Section 2 TROPICAL CYCLONE OVERVIEW FOR 2022
2.1 Review of tropical cyclones in 2022
**2.1.1 Tropical cyclones over the western North Pacific (including the South China Sea) **
In 2022, a total of 27 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 - 2020) average figure of around 30. During the year, 11 of the tropical cyclones attained typhoon intensity or above, less than the long-term average (1961 - 2020) of about 15, with four 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 2022.
During the year, six tropical cyclones made landfall over China, with two of them crossing the south China coast within 300 km of Hong Kong. Three traversed the Philippines and three made landfall over Vietnam. With an estimated maximum sustained wind speed of 230 km/h and a minimum sea-level pressure of 910 hPa near the centre (Table 4.1), Super Typhoon Hinnamnor (2211) in August to September (Figure 2.3) was the most intense tropical cyclone over the WNP and the SCS in 2022.
2.1.2 Tropical cyclones in Hong Kong’s area of responsibility
Amongst the 27 tropical cyclones in 2022, 13 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 more than the longterm annual average (1961-2020) figure of around 16 (Table 2.1). Five of them developed within Hong Kong’s area of responsibility. Altogether, 318 tropical cyclone warnings to ships and vessels were issued by the Hong Kong Observatory this year (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 2022, less than the long-term annual average (1961-2020) of around 12. Four of them formed over the SCS.
2.1.4 Tropical cyclones affecting Hong Kong
In 2022, the typhoon season in Hong Kong started on 29 June when Tropical Depression Chaba (2203) formed over the central part of the SCS, necessitating the issuance of the Standby Signal No. 1. The typhoon season ended with the cancellation of all tropical cyclone warning signals on 3 November when Tropical Depression Nalgae (2222) weakened and moved inland after making landfall over Zhuhai.Six tropical cyclones affected Hong Kong during 2022 (Figure 2.2), on par with the long-term (1961-2020) average of about six in a year (Table 2.2). They were Typhoon Chaba (2203) in June to July, Tropical Depression, Tropical Storm Mulan (2207) and Typhoon Ma-on (2209) in August,
Typhoon Nesat (2220) in October, and Severe Tropical Storm Nalgae (2222) in October to November. The No. 8 Gale or Storm Signal was issued during the passage of Chaba, Ma-on and Nalgae on 1 July, 24 August and 2 November respectively, the highest tropical cyclone warning signal issued in 2022. The No. 8 Gale or Storm Signal issued during the passage of Chaba was the first time on the HKSAR Establishment Day. Nalgae was the third tropical cyclone necessitating the issuance of the No. 8 Signal in November since 1946. The No. 3 Strong Wind Signal was issued during the passage of Mulan and Nesat. The Tropical Depression necessitated the issuance of the Standby Signal No. 1 in Hong Kong.
2.1.5 Tropical cyclone rainfall
Tropical cyclone rainfall for Hong Kong (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 2022 was 697.4 mm (Table 4.8.1). This accounted for approximately 31.6% of the year’s total rainfall of 2205.4 mm and slightly less than the 1961-2020 long-term average of 704.2 mm.
According to the above definition, Tropical Storm Mulan (2207) brought 206.5 mm of rainfall to Hong Kong (Table 4.8.1) and was the wettest tropical cyclone in 2022.