Tropical cyclone warnings and watches are alerts issued by national

weather forecasting Weather forecasting is the application of science and technology to predict the conditions of the atmosphere for a given location and time. People have attempted to predict the weather informally for millennia and formally since the 19th cen ...

bodies to coastal areas threatened by the imminent approach of a

tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate preparation for the cyclone, including evacuation of vulnerable areas where necessary. It is important that interests throughout the area of an alert make preparations to protect life and property, and do not disregard it on the strength of the detailed forecast track.

Western hemisphere

New tropical cyclone position and forecast information is available at least every twelve hours in the Southern Hemisphere and at least every six hours in the Northern Hemisphere from Regional Specialized Meteorological Centers and Tropical Cyclone Warning Centers. In conjunction with the

National Hurricane Center The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 3 ...

, the national meteorological and hydrological services of

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

, the northern

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

, and the northeastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

east of the

140th meridian west The meridian 140° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, North America, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole. The line is the divider in the area of ...

, excluding mainland Africa and Europe, all issue tropical storm/hurricane watches and warnings. Tropical storm watches are issued when gale and storm force winds of between 34 and 63 knots (39–73 mph; 63–118 km/h) are possible, within 48 hours in a specified area in association with a tropical, subtropical or post-tropical cyclone. These watches are upgraded to tropical storm warnings, when gale and storm force winds become expected to occur somewhere in the warning area within 36 hours. Hurricane watches are issued when sustained winds of are possible, within 48 hours in a specified area in association with a tropical, subtropical or post-tropical cyclone. These watches are upgraded to hurricane warnings, when hurricane-force winds become expected to occur somewhere in the warning area within 36 hours. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch and warnings are issued in advance of the anticipated onset of tropical-storm-force winds, rather than in advance of the anticipated onset of hurricane-force winds. At times a tropical storm warning and a hurricane watch can both be in effect due to uncertainties in the forecast. These watches and warnings are also issued by the

Central Pacific Hurricane Center The Central Pacific Hurricane Center (CPHC) of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central Pacifi ...

for the Hawaiian Islands and the Weather Forecast Office in

Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...

for parts of

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of about 2,000 small islands in the western Pacific Ocean. It has a close shared cultural history with three other island regions: the Philippines to the west, Polynesia to the east, ...

but not for

American Samoa American Samoa ( sm, Amerika Sāmoa, ; also ' or ') is an unincorporated territory of the United States located in the South Pacific Ocean, southeast of the island country of Samoa. Its location is centered on . It is east of the Internatio ...

due to an international agreement. Within the United States an

extreme wind warning An extreme wind warning ( SAME code EWW) is an alert issued by the National Weather Service for areas that will experience sustained surface winds 100 knots (115 mph, 185 km/h, 51 m/s) or greater within one hour, due to a lan ...

is issued by the National Weather Service for any land areas that are expected to be impacted by a major (Category 3 or higher) hurricane and by sustained surface winds greater than or equal to 100 knots (115 mph; 185 km/h). The warning is issued just prior to when the strongest winds of the eyewall are expected to impact an area. The warning is to be issued for the smallest area possible, and be valid for times of two hours or less. It was developed in response to confusion resulting from the landfall of

Hurricane Katrina Hurricane Katrina was a destructive Category 5 Atlantic hurricane that caused over 1,800 fatalities and $125 billion in damage in late August 2005, especially in the city of New Orleans and the surrounding areas. It was at the time the cost ...

. NWS offices in Jackson and

New Orleans New Orleans ( , ,New Orleans

Baton Rouge Baton Rouge ( ; ) is a city in and the capital of the U.S. state of Louisiana. Located the eastern bank of the Mississippi River, it is the parish seat of East Baton Rouge Parish, Louisiana's most populous parish—the equivalent of counti ...

issued 11 tornado warnings for areas that would not experience an actual

tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, alt ...

, but would experience extreme wind speeds commonly associated with tornadoes. The extreme wind warning is now expected to be used in these situations. In 2017, the National Hurricane Center introduced a new system of warnings and watches for

storm surge A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the ...

