Tropical cyclone warnings and watches

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Tropical cyclone warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone 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. Tropical cyclones are not points, and forecasting their track remains an uncertain science.

Weather forecasting application of science and technology to predict the conditions of the atmosphere for a given location and time

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 century. Weather forecasts are made by collecting quantitative data about the current state of the atmosphere at a given place and using meteorology to project how the atmosphere will change.

Tropical cyclone Is a rotating storm system

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. Depending on its location and strength, a tropical cyclone is referred to by different names, including hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean, and a typhoon occurs in the northwestern Pacific Ocean; in the south Pacific or Indian Ocean, comparable storms are referred to simply as "tropical cyclones" or "severe cyclonic storms".

Contents

Western hemisphere

Hurricane Warning
Hurricane conditions
expected within 36 hours.
Hurricane Watch
Hurricane conditions
possible within 48 hours.
Tropical Storm Warning
Tropical storm conditions expected within 36 hours.
Tropical Storm Watch
Tropical storm conditions possible within 48 hours.
Emergency alert issued for the Big Island about the message of hurricane warning during Hurricane Lane. Hurricane Lane warning (29254459177).jpg
Emergency alert issued for the Big Island about the message of hurricane warning during Hurricane Lane.

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. [1] [2] [3] [4] [5] In conjunction with the National Hurricane Center, the national meteorological and hydrological services of Central America, the northern Atlantic Ocean, and the northeastern Pacific Ocean east of the 140th meridian west, excluding mainland Africa and Europe, all issue tropical storm/hurricane watches and warnings. [6] Tropical storm watches are issued when gale and storm force winds of between 34–63 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. [7] 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. [7] Hurricane watches are issued when sustained winds of 64 knots (74 mph; 119 km/h) are possible, within 48 hours in a specified area in association with a tropical, subtropical or post-tropical cyclone. [7] These warnings are upgraded to hurricane warnings, when hurricane-force winds become expected to occur somewhere in the warning area within 36 hours. [7]

National Hurricane Center division of the United States National Weather Service

The National Hurricane Center (NHC) is the division of the United States' National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 30th parallel north in the northeast Pacific Ocean and the 31st parallel north in the northern Atlantic Ocean. The agency, which is co-located with the Miami branch of the National Weather Service, is situated on the campus of Florida International University in University Park, Florida.

Central America central geographic region of the Americas

Central America is located on the southern tip of North America, or is sometimes defined as a subcontinent of the Americas, bordered by Mexico to the north, Colombia to the southeast, the Caribbean Sea to the east, and the Pacific Ocean to the west and south. Central America consists of seven countries: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama. The combined population of Central America has been estimated to be 41,739,000 and 42,688,190.

Atlantic Ocean Ocean between Europe, Africa and the Americas

The Atlantic Ocean is the second largest of the world's oceans, with an area of about 106,460,000 square kilometers. It covers approximately 20 percent of the Earth's surface and about 29 percent of its water surface area. It separates the "Old World" from the "New World".

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. [7] 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 for the Hawaiian Islands and the Weather Forecast Office in Guam for parts of Micronesia but not for American Samoa due to an international agreement. [8]

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 Pacific region: from the equator northward, 140°W–180°W, most significantly for Hawai‘i. It is the Regional Specialized Meteorological Center (RSMC) for tropical cyclones in this region, and in this capacity is known as RSMC Honolulu.

Guam Island territory of the United States of America

Guam is an unincorporated and organized territory of the United States in Micronesia in the western Pacific Ocean. It is the easternmost point and territory of the United States, along with the Northern Mariana Islands. The capital city of Guam is Hagåtña and the most populous city is Dededo. The inhabitants of Guam are called Guamanians, and they are American citizens by birth. Indigenous Guamanians are the Chamorros, who are related to other Austronesian natives of Eastern Indonesia and Philippines and Taiwan. Guam has been a member of the Pacific Community since 1983.

Micronesia Subregion of Oceania

Micronesia is a subregion of Oceania, composed of thousands of small islands in the western Pacific Ocean. It has a shared cultural history with two other island regions: Polynesia to the east and Melanesia to the south.

Within the United States an extreme wind warning 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). [8] The warning is issued just prior to when the strongest winds of the eyewall are expected to impact an area. [9] The warning is to be issued for the smallest area possible, and be valid for times of two hours or less. [9] It was developed in response to confusion resulting from the landfall of Hurricane Katrina. NWS offices in Jackson and New Orleans/Baton Rouge issued 11 tornado warnings for areas that would not experience an actual tornado, but would experience extreme wind speeds commonly associated with tornadoes. [10] The extreme wind warning is now expected to be used in these situations.

