***********************
April 2010 was cooler and gloomier than usual. Frequent passage of cold fronts brought the monthly temperature to 21.0 degrees, about 1.5 degrees below normal. The total bright sunshine duration was 49.2 hours, only about 48% of the normal figure of 101.8 hours. The month was also drier than usual. The total rainfall in the month was 78.9 millimetres, about 58% below the normal figure of 188.5 millimetres. The accumulated rainfall since January 1 was 234.1 millimetres, about 31% below the normal figure of 337.1 millimetres for the same period.
Under the influence of a maritime airstream, it was mainly cloudy with coastal fog in Hong Kong on the first day of the month. With a cold front passing the south China coastal areas the next morning, the weather became cooler with some rain patches between April 2 and 4. The return of the maritime airstream brought foggy weather and a few light rain patches to the territory for the ensuing two days. The visibility at Waglan Island fell to around 100 metres during the morning of April 5.
Another cold front formed over southern China crossed the coast of Guangdong on the morning of April 7. The northeast monsoon behind the cold front brought cooler weather and some rain to Hong Kong from April 7 to 10 with a few squally thunderstorms on the morning of April 8. Dominated by a southerly airstream, the weather was warm and foggy from April 11 to 13. The temperature recorded at the Hong Kong Observatory rose to a maximum of 29.5 degrees during the afternoon of April 13, the highest of the month.
Meanwhile, a cold front developed over southern China on April 12 and crossed the costal areas of Guangdong later in the afternoon of April 13. Affected by the strong northeast monsoon behind the cold front, local weather was cloudy with rain from April 14 to 18. It was also rather cool on April 15 and 16 with the minimum temperature at the Hong Kong Observatory falling to a minimum of 13.5 degrees on April 15, the lowest of the month. Foggy weather returned on April 19 and persisted for the ensuing two days when a maritime airstream prevailed over the south China coastal areas.
A cold front from southern China crossed the coastal areas of Guangdong and brought occasional rain and a few squally thunderstorms to the territory on April 22. Gusts of around 100 kilometres per hour associated with the thunderstorms were recorded at Chek Lap Kok. Affected by a continental airstream, the weather turned dry with some sunny periods for the next three days. Another cold front crossed the coastal areas of Guangdong on April 26. The associated northeast monsoon brought a few rain patches to the territory from April 26 to 28.
With winds turning light, the visibility at Chek Lap Kok fell to below 1,000 metres early on April 29. A broad rainband developed over western Guangdong and moved eastwards across the Pearl River Estuary, bringing an episode of thundery showers to the territory later in the afternoon of April 29. Over 50 millimetres of rainfall were recorded over parts of the New Territories and Lantau Island. After the passage of the rainband, there were some sunny periods on the last day of the month.
There was no tropical cyclone 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 the norms of April are tabulated in Table 2.
Ends/Tuesday, May 4, 2010
Issued at HKT 18:20
NNNN