, which would cover the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

and

Gulf Coast The Gulf Coast of the United States, also known as the Gulf South, is the coast, coastline along the Southern United States where they meet the Gulf of Mexico. The list of U.S. states and territories by coastline, coastal states that have a shor ...

s of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. A storm surge watch would be issued when a life-threatening storm surge, associated with a potential or ongoing tropical, subtropical or post-tropical cyclone, is possible within the next 48 hours. These watches would be upgraded to storm surge warnings when there is a danger of life-threatening storm surge occurring within 36 hours. However, both watches and warnings may be issued earlier than specified if environmental conditions are expected to hamper preparations. In

Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...

, a color coded alert system is used to keep the public informed when a tropical cyclone or possible tropical cyclones poses a threat to the nation. The scale starts with blue at the bottom being minimal danger, then proceeds to a green alert, which means low level danger. A yellow alert signifies moderate danger, followed by an orange alert that means high danger level. The scale tops off with a red alert, the maximum level of danger.

Canada

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

, terminology is fairly similar to that of the United States, but there are a few differences: *Watches are issued 36 hours prior to a tropical cyclone making landfall. *Warnings are issued 24 hours prior to the tropical cyclone making landfall. *If sustained winds 70 km/h and/or gusts 90 km/h or stronger are predicted, a conventional wind warning will be issued along with the tropical cyclone watches and warnings. *A storm surge warning may be issued if abnormally high water levels are predicted.

West Pacific systems

China

A two-stage warning system was long-established in China for tropical cyclones of tropical storm intensity of above. Nowadays, the use of this system is restricted to coastal waters only. Thus, warnings may be discontinued even if a cyclone is maintaining tropical storm intensity inland. Color-coded alerts (below) may be in effect independently of any two-stage warnings. Later,

China Meteorological Administration The China Meteorological Administration (CMA) is the national weather service of the People's Republic of China. The institution is located in Beijing. History The agency was originally established in December 1949 as the Central Military Comm ...

standardized the system for national use. This set is part of a larger warning system that covers other forms of severe weather conditions, such as extreme temperature, torrential rainfall, drought, etc.

Guangdong

Guangdong Guangdong (, ), alternatively romanized as Canton or Kwangtung, is a coastal province in South China on the north shore of the South China Sea. The capital of the province is Guangzhou. With a population of 126.01 million (as of 2020 ...

continued to set up the White typhoon alert for typhoon, indicating that tropical cyclones may affect the area within 48 hours. In some inland areas that are less affected by tropical cyclones (such as

Qinghai Qinghai (; alternately romanized as Tsinghai, Ch'inghai), also known as Kokonor, is a landlocked province in the northwest of the People's Republic of China. It is the fourth largest province of China by area and has the third smallest po ...

, etc.), there is no typhoon warning signal, but when it is hit by tropical cyclones, a strong wind warning signal will be issued. The winds represented by each color are consistent with the typhoon warning signal. Typhoon warning signals used in

Guangzhou Guangzhou (, ; ; or ; ), also known as Canton () and Chinese postal romanization, alternatively romanized as Kwongchow or Kwangchow, is the Capital city, capital and largest city of Guangdong Provinces of China, province in South China, sou ...

from June 1, 1995, to November 1, 2000: Typhoon warning signals used from November 1, 2000, to May 2006： Typhoon warning signals used from June 1, 2006, to December 31, 2014: Typhoon warning signals used since January 1, 2015:

=
Shenzhen Shenzhen (; ; ; ), also historically known as Sham Chun, is a major sub-provincial city and one of the special economic zones of China. The city is located on the east bank of the Pearl River estuary on the central coast of southern provi ...

= Shenzhen currently uses a different signal from Guangdong Province:

=
Zhuhai Zhuhai (, ; Yale: ''Jyūhói''), also known as Chuhai is a prefecture-level city located on the west bank of Pearl River estuary on the central coast of southern Guangdong province, People's Republic of China, on the southeastern edge of P ...

= Zhuhai adopts the signal style of Guangdong Province, but the meaning of the signal is different:

Ball signal

= Shenzhen and Zhuhai

= Shenzhen and Zhuhai used digitally arranged typhoon signals from June 4, 1994, to November 1, 2000, but they have now been replaced by typhoon warning signals.

= Ports

= The coastal ports of various cities in mainland China will still hang the squash signal when the typhoon hits. The sign is roughly the same as the typhoon signal used in Shenzhen and Zhuhai.