Extreme wind warning

An extreme wind warning is an alert issued by the National Weather Service for areas are experiencing or could experience 100 knots within an hour due to the landfall of a powerful hurricane. EWWs are intended to provide guidance to the general public at a county or sub-county level of winds that could pose a significant threat of casualties. Their issuance is intended to cover as precise of an area as possible and can be issued no prior than two hours before the onset of extreme winds.

Hurricane Katrina Category 5 Atlantic hurricane in 2005

Hurricane Katrina was an extremely destructive and deadly Category 5 hurricane that made landfall on Florida and Louisiana, particularly the city of New Orleans and the surrounding areas, in August 2005, causing catastrophic damage from central Florida to eastern Texas. Subsequent flooding, caused largely as a result of fatal engineering flaws in the flood protection system known as levees around the city of New Orleans, precipitated most of the loss of lives. The storm was the third major hurricane of the record-breaking 2005 Atlantic hurricane season, as well as the fourth-most intense Atlantic hurricane on record to make landfall in the United States, behind only the 1935 Labor Day hurricane, Hurricane Camille in 1969, and Hurricane Michael in 2018.

Jackson, Mississippi Capital of Mississippi

Jackson, officially the City of Jackson, is the capital and most populous city of the U.S. state of Mississippi. It is one of two county seats of Hinds County, along with Raymond, Mississippi. The city of Jackson also includes around 3,000 acres comprising Jackson-Medgar Evers International Airport in Rankin County and a small portion of Madison County. The city's population was estimated to be 165,072 in 2017, a decline from 173,514 in 2010. The city sits on the Pearl River and is located in the greater Jackson Prairie region of Mississippi.

In 2017, the National Hurricane Center introduced a new system of warnings and watches for storm surge, which would cover the Atlantic and Gulf Coasts of the United States. 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. [11]

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, the severity of which is affected by the shallowness and orientation of the water body relative to storm path, as well as the timing of tides. Most casualties during tropical cyclones occur as the result of storm surges. It is a measure of the rise of water beyond what would be expected by the normal movement related to tides.

East Coast of the United States Coastline in the United States

The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the coastline along which the Eastern United States meets the North Atlantic Ocean. The coastal states that have shoreline on the Atlantic Ocean are, from north to south, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Delaware, Maryland, Virginia, North Carolina, South Carolina, Georgia, and Florida.

United States federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico. The State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate, and wildlife of the United States make it one of the world's 17 megadiverse countries.

In Mexico, 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. [12]

Mexico country in the southern portion of North America

Mexico, officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Covering almost 2,000,000 square kilometres (770,000 sq mi), the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 120 million people, the country is the eleventh most populous state and the most populous Spanish-speaking state in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states and Mexico City, a special federal entity that is also the capital city and its most populous city. Other metropolises in the state include Guadalajara, Monterrey, Puebla, Toluca, Tijuana and León.

Canada

In Canada, terminology is fairly similar to that of the United States, but there are a few differences: [13]

  • 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 90km/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

People's Republic of China

A two-stage warning system was long-established in China for tropical cyclones of tropical storm intensity of above. [14] 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 standardized the system for national use. [15] 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.

LevelNameSignMeaning
Blue typhoon alert
台风蓝色预警信号
Blue typhoon alert - China.svg Within 24 hours, it may or may have been affected by tropical cyclones. The average wind power on the coast or land is above 6, or the gust above 8 and may continue.
Yellow typhoon alert
台风黄色预警信号
Yellow typhoon alert - China.svg Within 24 hours, it may or may have been affected by tropical cyclones. The average wind power on the coast or land is above 8, or the gust above 10 and may continue.
Orange typhoon alert
台风橙色预警信号
Orange typhoon alert - China.svg Within 12 hours, it may or may have been affected by tropical cyclones. The average wind power on the coast or land is above 10, or the gust above 12 and may continue.
Red typhoon alert
台风红色预警信号
Red typhoon alert - China.svg Within 6 hours, it may or may have been affected by tropical cyclones. The average wind power on the coast or land is above 12, or the gust above 14 and may continue.

