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THE ENVIRONMENT
phenomena during the month included a tornado in San Tin on September 9 and a hail- storm on September 24.
October was an exceptionally warm month. The mean temperature of 26.4°C was the highest for the month of October while the mean daily maximum temperature of 28.9°C was the second highest for October since records began in 1884. The monthly mean cloudiness of 71 per cent was the second highest for October. The total monthly rainfall amount of 227.4 mm was nearly 90 per cent above average. On October 13, gale or storm signals, No. 8 NE and No. 8 SE, were displayed during the approach of Typhoon Joe. Altogether 58 people were injured, but no major damage was reported. On October 23, the strong wind signal, No. 3, was hoisted for Severe Tropical Storm Lex when it was centred over the northern part of the South China Sea.
November was the driest November on record. Only a trace of rain was recorded during the whole month. The monthly mean relative humidity of 59 per cent and the monthly mean cloudiness of 25 per cent were both the second lowest for the month. Apart from an interlude of cloudy weather between November 12 and 15, the weather was fine and sunny throughout the month.
The dry spell persisted into December until it was interrupted by rain on December 28 and 29. An intense surge of the winter monsoon arrived from the north on December 29. The weather was very cold on December 30 and a minimum temperature of 6.1°C was recorded at the Royal Observatory. Hoar frost was reported at Tai Mo Shan and Tate's Cairn where temperatures dropped to -3.6°C and -0.1°C respectively.
The Royal Observatory
The Royal Observatory was established in 1883 mainly to provide scientific information for the safe navigation of ships. During her visit to Hong Kong in April, HRH The Princess Anne officially opened a new nine-storey office block beside the original-observatory building. This marked the start of the centenary celebrations. Other highlights later in the year included an international seminar sponsored by the department and the World Meteorological Organisation; a joint symposium with the Hong Kong Institution of Engineers; and commemorative postage stamps issued in November.
Operations and Services
The department's most important function is the provision of weather forecasts and tropical cyclone warnings for the public, shipping and aviation. The Central Forecasting Office issues local weather forecasts and warnings of hazardous weather conditions to the press, government departments and radio and television broadcasting stations. When- ever Hong Kong is threatened by tropical cyclones, frequent warnings with advice on necessary precautions are issued at three-hourly intervals and widely disseminated. Other warnings cover thunderstorms, flooding, landslips, fire danger, strong monsoons and frost. Regular weather bulletins are issued to ships at sea, fishermen in coastal waters and yachtsmen. Specialised forecasts are prepared on request for offshore operations in the South China Sea.
Services for aviation are provided by the Airport Meteorological Office. About 80 aircraft each day are supplied with prognostic weather charts and landing forecasts. Special warnings are issued for adverse weather. Wind conditions at the airport and its vicinity are monitored continuously using a network of anemometers and a doppler acoustic radar at Lei Yue Mun under the southeastern approach to the airport.