Hong Kong and Macau

The

Pearl River Delta The Pearl River Delta Metropolitan Region (PRD; ; pt, Delta do Rio das Pérolas (DRP)) is the low-lying area surrounding the Pearl River estuary, where the Pearl River flows into the South China Sea. Referred to as the Guangdong-Hong Kong-Ma ...

uses a variety of warning systems to inform the public regarding the risks of tropical cyclones to the area. The

Hong Kong Observatory The Hong Kong Observatory is a weather forecast agency of the government of Hong Kong. The Observatory forecasts the weather and issues warnings on weather-related hazards. It also monitors and makes assessments on radiation levels in ...

issues typhoon signals to indicate the existence and effects of a tropical cyclone on

Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a List of cities in China, city and Special administrative regions of China, special ...

. The first numeric warning system was used in 1917. The

Macao Meteorological and Geophysical Bureau The Meteorological and Geophysical Bureau (SMG, ; pt, Direcção dos Serviços Meteorológicos e Geofisicos) is a department of the Macao Government. It provides weather forecasts and issues warnings on weather-related hazards. It also provides ...

Macau Macau or Macao (; ; ; ), officially the Macao Special Administrative Region of the People's Republic of China (MSAR), is a city and special administrative region of China in the western Pearl River Delta by the South China Sea. With a pop ...

uses a similar system. In Hong Kong the typhoon signal system consists of 8 signals in 5 levels numbered non-consecutively for historical reasons. Each signal has a day signal and a night signal for hoisting, which are still hoisted in Macau but no longer hoisted in Hong Kong. Day signals are also used as signal symbols in both places.

Japan

The Japan Meteorological Agency (JMA) is the government agency responsible for gathering and providing results for the public in

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...

, that are obtained from data based on daily scientific observation and research into natural phenomena in the fields of

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is call ...

seismology Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...

and

volcanology Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma and related geological, geophysical and geochemical phenomena (volcanism). The term ''volcanology'' is derived from the Latin word '' vulcan''. Vulcan was the an ...

, among other related scientific fields. Its headquarters is located in

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.46 ...

. JMA is also designated one of the Regional Specialized Meteorological Centers (RSMC) of the

World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Inter ...

. It has the responsibility for

tropical cyclone naming Tropical cyclones and subtropical cyclones are named by various warning centers to simplify communication between forecasters and the general public regarding forecasts, watches and warnings. The names are intended to reduce confusion in the ...

and distribution of warnings for

s in the

Northwestern Pacific The Northwestern Pacific Railroad is a regional shortline railroad utilizing a stretch of the 271 mile mainline between Schellville and Windsor with freight and Sonoma–Marin Area Rail Transit (SMART) commuter trains. Formerly, it was a re ...

region.

Philippines

The

Philippine Atmospheric, Geophysical and Astronomical Services Administration Pagasa may refer to: * ''Pagasa'' (genus), an insect genus in the family Nabidae * PAGASA, an acronym for the Philippine Atmospheric, Geophysical and Astronomical Services Administration *"May Pagasa", a pen-name of José Rizal José Prot ...

(PAGASA) releases tropical cyclone warnings in the form of Tropical Cyclone Wind Signals (TCWS, or "wind signals"). Within this warning system, an area having a wind signal may be under: *TCWS #1 - Tropical cyclone winds of 39–61 km/h are prevailing or expected within the next 36 hours. *TCWS #2 - Tropical cyclone winds of 62–88 km/h are prevailing or expected within the next 24 hours. *TCWS #3 - Tropical cyclone winds of 89–117 km/h are prevailing or expected within the next 18 hours. *TCWS #4 - Tropical cyclone winds of 118–184 km/h are prevailing or expected within 12 hours. *TCWS #5 - Tropical cyclone winds of 185 km/h or greater are prevailing or expected within 12 hours. These wind signals are hoisted when an area (in the Philippines only) is about to be directly affected by tropical cyclone winds. Wind signals for specific areas can be escalated to higher signal levels (and the lead times shortened consequently) as a tropical cyclone gains strength and/or gets closer to the areas about to be affected. De-escalation and/or lifting of wind signals are implemented once a tropical cyclone weakens and/or gets farther away from the affected areas. The lead time is also only valid for the first issuance.

