TROPICAL CYCLONES IN 2010
2.1 TROPICAL CYCLONE OVERVIEW FOR 2010
2.1.1 Tropical cyclones over the western North Pacific (including the South China Sea)
In 2010, only 18 tropical cyclones occurred over the western North Pacific and the South China Sea bounded by the Equator, 45°N, 100° and 180°E, considerably less than the normal (1971-2000) figure of around 30 tropical cyclones in a year. This was the lowest on record since 1946, breaking the previous record of 20 set in 1998. During the year, seven tropical cyclones attained typhoon intensity or above, eight below the normal figure of 15.
The first tropical cyclone of the year formed in March and the last one in December. Only one tropical cyclone occurred between January and June, 16 occurred between July and October, and another one occurred from November to December. Figure 2.1 shows the monthly frequencies of the occurrence of tropical cyclones in the western North Pacific and the South China Sea in 2010.
During the year, seven tropical cyclones made landfall over Mainland China, with two of them making landfall over the south China coast within 300 km of Hong Kong. One tropical cyclone crossed Taiwan, two made landfall over the Korean Peninsula, two made landfall over Japan, two traversed the Philippines and another two made landfall over Vietnam.
The most intense tropical cyclone in 2010 was Super Typhoon Megi (1013). Megi had an estimated maximum sustained wind speed of 270 km/h and a minimum sea-level pressure of 895 hPa (Table 4.1) when it was located over the western North Pacific about 590 km northeast of Manila (Fig. 2.3). Megi was the only super typhoon (maximum sustained wind speed of 185 km/h or above near the centre) in the region during 2010. It was also the most intense tropical cyclone in the region since Super Typhoon Tip in October 1979.
The track of Severe Tropical Storm Lionrock (1006) was the most complicated in 2010. Lionrock formed over the northern part of the South China Sea on 28 August. Under the influence of another two tropical cyclones Kompasu (1007) and Namtheun (1008) over the western North Pacific, Lionrock changed its track twice and affected Hong Kong in two separate episodes. figures 2.4 and 2.5 show respectively the tracks and a satellite image of the three tropical cyclones.
In December, a tropical depression moved east into the central North Pacific, after forming over the western North Pacific just west of the International Date Line. It was the last tropical cyclone of the year.
Partly due to the stronger than normal subtropical ridge of high pressure over the western North Pacific, which suppressed convection over the region, the number of tropical cyclones over the western North Pacific and the South China Sea was fewer than normal in 2010.
2.1.2 Tropical cyclones in Hong Kong's area of responsibility
Amongst the 18 tropical cyclones in 2010, 11 occurred inside Hong Kong's area of responsibility (i.e. the area bounded by 10°N, 30°N, 105°E and 125°E), less than the 30-year (1971-2000) annual average of 15.4 (Table 2.1). Seven of these 11 tropical cyclones developed within Hong Kong's area of responsibility. Altogether, 276 tropical cyclone warnings to ships and vessels were issued by the Hong Kong Observatory in 2010 (Table 4.2).
2.1.3 Tropical cyclones over the South China Sea
Nine tropical cyclones affected the South China Sea (i.e. the area bounded by 10°N, 25°N, 105°E and 120°E) in 2010. Four of them formed over the area. Five moved into the South China Sea from the western North Pacific.
2.1.4 Tropical cyclones affecting Hong Kong
In 2010, the typhoon season in Hong Kong started on 15 July when Severe Tropical Storm Conson (1002) moved across the South China Sea and necessitated the issuance of the Standby Signal No.1. The typhoon season ended on 22 October as Typhoon Megi moved away from Hong Kong and all tropical cyclone warning signals were cancelled.
