Hong Kong Tropical Cyclone Warning Signals
Encyclopedia
The Hong Kong
tropical cyclone warning signals or informally typhoon signals (颱風信號) are a set of signals used to indicate the threat or effects of a tropical cyclone
. The Hong Kong Observatory
issues the warning signal if a tropical cyclone is centred within 800 kilometres (497.1 mi) of Hong Kong and may affect Hong Kong later. A very similar system, which is maintained by the Macao Meteorological and Geophysical Bureau
, is used in Macau
.
The signals are represented as a set of numbers, symbols and lights.
, and the areas around Guam
and Manila
. The monitoring efforts later expanded to gathering information from various seafaring vessels. These works were done in conjunction with the Marine Department until 1886. At first, the monitoring and warning services were geared mainly towards seafarers, and not towards the residents of Hong Kong.
The forefathers of the warning signals that Hong Kong residents are familiar with today began in 1884, when a numerical warning system, consisting of symbols that are a combination of drums, balls, and cones was hoisted at various places in Victoria Harbour
. At first, the signals only gave information as to which cardinal direction
winds from the tropical cyclone are coming from. Revisions of the system in 1904 added alerts as to which ordinal directions the winds are coming from. Until 1917, there are two sets of warning signals, one signals with black symbols, and one with red. The black symbols indicate that the tropical cyclone in question is less than 300 miles (482.8 km) from Hong Kong, while the red symbols indicate that the tropical cyclone is over 300 miles (482.8 km) away from Hong Kong.
The alert system was also supplemented by a custom of firing guns (later cannons and bombs, whose louder sounds were considered an improvement) when a tropical cyclone hits Hong Kong, which was the system most Hong Kong residents at the time rely on for severe weather updates, as a scant few pay attention to the warning system that was intended for seafarers. The frequency of the firing was also an indication of how intense the tropical cyclone was, with three being the indication of a very intense cyclone. This custom ended in 1937, as the local residents began to rely on radio, newspapers, and notices at ferry piers for tropical cyclone information.
A system that partially resembles the modern warning system was devised in 1917, after a meeting in Japan
on the unification of cyclone warning standards failed to come to an agreement. Influenced by that meeting, the Observatory reformed its existing system, with the warning consisting of 7 levels (4 of which will ultimately became the 4 no. 8 signals that Hong Kong residents are familiar with today). The system was marketed to other countries along the South China Sea, to no avail. The system was later repurposed for domestic use, but by request from Hong Kong's Chamber of Commerce, another set of warning signals intended for tropical cyclones outside of Hong Kong was also used by the Hong Kong Observatory. The practice of maintaining two distinct set of warning systems, with different purposes, persisted until 1962.
Eventually, through the years, the storm signals deviated from its original purpose of serving mariners, and became a system for the domestic population. The 10-level warning system was eventually slimmed down to the 5 level system that is in use today.
In the past, the signals were physically hoisted at many locations in Hong Kong; there were 42 signal stations around the territory in the 1960s. However, as radio
and television
weather report
s became increasingly effective, the need to hoist physical signals diminished. The last signal station, Cheung Chau aeronautical meteorological station on Cheung Chau
, was decommissioned on 1 January 2002. Accordingly, the observatory has replaced the word hoist with issue in its official terminology, although the phrase "Signal No. __ has been hoisted" is still widely used by the public and the mass media. Weather authorities in Macao
, however, still use the term "hoisted" when issuing their tropical cyclone warnings, the system of which is based heavily upon Hong Kong's.
In accordance with legal codes and common practices in Hong Kong, once any signals higher than No. 3 are issued, all government agencies will shut down their operations. Schools will immediately cease their sessions, as well the financial markets and a majority of the private sector. Public transit agencies that operate on the sea or on surface streets and highways will either cease or scale back their operation. In an effort to minimise the disruptions and stress caused by the exodus of office workers from their workplace, the Hong Kong Observatory usually gives the city an advance warning of about two hours before actually issuing Signal No. 8.
As the system was originally intended to serve as warnings for mariners, the issuance of signals were based on wind speeds measured around the Victoria Harbour. However, the system has also been adopted for use by the public over the years, and with ongoing urbanization, some have come to question the relevance of the warning system's mechanism in this day and age, citing the following reasons:
Starting from the tropical cyclone season in 2007, the signals are issued based on a network of 8 near sea-level reference anemometers over Hong Kong.
The highest level, No. 10, is rarely issued. As of 22 September 2011, there have been only twelve No. 10 warnings in the last 65 years, and only one in the last 28 years (Typhoon York in 1999).
