THE ENVIRONMENT
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amount for the same period. As an active low pressure area approached, continuous heavy downpour and squally thunderstorms affected Hong Kong on May 11. Over 200 mm of rainfall was recorded in Tai Lam Chung, Tai Mo Shan and Tai Po. The heavy down- pour continued into the morning of May 12, causing 48 cases of flooding and seven landslips that day.
On the whole, June was a normal month in terms of temperature, cloudiness and precipitation. The rainfall of 415.9 mm recorded at the Royal Observatory was near the month's normal of 431.8 mm. However, it was unevenly distributed and rainfall on two separate days accounted for 58 per cent of the month's total: June 6 when a trough of low pressure passed rapidly through Hong Kong, and June 25 when a disturbance in the southwest monsoon affected the territory. Rainy weather continued after the downpour of June 6. As a result, minor flooding in Western District and a landslip in Ngau Chi Wan were reported on June 7. The disturbance on June 25 was accompanied by frequent squally showers.
July was wetter than usual, with 547.3 mm of rainfall being recorded at the Royal Observatory, 73 per cent above normal. Some 85 per cent of the month's rainfall was associated with the rainstorm on July 3 and 4 and with Typhoon Peggy, the first typhoon that necessitated the hoisting of tropical cyclone warning signals in Hong Kong during the year. Heavy showers and squally thunderstorms occurred on July 3 when a moisture-laden southwest monsoon affected the territory. Heavy and frequent thundery showers recurred the next morning. Typhoon Peggy crossed Luzon on July 9 and headed towards the South China coast. With light winds off the land ahead of Peggy, temperatures on July 10 rose to 34.8°C. On July 11, the weather deteriorated rapidly under the influence of Peggy, which reached land near Shanwei in the afternoon. Strong to gale force winds accompanied by widespread and frequent squally showers battered the territory until the morning of July 12. -
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August was hotter than usual with a mean temperature of 29.0°C, and frequent thunderstorm activity. From August 9 to 11, Hong Kong was affected by squally heavy showers and thunderstorms as a tropical depression over the South China Sea moved towards Hainan. Over 300 mm of rainfall was recorded at Tai Po, Sha Tau Kok and Sai Kung.
Wayne, the longest-lasting tropical cyclone ever over the South China Sea and the Pacific caused warning signals to be hoisted three times between August 19 and September 5. The storm took an exceptional track approaching first from the south on August 20. On August 21, after a very hot and sunny day, squally thunderstorms developed overland and moved southeastwards to affect Hong Kong in the evening. A waterspout was reported near Tap Mun and a tornado in Aberdeen. And on August 23, during severe morning thunderstorms 15 people were struck by lightning at separate locations.
After crossing Taiwan, Wayne weakened to a tropical storm and moved southwestwards back into the South China Sea. As Wayne headed westwards towards Dongsha, signals were hoisted in Hong Kong for a second time, on August 25, but were lowered the next day as it moved southwestwards. Wayne then turned northwestwards to affect the Bashi Channel and the Philippines. It then strengthened to a typhoon, heading westwards again to affect Hong Kong for a third time, on September 4 and 5.
September was a normal month apart from being slightly drier than usual. However, heavy and thundery showers affected Hong Kong on September 16 and 72.0 mm of rainfall were recorded at the Royal Observatory between 2 p.m. and 8 p.m. This caused some cases of flooding in Kowloon and the New Territories.