Five tropical cyclones affected Hong Kong during 2010 (Figure 2.2), less than the average number of 6.5 (Table 2.2). These five tropical cyclones were Typhoon Conson (1002) and Typhoon Chanthu (1003) in July, Severe Tropical Storm Lionrock (1006) in August - September, Severe Typhoon Fanapi (1011) in September and Super Typhoon Megi (1013) in October. The Strong Wind Signal No. 3 was issued during the passages of Chanthu, Fanapi and Megi, which was the highest tropical cyclone warning signal in 2010. Conson and Lionrock 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 2010 was 833.1 mm (Table 4.8.1). This was 12% above the normal of 745.5 mm and accounted for some 35% of the year's total rainfall of 2371.7 mm.
Severe Typhoon Fanapi, which affected Hong Kong on 19-21 September, brought 246.6 mm of rainfall to the Hong Kong Observatory Headquarters, and was the wettest tropical cyclone in 2010.
Heavy rain and squally thunderstorms associated with the outer rainbands of Typhoon Chanthu affected Hong Kong and brought widespread flooding to the territory. On 22 July, 182.4 mm of rainfall was recorded at Hong Kong Observatory Headquarters, the highest daily rainfall associated with tropical cyclone in 2010.
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 TO FEBRUARY
No tropical cyclone occurred over the western North Pacific and the South China Sea from January and February.
MARCH
Omais (1001) formed over the western North Pacific about 240 km east of Yap on 23 March and moved west-northwestwards. It intensified into a tropical storm on the evening of 24 March reaching its peak intensity with estimated maximum sustained winds of 65 km/h near its centre. It turned to move northwards the next day. Omais weakened into a tropical depression during the evening of 26 March and dissipated over the western North Pacific to the east-northeast of Luzon the following day.
APRIL TO JUNE
No tropical cyclone occurred over the western North Pacific and the South China Sea from April to June.
JULY
Conson (1002)formed as a tropical depression over the western North Pacific about 1 200 km east of Manila early on 12 July. Moving westwards, it intensified into a severe tropical storm that evening. Conson crossed the southern part of Luzon during the night of 13 July. It moved west-northwestwards across the South China Sea on 14 July but took on a more westerly track the following day. Conson moved in a northwest to west-northwest direction on 16 July. It intensified into a typhoon in the afternoon reaching its peak intensity with estimated maximum winds of 120 km/h near its centre. Conson skirted the coast of southwestern Hainan that night. It crossed Beibu Wan on 17 July, making landfall over the coast of northern Vietnam that evening and gradually weakening into a tropical storm. Conson weakened further into a tropical depression next morning and dissipated inland thereafter. According to press reports, at least 26 people and two people were killed in the Philippines and Hainan Island respectively, while 17 people were missing in Vietnam during the passage of Conson.
Chanthu (1003)formed as a tropical depression over the central part of the South China Sea about 900 km south-southeast of Hong Kong on 19 July. It moved generally northwestwards across the northern part of the South China Sea. Chanthu intensified into a typhoon to the east of Hainan Island in the early hours of 22 July, reaching its peak intensity with estimated maximum sustained winds of 120 km/h near its centre. Chanthu made landfall near Zhanjiang that afternoon and weakened into a severe tropical storm that evening. It moved across Guangxi on 23 July and eventually dissipated inland that night. According to press reports, Chanthu brought rainstorms to Guangdong where at least two people were killed.
A tropical depression formed over the western North Pacific about 170 km west of Okinawa on 19 July and moved generally north-northwestwards. The estimated maximum winds reached 45 km/h near its centre. The tropical depression dissipated over the East China Sea the next day.
AUGUST
On 8 August, Dianmu (1004) formed as a tropical depression over the western North Pacific about 530 km southeast of Taibei. It moved northwards and gradually intensified to a severe tropical storm reaching its peak intensity with estimated maximum sustained winds of 90 km/h near its centre on 9 August. It turned to move northeastwards across Jeju and the southeastern part of the Republic of Korea on 11 August and weakened into a tropical storm. Dianmu moved across the Sea of Japan on 12 August. It became an extra-tropical cyclone to the east of Japan that evening. According to press reports, five people were killed and around 130 houses were flooded in the Republic of Korea during the passage of Dianmu.
