Glossary of tropical cyclone terms

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Hurricane Kate of 2003 Hurricane Kate (2003)- Good pic.jpg
Hurricane Kate of 2003
Tropical cyclones
Formation and naming
Development - Structure
Naming - Seasonal lists - Full list

Watches and warnings
Storm surge - Notable storms
Retired names (Atlantic - Eastern Pacific - Western Pacific)

Effects of tropical cyclones effect of cyclone

The main effects of tropical cyclones include heavy rain, strong wind, large storm surges near landfall, and tornadoes. The destruction from a tropical cyclone, such as a hurricane or tropical storm, depends mainly on its intensity, its size, and its location. Tropical cyclones act to remove forest canopy as well as change the landscape near coastal areas, by moving and reshaping sand dunes and causing extensive erosion along the coast. Even well inland, heavy rainfall can lead to mudslides and landslides in mountainous areas. Their effects can be sensed over time by studying the concentration of the Oxygen-18 isotope within caves within the vicinity of cyclones' paths.

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.

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.


Climatology and tracking
Basins - RSMCs - TCWCs - Scales - Terminology
Observation - Forecasting
Rainfall forecasting
Rainfall climatology
Part of the Nature series: Weather

The following is a glossary of tropical cyclone terms.


Official information issued by tropical cyclone warning centers describing all tropical cyclone watches and warnings in effect along with details concerning tropical cyclone locations, intensity and movement, and precautions that should be taken. Advisories are also issued to describe: (a) tropical cyclones prior to issuance of watches and warnings and (b) subtropical cyclones.


Best track
A subjectively-smoothed representation of a tropical cyclone's location and intensity over its lifetime. The best track contains the cyclone's latitude, longitude, maximum sustained surface winds, and minimum sea-level pressure at 6-hourly intervals. Best track positions and intensities, which are based on a post-storm assessment of all available data, may differ from values contained in storm advisories. They also generally will not reflect the erratic motion implied by connecting individual center fix positions.


Generally speaking, the vertical axis of a tropical cyclone, usually defined by the location of minimum wind or minimum pressure. The cyclone center position can vary with altitude. In advisory products, refers to the center position at the surface.
Center / Vortex Fix
The location of the center of a tropical or subtropical cyclone obtained by reconnaissance aircraft penetration, satellite, radar, or synoptic data.
Central North Pacific Basin
The region north of the Equator between 140W and the International Dateline. The Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii is responsible for tracking tropical cyclones in this region.
Coriolis force
The fictitious force that causes the apparent deflection of an object that is moving in a straight line in an inertial reference frame as perceived by an observer in a rotating reference frame. The effect of this force is at its minimum at the equator and increases away from it. In the synoptic scales of the atmosphere, the Coriolis force will cause flow flowing towards a low pressure area to deflect perpendicularly to the pressure gradient driving the flow. [1] This causes the flow to rotate cyclonically about its center, producing geostrophic flow. [2] Tropical cyclones require a minimum distance of 500 km (310 mi) from the equator to sustain tropical cyclogenesis. [3]
An atmospheric closed circulation rotating counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.


Direct hit
A close approach of a tropical cyclone to a particular location. For locations on the left-hand side of a tropical cyclone's track (looking in the direction of motion), a direct hit occurs when the cyclone passes to within a distance equal to the cyclone's radius of maximum wind. For locations on the right-hand side of the track, a direct hit occurs when the cyclone passes to within a distance equal to twice the radius of maximum wind. Compare indirect hit, strike.


Eastern North Pacific Basin
The portion of the North Pacific Ocean east of 140W. The National Hurricane Center in Miami, Florida is responsible for tracking tropical cyclones in this region.
The roughly circular area of comparatively light winds that encompasses the center of a severe tropical cyclone. The eye is either completely or partially surrounded by the eyewall cloud.
Eyewall / Wall Cloud
An organized band or ring of cumulonimbus clouds that surround the eye, or light-wind center of a tropical cyclone. Eyewall and wall cloud are used synonymously.
A term used in advisories and tropical summaries to indicate that a cyclone has lost its "tropical" characteristics. The term implies both poleward displacement of the cyclone and the conversion of the cyclone's primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes. It is important to note that cyclones can become extratropical and still retain winds of hurricane or tropical storm force.
Extratropical cyclone
A cyclone of any intensity for which the primary energy source is baroclinic, that is, results from the temperature contrast between warm and cold air masses.


