South Atlantic tropical cyclones are unusual weather events that occur in theSouthern Hemisphere. Strongwind shear, which disrupts the formation ofcyclones, as well as a lack of weather disturbances favorable for development in theSouth Atlantic Ocean, make any strong tropical system extremely rare, andHurricane Catarina in 2004 is the only recorded SouthAtlantic hurricane in history. Storms can develop year-round in the South Atlantic, with activity peaking during the months from November through May. Since 2011, theBrazilian Navy Hydrographic Center has assignednames to tropical and subtropical systems in the western side of thebasin, near the eastern coast of Brazil, when they have sustained wind speeds of at least 65 km/h (40 mph), the generally accepted minimum sustained wind speed for a disturbance to be designated as atropical storm in the North Atlantic basin. Below is a list of notable South Atlantic tropical andsubtropical cyclones.
It was initially thought that tropical cyclones did not develop within the South Atlantic.[1] Very strong verticalwind shear in thetroposphere is considered a deterrent.[2] TheIntertropical Convergence Zone drops one to two degrees south of the equator,[3] not far enough from the equator for theCoriolis force to significantly aid development. Water temperatures in the tropics of the southern Atlantic are cooler than those in the tropical north Atlantic.[4]
Although they are rare, during April 1991 the United States'National Hurricane Center (NHC) reported that a tropical cyclone had developed over the Eastern South Atlantic.[1][5] In subsequent years, a few systems were suspected to have the characteristics needed to be classified as a tropical cyclone, including in March 1994 and January 2004.[6][7] During March 2004, anextratropical cyclone formally transitioned into a tropical cyclone and made landfall on Brazil, after becoming a Category 2 hurricane on theSaffir–Simpson hurricane wind scale. While the system was threatening the Brazilian state ofSanta Catarina, a newspaper used the headline "Furacão Catarina", which was originally presumed to mean "furacão (hurricane) threatening (Santa) Catarina (the state)".[1] After international presses started monitoring the system, "Hurricane Catarina" has formally been adopted.
At the Sixth WMO International Workshop on Tropical Cyclones (IWTC-VI) in 2006, it was questioned if any subtropical or tropical cyclones had developed within the South Atlantic before Catarina.[7] It was noted that suspect systems had developed in January 1970, March 1994, January 2004, March 2004, May 2004, February 2006, and March 2006.[7] It was also suggested that an effort should be made to locate any possible systems using satellite imagery and synoptic data; however, it was noted that this effort may be hindered by the lack of any geostationary imagery over the basin before 1966.[7] A study was subsequently performed and published during 2012, which concluded that there had been 63 subtropical cyclones in the Southern Atlantic between 1957 and 2007.[8] During January 2009, a subtropical storm developed in the basin, and in March 2010, a tropical storm developed, which was named Anita by the Brazilian public and private weather services.[9][10] In 2011, theBrazilian Navy Hydrographic Center started to assignnames to tropical and subtropical cyclones that develop within its area of responsibility, to the west of20°W, when they have sustained wind speeds of at least 65 km/h (40 mph).[11]
| Tropical storm (SSHWS) | |
 | |
| Duration | 10 April 1991 – 14 April 1991 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); |
A low-pressure area formed over theCongo Basin on 9 April. The next day it moved offshore northernAngola with a curved cloud pattern. It moved westward over an area of warm waters while the circulation became better defined. According to the United StatesNational Hurricane Center, the system was probably either a tropical depression or a tropical storm at its peak intensity. On 14 April, the system rapidly dissipated, as it was absorbed into a largesquall line.[5][12] This is the only recorded tropical cyclone in the eastern South Atlantic.
