Hong Kong Tropical Cyclone Warning Signals - History

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 Sea, 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 (480 km) from Hong Kong, while the red symbols indicate that the tropical cyclone is over 300 miles (480 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 reports 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.