Fujiwhara effect
The tendency of two nearby tropical cyclones to rotate cyclonically about each other.


Gale Warning
A warning of 1-minute or 10-minute sustained surface winds in the range 34 kn (39 mph or 63 km/h) to 47 kn (54 mph or 87 km/h) inclusive, either predicted or occurring and not directly associated with tropical cyclones.


High Wind Warning
A high wind warning is defined as 1-minute average surface winds of 35 kn (40 mph or 64 km/h) or greater lasting for 1 hour or longer, or winds gusting to 50 kn (58 mph or 93 km/h) or greater regardless of duration that are either expected or observed over land.
The short name for the Hurricane Database, the database for all tropical cyclones in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea since 1851, and the Northeast Pacific Ocean since 1949. [4]
Hurricane / Typhoon
A tropical cyclone in which the maximum sustained surface wind (using the U.S. 1-minute average) is 64 kn (74 mph or 119 km/h) or more. The term hurricane is used for Northern Hemisphere tropical cyclones east of the International Dateline to the Greenwich Meridian. The term typhoon is used for Pacific tropical cyclones north of the Equator west of the International Dateline.
Hurricane Local Statement
A public release prepared by local National Weather Service offices in or near a threatened area giving specific details for its county/parish warning area on (1) weather conditions, (2) evacuation decisions made by local officials, and (3) other precautions necessary to protect life and property.
Hurricane Season
The portion of the year having a relatively high incidence of hurricanes. The hurricane season in the Atlantic, Caribbean, and Gulf of Mexico runs from June 1 to November 30. The hurricane season in the Eastern Pacific basin runs from May 15 to November 30. The hurricane season in the Central Pacific basin runs from June 1 to November 30.
Hurricane Warning
An announcement that hurricane conditions (sustained winds of 74 mph or higher) are expected somewhere within the specified coastal area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane warning is issued 36 hours in advance of the anticipated onset of tropical-storm-force winds.
Hurricane Watch
An announcement that hurricane conditions (sustained winds of 74 mph or higher) are possible within the specified coastal area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds.


Indirect Hit
Generally refers to locations that do not experience a direct hit from a tropical cyclone, but do experience hurricane-force winds (either sustained or gusts) or tides of at least 4 feet above normal.
Inland Tropical Storm Warning
The equivalent of a Tropical Storm Warning for inland counties, put into use after multiple Tornado Warnings were issued for Hurricane Katrina, when tornadoes were not present, but winds were the equivalent of EF0-2 tornadoes. These are issued by local NWS forecast offices, not the NHC.
Inland Hurricane Warning
The equivalent of a Hurricane Warning for inland counties, put into use after multiple Tornado Warnings were issued for Hurricane Katrina, when tornadoes were not present, but winds were the equivalent of EF0-2 tornadoes. These are issued by local NWS forecast offices, not the NHC.
A weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g., microwave imagery) and/or running model guidance. Once a system has been designated as an invest, data collection and processing is initiated on a number of government and academic web sites, including the Naval Research Laboratory (NRL) and the University of Wisconsin Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS). The designation of a system as an invest does not correspond to any particular likelihood of development of the system into a tropical cyclone; operational products such as Tropical Weather Outlooks or Significant Tropical Weather Advisories should be consulted for this purpose.


Kelvin wave
An eastward moving atmospheric wave that can enhance deep convection and contribute to tropical cyclogenesis, especially over the Pacific Ocean. They towards the east at about 10° to 20° longitude per day.


The intersection of the surface center of a tropical cyclone with a coastline. Because the strongest winds in a tropical cyclone are not located precisely at the center, it is possible for a cyclone's strongest winds to be experienced over land even if landfall does not occur. Similarly, it is possible for a tropical cyclone to make landfall and have its strongest winds remain over the water. Compare direct hit, indirect hit, and strike.


