South Atlantic tropical depression?

By: Dr. Jeff Masters , 7:23 PM GMT on February 24, 2006

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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!

Jeff Masters

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36. SickOfDumbQuestions
4:54 AM GMT on February 27, 2006
MichaelSTL

Where is that link now?
35. Trouper415
1:32 AM GMT on February 25, 2006
Interesting! Thanks for the update.

Giants in 06
Member Since: September 22, 2005 Posts: 5 Comments: 637
34. KatrinaRitaWilmaZeta
1:27 AM GMT on February 25, 2006
i have up date my blog with some ? on it come see
31. Merovingian
1:11 AM GMT on February 25, 2006
This is quite peculiar, but exciting nonetheless!
29. DenverMark
12:54 AM GMT on February 25, 2006
Has a tropical depression ever formed anywhere in the Atlantic basin in February before?
Member Since: February 11, 2006 Posts: 125 Comments: 6988
28. RL3AO
12:40 AM GMT on February 25, 2006
Its ironic that the costliest storm in the north atlantic sounds very similar to the strongest recorded storm in the south atlantic (Catarina)
27. arcturus
12:25 AM GMT on February 25, 2006
Fshhead- It's a La Nina, and still exists at the same intensity.

26. CrazyC83
12:04 AM GMT on February 25, 2006
I've read that it has degenerated into a remnant low...so much for what I would call Tropical Depression One-Q.
Member Since: September 19, 2005 Posts: 0 Comments: 142
25. Skyepony (Mod)
11:41 PM GMT on February 24, 2006
Off to play "Taps" on the flute....
Member Since: August 10, 2005 Posts: 156 Comments: 36173
24. ForecasterColby
10:57 PM GMT on February 24, 2006
Yeah, I think it's dead. A shame...it would provide some excitement and wouldn't hurt anyone.
22. seflagamma
10:42 PM GMT on February 24, 2006
Thanks everyone for answering my questions and the other information you all posted that also answered questions I was going to ask!

Gams
Member Since: August 29, 2005 Posts: 294 Comments: 40840
20. Skyepony (Mod)
10:33 PM GMT on February 24, 2006
Yes the south Atlantic is seperate from the N Atlantic storm basin.

KShurricane, I read that recently, about the increase in S Atlantic storms could happen as SST rise, I don't remember it being = to N Atlantic. & could that have been in Emanuel's studies? There's a link in my blog on higher SST causing more cat 4 & 5 storms to his work, in the comments. I also got some great graphs finally posted in the comments as well, showing globally how we are having the same # of storms but more are cat 4 & 5.
Member Since: August 10, 2005 Posts: 156 Comments: 36173
19. KShurricane
10:16 PM GMT on February 24, 2006
Interestingly, I've read somewhere (don't remember where) that some models are predicting that, as global warming increases, the South Atlantic shear will start to fade and it will become almost as active as the North Atlantic.
18. KShurricane
10:11 PM GMT on February 24, 2006
"So, if this storm becomes a TD, will it be named and considered the first storm of the Atlantic season or now because, technically, the season has not started yet?"

I believe, from what I've gathered in my reading, that the South Atlantic is considered a seperate hurricane basin from the North Atlantic (the one that affects the US). Any storms that form there are not counted in the statistics for "our" hurricane season, and if it gets a name it would not be from the list used by the NHC. There is no official list for the South Atlantic. Of the 4 recorded storms, only the hurricane was awarded a name (Catarina). I doubt this one will be named unless it reaches hurricane strength too.
17. Jenniferan896
9:00 PM GMT on February 24, 2006
I didn't mean TD, I meant tropical storm, sorry
16. Jenniferan896
8:58 PM GMT on February 24, 2006
So, if this storm becomes a TD, will it be named and considered the first storm of the Atlantic season or now because, technically, the season has not started yet?
15. Geoman
8:52 PM GMT on February 24, 2006
According to the NHC Hurricane, Typhoons, Tropical Cyclone FAQ, "Though many people might speculate that the sea surface temperatures are too cold, the primary reasons that the South Atlantic Ocean gets few tropical cyclones are that the tropospheric (near surface to 200mb) vertical wind shear is much too strong and there is typically no inter-tropical convergence zone (ITCZ) over the ocean (Gray 1968). Without an ITCZ to provide synoptic vorticity and convergence (i.e. large scale spin and thunderstorm activity) as well as having strong wind shear, it becomes very difficult to nearly impossible to have genesis of tropical cyclones." Consider how narrow the South Atlantic is compared to the South Pacific.
Member Since: November 8, 2001 Posts: 65 Comments: 8
14. Fshhead
8:41 PM GMT on February 24, 2006
Has anyone heard if el-nino is still weakening????
Member Since: November 19, 2005 Posts: 9 Comments: 9960
12. lemonbalm
8:20 PM GMT on February 24, 2006
Here comes the 2006 Hurricane season.
Batten down the hatches, folks!
11. seflagamma
8:18 PM GMT on February 24, 2006
That is what I mean, Austrialia gets storms all of the time; why not South America????
Member Since: August 29, 2005 Posts: 294 Comments: 40840
10. Fshhead
8:16 PM GMT on February 24, 2006
BTW... Kate is the named storm off Austrailia right now!
Member Since: November 19, 2005 Posts: 9 Comments: 9960
9. Fshhead
8:14 PM GMT on February 24, 2006
Gamma,
there are storms off of Australia. Just look right now at the cyclone advisories!!!! I have seen quite a few in the past weeks!!
Member Since: November 19, 2005 Posts: 9 Comments: 9960
7. Skyepony (Mod)
8:08 PM GMT on February 24, 2006
TheSnowman~ ya missed the mention of a TD in April 1991. & with out the satellites before 1970.... This could have occured in the late 1880-1890, when we were in a cycle similair or the 1930's for that matter.

I looked for a corrilation yesterday since 2004 was so memerable, 1991 ~ 8 storms, 2 of which were majors.
Member Since: August 10, 2005 Posts: 156 Comments: 36173
6. seflagamma
8:00 PM GMT on February 24, 2006
sorry about the typos....
Member Since: August 29, 2005 Posts: 294 Comments: 40840
5. seflagamma
8:00 PM GMT on February 24, 2006
Is this a preview of the season to come for us?????

The waters are already getting primed up and ready to rumble or should I say, swirl????
Member Since: August 29, 2005 Posts: 294 Comments: 40840
4. seflagamma
7:59 PM GMT on February 24, 2006
Dr Masters,

Thanks for the very interesting information.

Why doesn't the South Atlantic get storms??? I mean doesn't it make sense they should because also get troopical storms? Doesn't Austrial gets them?
Anyone???

Gams
Member Since: August 29, 2005 Posts: 294 Comments: 40840
3. Fshhead
7:50 PM GMT on February 24, 2006
Hmmmmm.....
All these storms formed in the new "warming" period. Dr. Masters any thoughts on this?????
Member Since: November 19, 2005 Posts: 9 Comments: 9960
2. TheSnowman
7:43 PM GMT on February 24, 2006
it's amazing again as we look at "when has is the only time that this happened before that we know of??"

Answer - Jan. and March Only 2 Years ago
1. HeavySnow
7:32 PM GMT on February 24, 2006
Wow, that's interesting. What effect might it have if these systems began forming more regularly?
Member Since: July 7, 2004 Posts: 18 Comments: 2989

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.