Guangdong

Guangdong 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, 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 from June 1st 1995 to November 1st 2000 [16] :

NameMeaning
Windproof Info (Tropical Storm or Typhoon Info)indicates that a tropical storm or typhoon has entered the South China Sea (or has formed in the South China Sea) and is likely to move to the coastal areas of the province.
Windproof Warning (Tropical Storm and Typhoon Warning)Indicating that a tropical storm or typhoon warning enters the South China Sea, its route is moving in the direction of the Pearl River Estuary. If there is no change, it may land within 48 hours.
Windproof Special Alert (Tropical Storm or Typhoon Emergency Alert)Indicating that a tropical storm or typhoon hits the Pearl River Estuary within 24 hours, or landed in a coastal area within 150 kilometers of the Pearl River Estuary, which will have a serious impact on Guangzhou.
Disarming (Tropical Storm or Typhoon Disarming Alert)indicates that a tropical storm or typhoon has landed (or weakened to a low pressure).

Typhoon warning signals used from November 1st 2000 to May 2006 [17]

NameSignalMeaning
White typhoon alert Taf1.gif Tropical cyclones may affect the area within 48 hours.
Green typhoon alert Taf2.gif Tropical cyclones will be within 24 hours or are affecting the area, with an average wind level of strong winds (6-7) (41-62 km/h).
Yellow typhoon alert Kj3.gif Tropical cyclones will be within 12 hours or are affecting the area, with an average winds level of strong gale (8-9) (63-87 km/h).
Red typhoon alert Ty4.gif Tropical cyclones will be within 12 hours or are affecting the area, with an average winds level of strong storm (10-11) (88-117 km/h).
Black typhoon alert Jk5.gif Tropical cyclones will be within 12 hours or are affecting the area, with an average winds level of typhoon (>12).

Typhoon warning signals used from June 1st 2006 to December 31 2014 [18] :

NameSignalMeaning
White typhoon alert Typhoon 1 white.jpg Tropical cyclones may affect the area within 48 hours.
Blue typhoon alert Typhoon 2 blue.jpg It may be affected by tropical cyclones within 24 hours, the average wind power can reach above level 6, or gusts above 7; or it has been affected by tropical cyclones with an average wind power of 6-7, or gusts of 7-8, and may continue.
Yellow typhoon alert Typhoon 3 yellow.jpg It may be affected by tropical cyclones within 24 hours, the average wind power can reach above level 8, or gusts above 9; or it has been affected by tropical cyclones with an average wind power of 8-9, or gusts of 9-10, and may continue.
Orange typhoon alert Typhoon 4 orange.jpg It may be affected by tropical cyclones within 12 hours, the average wind power can reach above level 10, or gusts above 11; or it has been affected by tropical cyclones with an average wind power of 10-11, or gusts of 11-12, and may continue.
Red typhoon alert Typhoon 5 red.jpg It may be affected by tropical cyclones within 6 hours, the average wind power can reach above level 12; or it has been affected by tropical cyclones with an average wind power of 12, and may continue.

Typhoon warning signals used since January 1st 2015 [19] :

NameSignalMeaning
White typhoon alert 2015Ban Yan Dong Sheng Tai Feng Bai Se Yu Jing Xin Hao .gif Tropical cyclones may affect the area within 48 hours.
Blue typhoon alert 2015Ban Yan Dong Sheng Tai Feng Lan Se Yu Jing Xin Hao .gif It may be affected by tropical cyclones within 24 hours, the average wind power can reach above level 6, or gusts above 7; or it has been affected by tropical cyclones with an average wind power of 6-7, or gusts of 7-8, and may continue.
Yellow typhoon alert 2015Ban Yan Dong Sheng Tai Feng Huang Se Yu Jing Xin Hao .gif It may be affected by tropical cyclones within 24 hours, the average wind power can reach above level 8, or gusts above 9; or it has been affected by tropical cyclones with an average wind power of 8-9, or gusts of 9-10, and may continue.
Orange typhoon alert 2015Ban Yan Dong Sheng Tai Feng Cheng Se Yu Jing Xin Hao .gif It may be affected by tropical cyclones within 12 hours, the average wind power can reach above level 10, or gusts above 11; or it has been affected by tropical cyclones with an average wind power of 10-11, or gusts of 11-12, and may continue.
Red typhoon alert 2015Ban Yan Dong Sheng Tai Feng Hong Se Yu Jing Xin Hao .gif It may be affected by tropical cyclones within 6 hours, the average wind power can reach above level 12; or it has been affected by tropical cyclones with an average wind power of 12, and may continue.
Shenzhen

Shenzhen currently uses a different signal from Guangdong Province [18] [20] :

Zhuhai

Zhuhai adopts the signal style of Guangdong Province, but the meaning of the signal is different [21] :

Ball signal

Shenzhen and Zhuhai

Shenzhen and Zhuhai used digitally arranged typhoon signals from June 4 1994 to November 1 2000 [22] , 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 [23] . The sign is roughly the same as the typhoon signal used in Shenzhen and Zhuhai [24] .

