Tropical Cyclones In The South Atlantic And South-east Pacific.

[Konstantinos]

Hello everyone. In wikipedia I saw that the South Atlantic and South-east Pacific do not have tropical cyclones.

So I am wondering. Why?

Edited September 18, 2011 by Konstantinos

[Somerset Squall]

The South Atlantic does, but they are rare. There was a subtropical storm in the South Atlantic earlier this year, and a fully tropical storm last year. This is unprecedented. The main reason is high shear and lack of disturbances/monsoon troughs. I guess this is also the cause of the lack of tropical activity in the southeast Pacific.

Your picture shows one South Atlantic storm, and that was Catarina in 2004. It became a cat 2 hurricane and is the strongest South Atlantic TC on record.

Edited September 18, 2011 by Somerset Squall

[summer blizzard]

The south Atlantic and Pacific are indeed anomolies in that there location should yield quite a few tropical events each season.

Breaking it down..

South east Pacific - In theory should have plenty of activity at least during El Nino years however i would summise that if the ocean if fairly deep near the coast then the oceanic heat content is not there, the mountain chain running up the west of South America also produces a mean upper low which produces shear.

South west Atlantic - Synoptic pattern generally produces a lot of dry air coming off Brazil, so while shear is not too bad in theory the moisture content appears to be lacking, the ocean also appears to be fairly deep

South east Atlantic - In theory this region should be pretty much perfect, light shear and little dry air combined with relatively shallow seas, i have no idea why we do not see tropical activity here.

In summary, the West Pacific and Atlantic are active because of a combination of light shear, most of the dry air is mixed out by the time they near the USA and high oceanic heat content due to many islands. The east Pacific is in theory what the south east Pacific and eastern south Atlantic should be like.

[Konstantinos]

Thank you very much for your replies. I do not know if a reason why the south-east Pacific does not have cyclones is the continental mountain range Andes. Possibly.

This is a good article from wikipedia, about South Atlantic:

http://en.wikipedia....ropical_cyclone

Edited January 29, 2012 by Konstantinos