Overview of Tropical Cyclones

Overview of Tropical Cyclones in August 2018

Wednesday, 10th October 2018

 

Eleven tropical cyclones occurred over the western North Pacific and the South China Sea in August 2018, of which Bebinca necessitated the issuance of the tropical cyclone warning signals by the Observatory. The active tropical cyclone activity during June to August was mainly due to the stronger than normal Intertropical Convergence Zone which favoured the genesis of tropical cyclone. Moreover, the location of subtropical ridge over the western North Pacific was farther east and north than usual. The steering flow under this configuration favoured tropical cyclones formed over the western North Pacific to move towards the vicinity of eastern China and Japan, bringing stormy weather to the region.

Jongdari formed as a tropical depression over the western North Pacific about 690 km southwest of Iwo Jima on 25 July. Moving generally northeastward, it intensified gradually and became a typhoon on the night of 26 July. Jongdari reached its peak intensity on the morning of 27 August with an estimated maximum sustained wind of 140 km/h near its centre. It moved across the southern part of Honshu, and then the northern part of Kyushu of Japan on 29 July, and weakened into a tropical storm. Jongdari made an anti-clockwise loop over the seas south of Kyushu in the next two days and then moved across the East China Sea on a south-southwesterly course. Jongdari made a sharp turn to the north on the morning of 2 August and then picked up speed towards the west. It made landfall over the coast of Shanghai on 3 August during the day, moved inland and weakened into an area of low pressure over Jiangsu at night.

According to press reports, at least 24 people were injured and over 400 flights were cancelled in Japan during the passage of Jongdari. Electricity supply to more than 150,000 households was interrupted.

Shanshan formed as a tropical depression over the western North Pacific about 960 km northeast of Guam on the night of 2 August and tracked west-southwestwards at first. It intensified gradually and started to track north-northwestwards towards Japan on 3 August. Shanshan developed into a typhoon on 4 August, reaching its peak intensity on 7 August with an estimated maximum sustained wind of 145 km/h near its centre. Shanshan weakened gradually afterwards and skirted past the coastal areas of Kanto region on 9 August, and turned to move northeastwards. It evolved into an extratropical cyclone over the sea areas east of Japan the next day.

According to press reports, at least six people were injured in Japan during the passage of Shanshan.

Yagi formed as a tropical depression over the western North Pacific about 980 km southeast of Okinawa on 7 August and moved slowly at first. It intensified into a tropical storm the next day and turned to move towards Okinawa in the following few days. After sweeping across the sea areas south of Okinawa, Yagi moved across the East China Sea on a northwesterly course and reached its peak intensity on the night of 12 August with an estimated maximum sustained wind of 85 km/h near its centre. After making landfall over the coast of Zhejiang, Yagi moved inland and weakened. It finally degenerated into an area of low pressure over Shandong on 14 August.

According to press reports, Yagi left at least two deaths during its passage over eastern China.

Bebinca formed as a tropical depression over the northern part of the South China Sea about 540 km southwest of Hong Kong. Moving slowly northwards, it made landfall near Yangjiang of the western Guangdong around noon on 11 August. Bebinca then made an anti-clockwise loop over the coastal region of western Guangdong and moved back to the coastal waters that night. After drifting southeastwards on 12 August, Bebinca intensified into a tropical storm and looped slowly in anti-clockwise direction off the coast of western Guangdong on 13 and 14 August. Bebinca picked up speed to move west-southwestwards and intensified into a severe tropical storm on 15 August, reaching its peak intensity with an estimated maximum sustained wind of 90 km/hr near its centre. It moved across Beibu Wan the next day. Bebinca made landfall over the northern part of Vietnam and weakened into an area of low pressure inland on 17 August.

According to press reports, Bebinca brought torrential rain and squalls to Guangdong, Guangxi and Hainan. At least three people were killed and 2 were reported missing. Bebinca also caused extensive flooding and landslides in Vietnam during its passage, killing at least 10 people with another three missing. For Bebinca’s impact to Hong Kong, please refer to the Tropical Cyclone Report of Bebinca.