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| Category 2 hurricane (SSHWS) | |
  | |
| Duration | 24 March 2004 – 28 March 2004 |
|---|---|
| Peak intensity | 155 km/h (100 mph) (1-min); 972 hPa (mbar) |
Hurricane Catarina was an extraordinarily rare hurricane-strength tropical cyclone, forming in the southern Atlantic Ocean in March 2004.[13] Soon after becoming a hurricane, it hit the southern coast of Brazil in the state ofSanta Catarina on the evening of 28 March, with winds up to 100 miles per hour (160 km/h) making it a Category 2-equivalent cyclone on theSaffir–Simpson hurricane scale.[14] Catarina killed 3 to 11 people and caused millions of dollars in damage in Brazil.[15]
At the time, Brazilians were taken completely by surprise, and were initially skeptical that an actual tropical cyclone could have formed in the South Atlantic. Eventually, however, they were convinced, and adopted the previously unofficial name "Catarina" for the storm, after Santa Catarina state. This event is considered by somemeteorologists to be a nearly once-in-a-lifetime occurrence.
| Tropical storm (SSHWS) | |
  | |
| Duration | 8 March 2010 – 12 March 2010 |
|---|---|
| Peak intensity | 85 km/h (50 mph) (1-min); 995 hPa (mbar) |
On 8 March 2010, a previously extratropical cyclone developed tropical characteristics and was classified as a subtropical cyclone off the coast of southern Brazil. The following day, theUnited States Naval Research Laboratory began monitoring the system as a system of interest under the designation of90Q. TheNational Hurricane Center also began monitoring the system as Low SL90. During the afternoon of 9 March, the system had attained an intensity of 55 km/h (34 mph) and abarometric pressure of 1000 hPa (mbar). It was declared a tropical storm on 10 March and became extratropical late on 12 March.[16] Anita'saccumulated cyclone energy was estimated at 2.0525 by the Florida State University. There was no damage associated to the storm, except high sea in the coasts of Rio Grande do Sul and Santa Catarina. Post mortem, the cyclone was given the name "Anita" by private and public weather centers in Southern Brazil.[17]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 14 March 2011 – 16 March 2011 |
|---|---|
| Peak intensity | 85 km/h (50 mph) (1-min); 998 hPa (mbar) |
Early on 14 March 2011, the Navy Hydrographic Center-Brazilian Navy (SMM), in coordination with theNational Institute of Meteorology, were monitoring an organizing area ofconvection near the southeast coast of Brazil.[18] Later that day alow-pressure area developed just east ofVitória, Espírito Santo,[19] and by 12:00 UTC, the system organized into asubtropical depression, located about 140 km (87 mi) east ofCampos dos Goytacazes.[20] Guided by atrough and a weakridge to its north, the system moved slowly southeastward over an area of warm waters,[21][22] intensifying into Subtropical Cyclone Arani on 15 March,[23] as named by the Brazilian Navy Hydrographic Center,[24] and achieving its lowest pressure.[25] The storm was classified as subtropical, as the convection was east of the center. On 16 March, Arani began experiencing 25 kn (13 m/s; 46 km/h; 29 mph) of wind shear because anotherfrontal system bumped it from behind.[26] As it moved east-southeastwards, it achieved its highest winds as it transitioned back to an extratropical cyclone, process that was concluded on early 17 March.[25]
Before it developed into a subtropical cyclone, Arani produced torrential rains over portions of southeasternBrazil, resulting in flash flooding and landslides. Significant damage was reported in portions ofEspírito Santo, though specifics are unknown.[27] Increased swells along the coast prompted ocean travel warnings.[28]
| Subtropical depression (SSHWS) | |
  | |
| Duration | 23 January 2015 – 24 January 2015 |
|---|---|
| Peak intensity | 55 km/h (35 mph) (1-min); 1008 hPa (mbar) |
On late 22 January 2015, instability areas formed well south of thestate of Rio de Janeiro, associated with atrough attached with alow-pressure area active on the region.[29] Early on the next day, over a region with anomalous warm sea surface temperatures, convection organized over a low-level center of circulation, which achieved its peak intensity of 70 km/h (43 mph).[29] Shortly after the system was declared a subtropical depression, about 200 nautical miles (370 km; 230 mi) to the southeast ofSão Paulo,Brazil.[30]
For the rest of the day, the storm moved south and then turned southwestward,[31] until it lost its subtropical characteristics over high seas on the next day, becoming a remnant low about 427 nautical miles (790 km; 490 mi) to the east ofRio Grande do Sul,Brazil.[29]
