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Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of both tropical and extratropical cyclones.
As early as the 1950s, meteorologists were uncertain whether they should be characterized as tropical or extratropical cyclones. They were officially recognized and titled by the National Hurricane Center in 1972. Beginning in 2002, subtropical cyclones began receiving names from the official tropical cyclone lists in the North Atlantic basin. Subtropical cyclones are also recognized in the South-West Indian Ocean and South Atlantic basins.
There are two definitions currently used for subtropical cyclones depending on their location. Across the north Atlantic and southwest Indian Ocean, they require some central convection fairly near the center surrounding a warming core existing in the mid-levels of the troposphere. Across the eastern half of the northern Pacific however, they require a mid-tropospheric cyclone to be cut off from the main belt of the westerlies and with only a weak surface circulation. Subtropical cyclones have wider wind fields with the maximum sustained winds located further from the center than typical tropical cyclones, and have no weather fronts linked into their center.
Since they form from initially extratropical cyclones which have colder temperatures aloft than normally found in the tropics, the sea surface temperatures required for their formation are lower than the tropical cyclone threshold (around 26.5°C (79.7°F)) by 3°C (5°F), lying around 23 °C (73 °F). This also means that subtropical cyclones are more likely to form outside the traditional bounds of the North Atlantic hurricane season and at higher latitudes. Subtropical cyclones are also observed to form in the South Atlantic, where subtropical cyclones are observed in all months.
Throughout the 1950s and 1960s, the terms semi-tropical and quasi-tropical were used for what would become known as the subtropical cyclones. The term subtropical cyclone initially merely referred to any cyclone located in the subtropical belt near and just north of the horse latitudes. Later, intense debate ensued in the late 1960s, after a number of hybrid cyclones formed in the Atlantic Basin. In 1972, the National Hurricane Center (NHC) finally designated these "hybrid" storms as true subtropical cyclones in real-time, and updated the hurricane database to include subtropical cyclones from 1968 through 1971.
The term "neutercane" began to be used for small subtropical cyclones below 100 miles in diameter which formed from mesoscale features, and the NHC began issuing public statements during the 1972 Atlantic hurricane season employing that classification. This name was not noted as controversial in contemporary news reports, but it was quickly dropped less than a year later. Recent articles, published after the year 2000, have suggested that the name "neutercane" was considered sexist in the 1970s, but there do not appear to be any published reports from that period making this claim.
In the north Atlantic basin, subtropical cyclones were initially named from the NATO phonetic alphabet list in the early to mid-1970s. In the intervening years of 1975–2001, subtropical storms were either named from the traditional list and still was considered tropical in real-time, or used a separate numbering system instead. Between 1992 and 2001, two different numbers were given to subtropical depressions or subtropical storms, one for public use, the other one for NRL and NHC reference. For example, Hurricane Karen in 2001 was initially known as Subtropical Storm One as well as AL1301 (or 13L for short). In 2002, the NHC began giving numbers to subtropical depressions and names to subtropical storms from the same sequence as tropical cyclones. From 2002 onward, Subtropical Depression 13L would be known as Subtropical Depression Thirteen instead. Hurricane Gustav of 2002 was the first subtropical storm to receive a name but became tropical shortly after naming. Subtropical Storm Nicole from the 2004 Atlantic hurricane season was the first subtropical storm that did not become tropical since the policy change. A subtropical storm from the 2005 Atlantic hurricane season also did not become tropical, but was not named since it was not recognized until post-season analysis.
In the southern Indian Ocean, subtropical cyclones are also named once winds reach tropical storm or gale force.
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Subtropical cyclone AI simulator
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Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of both tropical and extratropical cyclones.
As early as the 1950s, meteorologists were uncertain whether they should be characterized as tropical or extratropical cyclones. They were officially recognized and titled by the National Hurricane Center in 1972. Beginning in 2002, subtropical cyclones began receiving names from the official tropical cyclone lists in the North Atlantic basin. Subtropical cyclones are also recognized in the South-West Indian Ocean and South Atlantic basins.
There are two definitions currently used for subtropical cyclones depending on their location. Across the north Atlantic and southwest Indian Ocean, they require some central convection fairly near the center surrounding a warming core existing in the mid-levels of the troposphere. Across the eastern half of the northern Pacific however, they require a mid-tropospheric cyclone to be cut off from the main belt of the westerlies and with only a weak surface circulation. Subtropical cyclones have wider wind fields with the maximum sustained winds located further from the center than typical tropical cyclones, and have no weather fronts linked into their center.
Since they form from initially extratropical cyclones which have colder temperatures aloft than normally found in the tropics, the sea surface temperatures required for their formation are lower than the tropical cyclone threshold (around 26.5°C (79.7°F)) by 3°C (5°F), lying around 23 °C (73 °F). This also means that subtropical cyclones are more likely to form outside the traditional bounds of the North Atlantic hurricane season and at higher latitudes. Subtropical cyclones are also observed to form in the South Atlantic, where subtropical cyclones are observed in all months.
Throughout the 1950s and 1960s, the terms semi-tropical and quasi-tropical were used for what would become known as the subtropical cyclones. The term subtropical cyclone initially merely referred to any cyclone located in the subtropical belt near and just north of the horse latitudes. Later, intense debate ensued in the late 1960s, after a number of hybrid cyclones formed in the Atlantic Basin. In 1972, the National Hurricane Center (NHC) finally designated these "hybrid" storms as true subtropical cyclones in real-time, and updated the hurricane database to include subtropical cyclones from 1968 through 1971.
The term "neutercane" began to be used for small subtropical cyclones below 100 miles in diameter which formed from mesoscale features, and the NHC began issuing public statements during the 1972 Atlantic hurricane season employing that classification. This name was not noted as controversial in contemporary news reports, but it was quickly dropped less than a year later. Recent articles, published after the year 2000, have suggested that the name "neutercane" was considered sexist in the 1970s, but there do not appear to be any published reports from that period making this claim.
In the north Atlantic basin, subtropical cyclones were initially named from the NATO phonetic alphabet list in the early to mid-1970s. In the intervening years of 1975–2001, subtropical storms were either named from the traditional list and still was considered tropical in real-time, or used a separate numbering system instead. Between 1992 and 2001, two different numbers were given to subtropical depressions or subtropical storms, one for public use, the other one for NRL and NHC reference. For example, Hurricane Karen in 2001 was initially known as Subtropical Storm One as well as AL1301 (or 13L for short). In 2002, the NHC began giving numbers to subtropical depressions and names to subtropical storms from the same sequence as tropical cyclones. From 2002 onward, Subtropical Depression 13L would be known as Subtropical Depression Thirteen instead. Hurricane Gustav of 2002 was the first subtropical storm to receive a name but became tropical shortly after naming. Subtropical Storm Nicole from the 2004 Atlantic hurricane season was the first subtropical storm that did not become tropical since the policy change. A subtropical storm from the 2005 Atlantic hurricane season also did not become tropical, but was not named since it was not recognized until post-season analysis.
In the southern Indian Ocean, subtropical cyclones are also named once winds reach tropical storm or gale force.