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Dominated by a relatively strong Pacific ridge, August 2010 was hotter and sunnier than usual. The mean temperature for the month was 28.8 degrees, about 0.4 degrees above normal. Meanwhile, the total bright sunshine duration for the month was 213.4 hours, about 12 percent above normal. The month was also drier than usual. The total rainfall in the month was 350.3 millimetres, about 21 percent below the normal figure of 444.6 millimetres. The accumulated rainfall since January 1 was 1705.3 millimetres, about 9 percent below the normal figure of 1873.7 millimetres for the same period.
Affected by a ridge of high pressure extended from the Pacific, the weather was generally fine and hot for the first four days of the month. Under generally light wind condition, it was very hot on August 5. The temperature at the Hong Kong Observatory rose to a maximum of 33.7 degrees, the highest of the month. Intense day heating triggered off heavy and thundery showers that evening. More than 50 millimetres of rainfall were recorded in the eastern part of Kowloon, Tseung Kwan O, Shatin and Sai Kung. A weak ridge of high pressure brought sunny periods to the territory on August 6.
A broad trough of low pressure extending from the northern part of the South China Sea brought thundery showers to the territory on August 7 and 8. As a weak ridge of high pressure re-establised over the coast of Guangdong, local weather became sunny and very hot again in the next two days. The temperature at the Hong Kong Observatory rose to a maximum of 33.7 degrees again on August 10, equalling the highest temperature of August 5.
A trough of low pressure extending from the coast of western Guangdong brought cloudy condition with some thundery showers to the territory on August 11. With a southerly airstream gaining dominance, there were sunny periods with a few showers from August 12 to 15. Another trough of low pressure over the coast of western Guangdong brought showers and a few squally thunderstorms to Hong Kong for the following two days. With a ridge of high pressure covering southern China, local weather turned mainly fine on August 18. Affected by an active easterly airstream, there were occasional showers and squally thunderstorms for the next two days. The weather turned mainly fine on August 21 and 22.
A tropical depression formed over the South China Sea on August 22. While moving generally westwards, it intensified into a tropical storm and was named ˇ§Mindulleˇ¨ on the morning of August 23. ˇ§Mindulleˇ¨ further intensified into a severe tropical storm that night and made landfall over the northern part of Vietnam the next day. Affected by the outer rainbands of ˇ§Mindulleˇ¨, local weather was cloudy with occasional showers and squally thunderstorms from August 23 to 25. With the dissipation of ˇ§Mindulleˇ¨, it became generally fine on the next two days. Under light wind condition and with intense day heating, some locally developed heavy and thundery showers affected Hong Kong on the afternoon of August 28. (Please refer to the attached figure.) More than 70 millimetres of rainfall were recorded in the western part of the New Territories, parts of Kowloon and Hong Kong Island.
An area of low pressure over the South China Sea intensified into a tropical depression on August 28. It intensified into a tropical storm and was named ˇ§Lionrockˇ¨ the next day. It drifted slowly over the northern part of the South China Sea on August 30. Under the influence of the subsiding air mass ahead of ˇ§Lionrockˇ¨, local weather was sunny and very hot on August 29 and 30. Light wind condition brought hazy weather to the territory on the last day of the month.
Five tropical cyclones occurred over the western North Pacific and the South China Sea in the month.
Details of the issuance and cancellation of various warnings/signals in the month are summarised in Table 1. Monthly meteorological figures and departures from normal of August are tabulated in Table 2.
Ends/Thursday, September 2, 2010
Issued at HKT 20:21
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