The Brazilian Navy noted in its post-season analysis that on early and mid 23 January the radiometer built into the AMSR-2 satellite found winds of 35 to 40 knots, which could led to the system been upgraded into a subtropical storm, but it didn't happen because no other measurement confirmed such findings.[29]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 5 February 2015 – 7 February 2015 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 992 hPa (mbar) |
On 5 February 2015, a subtropical depression developed about 105 nautical miles (195 km; 120 mi) to the southeast ofSão Paulo,Brazil.[32] During the next day, low-levelbaroclinity decreased around the system, as it moved southeastwards away from the Brazilian coast and into anomalously warm waters, where it intensified further.[33][34] The system was named Bapo by the Brazilian Navy Hydrography Center during 6 February as it had intensified into a subtropical storm.[35][36] Over the next couple of days the system continued to move south-eastwards, achieving its peak intensity just before it transitioned into anextratropical cyclone during 8 February.[37][34]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 10 March 2015 – 13 March 2015 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 998 hPa (mbar) |
On 10 March 2015, the Hydrographic Center of the Brazilian Navy began issuing warnings on Subtropical Depression 3 during early afternoon,[38] while theCenter for Weather Forecast and Climatic Studies (CPTEC inPortuguese) already assigned the nameCari for the storm.[39] At 00:00 UTC on 11 March, the Hydrographic Center of the Brazilian Navy upgraded Cari to a subtropical storm, also assigning this name to it.[40][41] On 12 March, the Brazilian Hydrographic Center downgraded Cari to a subtropical depression as it achieved its lowest pressure,[42][41] while the CPTEC stated that the storm had become a "Hybrid cyclone"[43] as it moved away from the continental coastline.[41] During early afternoon of 13 March, the Brazilian Navy declared that Cari became a remnant low.[44]
Cari brought heavy rainfall, flooding and landslides to eastern cities ofSanta Catarina andRio Grande do Sul states as it interacted with aSouth Atlantic Convergence Zone.[45][41] Rain totals from 100 to 180 mm (3.9 to 7.1 in) were observed associated with the storms and wind topped 75 km/h (47 mph) inCabo de Santa Marta.[45] A Navy buoy registered a 6-metre (20 ft) wave off the coast of Santa Catarina.[45]
| Subtropical depression (SSHWS) | |
  | |
| Duration | 5 January 2016 – 7 January 2016 |
|---|---|
| Peak intensity | 55 km/h (35 mph) (1-min); 1006 hPa (mbar) |
On 5 January 2016, the Hydrographic Center of the Brazilian Navy declared that a subtropical depression that formed from a dissipating extratropical cyclone, 325 nautical miles (600 km; 375 mi) east ofVitória, Espírito Santo.[46][47] On the next day, while shfting from a westward movement to a southward one, other agencies considered the system an invest for possible tropical transition, designating it as90Q.[48][49] However, on 7 January, the system degenerated into a remnant low 495 nautical miles (915 km; 570 mi) east of thestate of Rio de Janeiro.[46][48][50]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 15 November 2016 – 16 November 2016 |
|---|---|
| Peak intensity | 75 km/h (45 mph) (1-min); 998 hPa (mbar) |
On 15 November 2016, instability areas associated with atrough axis overRio de Janeiro's coastline led to the formation of a subtropical depression southwest of it.[51][52] It intensified into a subtropical storm and received the nameDeni on 16 November.[53] Moving south-southeastwards, Deni soon became extratropical shortly before 00:00 UTC on 17 November,[54] where it was absorbed by a mid-latitude frontal system.[51]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 4 December 2016 – 6 December 2016 |
|---|---|
| Peak intensity | 100 km/h (65 mph) (1-min); 992 hPa (mbar) |
An extratropical cyclone entered the South Atlantic Ocean fromSanta Catarina early on 4 December 2016.[55] Later, it intensified quickly and then transitioned into a subtropical storm shortly before 22:00BRST (00:00 UTC on 5 December), with the nameEçaí assigned by the Hydrographic Center of the Brazilian Navy.[56] Eçaí started to decay on 5 December as it moved Into cooler waters, and weakened into a subtropical depression at around 00:00 UTC on 6 December.[57][58] As it decayed and lost its subtropical characteristics, its center divided in two, with the new center moving away southeastwards and the old one degrading into a remnant frontal low.[57]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 9 December 2017 – 10 December 2017 |
