User:RandomInfinity17/Unusual areas of tropical cyclogenesis

Tropical cyclogenesis is formation and the strengthen of tropical cyclones in atmosphere. It generally occurs in one of seven basins officially recognized by the World Metrological Organization (WMO). These basins share the same requirements for tropical cyclone formation: warm sea surface temperatures, atmospheric instability, high humidity in the troposphere, enough Coriolis force to create a low-pressure system, a preexisting disturbance, and low vertical wind shear. However, tropical cyclones occasionally form outside these basins or form in areas with favorable conditions. The following is a list of unusual areas of tropical cyclogenesis.

South Atlantic
Due to high wind shear, a lack of disturbances from the Intertropical Convergence Zone (ITCZ), and cool sea surface temperatures, the tropical cyclogenesis development is rare in the South Atlantic. Despite this, there have been 57 subtropical cyclones, and six tropical cyclones that have formed in the region since 1957. Those six were a tropical storm off the coast of Angola in April 1991, a system off the coast of Bahia in January 2004, Hurricane Catarina in March 2004, Tropical Storm Antia in March 2010, Tropical Storm Iba in March 2019, and Tropical Storm 01Q in February 2021.

Other notable systems include Subtropical Storm Kurumí, which played a role in the 2020 Brazilian floods and mudslides, Subtropical Storm Ubá, which became the deadliest South Atlantic cyclone killing 15 in Bahia and Minas Gerais, and Subtropical Storm Yakecan, which caused freezing rain and killed two Southern Brazil and Uruguay.

Since 2011, the Brazilian Navy Hydrographic Center has given names to tropical and subtropical cyclones in METAREA V that have sustained winds of at least 65 km/h. The names are assigned in alphabetical order and without regard for year. The first name used was Arani and the last name used was Yakecan.

Mediterranean and Black Seas
Cool sea surface temperatures of 23 C and the lack of disturbances are the main caused for the lack of tropical cyclogenesis in the Mediterranean Sea. However, there have been many cases of tropical cyclogenesis happening at 17 C or lower, so the frequency of disturbances is a more likely explanation. On average, there are only 1-2 Mediterranean tropical-like cyclones form per year. However, there have been 100 instances of cyclogenesis between 1948 and 2021 in the region.

The deadliest storm of the 20th century in the region was a cyclone in 1969 that caused nearly 600 deaths in Tunisia and Algeria. A 20000-ton tanker in Malta split in half after striking a reef due to the storm. Another notable storm was Cyclone Celeno, which had winds of up to 135 km/h, equivalent to a category one hurricane on the Saffir-Simpson hurricane wind scale at its peak in January 1995. In November 2011, Tropical Storm Rolf became the first Mediterranean tropical-like cyclone to be recognized by NOAA. In November 2017, Cyclone Numa became the second deadliest Mediterranean cyclone on record after killing 22 in Italy, Greece, and Turkey. Cyclones Zorbas and Ianos in September 2018 and 2020 respectively both had hurricane force winds, with Ianos having category two force winds. The most recent storm was Storm Daniel in 2023, which killed over 4,000 people and caused over $21 billion in damages in Libya and Southeastern Europe.

The Black Sea is also a rare area for tropical cyclogenesis for similar reasons, and far less instances of tropical cyclogenesis have been seen. Major examples were in March 2002, August 2002, and September 2005.

Near the Equator
Due to the Coriolis force being weak around the equator, tropical cyclogenesis is rare around the equator. However. there have been many cases of tropical cyclones within 3° of the equator. In March 1956, Typhoon Sarah formed 1.7°N from the equator, the closest at the time and the third closest as of July. In January 1979, Typhoon Alice formed 2°N from the equator. In December 2001, Tropical Storm Vamei formed 1.4°N from the equator in the Natuna Sea, the closest formation to the equator on record.

In September 2002, an unnamed tropical storm became the closest equatorial tropical cyclone in the southern hemisphere, at 2.5°S. In November 2004, Cyclone Agni became the second most equatorial tropical cyclone on record at 1.5°N. Its remnant circulation later crossed the equator in early-December. Tropical Storm Peipah in April 2014 became the fourth closest tropical cyclone to the equator at 1.7°N. In December 2015, Tropical Depression Nine-C came 2.2°N, a record for the East Pacific basin. And in April 2019, Cyclone Fani developed only 1.9°N from the equator, the fifth closest tropical cyclone to the equator.

Middle latitudes
Low sea surface temperatures and high wind shear makes the mid-latitudes unfavorable for tropical cyclones. However, there have been many cases of tropical cyclogenesis of up to 42.0° from the equator. Most notable was in 1952, where an unnamed tropical storm in the North Atlantic formed at 42.0° N, a record for the Atlantic basin. An unnamed hurricane in 1971 attained hurricane status 46.0°N and reached 58.0°N while tropical. Tropical Storm Alberto in 1988 intensified into a tropical storm at 41.5°N, a record. Tropical Storm Nepartak in 2021 reached peak intensity 240 km east of Tokyo, later making the first landfall in the Miyagi Prefecture on record.

An unnamed hurricane in the Pacific in 1975 intensified into a hurricane at 41.0°N and reached 54.0°N while tropical, a record for the East Pacific. Tropical Storm Grace in 2009 became the farthest northeastern Atlantic tropical cyclone on record, reaching 48.8°N, 14.3°W. In 1997, Hurricane Guillermo maintained tropical storm intensity up to 39.0°N. Subtropical Storm Issa during the 2021–22 South-West Indian Ocean cyclone season developed at 30.8°S, one of the southernmost cyclones in the South-West Indian Ocean on record.