Major hurricane
A designation used by the National Hurricane Center reserved for hurricanes in the Atlantic or Northeast Pacific basins that achieve Category 3 in the Saffir–Simpson Hurricane Scale. These storms have winds of at least 96  knots (178 km/h; 111 mph). [5]


Air that flows outwards from a storm system; associated with ridging, or anticyclonic flow. Low-level outflow boundaries from mesoscale convective complexes can disrupt the center of small tropical cyclones. [6] However, outflow aloft is essential for the strengthening of a tropical cyclone. [7] If this outflow is undercut, the tropical cyclone weakens. If two tropical cyclones are in proximity, the upper level outflow from the system to the west can limit the development of the system to the east. [8]


Philippine Area of Responsibility
An area bounded by rhumb lines on the Philippine Tropical Cyclone Tracking Chart/Map or imaginary lines on the surface of the earth that makes equal oblique angles with all meridians joining the following points: 25°N 135°E, 25°N 120°E, 5°N 135°E, 5°N 115°E, 15°N 115°E, and 21°N 120°E. Tropical cyclone bulletins are issued by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) every six or twelve hours for all tropical cyclones within this area.
Post-storm Report
A report issued by a US National Weather Service office summarizing the impact of a tropical cyclone on its forecast area. These reports include information on observed winds, pressures, storm surges, rainfall, tornadoes, damage and casualties.
Post-tropical Cyclone
A former tropical cyclone. This generic term describes a cyclone that no longer possesses sufficient tropical characteristics to be considered a tropical cyclone. Post-tropical cyclones can continue carrying heavy rains and high winds. Note that former tropical cyclones that have become fully well as remnant lows...are two classes of post-tropical cyclones.
Potential Tropical Cyclone
At the start of the 2017 season, the NHC changed their internal policy to allow advisories and thus tropical cyclone watches and warnings to be issued for tropical disturbances that do not yet satisfy the definition of a tropical cyclone, but have a high chance at becoming one, and pose the threat of tropical storm-force winds to landmasses within 48 hours. These systems are designated as "Potential Tropical Cyclones". [9]
Preliminary Report
Now known as the "Tropical Cyclone Report". A report summarizing the life history and effects of an Atlantic or eastern Pacific tropical cyclone. It contains a summary of the cyclone life cycle and pertinent meteorological data, including the post-analysis best track (six-hourly positions and intensities) and other meteorological statistics. It also contains a description of damage and casualties the system produced, as well as information on forecasts and warnings associated with the cyclone. NHC writes a report on every tropical cyclone in its area of responsibility.
Present Movement
The best estimate of the movement of the center of a tropical cyclone at a given time and given position. This estimate does not reflect the short-period, small scale oscillations of the cyclone center.


Radius of maximum wind
The distance from the center of a tropical cyclone to the location of the cyclone's maximum winds. In well-developed hurricanes, the radius of maximum winds is generally found at the inner edge of the eyewall.
Radius of outermost closed isobar (ROCI)

One of the quantities used to determine the size of a tropical cyclone. The ROCI is determined by measuring the radii from the center of the storm to its outermost closed isobar in four quadrants, which is then averaged to come up with a scalar value. It generally delimits the outermost extent of a tropical cyclone's wind circulation. [10]

A scalar or scalar quantity in physics is a physical quantity that can be described by a single element of a number field such as a real number, often accompanied by units of measurement. A scalar is usually said to be a physical quantity that only has magnitude and no other characteristics. This is in contrast to vectors, tensors, etc. which are described by several numbers that characterize their magnitude, direction, and so on.

Rapid deepening
An increase in the maximum sustained winds of a tropical cyclone of at least 30 kn in a 24-h period.
A term used in an advisory to indicate that a vector drawn from the preceding advisory position to the latest known position is not necessarily a reasonable representation of the cyclone's movement.
A term used in an advisory to indicate that the center of a tropical cyclone, usually weak, has dissipated and a new center has formed at a different location. This will sometimes lead to an incorrect representation of movement. The center of a cyclone can reform multiple times in its life. The new center is not given a new name, unless there is a period of time between old center dissipation and new center reformation.
Remnant Low
A post-tropical cyclone that no longer possesses the convective organization required of a tropical cyclone...and has maximum sustained winds of less than 34 knots. The term is most commonly applied to the nearly deep-convection-free swirls of stratocumulus in the eastern North Pacific.