|---|---|
| Peak intensity | 75 km/h (45 mph) (1-min); 996 hPa (mbar) |
On 8 December 2017 aSouth Atlantic Convergence Zone aligned with a through axis led to the formation of several instability areas.[59] On 9 December a subtropical storm formed from this setup, on border betweenEspírito Santo andBahia, moving southeastwards away from land.[59][60][61][62] On late 10 December, aCold front pushed Guará southwards towards cooler waters, where it started transitioning into anextratropical cyclone.[59] On early 11 December Guará attained its peak intensity,[63] shortly thereafter degenerating into a low-pressure area associated with a through axis.[59][64]
| Tropical storm (SSHWS) | |
  | |
| Duration | 23 March 2019 – 27 March 2019 |
|---|---|
| Peak intensity | 85 km/h (50 mph) (1-min); 1006 hPa (mbar) |
On 22 March 2019, a low-pressure area formed off the coast ofBahia after the passage of a frontal system.[65] On the next day, the cyclone developed a deep warm-core, thus being designated as a tropical depression.[65][66][67] On 24 March, the system intensified into a tropical storm, receiving the nameIba from the Brazilian Navy Hydrographic Center.[65] After moving southwestward for a couple of days, on 26 March, Iba reached its peak intensity.[65] Afterward, a cold front would approach the storm, which helped intensify the wind shear impacting Iba, leading to its weakening and extratropical transition.[65] On early 28 March, Iba would degenerate into a remnant low, becoming fully extratropical a day later.[65][68]
Iba was the first tropical storm to develop in the basin since Anita in 2010, as well as the first fully tropical system to be named from the Brazilian naming list.[69]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 19 May 2019 – 21 May 2019 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 1010 hPa (mbar) |
On 19 May 2019 several instability areas formed from a through axis off the coast ofEspírito Santo, which later coalesced into a subtropical depression.[70] On 20 May, the system strengthened into a subtropical storm, receiving the nameJaguar from the Brazilian Navy Hydrographic Center.[71] However, the system did not intensify any further, as it soon encountered unfavorable conditions while moving southeastwards, weakening into a subtropical depression on early 21 May.[70] Later that day, Jaguar degenerated into several sparse instability areas associated with a low-pressure area, which was absorbed by a frontal system on 22 May.[70]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 23 January 2020 – 24 January 2020 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 998 hPa (mbar) |
On 21 January 2020, the Brazilian Navy Hydrographic Center began monitoring an area of persisting thunderstorms nearSão Paulo for potential subtropical cyclone development. Generally tracking southeastward, the system began to organize within the afternoon of 22 January, aided by the establishment of aSouth Atlantic Convergence Zone, and was designated a subtropical depression early on 23 January.[72] Several hours later, due to a lack of wind shear, the system intensified into a subtropical storm and was given the nameKurumí.[73] After this bout of intensification, Kurumí moved southward and began to succumb to much more unfavorable conditions. It weakened back to a subtropical depression on late 24 January, due to an intensification of wind shear over its circulation due to the formation of anextratropical cyclone to its southeast.[72][74] The last advisory was issued on Kurumí later that same day, as it degenerated into atrough while also beginning to merge with the nearby frontal system.[72]
Thefront associated with Kurumí would later play a role in the2020 Brazilian floods and mudslides, producing heavy rainfall. Over 171.8 mm (6.76 in) of rain fell in theBelo Horizonte metro area on 24 January, triggering a landslide and killing 3 people and leaving 1 missing.[75]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 25 October 2020 – 27 October 2020 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 1004 hPa (mbar) |
On 24 October 2020, atrough axis persisted off the coast of the border betweenEspírito Santo andBahia, which led to the formation of a subtropical depression on the next day.[76][77] Later that day it intensified into a subtropical storm, which led it to be namedMani at 00:00 UTC on 26 October.[76][78] As it moved away from aSouth Atlantic Convergence Zone on 27 October, Mani gradually lost its subtropical characteristics, until it weakened to a low pressure area.[76][79]