Mindulle (1005)formed as a tropical depression over the northern part of the South China Sea about 300 km east of Xisha on 22 August and moved westwards. It turned west-northwest and intensified gradually into a severe tropical storm the next day. On 24 August, Mindulle reached its peak intensity with estimated maximum sustained winds of 105 km/h near its centre. It moved northwestwards across Beibu Wan that day and made landfall over northern Vietnam in the evening. It subsequently dissipated over Laos on 25 August.
Lionrock (1006)formed as a tropical depression over the northern part of the South China Sea about 600 km south-southeast of Hong Kong on 28 August and moved northwestwards. It intensified into a tropical storm the next day and turned to the north. Lionrock moved eastwards on 30 August and intensified into a severe tropical storm with maximum sustained winds of 90 km/h near its centre. Lionrock moved east-northeastwards over the northeastern part of the South China Sea on 31 August, but turned to move generally northwestwards across the northeastern part of the South China Sea on 1 September. It made landfall over the coast of southern Fujian on 2 September and weakened into a tropical storm. Lionrock then moved generally westwards and subsequently dissipated over Guangdong on 3 September. According to press reports, Lionrock brought rainstorms to Guangdong where at least 165 houses collapsed.
Kompasu (1007)formed as a tropical depression over the western Pacific about 1 280 km southeast of Okinawa on 29 August and moved northwestwards. It gradually intensified and became a typhoon to the southeast of Okinawa on 31 August, with maximum sustained winds of 145 km/h near its centre. Kompasu moved north across the seas to the west of Jeju on 1 September. It turned to move northeastwards crossing the Korean Peninsula and entering the Sea of Japan on 2 September and weakened into a tropical storm. Kompasu became an extra-tropical cyclone over the Sea of Japan the following day. According to press reports, Kompasu caused the death of five people in the Republic of Korea and power outage to tens of thousands of homes. More than 60 international flights were cancelled or delayed.
Namtheun (1008)formed as a tropical depression over the southern part of the East China Sea about 160 km northeast of Taibei on 30 August and moved west-southwestwards. It intensified into a tropical storm that evening, reaching its peak intensity with maximum sustained winds of 65 km/h near its centre. Namtheun moved across the Taiwan Strait on 31 August and weakened into a tropical depression. It dissipated over the coastal waters of southeastern China to the east of Xiamen on 1 September.
SEPTEMBER
Malou (1009)formed over the western North Pacific about 490 km southeast of Okinawa on 3 September and moved west-northwestwards. It intensified into a tropical storm the next day. Malou turned to move northwards on 5 September. It reached its peak intensity with maximum sustained winds of 85 km/h near its centre on 6 September and turned to move northeastwards. Malou crossed the Sea of Japan the following day. It then made landfall over central Honshu on 8 September and became an extra-tropical cyclone to the east of Japan on 9 September. According to press reports, an oil rig at Bo Ha was tilted by strong winds to about 45 degrees. All affected were rescued.
Meranti (1010)formed as a tropical depression about 190 km south-southeast of Gaoxiong on 8 September and moved westwards. It intensified into a tropical storm on 9 September and turned to move northwards. Meranti intensified into a severe tropical storm that evening, reaching its peak intensity with maximum sustained winds of about 110 km/h. Meranti made landfall over the coast of southeast China on 10 September and gradually dissipated over Zhejiang that evening. According to press reports, Meranti triggered landslides in Taitung County in southeastern Taiwan, trapping about 700 people there. In Quanzhou, Fujian, three people were killed and over 350 houses collapsed. The direct economic losses amounted to 100 million RMB.
