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September 2005 was marked by the hazy weather in association with the northeast monsoon and approaching tropical cyclones. The number of hours of reduced visibility observed at the Hong Kong International Airport reached 237 hours in the month, a record high for September since 1997. The rainfall attributed to Typhoon Damrey made September, 2005, a relatively wet month. The monthly rainfall of 352.6 millimetres was 52.9 millimetres above normal. The accumulated rainfall since January 1 was 3196.8 millimetres, about 59% more than the normal figure of 2007.1 millimetres.
It was fine, hot and hazy on the first two days of the month. The weather became cloudy with thundery showers on September 3 and 4 as an area of low pressure affected the south China coastal areas. On September 4, a man was swept away by sea waves which were whipped up by the gusty easterly winds around Shek O.
Dominated by a continental airstream, it was mainly fine and hazy on September 5. Apart from a few isolated showers, the hazy conditions continued in the following seven days. The visibility in the Hong Kong International Airport dropped below 2000 metres on September 11 and 12.
The outer rain band of a tropical depression over Vietnam brought some showers to Hong Kong on September 13.
With the establishment of a ridge of high pressure over southeastern China, the weather turned fine on September 14 and remained so for the ensuing two days.
On September 17, under the combined effect of a ridge of high pressure over southeastern China and Tropical Storm Vicente over the South China Sea, local winds were occasionally strong and there were some squally showers. Windy and showery weather continued on September 18 as Vicente drifted northwest towards the northern part of Vietnam. During the inclement weather in these two days, two men were drowned while swimming in the rough sea in Sai Kung.
Sunny weather returned when a ridge of high pressure set in on September 19. The weather stayed fine in the next two days.
The Standby Signal No. 1 was issued on the morning of September 22 when Tropical Storm Damrey entered the South China Sea. With the air descending and warming up ahead of Damrey, it was very hot and hazy on September 22. The maximum temperature rose to 34.3 degrees that afternoon, the highest in the month.
As Damrey continued to intensify and moved across the northern part of the South China Sea, the first Strong Wind Signal No. 3 this year was issued on the morning of September 24. Damrey intensified into a typhoon on September 25 and made landfall over Hainan Island on the early morning of September 26. Locally, the weather started to deteriorate in the evening of September 23. Strong winds and squally heavy showers buffeted the territory in the following two days. More than 100 millimetres of rainfall were recorded in some parts of the territory on September 25.
Right after the departure of Damrey, an intense northeast monsoon set in and maintained the windy and showery weather on September 26. Although local winds abated gradually during the day, it was cloudy with scattered showers on September 27.
The weather improved on September 28. It was mainly fine for the rest of the month.
Eight tropical cyclones occurred in the western North Pacific and South China Sea in the month.
Details of the issuance and cancellation of various warnings/signals in the month are summarised in Table 1.1. Monthly meteorological figures and departures from normal of September are shown in Table 1.2.
Ends/Tuesday, October 4, 2005
Issued at HKT 14:01
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