The storm caused significant damage inEspírito Santo, with landslides of stones and earth leaving more than 400 people homeless.[80] The storm also impacted almost the entire state ofMinas Gerais and the northern region ofRio de Janeiro.[81]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 27 December 2020 – 30 December 2020 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 998 hPa (mbar) |
On 26 December 2020, the prior presence of aSouth Atlantic Convergence Zone and the subsequent passage of a frontal system led to the presence of several instability areas off the coast east ofRio Grande do Sul,[82] which coalesced into a subtropical depression a day later.[83] Moving southwestward, the system's central pressure dropped to 1,010 millibars (30 inHg) by 00:00 UTC on 28 December.[84] Later that day, the system's winds intensified, and it was namedOquira by the Brazilian Hydrographic Center.[85] On 29 December, Oquira continued to strengthen, deepening while heading further southwestward away from the Brazilian mainland, and reaching a pressure of 1,002 millibars (29.6 inHg).[86] Afterwards, Oquira's movements shifted southeastwards, and its winds decreased as it started to lose its subtropical characteristics, weakening to a subtropical depression on 30 December, but its pressure continued to drop, bottoming out at a minimum central pressure of 998 millibars (29.5 inHg).[82][87] Later that day, Oquira transitioned into an extratropical low, and the Hydrographic Center issued their final advisory on the storm as it was absorbed by a frontal system.[82][88]
| Tropical storm (SSHWS) | |
  | |
| Duration | 4 February 2021 – 6 February 2021 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 990 hPa (mbar) |
On 4 February 2021, an extratropical storm off the coast ofRio Grande do Sul developed into abomb cyclone.[89] On 6 February, the storm began separating from its weather fronts and developed subtropical characteristics, before fully separating from the frontal zone and transitioning into a fully-tropical storm later that day. As a result, the NOAA classified the system as a tropical storm at 17:30 UTC, with the system being designated asTropical Storm 01Q.[90] However, the storm was short-lived, as it lost its tropical characteristics several hours later, with the NOAA issuing their final bulletin on the storm at 23:30 UTC that day. The storm dissipated soon afterward.[91][92] Although the NOAA issued bulletins on the storm, the Hydrographic Center of the Brazilian Navy did not monitor it.
| Subtropical depression (SSHWS) | |
  | |
| Duration | 14 February 2021 – 16 February 2021 |
|---|---|
| Peak intensity | 55 km/h (35 mph) (1-min); 1002 hPa (mbar) |
On 13 February 2021, instability areas associated with alow-pressure area off the coast of the state ofRio Grande do Sul acquired subtropical characteristics on the next day, becoming a subtropical depression about 700 kilometres (430 mi) from the state.[93][94] For the next few days, the storm slowly meandered southeastward and then southwestward alongside a trough axis to its east,[93] until it lost its subtropical characteristics over high seas on 17 February, becoming a remnant low.[93][95]
The Brazilian Navy noted in its post-season analysis that on late 14 February the system could have intensified into a subtropical storm, since the radiometer built into the AMSR-2 satellite found winds of 35 knots, but it wasn't upgraded because no other measurement confirmed such findings.[93]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 19 April 2021 – 24 April 2021 |
|---|---|
| Peak intensity | 75 km/h (45 mph) (1-min); 1006 hPa (mbar) |
A low south of Rio de Janeiro transitioned into a subtropical depression on 19 April 2021.[96]On 20 April 2021, the system intensified into a subtropical storm, which Brazilian Navy then decided to name itPotira.[97] Potira moved slowly northeastwards for a couple of days over unusually warmer waters, favorable upper-level tropospheric winds and strong low-level convergence, which led to its intensification and persistence of its peak intensity until 23 April.[98] As it completed a clockwise loop, Potira weakened into a subtropical depression, with the Brazilian Navy downgrading it to a low-pressure area on late 24 January.[98][99]
The storm caused a gale in theCopacabana fort and the gusts of wind went over 60 km/h (37 mph).[100] In the municipalities ofBalneário Camboriú andFlorianópolis (SC), the hangover caused by Potira caused flooding in the streets and damage to the sidewalks.[101] The ports of Itajaí and Navegantes were closed for 3 days. No economic or material damage caused by the cyclone has been reported.[102]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 29 June 2021 – 1 July 2021 |
