Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 7:23 PM GMT on February 24, 2006
Satellite imagery shows what may be a rare tropical depression forming in the South Atlantic off the coast of Brazil. At 2pm EST, the system was located near 30S 35W, about 600 miles southeast of Rio de Janeiro, Brazil. The system is moving east--away from Brazil--at about 20 mph. This is a very small storm, and is not a threat to any land. The system does have a closed ciculation, but little spiral banding. It is currently over waters of about 27 degrees C, well above the 26 C threshold needed for tropical storm formation. A modest area of deep convection with quite cold cloud tops has developed in the past three hours on the southeast side of the center. Upper-level wind shear from the northwest appears to be keeping this convection from wrapping all the way around the center. The high wind shear will probably interfere with the storm's organization enough to keep a tropical depression from forming, and the system should dissipate by Saturday. The best way to track the storm is by using the visible and IR floater satellite loops.
Figure 1.Visible image from 1613 GMT February 24, 2006, taken by the polar-orbiting AQUA satellite, showing a possible tropical depression forming in the South Atlantic.
Only one hurricane and two tropical depressions have ever been observed in the South Atlantic. Satellites first began monitoring the ocean in 1970, so other tropical cyclones may have formed before that time. Tropical Cyclone Catarina, which struck Brazil's Catarina State as a Category 1 hurricane in March, 2004, was the only hurricane on record in the South Atlantic. Tropical depressions were observed in January 2004 off of the Brazilian coast, and in April 1991 off of the coast of Angola.
I'll have an update early this evening with more information. There is a pass of the Quikscat satellite coming up soon, so we should be able to get an idea of the winds of this system. It is difficult to assemble information on the storm, all of my tools are geared for the North Atlantic!
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