CategoryWind SpeedDamage
174 - 95Very dangerous winds will produce some damage
296 - 110Extremely dangerous winds will cause extensive damage
3111 - 130Devastating damage will occur
4131 - 155Catastrophic damage will occur
5> 155Catastrophic damage will occur
Saffir-Simpson Hurricane Scale/Saffir-Simpson Hurricane Wind Scale
The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the indicated time. The scale provides examples of the type of damage and impacts in the United States associated with winds of the indicated intensity. The following table shows the scale broken down by winds:
Sea surface temperature
Water temperature close to the surface of a large body of water, such as an ocean or sea. Normally, an ocean temperature of 26.5 °C (79.7 °F) spanning through at least a 50-metre depth is one of the six requirements needed to maintain the special mesocyclone that is the tropical cyclone. [3] These warm waters are needed to maintain the warm core that fuels tropical systems.
Severe Tropical Storm
A term used by the Japan Meteorological Agency to describe a typhoon with 10-minute windspeeds between 88–117 km/h (55–73 mph).
Severe Typhoon
A term used by the Hong Kong Observatory to describe a typhoon with 10-minute windspeeds between
Storm surge
An abnormal rise in sea level accompanying a hurricane or other intense storm, and whose height is the difference between the observed level of the sea surface and the level that would have occurred in the absence of the cyclone. Storm surge is usually estimated by subtracting the normal or astronomic high tide from the observed storm tide.
Storm tide
The actual level of sea water resulting from the astronomic tide combined with the storm surge.
Storm Warning
A warning of 1-minute sustained surface winds of 48 kn (55 mph or 88 km/h) or greater, either predicted or occurring, not directly associated with tropical cyclones.
strike zone diagram For any particular location, a hurricane strike occurs if that location passes within the hurricane's strike circle, a circle of 125 nmi diameter, centered 12.5 nmi to the right of the hurricane center (looking in the direction of motion). This circle is meant to depict the typical extent of hurricane-force winds, which are approximately 75 nmi to the right of the center and 50 nmi to the left.
Subtropical cyclone
A non-frontal low pressure system that has characteristics of both tropical and extratropical cyclones. This system is typically an upper-level cold low with circulation extending to the surface layer and maximum sustained winds generally occurring at a radius of about 100 miles or more from the center. In comparison to tropical cyclones, such systems have a relatively broad zone of maximum winds that is located farther from the center, and typically have a less symmetric wind field and distribution of convection.
Subtropical Depression
(Atlantic/Eastern Pacific Ocean) - A subtropical cyclone in which the maximum sustained surface wind speed is 33 kn (38 mph or 62 km/h) or less.
Subtropical Depression
(South-West Indian Ocean) - a named or unnamed subtropical cyclone.
Subtropical Storm
A subtropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 34 kn (39 mph or 63 km/h) or more.
Super Tropical Cyclone
A term used by RSMC Nadi and the Tropical Cyclone Warning Centers in Perth, Darwin, Jakarta, Port Moresby and Wellington, to describe an Australian category 3, 4 or 5 tropical cyclone that has windspeeds greater than 120 km/h (75 mph).
Super Typhoon (CMA)
A term used by the China Meteorological Administration, to describe a typhoon in the Western Pacific that has sustained windspeeds greater than over a 3-minute period
Super Typhoon (HKO)
A term used by the Hong Kong Observatory, to describe a typhoon in the Western Pacific that has sustained windspeeds greater than over a 10-minute period
Super Typhoon (JTWC)
A term used by the Joint Typhoon Warning Center in the Western Pacific, to describe a typhoon that has sustained windspeeds greater than 130 knots over a 1-minute period.
Super Typhoon (PAGASA)
A term used by PAGASA to unofficially describe a typhoon in the Western Pacific, that the Joint Typhoon Warning Center has called a Super Typhoon.
Synoptic flights
Weather reconnaissance mission flown to provide vital meteorological information in data sparse ocean areas as a supplement to existing surface, radar, and satellite data. Synoptic flights better define the upper atmosphere and aid in the prediction of tropical cyclone development and movement.