|---|---|
| Peak intensity | 85 km/h (50 mph) (1-min); 986 hPa (mbar) |
Anextratropical cyclone formed on 26 June 2021, about 520 km (320 mi) east-southeast ofMontevideo,Uruguay, associated with a cold airmass that acted over the region.[103] On the next day, the cyclone acquired awarm seclusion while intensifying, while it moved westwards and separated from the frontal system it was previously attached to.[103] As the systemoccluded, the seclusion deepened and started to acquire subtropical characteristics, which led it to be designated as a subtropical storm on 29 June.[103][104] It remained unnamed due to it being outside of theBrazilian Navy's area of responsibility.[105] By 23:30 UTC on 28 June, the Satellite Products and Services Division of theNESDIS declared the system to have become atropical storm, based on aDvorak rating of 3.5,[106] assigning aninvest tag to it.[103] Although being affected by strong wind shear to its north due to asubtropical jet caused by the presence of a frontal system nearby, it further intensified and achieved a minimum pressure 986 millibars (29.1 inHg), while tracking northeastwards towards the Brazilian area of authority.[103][107] At around 12:00 UTC on the next day, as the storm entered the boundary ofMETAREA V,Brazilian Navy's area of responsibility, thus it was assigned the nameRaoni.[108] Continuing moving northeastwards, Raoni further developed aneye feature as well as a robust band to the east of the system.[109] Raoni began to weaken by 30 June, as the subtropical jet broke thebarotropic flow over it, and NESDIS dropped the tag as it lost its convective bands.[103][110] On 1 July, Raoni lost its subtropical characteristics and degenerated into a low-pressure area.[103][111]
The predecessorextratropical cyclone of Raoni caused heavy rains and strong winds gust up to 104 km/h (65 mph), downing trees and causing damages to different public and private establishments acrossPunta del Este.[112] The area's waters were also rough due to the storm. Downpours with continuous gales were also experienced inUruguay's capitalMontevideo.[112] From 24 June to 2 July, Raoni channeled cold air fromAntarctica into portions ofSouth America, leading to an unusually potentcold wave acrossArgentina,Uruguay,Paraguay,Bolivia, and Brazil, with the temperature dropping as much as 15 °C (27 °F) below average in some areas. The combination of the cyclone and the cold wave also produced snowfall across the southern portion of South America, with snowfall observed as far north as southern Brazil.[113]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 9 December 2021 – 12 December 2021 |
|---|---|
| Peak intensity | 65 km/h (40 mph) (1-min); 997 hPa (mbar) |
On 9 December 2021, instability areas remained off the coast ofEspírito Santo andRio de Janeiro after the passage of a frontal system and aSouth Atlantic Convergence Zone.[114][115] Overnight the system coalesced into anoccluded front, which transitioned into a subtropical depression.[114][116] On the morning of the next day, the system was upgraded to subtropical storm status, receiving the nameUbá.[117] On 11 December Ubá gradually weakened while moving southeastwards, being downgraded to depression status.[114] It degenerated into a remnant low-pressure area on the next day.[118]
The precursor extratropical cyclone andSouth Atlantic Convergence Zone caused heavy rains inMinas Gerais,Espírito Santo and southernBahia, where heavy precipitation accumulated 450 mm (18 in) inItamaraju and 331 mm (13 in) inMonte Formoso, killing fifteen people.[119][120][121]
| Subtropical storm (SSHWS) | |
  | |
| Duration | 16 May 2022 – 19 May 2022 |
|---|---|
| Peak intensity | 95 km/h (60 mph) (1-min); 990 hPa (mbar) |
On 15 May 2022, an extratropical cyclone moved through the southern region of Brazil and stopped offshore.[122] The low occluded and separated form its precursor extratropical cyclone, obtaining subtropical characteristics in the process.[122] On the morning of 17 May, the cyclone fully transitioned into a subtropical storm, and was given the nameYakecan.[123] Taking a more northwestwardly movement, Yakecan moved away from the coastline, gradually losing its subtropical characteristics.[122] On late 19 May, it acquired frontal characteristics and transitioned to an extratropical cyclone.[122][124]
During its trajectory, the storm caused snow in the Gaúcha and Catarinense Mountains, setting record lows for this time of year.[125] Two people died in Uruguay and Brazil due to the passage of the cyclone.[126][127] Yakecan is the last name from the regular naming list, which has been in use since 2011.
