Tropical cyclone warning signals in Hong Kong

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The Hong Kong Tropical Cyclone Warning Signals ( Chinese  熱帶 氣旋 警告 信號 , English Hong Kong tropical cyclone warning signals ) or informal Typhoon Warnings (颱風 信號, typhoon warnings ) are a series of signals that are used to indicate the dangers or effects of a tropical cyclone to display. The Hong Kong Observatory sets warning signals when a tropical cyclone approaches Hong Kong within 800 kilometers and can later affect Hong Kong. A very similar system is used by the Direcção dos Serviços Meteorológicos e Geofisicos de Macau .

These signals consist of a set of numbers, symbols and lights.

history

In 1884 work began, a combination of operating under a drum balls and cones raise to sailors in Victoria Harbor in front of an approaching typhoon warning. A cannon was fired for the general public . This cannon was replaced by explosive charges in 1907 because they were louder and considered an improvement. The last such explosion occurred in 1937.

The first number-based warning system was introduced in 1917. The numbers ran from 1 to 7, with the numbers 2 to 5 signaling expected storm winds from each of the four quadrants . The system was changed in 1931. Now the numbers 1, 5, 6, 7, 8, 9 and 10 were used, with the numbers 5 to 8 representing the quadrants. Signal number 3 - strong wind - was introduced in 1956 as an intermediate stage to signal number 1 - readiness - and the storm warning signals.

In the past, these signals were hoisted in many places in Hong Kong. In the 1960s there were 42 of these sea ​​marks in the Crown Colony . Weather reports on radio and television became increasingly important and effective, reducing the need for signals. The last signal station on Cheung Chau was shut down on January 1, 2002. Accordingly, the observatory has changed the wording and replaced the word hoist (to raise) in its official terminology with issue (to spend). However, the expression “signal number __ has been raised” is still widely used by the public.

Current system

Starting on January 1, 1973, signals 5 to 8 were replaced by 8 NW, 8 SW, 8 NE and 8 SE in order to avoid misunderstandings in public. This system has been in use ever since.

According to the legal regulations and the usual procedures in Hong Kong, all authorities cease their activities as soon as a higher signal than number 3 is issued. Schools instantly end their classes, financial markets and other businesses close. Public traffic at sea or on roads and highways is at a standstill or is being reduced. To minimize disruption and stress caused by workers returning from their workplaces, the Hong Kong Observatory usually gives an advance warning two hours before signal number 8 is issued.

Since the system was originally used to warn seafarers, the output of warning signals was based on wind speeds measured around Victoria Harbor . Over the years the system has been adopted by the general public in Hong Kong. From the 2007 typhoon season onwards, the output of warning signals is based on wind measurements practically at sea ​​level from eight measuring points spread across Hong Kong.

Meaning of the signals

The warning signals are defined as follows:

Signal
number 		Signal
name 		Wind strength in km / h (mph)
Wind strength on the Beaufort scale 		Gusts
in km / h
(mph) 		Signal
sign 		annotation
1 Standby (戒備 / standby) - - No. 01 Standby Signal.png A tropical cyclone has its center within half a mile of Hong Kong and may later reach the territory or there will be strong winds in Hong Kong's waters
3 Strong or stiff wind (強 風) 41 - 62 (26–37)
wind force 6–7 		can exceed 110 (69) No. 03 Strong Wind Signal.png Strong or stiff winds are expected or generally blow at sea level in Hong Kong and no change in storm conditions is expected
8 NE Stormy wind or storm
(烈風 或 暴風) 		63 - 117 (38–73)
wind force 8–11 		can exceed 180 (113) No. 8 Northeast Gale or Storm Signal.png Storm or hurricane winds are expected or blow in Hong Kong at sea level from the Northwest Quadrant and no change in storm conditions is expected
8 NW No. 8 Northwest Gale or Storm Signal.png Storm or hurricane winds are expected or blow in Hong Kong at sea level from the Northeast Quadrant and no change in storm conditions is expected
8 SE No. 8 Southeast Gale or Storm Signal.png Storm or hurricane winds are expected or blow in Hong Kong at sea level from the Southeast Quadrant and no change in storm conditions is expected
8 SW No. 8 Southwest Gale or Storm Signal.png Storm or hurricane winds are expected or blow in Hong Kong at sea level from the Southwest Quadrant and no change in storm conditions is expected
9 Becoming more
severe or gale force storm
(烈風或暴風風力增強) 		88 - 117 exceeding (55–73)
wind force 10–11 		- No. 09 Increasing Gale or Storm Signal.png Wind in gale force or hurricane strength increases.
10 Hurricane (颶風) > 118 (> 74)
wind force 12 		can exceed 220 (138) No. 10 Hurricane Signal.png Hurricane winds. The eye of the typhoon may drift right over Hong Kong.

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