Tropical cyclogenesis
Tropical cyclogenesis is the technical term that describes the development and strengthening of a tropical cyclone in the atmosphere. [11] Tropical cyclogenesis involves the development of a warm-core cyclone, due to significant convection in a favorable atmospheric environment. [12] There are six main requirements for tropical cyclogenesis: sufficiently warm sea surface temperatures, atmospheric instability, high humidity in the lower to middle levels of the troposphere, enough Coriolis force to develop a low pressure center, a preexisting low level focus or disturbance, and low vertical wind shear. [3]
Tropical cyclone
A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat export at the low temperatures of the upper troposphere. In this they differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere (baroclinic effects).
Tropical depression
A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 33 kn (38 mph or 62 km/h) or less.
Tropical disturbance
A discrete tropical weather system of ostensibly organized convectiongenerally 100 to 300 nmi in diameteroriginating in the tropics or subtropics, having a non-frontal migratory character, and maintaining its identity for 24 hours or more. It may or may not be associated with a detectable perturbation of the wind field.
Tropical storm
A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) ranges from 34 kn (39 mph or 63 km/h) to 63 kn (73 mph or 118 km/h).
Tropical Storm Warning
An announcement that tropical storm conditions (sustained winds of 39 to 73 mph) are expected somewhere within the specified coastal area within 36 hours.
Tropical Storm Watch
An announcement that tropical storm conditions (sustained winds of 39 to 73 mph) are possible within the specified coastal area within 48 hours.
Tropical wave
A trough or cyclonic curvature maximum in the trade-wind easterlies. The wave may reach maximum amplitude in the lower middle troposphere.
Tropical Weather Outlook (TWO)
An official forecast highlighting the probability of a tropical cyclone developing.
A tropical cyclone with winds exceeding 74 mph (118 km/h) in the western Pacific Ocean, the equivalent of a hurricane


Western North Pacific Basin
The portion of the North Pacific Ocean from 100E to 180E. The Joint Typhoon Warning Center in Pearl Harbor, Hawaii, and the Japan Meteorological Agency are both responsible for tracking tropical cyclones in this region

See also

This article serves as a glossary of climate change terms. It lists terms that are related to global warming.

Glossary of meteorology Wikimedia list article

This glossary of meteorology is a list of terms and concepts relevant to meteorology and the atmospheric sciences, their sub-disciplines, and related fields.

The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.

Related Research Articles

Cyclone large scale air mass that rotates around a strong center of low pressure

In meteorology, a cyclone is a large scale air mass that rotates around a strong center of low atmospheric pressure. Cyclones are characterized by inward spiraling winds that rotate about a zone of low pressure. The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale. Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale. Mesocyclones, tornadoes and dust devils lie within smaller mesoscale. Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the tropical upper tropospheric trough during the summer months in the Northern Hemisphere. Cyclones have also been seen on extraterrestrial planets, such as Mars and Neptune. Cyclogenesis is the process of cyclone formation and intensification. Extratropical cyclones begin as waves in large regions of enhanced mid-latitude temperature contrasts called baroclinic zones. These zones contract and form weather fronts as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones occlude as cold air masses undercut the warmer air and become cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical jet stream.

Subtropical cyclone

A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone.

The Saffir–Simpson hurricane wind scale (SSHWS), formerly the Saffir–Simpson hurricane scale (SSHS), classifies hurricanes – Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms – into five categories distinguished by the intensities of their sustained winds.

Tropical cyclones and subtropical cyclones are named by various warning centers to provide ease of communication between forecasters and the general public regarding forecasts, watches, and warnings. The names are intended to reduce confusion in the event of concurrent storms in the same basin. Generally once storms produce sustained wind speeds of more than 33 knots, names are assigned in order from predetermined lists depending on which basin they originate. However, standards vary from basin to basin: some tropical depressions are named in the Western Pacific, while tropical cyclones must have a significant amount of gale-force winds occurring around the centre before they are named in the Southern Hemisphere.

Typhoon type of tropical cyclone

A typhoon is a mature tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere. This region is referred to as the Northwestern Pacific Basin, and is the most active tropical cyclone basin on Earth, accounting for almost one-third of the world's annual tropical cyclones. For organizational purposes, the northern Pacific Ocean is divided into three regions: the eastern, central, and western. The Regional Specialized Meteorological Center (RSMC) for tropical cyclone forecasts is in Japan, with other tropical cyclone warning centers for the northwest Pacific in Hawaii, the Philippines and Hong Kong. While the RSMC names each system, the main name list itself is coordinated among 18 countries that have territories threatened by typhoons each year A hurricane is a storm that occurs in the Atlantic Ocean or the northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, and a tropical cyclone occurs in the South Pacific or the Indian Ocean.

Tropical cyclones are unofficially ranked on one of five tropical cyclone intensity scales, according to their maximum sustained winds and which tropical cyclone basin(s) they are located in. Only a few scales of classifications are used officially by the meteorological agencies monitoring the tropical cyclones, but some alternative scales also exist, such as accumulated cyclone energy, the Power Dissipation Index, the Integrated Kinetic Energy Index, and the Hurricane Severity Index.