Leepi formed as a tropical depression over the western North Pacific about 560 km south-southeast of Iwo Jima on the night of 11 August. It tracked northwestward and intensified gradually. Leepi developed into a severe tropical storm on 13 August, reaching its peak intensity with an estimated maximum sustained wind of 90 km/h near its centre. Leepi swept across Kyushu of Japan on 15 August and then weakened into an area of low pressure over the seas south of the Korean Peninsula.

According to press reports, Leepi brought torrential rain and squalls to Kyushu of Japan. One person fell into the sea under strong wind and suffered from serious injury.

Originating from the eastern North Pacific, tropical storm Hector crossed the International Date Line and entered the western North Pacific on the small hours of 14 August, with an estimated maximum sustained wind of 75 km/h near its centre. Moving west-northwestwards, Hector continued to weaken and dissipate over sea the next day.

Rumbia formed as a tropical depression over the western North Pacific about 90 km north-northwest of Okinawa on the morning of 15 August, and developed into a tropical storm that afternoon. It generally took on a northwest or west-northwesterly course across the East China Sea. Rumbia reached its peak intensity with an estimated maximum sustained wind of 85 km/h near its centre on the night of 16 August. After making landfall over the coast of Shanghai on the morning of 17 August, Rumbia moved inland on a west-northwesterly course and weakened gradually. It finally degenerated into an area of low pressure over Henan the next night.

According to press reports, at least 22 people were killed and seven were missing in eastern and central China during the passage of Rumbia. More than 10 million people were affected, with a direct economic loss of about five billion RMB.

Soulik formed as a tropical depression over the western North Pacific about 340 km northwest of Guam on the night of 16 August. It generally took on a northerly track and intensified gradually. Soulik intensified into a severe typhoon over the sea areas west of Iwo Jima on the night of 18 August and turned to move west-northwestwards. It reached its peak intensity with an estimated maximum sustained wind of 165 km/h near its centre the next morning. Soulik swept across the East China Sea and the Yellow Sea afterwards and weakened gradually. It turned to track northeastwards, weakened into a severe tropical storm during the night of 23 August and moved across the Korean Peninsula. Soulik evolved into an extratropical cyclone over the seas north of Honshu, Japan the next night.

According to press reports, one people was swept away by freak waves and reported missing and two others were injured in the Republic of Korea during the passage of Soulik. At least one person was injured and electricity supply to over 20 000 households was interrupted on the island of Amami Oshima, Japan during the passage of Soulik.

Cimaron formed as a tropical depression over the western North Pacific about 1 060 km east of Guam on the morning of 18 August. It took on a northwesterly track in the direction of the sea areas south of Japan and intensified gradually. Cimaron developed into a severe typhoon on 22 August, reaching its peak intensity with an estimated maximum sustained wind of 155 km/h near its centre. After skirting over Shikoku and then moving across the western part of Honshu, Japan on the night of 23 August, Cimaron finally evolved into an extratropical cyclone over the seas north of Honshu, Japan the next day.

According to press reports, Cimaron brought torrential rain and squalls to Japan with unleashed landslides, leaving at least three deaths and 22 injuries. Electricity supply to about 100,000 households was interrupted.

Originating in the northeastern part of the South China Sea, an area of low pressure near Taiwan developed into a tropical depression about 40 km north of Gaoxiong on the morning on 23 August with an estimated maximum sustained wind of 55 km/h near its centre. The tropical depression moved slowly and lingered around western Taiwan on that day. It swept across the Taiwan Strait on a northwesterly course on 24 August and made landfall over the coast of Fujian on the morning of 25 August. The tropical depression weakened into an area of low pressure over inland Fujian during the day.

According to press reports, torrential rain and squalls brought by the tropical depression triggered extensive flooding in Taiwan. At least seven people were killed and 119 people were injured.

Jebi formed as a tropical depression over the western North Pacific about 1 520 km east of Guam on the night of 27 August. It tracked northwestwards at first and intensified rapidly. Jebi intensified into a typhoon on 29 August and turned to move westwards. It further developed into a super typhoon on 31 August and moved in the direction of seas east of Ryukyu Islands.