Weather Monitoring and Forecasting

To provide weather forecasts and warnings of hazardous weather, the
Hong Kong Observatory maintains a close meteorological watch
round-the-clock.

The Observatory exchanges weather observations with the rest of the
world through the Global Telecommunications System operated under
the auspices of the World Meteorological Organisation. Through its
telecommunication lines with meteorological centres in Beijing, Tokyo
and Bangkok, about 20 000 weather reports are received each day.

Hourly cloud pictures received from the Geostationary Meteorological
Satellite of the Japan Meteorological Agency give general indications of
tropical cyclones, severe storms and frontal systems approaching the
south China coast. The Observatory's weather radar system at Tate's
Cairn detects rain within about 500 km of Hong Kong and gives estimates
of rain intensity and movement. Information on thunderstorms as
detected by a lightning location system is also available to forecasters.

Weather observers and automatic weather stations at about 40 locations
in Hong Kong provide comprehensive and real-time coverage of regional
weather variations, while observations from Voluntary Observing Ships
provide valuable information on weather at sea.

Rainfall information is important because of Hong Kong's vulnerability to
floods and susceptibility to landslips during heavy rain. A dense network
of about 70 automatic reporting rain-gauges provides real-time
information on rain distribution and intensity over Hong Kong for the
operation of rainstorm, flood and landslip warnings.

The Observatory operates tide gauges for monitoring coastal flooding and
raised sea levels caused by tropical cyclones. To probe the atmosphere
aloft, radiosondes carried by balloons are launched four times a day at
King's Park to relay weather information from the upper air.

The Observatory exchanges weather radar images with the Guangdong
Meteorological Bureau and operates four solar-powered automatic
weather stations at Huangmao Zhou, Neilingding Island and Wailingding
Island west of Hong Kong, and the Tuoning Islands to the east, to give
earlier indication and better timing of the approach of hazardous weather
such as fronts, squall lines and tropical cyclones. Using guidance from
numerical products from both global and limited area models, forecasters
can now issue weather forecasts several days ahead with reasonable
confidence.

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