Hong Kong and Macau

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

The Hong Kong Observatory issues typhoon signals to indicate the existence and effects of a tropical cyclone on Hong Kong. The first numeric warning system was used in 1917.

The Macao Meteorological and Geophysical Bureau in Macau uses a similar system. [25]

In Hong Kong the typhoon signal system consists of 8 signals in 5 levels numbered non-consecutively for historical reasons. [26] [27] 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.

SignalSymbolNoteWind speedGust
No.1 No. 01 Standby Signal.png (Standby) A tropical cyclone is centred within 800 km of the territory.NANA
No.3 No. 03 Strong Wind Signal.png A definite warning that a tropical cyclone is expected to come near enough to Hong Kong to cause strong winds in Hong Kong. It normally gives 12 hours warning of strong winds generally over Hong Kong at sea level, but in exposed areas, winds may become strong sooner.

Impliction for citizens: Do not need to go to kindergartens, some places and events.

Strong wind with a sustained speed of 41–62 km/h≥ 110 km/h
No.8. NW / SW / NE / SE No. 8 Northwest Gale or Storm Signal.png No. 8 Southwest Gale or Storm Signal.png No. 8 Northeast Gale or Storm Signal.png No. 8 Southeast Gale or Storm Signal.png Gale or storm force wind.

4 different symbols for different directions.

Implication for citizens: usually no need to go to school or work for most people if hosted before a certain hours before official work hours; depends on official announcement & employment contracts.

sustained speed of 63–117 km/h from the northwest, southwest, northeast, southeast quadrants respectively≥ 180 km/h.
No. 9 No. 09 Increasing Gale or Storm Signal.png (Hong Kong) Gale or storm force wind is increasing or expected to increase significantly in strength. / (Macau) The centre of a tropical cyclone is approaching and Macau is expected to be severely affected.It usually implies that wind speeds are expected to reach the range 88 to 117 kilometres per hour.
No. 10 No. 10 Hurricane Signal.png Hurricane force wind.

Implication for citizens: no need to go to work or school. Most public transportation stop.

winds range upwards from 118 kilometres per hour.≥ 220 km/h

Japan

The Japan Meteorological Agency (JMA) is the government agency responsible for gathering and providing results for the public in Japan, that are obtained from data based on daily scientific observation and research into natural phenomena in the fields of meteorology, hydrology, seismology and volcanology, among other related scientific fields. Its headquarters is located in Tokyo.

is also designated one of the Regional Specialized Meteorological Centers (RSMC) of the World Meteorological Organization. It has the responsibility for weather forecasting, tropical cyclone naming and distribution of warnings for tropical cyclones in the Northwestern Pacific region.

Philippines

Signal #1
winds of 30–60 km/h (20-37 mph) are expected to occur within 36 hours
Signal #2
winds of 61–120 km/h (38–73 mph) are expected to occur within 24 hours
Signal #3
winds of 121–170 km/h, (74–105 mph) are expected to occur within 18 hours.
Signal #4
winds of 171–220 km/h, (106–137 mph) are expected to occur within 12 hours.
Signal #5
winds of at least 220 km/h, (137 mph) are expected to occur within 12 hours.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) releases tropical cyclone warnings in the form of Public Storm Warning Signals (or just storm signals). [28] An area having a storm signal may be under:

  • PSWS #1 - Tropical cyclone winds of 30–60 km/h are expected within the next 36 hours. (Note: If a tropical cyclone forms very close to the area, then a shorter lead time is seen on the warning bulletin.)
  • PSWS #2 - Tropical cyclone winds of 61–120 km/h are expected within the next 24 hours.
  • PSWS #3 - Tropical cyclone winds of 121–170 km/h are expected within the next 18 hours.
  • PSWS #4 - Tropical cyclone winds of 171–220 km/h are expected within 12 hours.
  • PSWS #5 - Tropical cyclone winds greater than 220 km/h are expected within 12 hours.

These storm signals are usually hoisted when an area (in the Philippines only) is about to be hit by a tropical cyclone. Thus, as a tropical cyclone gains strength and/or gets closer to an area having a storm signal, it may be raised to another higher signal in that particular area. Whereas, as a tropical cyclone weakens and/or gets farther away from an area, it may be downgraded to a lower signal or may be lifted (that is, an area will have no storm signal).

