outflow structure, warm water temperatures of , little shear, a warm core low, overall tropical characteristics, and occurred in March (equivalent to September in the Northern Hemisphere, the peak of hurricane season), it was considered to be a hurricane by the National Hurricane Center (NHC) in the United States. Though it is most commonly known as Catarina, all names for this storm are "unofficial", in that it was not named by any hurricane-monitoring meteorological agency affiliated with the World Meteorological Organization (WMO). (Tropical cyclone names are predetermined by an international committee of the WMO.) It has also been unofficially called "Aldonça", and the advisory names for it were "01T-ALPHA" from the United Kingdom's Met Office, and "50L-NONAME" from the United States' National Hurricane Center, which keeps it well outside normal designation, which start at 01L for named storms and use 90L to 99L for invests. Rare formation Typically, tropical cyclones do not form in the South Atlantic Ocean, due to strong upper level shear, cool water temperatures, and the lack of a convergence zone of convection. Occasionally though, as seen in 1991 and early 2004, conditions can become slightly more favorable. For Catarina, it was a combination of climatic and atmospheric anomalies. Water temperatures on Catarina's path ranged from , slightly less than the temperature of a normal tropical cyclone, but sufficient for a storm of baroclinic origin. Catarina remains the only hurricane strength tropical cyclone ever observed in the South Atlantic Ocean (reliable continuous and relatively comprehensive records only began with the satellite era beginning about 1970). Other systems have been observed in this region; however, none have reached hurricane strength. While Catarina formed in an unusual area, its relation to global warming or any other type of global climatic change is still up for debate. The attributed it to "climatic changes and atmospheric anomalies", while other researchers have indicated that it could be the result of the Southern Annular Mode or other seasonal variations in weather within the Southern Hemisphere, again linked to global changes in climate. However, more research in the area is still needed to make a conclusion. Impact Like normal tropical cyclones, Catarina brought heavy flooding with it. Despite the uncertainty in the future of the storm, Brazilian officials took the appropriate actions to ensure the safety of the residents who lived along the coastline. A successful evacuation was executed for numerous residents along the