Southeast Pacific
The presence of cold sea surface temperatures and windshear from Humboldt Current causes Southeast Pacific to be hostile to tropical cyclogenesis. Tropical cyclogenesis is so rare in the region, that there is no official warning center east of 120°W. However, there have been five tropical or subtropical cyclones in the region. In May 1983, a short lived tropical depression developed near 110°W, the easternmost development in the South Pacific at the time. In February 1989, Cyclone Hinano developed at 124°W, the easternmost tropical cyclone that was officially named by a metrological service. It also became the strongest cyclone so far east.

In late-April and early-May of 2015, a subtropical cyclone formed at 102.9°W, breaking the record for the easternmost development at the time. It formed during a powerful El Niño, which raised sea surface temperatures by 1 °C (2 °F) and reduced wind shear. The system was unofficially named Katie by researchers. Another system, unofficially named Lexi by researchers, formed even further east at 83.7°W and reached 78.8°W while subtropical. This became the easternmost subtropical cyclone in the South Pacific on record. In January 2022, a subtropical storm, unofficially named Humberto, formed near 89.5°W and reached 85.6°W. In March 2023, an "unorganized tropical cyclone" formed off the coast of Peru, named Yaku by the National Meteorological and Hydrological Service of Peru. At least eight people were killed and $690 million in damages occurred.

Great Lakes
Due to cool sea surface temperatures and the northerly latitude of the region, there has only been five instances of tropical or subtropical cyclones over the Great Lakes. In October 1893, the Hurricane Nine crossed Lake Ontario as a tropical storm, killing at least 54 people and caused $700,000 (1893 USD) in damages. 10 vessels were lost and 29 were stranded. The 1898 Georgia hurricane crossed the Great Lakes as a tropical depression in October, causing no known damage. In August 1955, Hurricane Connie crossed both Lake Erie and Lake Huron as a tropical storm. Connie caused three people to drown and brought 65 mm of rainfall. 27 boats were destroyed and $150,000 in damages were caused by Connie in the Great Lakes area.

Two (sub)tropical cyclones occurred in the Great Lakes region in 1996. The first one was Hurricane Fran, which moved over Lake Erie as a tropical depression, bringing up to 164 mm of rainfall and causing $40 million in damages. The second one was the 1996 Lake Huron cyclone, the only recorded instance of a (sub)tropical cyclone forming over the Great Lakes. The system developed in mid-September, when the sea surface temperatures in the lakes are the highest. It caused over 100 mm of rain in the region, causing flooding on the eastern shores of Lake Huron.

Inland intensification
The lack of ocean energy and increased windshear over land is the main cause of tropical cyclones weaking over land. However, flat areas with ample moisture in the ground allow tropical cyclones to maintain or gain strength over land. The United States, China, and Australia are the main areas where this affect is observed. There has also been many cases of the brown ocean effect over South Asia. In August 1973, a tropical wave inland over Guinea developed into a tropical depression, later becoming Tropical Storm Christine. In June 2001, Tropical Storm Allison spent nearly 12 days inland over the Southern United States. While over Mississippi, it strengthened into a subtropical storm from a subtropical depression while over the Gulf of Mexico.

In August 2007, the remnants of Tropical Storm Erin intensified over Oklahoma into a gale force system, causing major rainfall and extensive flooding. In September 2016, a tropical depression over eastern Florida intensified into Tropical Storm Julia, another example of the brown ocean effect. In February 2018, Cyclone Kelvin peaked over land in Western Australia and weakened at a slow rate, causing extreme flooding and rainfall. In late-January and early February in 2021, Tropical Low 12U formed over Western Australia and peaked inland before moving out to sea. In August 2022, Deep Depression BOB 06 maintained strength as a tropical depression for three days over India, causing extreme flooding.

Elsewhere
The eastern North Atlantic, mainly between West Africa and Cape Verde, and near the Canary Islands, is unfavorable for tropical cyclones due to high wind shear. Only a few tropical cyclones have ever existed within this area. They are: Tropical Storm Becky in 1962, Tropical Storm Ginger in 1967, an unnamed tropical storm in 1988, Tropical Storm Delta in 2005, Tropical Storm Theta in 2020, and Tropical Storm Hermine in 2022. A study by the Climate Change Institute at the University of Maine showed that environmental conditions will becoming more hostile to tropical cyclogenesis in the area as the Earth warms.

Similar conditions along with cool sea surface temperatures around Morocco make tropical cyclones rare around the area. Thus, there has only been three tropical cyclones or remnants of tropical cyclones to pass within 200 km of the country. They are: Tropical Depression Vince in 2005, Extratropical Cyclone Delta in 2005, and Extratropical Cyclone Joaquin in 2015. A potential subtropical cyclone with a well-defined eye in mid-February 2002 formed near Rabat.

The extreme presence of dry air in the Red Sea, Persian Gulf, Gulf of Aden, and Gulf of Oman make tropical cyclones extremely rare. Only Cyclone One in 1984, Cyclone Gonu in 2007, Cyclone Sagar in 2018, and Cyclone Shaheen in 2021 managed to exist in these areas.

The West Coast of the United States is also hostile for tropical cyclones as cold sea surface temperatures and wind patterns in the atmosphere make tropical cyclones avoid the area. Thus, there only has been three tropical cyclones to affect the West Coast while out to sea. The first one was a possible hurricane in 1854, the second was the 1858 San Diego hurricane, and the third was the 1939 California tropical storm. In 2023, the center of Hurricane Hilary passed directly over Southern California and caused the first ever tropical storm warnings for the state. However, the National Hurricane Center marked a landfall in Baja California.