South Pacific basin

The Australian Bureau of Meteorology 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 62 km/h (40 mph) within 24–48 hours and subsequently make landfall. [29] 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 62 km/h (40 mph) within 24 hours and is subsequently expected to make landfall. [29]

The Fiji Meteorological Service (FMS) issues a tropical cyclone alert for the Cook Islands, Fiji, Kiribati, Nauru, Niue, Tokelau, Tonga and Tuvalu, when a tropical cyclone has a significant probability of causing gale-force winds or stronger winds within 24–48 hours. [30] 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. [30]

Météo-France is responsible for the issuance of tropical cyclone watches and warnings for New Caledonia, Wallis and Futuna, French Polynesia and the Pitcairn Islands. [30] The National Meteorological and Hydrological Services of the Solomon Islands, Samoa, Indonesia, Papua New Guinea, New Zealand, Vanuatu, Timor Leste and American Samoa are responsible for their own watches and warnings. [30]

Indian Ocean systems

The India Meteorological Department (IMD/RSMC New Delhi) is responsible for tracking tropical cyclones within the North Indian Ocean. Météo-France in Réunion (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

Cyclone Watch
Cyclonic storm conditions possible within 72 hours.
Cyclone Alert
Cyclonic storm conditions possible within 48 hours.
Cyclone Warning
Cyclonic storm conditions expected within 24 hours.
Landfall Outlook
Cyclonic storm conditions expected within 12 hours.

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. [31]

Military advisories

Tropical Cyclone Condition of Readiness

The United States Department of Defense uses a multi-stage system called the Tropical Cyclone Condition of Readiness (TC-CORs) otherwise known as the Hurricane Condition of Readiness (HURCONs), to prepare bases and evacuate assets and personnel in advance of adverse weather associated with tropical cyclones. [32]

TC-CORHoursNotes
596This is set by military bases in the US, throughout the Atlantic hurricane season.
472Guam is in TC-COR 4 throughout the year, while Japanese bases set this from June 1 - November 30.
348Destructive winds are possible within 48 hours.
224Destructive winds are now expected within 24 hours.
112Destructive winds are now expected within 12 hours, but gale force winds are not yet occurring.
1C12Gale-force winds are occurring.
1E0Winds of above 50 kn (58 mph; 93 km/h) are occurring.
1RWinds of above 50 kn (58 mph; 93 km/h) are no longer occurring, but gale-force winds are occurring.
Storm WatchThe system is moving away but the base is still feeling some effects.
All-ClearRevert to seasonal TC-COR

TC-CORs are recommended by weather facilities either on base or by central sites like the National Hurricane Center or the Joint Typhoon Warning Center and are generally related to the timing and potential for destructive sustained windspeeds of above 50 kn (58 mph; 93 km/h). [32] Recommendations are then considered by base or area commanders along with other subjective factors for setting the TC-CORs like assets, holidays or the bases experience in emergency preparedness. [32] The bases prefer to set these TC-CORs sequentially, from TC-COR 5 with destructive winds expected within 96 hours, through TC-COR 4, 3, 2 and if needed to a series of four different TC-COR 1 conditions, however depending on the cyclone's movement or location some of these signals can be skipped. [32] [33] After a system passes and stops affecting the base, the authorities can decide to revert to the seasonal TC-COR or stay in a heightened approach as another tropical cyclone is approaching. [32]

See also

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Typhoon Neoguri, known in the Philippines as Typhoon Ambo, was the earliest tropical cyclone on record to strike The People's Republic of China. The first named storm in the 2008 Pacific typhoon season, named after the Korean word for raccoon dog, it formed from a low pressure area on April 13 to the east of the Philippine island of Mindanao, and after crossing the island it intensified into a tropical storm in the South China Sea. Environmental conditions allowed for quick strengthening, with Neoguri attaining typhoon status on April 16. The typhoon reached its peak intensity on April 18 as it approached the island of Hainan, and subsequently it turned northward. Due to increased wind shear and cooler waters, Neoguri rapidly weakened and made landfall as a minimal tropical storm in southern China on April 19.

2008–09 Australian region cyclone season cyclone season in the Australian region

The 2008–09 Australian region cyclone season was a near average tropical cyclone season. It officially started on 1 November 2008, and officially ended on 30 April 2009. This season was also the first time that the BoM implemented a "tropical cyclone year." The regional tropical cyclone operational plan defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2008 and ended on 30 June 2009.

Typhoon Pabuk (2007) Pacific typhoon in 2007

Typhoon Pabuk, known in the Philippines as Tropical Storm Chedeng, was a minimal typhoon that formed during the day of August 5, 2007. The system made landfall on Taiwan on August 7, and on August 9 Pabuk passed to the south of Hong Kong.