| Subtropical depression (SSHWS) | |
  | |
| Duration | 6 January 2023 – 9 January 2023 |
|---|---|
| Peak intensity | 55 km/h (35 mph) (1-min); 1010 hPa (mbar) |
On late 6 January 2023, a subtropical depression formed from a quasi-stationary frontal system, about 528 nmi (978 km) east of the state ofSanta Catarina.[128][129] On the next day, the system achieved its lowest pressure of 1,010 millibars (30 inHg) as it moved southeastward, away from the frontal system while being enhanced by both anomally high sea-surface temperatures and the presence of aSouth Atlantic Convergence Zone (SACZ) on the vicinity.[128] On January 8 the system mantained the same direction, moving away from both the SACZ and the Brazilian coast, without affecting any area, gradually diminishing its convective activity.[128] This process lasted until afternoon 10 January, as it opened into a through, about 620 nmi (1,150 km) east of the state ofRio Grande do Sul.[128][130]
| Tropical storm (SSHWS) | |
  | |
| Duration | 16 February 2024 – 22 February 2024 |
|---|---|
| Peak intensity | 85 km/h (50 mph) (1-min); 994 hPa (mbar) |
In February 2024, a low-pressure area began developing along a stalled cold front. Moisture from the tropics began feeding into the circulation of the developing disturbance, helping it to intensify.[131] On 16 February 2024, the Brazilian Navy designated the system, which at the time was east southeast ofRio de Janeiro, Brazil, as a subtropical depression.[132] Two days later, the system transitioned into a tropical cyclone.[133] Early on 19 February, the system intensified into a tropical storm, receiving the nameAkará from the Brazilian Navy.[134] However, two days later, the system lost its tropical characteristics and weakened into a subtropical depression.[135] The next day, the system lost its subtropical characteristics, thus the Brazilian Navy ceased all bulletins.[135]
The precursor extratropical cyclone to Akará brought heavy rainfall to South America.[136]Nova Iguaçu was affected with intense rainfall and winds.[137] Akará was the first named tropical storm to develop in the basin since Iba in 2019.
| Subtropical storm (SSHWS) | |
  | |
| Duration | 14 December 2024 – 16 December 2024 |
|---|---|
| Peak intensity | 95 km/h (60 mph) (1-min); 998 hPa (mbar) |
Early on 15 December 2024, a subtropical storm formed off the coast of theBrazil–Uruguay border, receiving the nameBiguá from the Brazilian Navy.[138] As it moved southeastwards, away from the coastline, the system was downgraded to subtropical depression.[139] On early 17 December 2024, the cyclone was downgraded to a low-pressure area as it transitioned to aextratropical cyclone.[140]
The closeness to the Brazilian shore caused wind gusts over the southeasternRio Grande do Sul, leading to power losses and structural damages on nearby cities.[141]
According to a presentation at the Sixth WMO International Workshop on Tropical Cyclones (IWTC-VI), satellite imagery from January 1970 showed that a system with an eyewall had developed behind a cold front and that the system needed further analysis to determine if it was tropical or subtropical.[7] On 27 March 1974, a weak area of low pressure that had originated over the Amazon River started to intensify further.[142] Over the next 48 hours the system quickly developed further and was classified as subtropical, as it developed a banding structure and deep convection near its warm core.[142] On 29 March, a north-westerly flow encroached on the systems environment, which caused the system to rapidly move towards 40S and the cold waters that were present to the south of 40°S.[142]
In March 1994, a system that was thought to be weaker than Catarina was spawned but was located over cool and open waters.[143] According to the Zambia Meteorological Department,Cyclone Bonita moved off the coast ofAngola and entered the South Atlantic Ocean on 19 January 1996. By the next day, the system had succumbed to cold waters and days of land interaction, dissipating completely. It was the first tropical cyclone known to have traversed southern Africa from the South-West Indian Ocean to the South Atlantic.[144]
