Tropical Cyclone Warning Services for the Public, Shipping, Aviation and Specialized Users
Separate warning services are provided for the public, for shipping, for aviation and for other specialized users.
(A) Tropical Cyclone Warnings for the public
The Hong Kong Observatory's tropical cyclone warnings are related to the threat and danger a tropical cyclone poses to Hong Kong and the expected wind conditions in the territory.
Whenever a tropical cyclone warning signal is in effect, bulletins are issued to the Information Services Department for distribution to the mass media and for immediate broadcast by radio and television stations. The Hong Kong Observatory also operates an automatic telephone answering service " Dial-a-weather" (Tel. 1878200) to provide similar information.
A great deal of information is broadcast about each tropical cyclone as it approaches, and this information is updated at frequent intervals. When warnings of gales or higher winds are in effect, broadcasts are made by Radio Television Hong Kong and Commercial Radio Hong Kong every half hour in English and four times each hour in Chinese at quarter past, half past, quarter to and two minutes to each hour. Each advisory of warning bulletin contains some or all of the following information :
(1) The signal in force and its meaning.
(2) The latest position and the expected movement of the centre of the tropical cyclone.
(3) Changes in the intensity of the tropical cyclone.
(4) Information concerning wind strength near the centre, including reports from ships.
(5) The latest observations and forecasts of wind and gusts in Hong Kong.
(6) Information about the levels of the sea in Hong Kong waters and their predicted changes when these are significant
(7) Information on rainfall.
(8) Advice on precautions.
Information on tropical cyclones which may affect fishing vessels, pleasure boats and yachts operating in the coastalareas of south China are given as part of a Weather Bulletin for South China Coastal Waters. The Bulletin is broadcast at regular intervals on the radio.
(B) Tropical Cyclone Warnings for Shipping
When a tropical cyclone is located within the area bounded by latitudes 10ﾰN and 30ﾰN, and longitudes 105ﾰE and 125ﾰE, warning bulletins are issued at 3-hourly intervals.
These warnings are broadcast via NAVTEX, an international broadcast system for disseminating navigational information for ships plying in the region.
Starting from 1992, warnings are also prepared for the International Maritime Organization's Global Maritime Distress and Safety System whenever a tropical cyclone is located within the area bounded by the Equator and 30ﾰN, longitudes 100ﾰE and 125ﾰE. These bulletins are broadcast via the INMARSAT communication satellites eight times a day for ships on high seas.
(C) Tropical Cyclone Warnings for Aviation
Based on the warnings issued by the Central Forecasting Office at the Hong Kong Observatory, the Airport Meteorological Office issues SIGMETs (warnings of hazardous weather to aircraft) on tropical cyclones. SIGMETs are disseminated to all users in aviation.
(D) Tropical Cyclone Warnings for Special Users
Tropical cyclone warnings may be issued to meet specialized requirements such as those of the civil engineers and building contractors, wharfing companies, coastal transport and carrier operators etc. Depending on the special requirements and how the warnings are transmitted, a cost-recovery charge may be levied.