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
tropical cyclone warning signals or informally typhoon signals (颱風信號) are a set of signals used to indicate the threat or effects of a tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
. The Hong Kong Observatory
Hong Kong Observatory
Hong Kong Observatory is a department of the Hong Kong government. The Observatory forecasts weather and issues warnings on weather-related hazards...
issues the warning signal if a tropical cyclone is centred within 800 kilometres (497.1 mi) of Hong Kong and may affect Hong Kong later. A very similar system, which is maintained by the Macao Meteorological and Geophysical Bureau
Macao Meteorological and Geophysical Bureau
The Macao Meteorological and Geophysical Bureau is a department of the Macao Government. The services provides forecasts weather and issues warnings on weather-related hazards...
, is used in Macau
Macau
Macau , also spelled Macao , is, along with Hong Kong, one of the two special administrative regions of the People's Republic of China...
.
The signals are represented as a set of numbers, symbols and lights.
History
The Hong Kong Observatory began issuing warnings for tropical cyclones in 1884, when it began to monitor and report news of tropical cyclones within the South China SeaSouth China Sea
The South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around...
, and the areas around Guam
Guam
Guam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...
and Manila
Manila
Manila is the capital of the Philippines. It is one of the sixteen cities forming Metro Manila.Manila is located on the eastern shores of Manila Bay and is bordered by Navotas and Caloocan to the north, Quezon City to the northeast, San Juan and Mandaluyong to the east, Makati on the southeast,...
. The monitoring efforts later expanded to gathering information from various seafaring vessels. These works were done in conjunction with the Marine Department until 1886. At first, the monitoring and warning services were geared mainly towards seafarers, and not towards the residents of Hong Kong.
The forefathers of the warning signals that Hong Kong residents are familiar with today began in 1884, when a numerical warning system, consisting of symbols that are a combination of drums, balls, and cones was hoisted at various places in Victoria Harbour
Victoria Harbour
Victoria Harbour is a natural landform harbour situated between Hong Kong Island and the Kowloon Peninsula in Hong Kong. The harbour's deep, sheltered waters and strategic location on the South China Sea were instrumental in Hong Kong's establishment as a British colony and its subsequent...
. At first, the signals only gave information as to which cardinal direction
Cardinal direction
The four cardinal directions or cardinal points are the directions of north, east, south, and west, commonly denoted by their initials: N, E, S, W. East and west are at right angles to north and south, with east being in the direction of rotation and west being directly opposite. Intermediate...
winds from the tropical cyclone are coming from. Revisions of the system in 1904 added alerts as to which ordinal directions the winds are coming from. Until 1917, there are two sets of warning signals, one signals with black symbols, and one with red. The black symbols indicate that the tropical cyclone in question is less than 300 miles (482.8 km) from Hong Kong, while the red symbols indicate that the tropical cyclone is over 300 miles (482.8 km) away from Hong Kong.
The alert system was also supplemented by a custom of firing guns (later cannons and bombs, whose louder sounds were considered an improvement) when a tropical cyclone hits Hong Kong, which was the system most Hong Kong residents at the time rely on for severe weather updates, as a scant few pay attention to the warning system that was intended for seafarers. The frequency of the firing was also an indication of how intense the tropical cyclone was, with three being the indication of a very intense cyclone. This custom ended in 1937, as the local residents began to rely on radio, newspapers, and notices at ferry piers for tropical cyclone information.
A system that partially resembles the modern warning system was devised in 1917, after a meeting in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
on the unification of cyclone warning standards failed to come to an agreement. Influenced by that meeting, the Observatory reformed its existing system, with the warning consisting of 7 levels (4 of which will ultimately became the 4 no. 8 signals that Hong Kong residents are familiar with today). The system was marketed to other countries along the South China Sea, to no avail. The system was later repurposed for domestic use, but by request from Hong Kong's Chamber of Commerce, another set of warning signals intended for tropical cyclones outside of Hong Kong was also used by the Hong Kong Observatory. The practice of maintaining two distinct set of warning systems, with different purposes, persisted until 1962.
Eventually, through the years, the storm signals deviated from its original purpose of serving mariners, and became a system for the domestic population. The 10-level warning system was eventually slimmed down to the 5 level system that is in use today.
In the past, the signals were physically hoisted at many locations in Hong Kong; there were 42 signal stations around the territory in the 1960s. However, as radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
and television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
weather report
Weather report
Weather report may refer to:*Weather forecasting, the application of science and technology to predict the weather*Weather Report, a jazz fusion musical group...
s became increasingly effective, the need to hoist physical signals diminished. The last signal station, Cheung Chau aeronautical meteorological station on Cheung Chau
Cheung Chau
Cheung Chau is a small island 10 km southwest of Hong Kong Island, is nicknamed as the 'dumbbell island' for its shape. It has been inhabited for longer than most other places in the territory of Hong Kong, with a population of about 23,000 up to 2006...
, was decommissioned on 1 January 2002. Accordingly, the observatory has replaced the word hoist with issue in its official terminology, although the phrase "Signal No. __ has been hoisted" is still widely used by the public and the mass media. Weather authorities in Macao
Mação
Mação is a municipality in Portugal with a total area of 400.0 km² and a total population of 7,763 inhabitants.The municipality is composed of eight parishes, and is located in the Santarém District....
