Subtropical cyclone
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A subtropical cyclone is a cyclonic weather system that has some characteristics of a tropical cyclone and some characteristics of an extratropical cyclone. They can form in a wide band of latitude, from the equator to 50°.
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[edit] Terms
A subtropical cyclone is a cyclonic weather system that is not purely tropical as a tropical cyclone, but has more tropical characteristics than an extratropical cyclone. Subtropical cyclones are only monitored in the northern Atlantic Ocean and in the eastern Pacific Ocean (east of the dateline). Like regular tropical cyclones, the majority of subtropical cyclones are known to have maximum windspeeds of at least 39 mph to 74 mph. Subtropical cyclones that have windspeeds less than 39 mph are known as "subtropical depressions".
[edit] Formation
A subtropical cyclone can form in many ways...
- Transition from an extratropical cyclone to a tropical cyclone (or vice-versa)
- An upper-level low assocuated with a cold core and deep convection.
- From the remants of a tropical cyclone after landfall while losing its tropical characteristics (although they are hardly monitored as such).
[edit] Naming
For the Atlantic and estern Pacific Oceans, the National Hurricane Center (which is the official place where people track Atlantic hurricanes) began monitoring subtropical cyclones the same with tropical cyclones in 2002 as well as naming them. In 1972 and 1973, the NHC used an extra list of names for subtropical cyclones, but were quickly rejected by many people. Then it used numbering for subtropical cyclones. In the 2004 Atlantic hurrican season, the NHC monitored the first and currently only named subtropical cyclone, its name was Subtropical Storm Nicole. In addition, another unnamed subtropical cyclone was identified from the 2005 Atlantic hurricane season by post-analysis of the season. Although it could have been named, the subtropical storm remained unnamed and had no official desginations since the time of the discovery was well past from the offical season time.