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TROPICAL CYCLONE OVERVIEW FOR 2019
2.1 Review of tropical cyclones in 2019
2.1.1 Tropical cyclones over the western North Pacific (including the South China Sea)
In 2019, a total of 28 tropical cyclones occurred over the western North Pacific (WNP) and the South China Sea (SCS) bounded by the Equator, 45°N, 100°E and 180°, less than the long-term (1961 - 2010) average figure of around 30. During the year, 16 of the tropical cyclones attained typhoon intensity or above, slightly more than the long-term average (1961 - 2010) of about 15, with seven of them reaching super typhoon intensity (maximum 10-minute wind speed of 185 km/h or above near the centre).
Figure 2.1 shows the monthly frequencies of the occurrence of tropical cyclones in WNP and SCS in 2019.
During the year, six tropical cyclones made landfall over China, with one of them crossing the south China coast within 300 km of Hong Kong and one crossing Taiwan. Four tropical cyclones made landfall over the Korean Peninsula, five made landfall over Japan, four traversed the Philippines and six made landfall over Vietnam. With an estimated maximum sustained wind speed of 250 km/h and a minimum sea-level pressure of 905 hPa near the centre (Table 4.1), Super Typhoon Halong (1923) in November (Figure 2.3) was the most intense tropical cyclone over the WNP and the SCS in 2019.
2.1.2 Tropical cyclones in Hong Kong’s area of responsibility
Amongst the 28 tropical cyclones in 2019, 15 of them occurred inside Hong Kong’s area of responsibility (i.e. the area bounded by 10°N, 30°N, 105°E and 125°E), slightly less than the long-term annual average figure of around 16 (Table 2.1). Five of them developed within Hong Kong’s area of responsibility. Altogether, 349 tropical cyclone warnings to ships and vessels were issued by the Hong Kong Observatory in 2019 (Table 4.2).
2.1.3 Tropical cyclones over the South China Sea
Nine tropical cyclones affected SCS bounded by 10°N, 25°N, 105°E and 120°E in 2019, less than the long-term annual average of around 12. Five of them formed within SCS.
2.1.4 Tropical cyclones affecting Hong Kong
In 2019, the typhoon season in Hong Kong started on 2 July when Tropical Depression Mun (1904) formed in the northern part of the South China Sea, necessitating the issuance of the Standby Signal No. 1. The typhoon season ended with the cancellation of all tropical cyclone warning signals on 3 September when Tropical Depression Kajiki (1914) moved away from Hong Kong and local winds were weakened that day.
Five tropical cyclones affected Hong Kong during 2019 (Figure 2.2), slightly less than the long-term (1961-2010) average of about six in a year (Table 2.2). They were Tropical Depression Mun (1904) in July, Tropical Storm Wipha (1907) in July to August, Severe Tropical Storm Bailu (1911) and Tropical Storm Podul (1912) in August, and Tropical Depression Kajiki (1914) in September. Wipha necessitated the issuance of the No.8 Gale or Storm Signal on 31 July which was the highest tropical cyclone warning signal issued in 2019. Wipha is also the farthest tropical storm necessitating the issuance of the No.8 Gale or Storm Signal in Hong Kong since 1961. Tropical Depression Kajiki necessitated the issuance of the Strong Wind Signal No. 3 in Hong Kong.
2.1.5 Tropical cyclone rainfall
Tropical cyclone rainfall (total rainfall recorded at the Hong Kong Observatory Headquarters from the time when a tropical cyclone comes within 600 km of Hong Kong to 72 hours after it has dissipated or moved more than 600 km away from Hong Kong) in 2019 was 856.9 mm (Table 4.8.1). This accounted for approximately 35.8 % of the year’s total rainfall of 2396.2 mm and was about 18 % above the 1961-2010 long-term average of 728.8 mm.
Severe Tropical Storm Bailu (1911) brought 269.6 mm of rainfall to the Hong Kong Observatory Headquarters (Table 4.8.1) and was the wettest tropical cyclone in 2019.