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Under the prevalence of a warm southerly airstream punctuated by episodes of inclement weather, especially during the latter half of the month, June 2011 was hotter and wetter than usual. The month's mean temperature was 28.6 degrees, 0.7 degrees above the normal figure of 27.9 degrees. Amber rainstorm warnings were issued for periods of heavy rain associated with tropical storm Sarika, a convective disturbance around mid June and an active trough of low pressure towards the end of the month. Total monthly rainfall recorded at Hong Kong Observatory was 435.6 millimetres, about 12 per cent above normal. Despite a wet June, the accumulated rainfall since January 1 was only 707.9 millimetres, a deficit of 33 per cent compared to the average figure of 1054.7 millimetres for the same period.
With a balmy southerly airstream prevailing, the weather in Hong Kong was generally fine and hot apart from one or two showers for the first eight days of the month. Under light wind conditions, it was very hot on June 9 and 10. The temperatures at Hong Kong Observatory soared to a maximum of 34.5 degrees on June 9, the highest record in June since 1980.
A tropical depression developed over the seas west of Luzon and was named Sarika on June 9. While moving northwards and edging closer to southeastern China, Sarika intensified into a tropical storm on June 10. It made landfall near Shantou on the morning of June 11 and weakened into an area of low pressure during the day. Affected by Sarika and its remnants, local weather became cloudy with occasional showers and squally thunderstorms on June 11 and 12. A southerly airstream continued to bring showers to the territory in the ensuing three days.
Under the influence of a convective disturbance, local weather deteriorated again with occasional heavy rain and a few squally thunderstorms on June 16 and 17. Over 200 millimetres of rainfall was recorded over parts of the urban area and Sha Tin on these two days. With the dissipation of the convective disturbance, the rain eased off and it became mainly fine on June 18 and 19.
A tropical depression crossed the Luzon Strait on June 20, entered the northern part of the South China Sea and was named Haima on June 21. Affected by the subsiding air mass ahead of Haima, local weather was very hot for these two days, apart from a few squally showers. Haima crossed the northern part of the South China Sea and intensified into a tropical storm on June 22. Locally, there were heavy squally showers with strong east to southeasterly winds, reaching gale force offshore and on high ground occasionally on that day. Haima made landfall over the coast of western Guangdong the next day. Under the influence of its outer rain bands, it remained cloudy with a few squally showers in Hong Kong on June 23.
As Haima moved west-southwestwards and drew further away from Hong Kong, local weather turned generally fine and hot on June 24 and 25. Affected by a southerly airstream, there were a few isolated showers and thunderstorms over the next two days. An active trough of low pressure brought occasional heavy rain and squally thunderstorms to the territory on June 28 and 29. More than 120 millimetres of rainfall were recorded over the western part of Hong Kong Island on June 28 and more than 100 millimetres over Yuen Long, Sha Tin and the northeastern part of the New Territories on June 29. The trough of low pressure weakened gradually during the last day of the month but local weather remained cloudy with showers and a few squally thunderstorms.
Three tropical cyclones occurred over the South China Sea and the western North Pacific 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 June are tabulated in Table 2.
Ends/Tuesday, July 5, 2011
Issued at HKT 19:11
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