South Pacific basin

The Australian

Bureau of Meteorology The Bureau of Meteorology (BOM or BoM) is an executive agency of the Australian Government responsible for providing weather services to Australia and surrounding areas. It was established in 1906 under the Meteorology Act, and brought together ...

will issue a cyclone watch for a specified part of Australia, when a tropical cyclone is expected to cause gale-force winds in excess of within 24–48 hours and subsequently make landfall. A cyclone warning is subsequently issued for a specified part of Australia when a tropical cyclone, is expected to cause or is causing gale-force winds in excess of within 24 hours and is subsequently expected to make landfall. The Fiji Meteorological Service (FMS) issues a tropical cyclone alert for the

Cook Islands ) , image_map = Cook Islands on the globe (small islands magnified) (Polynesia centered).svg , capital = Avarua , coordinates = , largest_city = Avarua , official_languages = , lan ...

Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consis ...

Kiribati Kiribati (), officially the Republic of Kiribati ( gil, ibaberikiKiribati),Kiribati
''The Wor ...

Nauru Nauru ( or ; na, Naoero), officially the Republic of Nauru ( na, Repubrikin Naoero) and formerly known as Pleasant Island, is an island country and microstate in Oceania, in the Central Pacific. Its nearest neighbour is Banaba Island in ...

Niue Niue (, ; niu, Niuē) is an island country in the South Pacific Ocean, northeast of New Zealand. Niue's land area is about and its population, predominantly Polynesian, was about 1,600 in 2016. Niue is located in a triangle between T ...

Tokelau Tokelau (; ; known previously as the Union Islands, and, until 1976, known officially as the Tokelau Islands) is a dependent territory of New Zealand in the southern Pacific Ocean. It consists of three tropical coral atolls: Atafu, Nukunonu, a ...

and

Tuvalu Tuvalu ( or ; formerly known as the Ellice Islands) is an island country and microstate in the Polynesian subregion of Oceania in the Pacific Ocean. Its islands are situated about midway between Hawaii and Australia. They lie east-northea ...

, when a tropical cyclone has a significant probability of causing gale-force winds or stronger winds within 24–48 hours. Gale, storm and hurricane-force wind warnings are subsequently issued for the above areas by FMS, when a tropical cyclone is either causing or expected to cause either gale storm or hurricane-force winds within 24 hours. Météo-France is responsible for the issuance of tropical cyclone watches and warnings for

New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...

Wallis and Futuna Wallis and Futuna, officially the Territory of the Wallis and Futuna Islands (; french: Wallis-et-Futuna or ', Fakauvea and Fakafutuna: '), is a French island collectivity in the South Pacific, situated between Tuvalu to the northwest, Fiji ...

French Polynesia )Territorial motto: ( en, "Great Tahiti of the Golden Haze") , anthem = , song_type = Regional anthem , song = "Ia Ora 'O Tahiti Nui" , image_map = French Polynesia on the globe (French Polynesia centered).svg , map_alt = Location of French ...

and the

Pitcairn Islands The Pitcairn Islands (; Pitkern: '), officially the Pitcairn, Henderson, Ducie and Oeno Islands, is a group of four volcanic islands in the southern Pacific Ocean that form the sole British Overseas Territory in the Pacific Ocean. The four is ...

. The National Meteorological and Hydrological Services of the

Solomon Islands Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its capit ...

Samoa Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ( Savai'i and Upolu); two smaller, inhabited islands ( Manono and Apolima); ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

Tonga Tonga (, ; ), officially the Kingdom of Tonga ( to, Puleʻanga Fakatuʻi ʻo Tonga), is a Polynesian country and archipelago. The country has 171 islands – of which 45 are inhabited. Its total surface area is about , scattered over in ...

, New Zealand,

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (french: link=no, République de Vanuatu; bi, Ripablik blong Vanuatu), is an island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of ...

, Timor Leste and

are responsible for their own watches and warnings.

Indian Ocean systems

The Indian Meteorological Department (IMD/RSMC New Delhi) is responsible for tracking tropical cyclones within the North Indian Ocean.

Météo-France Météo-France is the French national meteorological service. Organisation The organisation was established by decree in June 1993 and is a department of the Ministry of Transportation. It is headquartered in Paris but many domestic operations ...

