TROPICAL CYCLONES IN 2009

3.1	Severe Tropical Storm Linfa (0903): 17 - 23 June 2009

Linfa was the first tropical cyclone that necessitated the issuance of a tropical cyclone warning signal in Hong Kong in 2009.

Tropical Depession Linfa formed over the northern part of the South China Sea about 520 km south-southeast of Hong Kong on 17 June and moved slowly. It intensified into a tropical storm the next day. Linfa started to move northwards across the South China Sea on 19 June and intensified into a severe tropical storm that night. It moved north-northeastwards during the day on 20 June and reached its peak intensity in the evening with estimated maximum winds of 110 km/h near its centre. Linfa approached the coast of southeast China on 21 June and weakened into a tropical storm that afternoon. It made landfall near Dongshi Town, Jinjiang City, Fujian Province in the evening. After moving northeastwards across the coast of Fujian on 22 June, Linfa entered the East China Sea and weakened into a tropical depression that evening. It further weakened into an area of low pressure over the East China Sea the next day. According to press reports, at least one person was missing in Fujian, some 200 000 people were affected, 32 000 hectares of farmland were damaged and the direct economic losses amounted to RMB$336 million. Linfa caused flooding in Guandong, resulting in five deaths and direct economic losses amounted to RMB$333 million. A barge ran into difficulties in the waters of Zhejiang and five seamen on board were rescued. In Taiwan, at least five people were injured and one person was drowned. The electricity supply to over 3 300 households was interrupted on the islands of Penghua and Kinmen. A freighter wrecked near the southern tip of Taiwan and nine seamen on board were rescued.

Early on 20 June, Linfa moved closer to the south China coast and posed a threat to Hong Kong. The Standby Signal No. 1 was issued at 10:40 a.m. when Linfa was about 390 km southeast of Hong Kong. Local winds were light, mainly from the west to northwest on that day. Linfa was closest to Hong Kong at around 2 p.m. on that day when it was about 380 km to the east-southeast. At the Hong Kong Observatory Headquarters, the lowest instantaneous mean sea-level pressure of 999.7 hPa was recorded between 5:08 p.m. and 5:14 p.m. on the same day, when Linfa was about 400 km to the east-southeast. All tropical cyclone warning signals were cancelled at 5:45 a.m. on 21 June as Linfa gradually moved away from Hong Kong. Light to moderate westerlies prevailed in Hong Kong that morning. The maximum winds recorded at various stations during the passage of Linfa are given in Table 3.1.1.

The weather in Hong Kong was hot with sunny periods on 20 June, but there were isolated showers in the New Territories that evening. It was mainly cloudy with isolated thundery showers on the next day with over 100 millimetres of rainfall recorded in Mui Wo.

Information on the daily rainfall and maximum sea level in Hong Kong during the passage of Linfa is given in Tables 3.1.2 and 3.1.3 respectively. Figures 3.1.1 - 3.1.4 show respectively the track of Linfa, the rainfall distribution for Hong Kong, a satellite imagery of Linfa and a related radar imagery.

- Top -