2010 Pacific typhoon season typhoon season in the Pacific Ocean

The 2010 Pacific typhoon season was the least active Pacific typhoon season on record, featuring only 14 named storms; seven of them strengthened into typhoons while one reached super typhoon intensity. The Pacific typhoon season during 2010 was in fact less active than the 2010 Atlantic hurricane season, the only such occurrence other than 2005. In the same year, the Pacific hurricane season broke the same record being the least active season on record. During the season no storms have made landfall in mainland Japan, the only second such occurrence since 1988. Also, all of the 14 named storms developed west of 150°E. Moreover, the season had an index total Accumulated Cyclone Energy (ACE) of 115, which is the second lowest in the basin after 1999. It was also the fourth consecutive year with a below average ACE index.

Cyclone Tam Category 1 South Pacific cyclone in 2006

Tropical Cyclone Tam was the first named storm of the 2005–06 South Pacific cyclone season. Forming out of a tropical depression on January 6, the storm gradually intensified, becoming a tropical cyclone on January 12 and receiving the name Tam. Although it was traveling at a quick pace, the storm gained organization and reached its peak intensity with winds of 85 km/h (50 mph) the following day. However, the increasing forward motion of the storm, combined with strengthening wind shear, caused Tam to rapidly weaken on January 14. Around that time, it entered the Tropical Cyclone Warning Centre in Wellington, New Zealand's area of responsibility. Shortly thereafter, the storm transitioned into an extratropical cyclone and dissipated early the next day. Cyclone Tam produced heavy rainfall and strong winds over American Samoa upon being named. The precipitation caused several mudslides and flooding, which inflicted $26,000 in damage. The storm also had minor effects on Niue, Tonga, and Futuna.

Typhoon Melor (2009) Pacific typhoon in 2009

Typhoon Melor, known in the Philippines as Typhoon Quedan, was the second category 5 typhoon in 2009. It interacted with Typhoon Parma in the first week of October southeast of Taiwan.

Cyclone Gwenda Category 5 Australian region cyclone in 1999

Severe Tropical Cyclone Gwenda was tied with Cyclone Inigo as the most intense Australian tropical cyclone on record, with a barometric pressure of 900 hPa (mbar) and was the most intense storm worldwide in 1999. Forming out of a tropical disturbance over the Arafura Sea on 2 April 1999, the precursor to Gwenda tracked slowly westward and gradually became more organised. On 4 April, the system developed into a Category 1 cyclone and was named Gwenda. It began to undergo explosive intensification the following day, and in a 30-hour span ending early on 7 April, the storm's maximum 10-minute sustained wind speed increased from 75 km/h (45 mph) to 225 km/h (140 mph) and its barometric pressure decreased to 900 hPa (mbar). The Joint Typhoon Warning Center reported that the storm had peaked as a high-end Category 4 equivalent on the Saffir–Simpson hurricane scale.

2017 Pacific typhoon season typhoon season in the Pacific Ocean

The 2017 Pacific typhoon season was a below-average season in terms of Accumulated Cyclone Energy and the number of typhoons and super typhoons, and the first and latest since the 1977 season to not produce a Category 5-equivalent typhoon on the Saffir-Simpson scale. The season produced a total of 27 named storms, 11 typhoons, and only two super typhoons, making it an average season in terms of storm numbers. It was an event in the annual cycle of tropical cyclone formation, in which tropical cyclones form in the western Pacific Ocean. The season runs throughout 2017, though most tropical cyclones typically develop between May and October. The season's first named storm, Muifa, developed on April 25, while the season's last named storm, Tembin, dissipated on December 26. This season also featured the latest occurrence of the first typhoon of the year since 1998, with Noru reaching this intensity on July 23.

Cyclone Magda Category 3 Australian region cyclone in 2010

Severe Tropical Cyclone Magda was a relatively small tropical cyclone that brought minor damage to parts of Western Australia in January 2010. The third named storm of the 2009–10 Australian region cyclone season, Magda originated from a tropical low near the Indonesian island of Roti on 18 January. Quickly strengthening, the system attained tropical cyclone status on 20 January and later reached severe tropical cyclone intensity on 21 January as it approached Western Australia. Late on 21 January, Magda made landfall in the Kimberley region with winds of 130 km/h (80 mph) before quickly weakening over land. The remnants of Magda persisted until 24 January, at which time they dissipated east of Port Hedland.

Glossary of tropical cyclone terms

The following is a glossary of tropical cyclone terms.