During 2004, the large-scale conditions over the South Atlantic were more conducive than usual for subtropical or tropical systems, with 4 systems noted.[7] The first possible tropical cyclone developed within a trough of low pressure, to the southeast of Salvador, Brazil on 18 January.[6][7] The system subsequently displayed a smallcentral dense overcast (CDO) and was suspected to be at the peak of its development as either a tropical depression or a tropical storm during the next day.[6] The system was subsequently affected by some strong shear, before it moved inland and weakened along the coast of Brazil before it was last noted during 21 January.[6] Within Brazil the system caused heavy rain and flooding with a state of emergency declared inAracaju, after the river overflowed and burst its banks which flooded homes, destroyed crops and caused parts of the highway to collapse.[6] However, it was noted that not all of the heavy rain and impacts were attributable to the system, as a large monsoon low covered much of Brazil at the time.[6] The second system was a possible hybrid cyclone that developed near south-eastern Brazil between 15 and 16 March.[7] Hurricane Catarina was the third system, while the fourth system formed off the coast of Brazil on 15 May 2004.[7]
On 22 February 2006, a baroclinic cyclone intensified quickly and was estimated to have peaked with 1-minute sustained wind speeds of 105 km/h (65 mph), after radar data showed that the system had developed an eye and banding.[7] However, there were questions about how tropical the system was, as it did not separate from the westerlies or the baroclinic zone it was in.[7][145] Between 11 and 17 March 2006, another system with a warm core developed and moved southward along the South Atlantic Zone, before dissipating.[7]
Two subtropical cyclones affected bothUruguay andRio Grande do Sul state in Brazil between 2009 and 2010. On 28 January 2009, a cold-core mid to upper-leveltrough in phase with a low-level warm-corelow formed asystem and moved eastward into the South Atlantic.[146] The storm produced rainfall in 24 hours of 300 mm (12 in) or more in some locations ofRocha (Uruguay) and southern Rio Grande do Sul. The weather station owned by MetSul Weather Center inMorro Redondo, Southern Brazil, recorded 278.2 mm (10.95 in) in a 24-hour period. The storm caused fourteen deaths and the evacuation of thousands, with an emergency declared in four cities.[9] It lasted until 1 February, when the cyclone became extratropical.[147]
On 16 November 2010, a cold-core mid to upper-leveltrough in phase with a low-level warm-corelow developed a low-pressuresystem overBrazil, and moved southeastward into theSouth Atlantic, where it slightly deepened.[148] The system brought locally heavy rains in southern Brazil and northeast of Uruguay that exceeded 200 millimeters within a few hours, in some locations of Southern Rio Grande do Sul, northwest of Pelotas.[149] Damages and flooding were observed in Cerrito, São Lourenço do Sul and Pedro Osório.[149] Bañado de Pajas, department of Cerro Largo in Uruguay, recorded 240 mm (9.4 in) of rain.[149] The subtropical cyclone then became a weak trough on 19 November, according to the CPTEC.[150]
Between 23 December 2013 and 24 January 2015, the CPTEC and Navy Hydrography Center monitored three aditional subtropical depressions to the south ofRio de Janeiro. The first one lasted untilChristmas Day, 2013.[151][152][153][154] Two subtropical depressions formed in 2014: one in late-February 2014 and the other in late-March 2014.[155][156][157]
On 3 January 2021, according to theMétéo-France, the remnants ofTropical Storm Chalane from the South-West Indian Ocean crossed southern Africa and briefly emerged into the eastern South Atlantic before dissipating.[158]
The following names are published by theBrazilian Navy Hydrographic Center's Marine Meteorological Service and used for tropical and subtropical storms that form in the area west of20ºW and south of equator in the South Atlantic Ocean. Originally announced in 2011,[11] the list was extended from 10 to 15 names in 2018.[159] In 2022, 32 new names were added after the previous ones were exhausted.[160] The names are assigned in alphabetical order and used sequentially without regard to year.
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Kamby was replaced byKurumí in 2018 without being used.[11]
There have been 88 recorded tropical and subtropical cyclones in the South Atlantic Ocean since 1957. Like most southern hemisphere cyclone seasons, most of the storms have formed between November and May.
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