Rare tropical storm forms in South Atlantic

Only seven tropical storms have formed in the Sputh Atlantic in recorded history. The reasons for this are primarily due to strong upper-air wind shear and cool sea surface temperatures (Source: Earthweek). This week Invest 90Q did indeed form off the coast and grow to tropical storm strength.

90Q: A curious short-lived 'tropical' cyclone in the southern Atlantic (R&D Mag)

Tropical cyclones typically don't form in the Southern Atlantic because the waters are usually too cool. However, forecasters at the Naval Research Laboratory noted that a low pressure system off the coast of Brazil appeared to have tropical storm-force winds yesterday.

On Wednesday, March 10 at 1400 UTC (9:00 a.m. ET) "System 90Q" was located near 29.8 degrees South latitude and 48.2 degrees West longitude, about 180 miles east of Puerto Alegre, Brazil. The Naval Research Laboratory said on March 10 the system had maximum sustained winds near 39 mph (35 knots) but has weakened today below the tropical storm-force winds threshold.

Weather Underground meteorologist Dr. Jeff Masters has discussed this system over the past few days. He pointed out that the system had a defined circulation and windspeeds that approached tropical storm speeds.

Brazilian tropical/subtropical storm deserves a name (Dr. Jeff Masters' WunderBlog)

The South Atlantic tropical/subtropical storm we've been tracking this week has moved over colder waters and has now transitioned to a regular extratropical storm. Earlier this week, the storm became just the 7th tropical or subtropical cyclone on record in the South Atlantic. According to a statement put out by MetSul Meteorologia, a Brazilian weather company, this storm is now named "Tropical Storm Anita:"

The regional weather centers and the private weather enterprises of both Rio Grande do Sul and Santa Catarina, southernmost Brazilian states, in a joint decision, named Anita the rare tropical storm of March 9th and 10th in the coastal areas of the region. The name was chosen considering a historic figure of Rio Grande do Sul and Santa Catarina, both states affected by the tropical cyclone. Anita Garibaldi (1821-1849) was a heroine of the Farroupilha Revolution (1835-1845), one of the most important events in the Brazilian history that took place in the Southern part of the country. Anita was used in the past to designate tropical cyclones in other basins: North Atlantic, the Pacific and the Indian Ocean.

Tropical torm Anita is moving away from the Brazilian coast and is weakening. By the week end Anita will be extratropical and become absorbed in the cold front over the South Atlantic Ocean.

Photo courtesy of NASA via Weather Underground