Réunion Réunion (; french: La Réunion, ; previously ''Île Bourbon''; rcf, label= Reunionese Creole, La Rényon) is an island in the Indian Ocean that is an overseas department and region of France. It is located approximately east of the island o ...

(MFR/RSMC La Reunion) is responsible for the issuing advisories and tracking of tropical cyclones in the southwest part of the basin, however, the naming of systems is deferred to the Mauritius and Madagascar weather services.

India

The IMD issues warnings in four stages for the Indian coast. * Stage 1: Cyclone watch - Issued 72 hours in advance, it discusses the likelihood of development of a cyclonic disturbance in the north Indian Ocean and the coastal region likely to experience adverse weather. * Stage 2: Cyclone alert - Issued 48 hours in advance of the commencement of adverse weather over the coastal areas. * Stage 3: Cyclone warning - Issued 24 hours in advance of the commencement of adverse weather over the coastal areas. The location of landfall is discussed at this stage. * Stage 4: Landfall outlook - Issued 12 hours in advance of the commencement of adverse weather over the coastal areas. The track of the cyclone after the landfall and the possible impact inland is discussed at this stage. Cyclonic storm conditions mean what winds in excess of 63 km/h (39 mph) are possible.

Mauritius

Mauritius Meteorological Services is responsible for naming tropical systems in the South-West Indian Ocean between 55°E and 90°E. They issue four different levels of cyclone warnings for the islands of

Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label= Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It ...

and

Rodrigues Rodrigues (french: Île Rodrigues, link=yes ; Creole: ) is a autonomous outer island of the Republic of Mauritius in the Indian Ocean, about east of Mauritius. It is part of the Mascarene Islands, which include Mauritius and Réunion. R ...

. * Class I cyclone warnings are issued 36 to 48 hours before the islands are affected by wind gusts of at least 120 km/h (75 mph). * Class II cyclone warnings are issued when there are 12 hours of daylight left before gusts of 120 km/h (75 mph) affect the islands. * Class III cyclone warnings are issued when there are 6 hours of daylight left before gusts of 120 km/h (75 mph) affect the islands. * Class IV cyclone warnings are issued when gusts of at least 120 km/h (75 mph) are occurring in the islands. These warnings are cancelled when there is no longer a risk of gusts of 120 km/h (75 mph) or higher affecting the islands.

Réunion

issues five levels of alerts for the French overseas department and region of

. *Pre-alert/Yellow alert – issued when a tropical system may impact Réunion between 24 and 72 hours. *Orange alert – issued when a tropical storm or cyclone may impact Réunion in the next 24 hours. *Red alert – issued when a tropical storm or cyclone is impacting part or all of Réunion. *Purple alert – issued when a major tropical cyclone with winds exceeding is impacting part or all of Réunion. *Safeguard phase – issued when a tropical storm or cyclone is moving away from Réunion, but hazards relating to damage caused by the system, such as fallen trees, flooded roads, mudslides, and downed power lines, still remain.

Military advisories

HURCON/TCCOR

The

United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national sec ...

uses a multi-stage system called the Hurricane Condition (HURCON) in the North Atlantic and the Northeast Pacific and the Tropical Cyclone Condition of Readiness (TCCOR) in the western Pacific to prepare bases and evacuate assets and personnel in advance of adverse weather associated with tropical cyclones. The alerts are recommended by weather facilities either on base or by central sites like the

or the

Joint Typhoon Warning Center The Joint typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, So ...

and are generally related to the timing and potential for destructive sustained windspeeds of above . Recommendations are then considered by base or area commanders along with other subjective factors for setting the alert status like assets, holidays or the bases experience in emergency preparedness. The bases prefer to set these alerts sequentially, from HURCON or TCCOR 5 with destructive winds expected within 96 hours, through levels 4, 3, 2 and if needed to a series of four different level 1 conditions, however depending on the cyclone's movement or location some of these signals can be skipped. After a system passes and stops affecting the base, the authorities can decide to revert to the lowest level or stay in a heightened approach if another tropical cyclone is approaching.

References

External links

NHC - watches and warnings
{{DEFAULTSORT:Tropical Cyclone Warnings And Watches Tropical cyclone meteorology Weather warnings and advisories