, however, still use the term "hoisted" when issuing their tropical cyclone warnings, the system of which is based heavily upon Hong Kong's.
Current system
Starting from 1 January 1973, signals 5 to 8 were replaced by 8 NW, 8 SW, 8 NE and 8 SE respectively so as to avoid misunderstanding by the public. This system has been in use ever since.In accordance with legal codes and common practices in Hong Kong, once any signals higher than No. 3 are issued, all government agencies will shut down their operations. Schools will immediately cease their sessions, as well the financial markets and a majority of the private sector. Public transit agencies that operate on the sea or on surface streets and highways will either cease or scale back their operation. In an effort to minimise the disruptions and stress caused by the exodus of office workers from their workplace, the Hong Kong Observatory usually gives the city an advance warning of about two hours before actually issuing Signal No. 8.
As the system was originally intended to serve as warnings for mariners, the issuance of signals were based on wind speeds measured around the Victoria Harbour. However, the system has also been adopted for use by the public over the years, and with ongoing urbanization, some have come to question the relevance of the warning system's mechanism in this day and age, citing the following reasons:
- The city enters a complete standstill once Signal No. 8 is issued, and economic losses are incurred as a result of disruptions to financial activities.
- An overwhelming majority of buildings in Hong Kong are now built using concrete, and thus are able to withstand substantially higher wind speeds.
- With many tall skyscrapers acting as barriers, wind speeds are slowed, thus minimising the danger that citizens are exposed to.
- The advent of Mass Transit Railway (MTRMTRMass Transit Railway is the rapid transit railway system in Hong Kong. Originally opened in 1979, the system now includes 211.6 km of rail with 155 stations, including 86 railway stations and 69 light rail stops...
) has allowed transportation to operate underground, free from weather interferences. - After being released from work due to an impending storm, many officeworkers treat their time off as an opportunity to go out and socialize, as evident by full restaurants and queues outside cinemas, rather than to go home and ride out the storm, exemplifying the trust Hong Kongers have in the city's storm defenses.
Starting from the tropical cyclone season in 2007, the signals are issued based on a network of 8 near sea-level reference anemometers over Hong Kong.
Meaning of signals
The Saffir–Simpson Hurricane Scale, also referred to as the Saffir–Simpson Hurricane Wind Scale, is a classification used for some Western Hemisphere tropical cyclones. However Hong Kong has a similar five level official definitions of the signals as shown in the table below.The highest level, No. 10, is rarely issued. As of 22 September 2011, there have been only twelve No. 10 warnings in the last 65 years, and only one in the last 28 years (Typhoon York in 1999).
| Signal Number | Signal Name | Sustained Wind Speed (km/h, (mph, Beaufort scale)) | Gusts (km/h (mph)) | Signal Sign | Light Signal (Abolished) | Remarks |
1 | Stand-by (戒備) | N/A | N/A | White White White | A tropical cyclone is centred within 800 kilometres of Hong Kong and may later affect the territory, or there are strong winds in Hong Kong waters | |
3 | Strong winds (強風) | 41 - 62 (26-37, Beaufort Force 6-7) | may exceed 110 (69) | Green White Green | Strong winds are expected or blowing generally in Hong Kong near the sea level, and the wind condition is expected to persist | |
8 NE | Gale or storm force winds(烈風或暴風) | 63 - 117 (38-73, Beaufort Force 8-11) | may exceed 180 (113) | Green Green White | Gale or storm force winds are expected or blowing generally in Hong Kong near the sea level from the NW quadrant, and the wind condition is expected to persist | |
8 NW | White Green Green | Gale or storm force winds are expected or blowing generally in Hong Kong near the sea level from the NE quadrant, and the wind condition is expected to persist | ||||
8 SE | White White Green | Gale or storm force winds are expected or blowing generally in Hong Kong near the sea level from the SE quadrant, and the wind condition is expected to persist | ||||
8 SW | Green White White | Gale or storm force winds are expected or blowing generally in Hong Kong near the sea level from the SW quadrant, and the wind condition is expected to persist | ||||
9 | Increasing | 88 - 117, increasing (55-73, Beaufort Force 10-11) | N/A | Green Green Green | Gale or storm force winds are increasing. | |
10 | Typhoon(颶風) | >118 (74+, Beaufort Force 12) | may exceed 220 (138) | Red Green Red | Hurricane force winds. Eye of typhoon may be passing directly over Hong Kong. |
See also
- Hong Kong ObservatoryHong Kong ObservatoryHong Kong Observatory is a department of the Hong Kong government. The Observatory forecasts weather and issues warnings on weather-related hazards...
- Hong Kong rainstorm warning signalsHong Kong rainstorm warning signalsThe rainstorm warning signals are a set of signals used in Hong Kong to alert the public about the occurrence of heavy rain which is likely to bring about major disruptions such as traffic congestion and floods...