Saturday, April 21, 1973
The Royal Observatory has introduced a new numbering system
for the tropical cyclone signals which will be simpler than the previous systep and should help to eliminate nisunderstandings.
Signals that were formerly numbered 5 to 8 were now renamed 8NU, 8SW, 8NE and 85E respectively, differentiating between directions of winds with the same force while at the same time avoiding any suggestion that wind speed, and the likelihood of danger, correspond with numerical
sequence,
Information is collected by radio from all available sources,
including ships, islands, land stations and aircraft over a wide area. Pictures transmitted by weather satellites, both visual and infra-red, are received daily.
Centre
When the centre of a well-developed tropical cyclone comes within about 240 nautical miles of Hong Kong it may be located by the observatory's radars mounted on top of Tate's Caim (580 m) and tracked continuously.
The Central Forecasting Office issues warnings of violent rainstorms and thunderstorms which are also tracked by radar. A special iscecho device enables intensity of rainfall in different areas to be mapped and rainfall amounts estimated.
The Police are geared to respond to an alert immediately signal
No. 3 is hoisted. Emergency equipment is checked to ensure it is readily available and in good working order. At signals above No. 3, district and divisional operations rooms are opened and all police officers return to
duty.
/The 999