Typhoon Usagi (2013) Pacific typhoon in 2013

Typhoon Usagi, known in the Philippines as Typhoon Odette, was a violent tropical cyclone which affected Taiwan, the Philippines, China, and Hong Kong in September 2013. Usagi, or which means the constellation Lepus in Japanese, was the fourth typhoon and the nineteenth tropical storm in the basin. Developing into a tropical storm east of the Philippines late on September 16, Usagi began explosive intensification on September 19 and ultimately became a violent and large typhoon. Afterwards, the system weakened slowly, crossed the Bashi Channel on September 21, and made landfall over Guangdong, China on September 22.

Typhoon Rammasun Pacific typhoon in 2014

Typhoon Rammasun, known in the Philippines as Typhoon Glenda, was one of the only two Category 5 super typhoons on record in the South China Sea, with the other one being Pamela in 1954. Rammasun had destructive impacts across the Philippines, South China, and Vietnam in July 2014. Rammasun is a Siamese word for thunder god. After Lingling and Kajiki earlier in 2014, Rammasun became the third tropical cyclone, and first typhoon to directly impact the Philippines in 2014. The ninth named storm and the third typhoon of the annual typhoon season, Rammasun formed in the Intertropical Convergence Zone, an area near the equator where the northeast and southeast trade winds come together, and slowly drifted northwest. Having passed through the islands of Micronesia, the system turned west and quickly moved under the influence of a subtropical ridge (STR). Rammasun posed a significant threat to the Philippine island of Luzon, as it was expected to reach typhoon intensity before making landfall there. Though initially forecast to make landfall in Cagayan Valley, the storm followed a more westerly path and was later forecast to make landfall in the Bicol Region and then pass through Bataan and Zambales before brushing past Metro Manila.

Typhoon Hagupit (2014)

Typhoon Hagupit, known in the Philippines as Typhoon Ruby, was the second most intense tropical cyclone in 2014. Hagupit particularly impacted the Philippines in early December while gradually weakening, killing 18 people and causing $114 million in the country. Prior to making landfall, Typhoon Hagupit was considered the worst threat to the Philippines in 2014, but it was significantly smaller than 2013's Typhoon Haiyan.

Typhoon Koppu Pacific typhoon in 2015

Typhoon Koppu, known in the Philippines as Typhoon Lando, was a powerful and devastating tropical cyclone that struck Luzon in October 2015. It was the twenty-fourth named storm and the fifteenth typhoon of the annual typhoon season. Similar to Goni earlier in the year, Koppu originated from a tropical disturbance east of the Mariana Islands on October 10. Moving briskly west, the system consolidated into a tropical depression the following day and further into a tropical storm on October 13. Situated over the warm waters of the Philippine Sea, Koppu quickly deepened. The storm reached its peak intensity on October 17 with ten-minute sustained winds of 185 km/h (115 mph) according to the Japan Meteorological Agency (JMA). The Joint Typhoon Warning Center assessed Koppu to have been a Category 4-equivalent super typhoon with one-minute sustained winds of 240 km/h (150 mph). The storm subsequently made landfall at this strength near Casiguran, Philippines. Rapid weakening ensued due to interaction with the mountainous terrain of Luzon and the disheveled core of Koppu emerged over the West Philippine Sea on October 19. Unfavorable environmental conditions inhibited reorganization and the system diminished to a tropical depression on October 21.

Tropical Storm Nida (2016)

Severe Tropical Storm Nida, known in the Philippines as Severe Tropical Storm Carina, was a tropical cyclone that struck Luzon, Philippines and Guangdong, China in late July and early August respectively. The fourth named storm of the annual typhoon season, Nida formed on July 28, 2016 as a tropical depression in the Philippine Sea. Tracking generally north-northwestward, it intensified into a severe tropical storm and skirted northern Luzon before turning to the west-northwest, entering the South China Sea and intensifying further. Nida made landfall over Dapeng Peninsula in Shenzhen late on August 1 and dissipated on August 3.