Rapid intensification

Rapid intensification is a meteorological condition that occurs when a tropical cyclone intensifies dramatically in a short period of time. The United States National Hurricane Center (NHC) defines rapid intensification as an increase in the maximum 1-min sustained winds of a tropical cyclone of at least 30 knots in a 24-hour period.

2006 Central Pacific cyclone

The 2006 Central Pacific cyclone, also known as Invest 91C or Storm 91C, was an unusual weather system that formed in 2006. Forming on October 30 from a mid-latitude cyclone in the north Pacific mid-latitudes, it moved over waters warmer than normal. The system acquired some features more typical of subtropical and even tropical cyclones. However, as it neared western North America, the system fell apart, dissipating soon after landfall, on November 4. Moisture from the storm's remnants caused substantial rainfall in British Columbia and the Pacific Northwest. The exact status and nature of this weather event is unknown, with meteorologists and weather agencies having differing opinions.

1994 North Indian Ocean cyclone season cyclone season in the North Indian ocean

The 1994 North Indian Ocean cyclone season was the period in which tropical cyclones formed within the north Indian Ocean. The season has no official bounds but cyclones tend to form within this basin between April and December. There are two main seas in the North Indian Ocean — the Bay of Bengal to the east of the Indian subcontinent and the Arabian Sea to the west of India. The official Regional Specialized Meteorological Centre in this basin is the India Meteorological Department (IMD), while the Joint Typhoon Warning Center releases unofficial advisories. An average of four to six storms form in the North Indian Ocean every season with peaks in May and November. Cyclones occurring between the meridians 45°E and 100°E are included in the season by the IMD.

Tropical Storm Faxai (2007) Pacific severe tropical storm in 2007

Severe Tropical Storm Faxai, known in the Philippines as Tropical Storm Juaning, was a short-lived tropical storm that had minor effects on land. The twentieth named storm of the 2007 Pacific typhoon season, Faxai originated from a tropical depression over the open waters of the western Pacific Ocean in late October. The storm quickly strengthened, becoming a severe tropical storm on October 26 as it rapidly traveled towards the northeast. The storm became extratropical the following day as it brushed Japan. The remnants dissipated on October 28.

2010–11 South-West Indian Ocean cyclone season cyclone season in the South-West Indian ocean

The 2010–11 South-West Indian Ocean cyclone season was the least active cyclone season on record in the basin, tied with 1982–83, producing only four systems of gale intensity. This was due to cooler than normal water temperatures and the Walker circulation – a broad atmospheric circulation – causing unusually moist conditions in the eastern Indian Ocean and unusually dry conditions in the western Indian Ocean. The basin includes the waters of the ocean south of the equator and west of 90º E to the eastern coast of Africa.

Typhoon Nida (2009) Pacific typhoon in 2009

Typhoon Nida, known in the Philippines as Tropical Storm Vinta, was the most intense tropical cyclone in the Northwest Pacific Ocean during the 2000s, tied with Jangmi in 2008.

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.

1994–95 South Pacific cyclone season cyclone season in the South Pacific ocean

The 1994–95 South Pacific cyclone season was one of the least active South Pacific tropical cyclone season's on record, with only two tropical cyclones officially occurring within the South Pacific Ocean basin between 160°E and 120°W. The season ran from November 1, 1994, until April 30, 1995, with the first disturbance of the season developing on November 12 and the last disturbance dissipating on March 17. The most intense tropical cyclone during the season was Tropical Cyclone William, which affected the Cook Islands. After the season the name William was retired from the tropical cyclone naming lists.

Meteorological history of Typhoon Haiyan

Typhoon Haiyan's meteorological history began with its origins as a tropical disturbance east-southeast of Pohnpei and lasted until its degeneration as a tropical cyclone over Southern China. The thirteenth typhoon of the 2013 Pacific typhoon season, Haiyan originated from an area of low pressure several hundred kilometers east-southeast of Pohnpei in the Federated States of Micronesia on November 2. Tracking generally westward, environmental conditions favored tropical cyclogenesis and the system developed into a tropical depression the following day. After becoming a tropical storm and attaining the name Haiyan at 0000 UTC on November 4, the system began a period of rapid intensification that brought it to typhoon intensity by 1800 UTC on November 5. By November 6, the Joint Typhoon Warning Center (JTWC) assessed the system as a Category 5-equivalent super typhoon on the Saffir-Simpson hurricane wind scale; the storm passed over the island of Kayangel in Palau shortly after attaining this strength.

