, Dujuan attained typhoon strength and moved towards the seas near southern Taiwan. After crossing the seas south of Taiwan on 1 September, Dujuan headed westwards towards the South China coast. The maximum sustained wind speed near its centre reached 175 km/h. In southern Taiwan, three people were killed, one found missing and eight injured during the approach of Dujuan. Electricity supply to about 590 000 families were interrupted. All transportation services in southern Taiwan were temporarily suspended and the agricultural loss reached NT$200 millions. Dujuan entered the South China Sea on the early morning of 2 September and moved westwards towards the coast of Guangdong. On the night of 2 September, Dujuan skirted the north of Hong Kong and hit Shenzhen. It then continued to move westwards crossing Guangdong. Dujuan weakened rapidly into a tropical storm on the morning of 3 September and became an area of low pressure over Guangxi afterward. The approach of Dujuan resulted in four people missing and 24 others injured in Hong Kong. 40 people were killed and about 1 000 were injured as Dujuan rampaged across Guangdong. Power supplies in 90 % of the area in Shenzhen were interrupted. The direct economic loss caused by Dujuan was some 2.3 billions RMB.

SEPTEMBER

On the early morning of 6 September, Maemi (0314) formed as a tropical depression over the Pacific, about 130 km west-northwest of Guam. It strengthened into a tropical storm the same day. While tracking northwestwards in the next couple of days, Maemi intensified into a severe tropical storm on the early morning of 8 September and further intensified into a typhoon the next day. On 10 September, the maximum sustained wind speed near its centre reached 220 km/h. Maemi turned to the north-northeast on 11 September and passed through the seas west of Okinawa, resulting in at least one death and 71 injuries. After moving across the East China Sea, Maemi made landfall near Busan in South Korea on the night of 12 September. Moving northeastwards, it weakened into a severe tropical storm on the early morning of 13 September and entered the Sea of Japan. Maemi then became an extratropical cyclone the same day. In South Korea, Maemi killed at least 113 people and caused 14 other missing. About 34 000 hectares of farmland were inundated and 5 000 houses were destroyed. Hundreds of roads and bridges were damaged. The economic loss was estimated to be over USD 1.3 billions.

Choi-wan (0315) developed as a tropical depression about 1 100 km northeast of Manila on the early morning of 18 September. It moved mainly to the north-northwest and intensified into a tropical storm the same day. Choi-wan intensified into a severe tropical storm on 19 September and then moved across Ryukyu Islands. On 20 September, it further intensified into a typhoon and moved east-northeast towards the seas south of Japan. Choi-wan accelerated towards the northeast on 21 September and weakened into a severe tropical storm the next night. It transformed into an extratropical cyclone on the early morning of 23 September.

Koppu (0316) formed as a tropical depression about 1 030 km west-northwest of Guam over the Pacific on 25 September. Koppu intensified into a tropical storm on 27 September and further intensified into a severe tropical storm that night. It attained typhoon strength on 29 September and accelerated towards the northeast. Koppu weakened into a severe tropical storm on 30 September and became an extratropical cyclone later the same day.

OCTOBER

Ketsana (0317) developed as a tropical depression about 1 000 km east of Manila on the morning of 19 October and intensified into a tropical storm the same day. While moving slowly, it intensified into a severe tropical storm on 20 October and further intensified into a typhoon the next day. Ketsana turned northeastwards on 22 October and speeded up in the next few days. It weakened into a severe tropical storm on the early morning of 26 October and then became an extratropical cyclone the same day.

Parma (0318) formed as a tropical depression about 500 km south-southeast of Iwo Jima on the early morning of 21 October. Tracking northeastwards, it intensified into a tropical storm the same day. Parma intensified into a severe tropical storm on 22 October and further intensified into a typhoon the same day. Parma turned southeastwards on 25 October and then towards the west the next day after weakening into a severe tropical storm. It strengthened into a typhoon again on 28 October and tracked northeastwards again on the night of 29 October. Parma gradually weakened into a tropical storm on 31 October and became an extratropical cyclone that night.

Melor (0319) formed as a tropical depression about 750 km east-southeast of Manila on the night of 30 October. It tracked northwestwards and intensified into a tropical storm on the early morning of 31 October. It further intensified into a severe tropical storm the same day and headed towards Luzon. Melor moved across the northern part of Luzon on 1 November. The next day, it entered Luzon Strait and tracked northeastwards. Melor weakened into a tropical storm while skirting the southeastern part of Taiwan on the early morning of 3 November. It weakened into a tropical depression on 4 November and then dissipated over the seas east of Taiwan the same day. The approach of Melor resulted in one death, three people missing and two injuries in Taiwan.

NOVEMBER

Nepartak (0320) formed as a tropical depression about 530 km west-northwest of Yap on the night of 12 November. Tracking westwards, it intensified into a tropical storm on 13 November. On 14 November, Nepartak moved across the central part of the Philippines and entered the South China Sea. On 15 November, it intensified into a severe tropical storm and tracked northwestwards. Nepartak attained typhoon strength on the early morning of 18 November. It skirted western Hainan the same day and weakened gradually into a severe tropical storm that night. Nepartak weakened further and became an area of low pressure over Beibu Wan on 19 November. Nepartak caused four deaths in the Philippines.

DECEMBER

Lupit (0321) formed as a tropical depression over the Pacific about 1200 km south-southwest of Wake Island on 19 November and moved generally westwards. It intensified into a tropical storm on 21 November and strengthened into a severe tropical storm the next day. Lupit further strengthened into a typhoon on 23 November and tracked northwestwards on 24 November. It attained a maximum sustained wind speed of 230 km/h on the night of 26 November. Lupit turned northeastwards on 29 November and started to accelerate the next day. It weakened into a severe tropical storm on 1 December. Lupit further weakened into a tropical storm on 2 December and became an extratropical cyclone the same day.

A tropical depression formed at about 990 km east of Manila on the night of 25 December and was slow-moving. It weakened into an area of low pressure over the seas east of the Philippines the next day.

Note: Casualties and damage figures were compiled from press reports.

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