References

  1. "Regional Specialized Meteorological Center". Tropical Cyclone Program (TCP). World Meteorological Organization. April 25, 2006. Retrieved November 5, 2006.
  2. Fiji Meteorological Service (2017). "Services" . Retrieved 2017-06-04.
  3. Joint Typhoon Warning Center (2017). "Products and Service Notice". United States Navy. Retrieved 2017-06-04.
  4. National Hurricane Center (March 2016). "National Hurricane Center Product Description Document: A User's Guide to Hurricane Products" (PDF). National Oceanic and Atmospheric Administration. Retrieved 2017-06-03.
  5. Japan Meteorological Agency (2017). "Notes on RSMC Tropical Cyclone Information" . Retrieved 2017-06-04.
  6. RA IV Hurricane Committee (May 30, 2013). Hurricane Operational Plan (PDF) (Technical Document). World Meteorological Organization. Archived (PDF) from the original on December 16, 2013. Retrieved December 15, 2013.
  7. 1 2 3 4 5 "Glossary of NHC Terms". United States National Oceanic and Atmospheric Administration's National Weather Service. March 25, 2013. Archived from the original on December 16, 2013. Retrieved December 15, 2013.
  8. 1 2 Tropical Cyclone Products (PDF) (National Weather Service Instruction 10-601). United States National Oceanic and Atmospheric Administration's National Weather Service. June 11, 2013. pp. 4–9, 56. Archived (PDF) from the original on December 16, 2013. Retrieved December 15, 2013.
  9. 1 2 National Weather Service. "Product Description Document: Extreme Wind Warning (EWW)" (PDF). Retrieved 2007-10-04.
  10. U.S. Department of Commerce. "Service Assessment. Hurricane Katrina: August 23–31, 2005" (PDF). Archived from the original (PDF) on 2007-07-11. Retrieved 2007-10-04.
  11. Storm surge watch & warning to become operational in 2017 (pdf) (Report). United States National Oceanic and Atmospheric Administration's National Weather Service. January 23, 2017. Retrieved January 26, 2017.
  12. "Be Prepared for Hurricane Season in Cancun". Royal Sunset. October 22, 2013. Retrieved August 15, 2016.
  13. https://www.canada.ca/en/environment-climate-change/services/types-weather-forecasts-use/public/criteria-alerts.html
  14. Typhoon.gov.cn Archived August 30, 2006, at the Wayback Machine
  15. CMA.gov.cn Archived August 22, 2006, at the Wayback Machine
  16. 广州市防风工作方案
  17. 广东省台风、暴雨、寒冷预警信号发布规定
  18. 1 2 "台风预警信号 - 深圳市气象局". szmb.gov.cn. Archived from the original on 2010-08-24.
  19. "存档副本". Archived from the original on 2014-12-31. Retrieved 2014-12-31.
  20. "深圳市台风暴雨灾害公众防御指引(试行)". szmb.gov.cn. Archived from the original on 2015-02-16.
  21. "珠海气象局". zhmb.gov.cn. Archived from the original on 2014-12-31.
  22. 深圳经济特区防洪防风规定
  23. 廣州市氣象台风球信号说明
  24. 1997年颱風維克托風暴消息(6/10) - 考慮改掛十號風球 on YouTube
  25. "Meaning of Tropical Cyclone Signals and the relevant recommended safety precautions". Macao Meteorological and Geophysical Bureau. Retrieved 10 April 2017.
  26. John YK Leung and WH Lui (9 August 2012). "Tropical Cyclone Warning Signal No.5 in the Past". Hong Kong Observatory. Retrieved 10 April 2017.
  27. "History of the Hong Kong Tropical Cyclone Warning Signals". Hong Kong Observatory. Retrieved 10 April 2017.
  28. "Philippine Tropical Cyclone Warning Signals". Philippine Atmospheric, Geophysical and Astronomical Services Administration . Retrieved 17 December 2017.
  29. 1 2 "Tropical Cyclone Warning Advice". Australian Bureau of Meteorology. Retrieved December 15, 2013.
  30. 1 2 3 4 RA V Tropical Cyclone Committee (December 12, 2012). Tropical Cyclone Operational Plan for the South-East Indian Ocean and the Southern Pacific Ocean 2012 (PDF) (Report). World Meteorological Organization. pp. 7–13. Archived (PDF) from the original on April 1, 2013. Retrieved December 15, 2013.
  31. "Four Stage Warning". India Meteorological Department. Retrieved 23 October 2016.
  32. 1 2 3 4 5 Sampson, Charles R; Schumacher, Andrea B; Knaff, John A; DeMaria, Mark; Fukada, Edward M; Sisko, Chris A; Roberts, David P; Winters, Katherine A; Wilson, Harold M. "Objective Guidance for Use in Setting Tropical Cyclone Conditions of Readiness". Weather and Forecasting. 27 (4): 1052–1060. Bibcode:2012WtFor..27.1052S. doi:10.1175/WAF-D-12-00008.1.
  33. Fleet Weather Center (February 8, 2013). "Tropical Cyclone Quick Reference Guide 2013" (PDF). United States Navy. p. 2. Retrieved December 15, 2013.