Hurricane Genevieve (2014)

Hurricane Genevieve, also referred to as Typhoon Genevieve, was the fourth-most intense tropical cyclone of the North Pacific Ocean in 2014. A long-lasting system, Genevieve was the first one to track across all three northern Pacific basins since Hurricane Dora in 1999. Genevieve developed from a tropical wave into the eighth tropical storm of the 2014 Pacific hurricane season well east-southeast of Hawaii on July 25. However, increased vertical wind shear caused it to weaken into a tropical depression by the following day and degenerate into a remnant low on July 28. Late on July 29, the system regenerated into a tropical depression, but it weakened into a remnant low again on July 31, owing to vertical wind shear and dry air.

Typhoon Songda (2016)

Typhoon Songda was the sixth most intense tropical cyclone of the Northwest Pacific Ocean in 2016. Also known as the Ides of October storm, it struck the Pacific Northwest region of the United States and Canada as a powerful extratropical cyclone. Songda was the twentieth named storm and the ninth typhoon of the annual typhoon season. The system developed into a tropical storm south of Minamitorishima on October 8 and strengthened into a typhoon on October 10. Songda reached its peak intensity southeast of Japan late on October 11 at an unusually high latitude, before it became extratropical on October 13.

Typhoon Irving (1982)

Typhoon Irving, known in the Philippines as Typhoon Ruping, was a mid-season tropical cyclone that affected the Philippines and China during September 1982. An area of disturbed weather developed within the monsoon trough in early September 1982 near Guam. Following an increase in organization, a tropical depression developed on the morning of September 5. Later that day, the depression intensified into Tropical Storm Irving. Irving tracked westward, nearly becoming a typhoon before hitting the central Philippines. There, Irving uprooted trees, downed power and telephone lines, triggered landslides and forced the cancellation of several domestic airline flights. Irving damaged 7,890 houses in Albay and Sorsogon provinces alone, resulting in 138,500 people rendered homeless. Nation-wide, 65 people were killed, 26 others were hurt, and 29 were rendered missing. A total of 44,383 families or 248,040 residents sought shelter. Moreover, 18,488 homes were damaged and 5,599 others were demolished. Damage in the country was assessed at US$23.3 million, including US$14.2 million in crops. While crossing the island chain, Irving turned northwestward. After entering the South China Sea, Irving continued generally northwest, and became a typhoon on September 11. After developing a well-defined eye, Irving attained peak intensity the following day. Land interaction with Hainan Island resulted in a weakening trend, and Irving was downgraded to a tropical storm before striking the southern coast of China. Across the Leizhou Peninsula, 90% of homes were damaged. Onshore, Irvine rapidly weakened and the storm dissipated on September 16.

Hurricane Olivia (2018)

Hurricane Olivia was the first tropical cyclone to make landfall on Maui and Lanai in recorded history. The fifteenth named storm, ninth hurricane, and sixth major hurricane of the 2018 Pacific hurricane season, Olivia formed southwest of Mexico on September 1. The depression slowly organized and strengthened into Tropical Storm Olivia on the next day. Olivia then began a period of rapid intensification on September 3, reaching its initial peak on September 5. Soon after, Olivia began a weakening trend, before re-intensifying on September 6. On the next day, Olivia peaked as a Category 4 hurricane, with winds of 130 mph and a minimum central pressure of 951 mbar. Six hours later, Olivia began another weakening trend that resulted in the hurricane being downgraded to Category 1 status on September 8, east of the 140th meridian west. On September 9, Olivia entered the Central Pacific Basin. Over the next couple of days, Olivia prompted the issuance of Tropical Storm Watches and Warnings for Hawaii County, Oahu, Maui County, and Kauai County. Olivia weakened into a tropical storm on September 11, before making brief landfalls in northwest Maui and Lanai on the next day, becoming the first tropical cyclone to impact the islands in recorded history. Tropical storm-force winds mainly affected Maui County and Oahu. Torrential rains affected the same area from September 11 to 13, causing flash flooding. Olivia caused a total of US$25 million in damages. Olivia was downgraded to a tropical depression on September 13 while continuing to head west. Due to wind shear disrupting Olivia's convection, the system weakened into a remnant low on September 14. Olivia crossed into the West Pacific Basin on September 19 as a remnant low, before dissipating later that day.


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PD-icon.svg This article incorporates  public domain material from the NOAA document "Glossary of NHC Terms" .