Fanapi (1011) formed as a tropical depression over the western North Pacific about 710 km south of Okinawa on 15 September and moved northwestwards. It intensified into a tropical storm that evening. Fanapi intensified into a severe tropical storm on 16 September and moved northeastwards slowly. It resumed a northwesterly track on 17 September and intensified into a typhoon to the east of Taiwan. Fanapi intensified further into a severe typhoon on 18 September, reaching its peak intensity with estimated maximum sustained winds of 165 km/h near its centre and turning to move generally westwards. It crossed Taiwan on 19 September and weakened into a typhoon. Fanapi crossed the Taiwan Strait that night and made landfall over the coastal areas of southern Fujian on 20 September. Fanapi then gradually weakened and tracked westwards across southern China and finally dissipated near Guangzhou on 21 September. According to press reports, Fanapi caused the death of two people in Taiwan, and another 33 people being killed and 42 people missing in Guangdong.
Malakas (1012)formed as a tropical depression over the western North Pacific about 520 km north of Guam on 21 September and moved generally west-northwestwards. It intensified into a tropical storm the next day. Malakas turned to move northwards on 23 September and gradually intensified into a typhoon on 24 September. It turned to move north-northeastwards on 25 September and intensified into a severe typhoon, reaching its peak intensity with estimated maximum sustained winds of 155 km/h near its centre. Malakas became an extra-tropical cyclone over the western North Pacific to the east of Japan that evening.
OCTOBER
A tropical depression formed over the Beibu Wan about 110 km west-northwest of Sanya on 5 October and was slow moving. The tropical depression remained weak with maximum sustained winds of 45 km/h near the centre. It dissipated over the coastal waters of western Hainan on 7 October.
Megi (1013) formed as a tropical depression over the western North Pacific about 450 km west-southwest of Guam on 13 October and moved west-northwestwards. It intensified into a tropical storm that evening. On 15 October, Megi moved northwestwards and gradually intensified into a typhoon over the Pacific to the east of the Philippines. Megi moved west-northwestwards the next day. It turned to move west-southwestwards and became a super typhoon on 17 October, reaching its peak intensity with maximum sustained winds of about 270 km/h near its centre. Megi crossed Luzon on 18 October and weakened into a severe typhoon. It moved generally westwards across the South China Sea on 19 October, but turned to move generally northwards for the next four days. Megi weakened into typhoon over the northeastern part of the South China Sea on 22 October. It made landfall over the coast of Zhangpu, Fujian on 23 October and weakened into a severe tropical storm. Megi continued to move further inland and dissipated on the morning of 24 October. According to press reports, Megi caused the death of at least 36 people in the Philippines, and the death of at least 13 people with 26 others missing in Taiwan. A freighter and a fishing boat sank in the waters of Fujian and Zhejiang respectively, with one person killed and 20 others missing.
A tropical depression formed over the western North Pacific about 690 km west of Wake Island on 21 October and moved west-northwestwards. The maximum sustained winds near the centre of the tropical depression were around 55 km/h. The tropical depression turned to move east-northeastwards on 23 October and dissipated over the western North Pacific to the west-northwest of Wake Island that evening.
Chaba (1014) formed as a tropical depression over the western North Pacific about 810 km north of Yap on 22 October and moved westwards at first. It turned to move southwestwards the next day. Chaba took on a northwesterly track on 24 October, gradually intensifying. Chaba became a severe tropical storm on 25 October and a typhoon to the south-southeast of Ryukyu Islands the next day. It turned north on 27 November and intensified further into a severe typhoon, reaching its peak intensity with maximum sustained winds of about 175 km/h near its centre. Chaba turned to move northeast on 28 October. It gradually weakened into a severe tropical storm and crossed the seas to the south of Japan on 30 October. Chaba became an extra-tropical cyclone over the western North Pacific to the east of Honshu on 31 October.
NOVEMBER
No tropical cyclone formed over the western North Pacific and the South China Sea in November.
DECEMBER
A tropical depression formed over the western North Pacific about 1 360 km east of Wake Island on 19 December and moved mainly southwards. The maximum sustained wind near its centre was about 55 km/h. The tropical depression turned to move eastwards across the International Date Line into the central North Pacific the following day and intensified into a tropical storm.
Note: Casualties and damage figures were compiled from press reports.
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