TROPICAL SOUTH ATLANTIC?

Tropical systems in the southern hemisphere, everything south of the equator, happen throughout the world on a consistent basis. In the south Pacific tropical cyclones affect areas near the Philippines and eastern Australia. The southern Indian ocean sees storms affecting western Australia and as far west as eastern Africa. Tropical systems south of the equator spin in a clockwise rotation, as opposed to the counter-clockwise spin we typically see in our part of the world.

When you think of tropical systems in the Atlantic ocean, you think of the area north of the equator between Africa and North America. This includes the Caribbean Sea, the Gulf of Mexico, and the entire eastern seaboard of the United States. This is because this is where almost all tropical systems in the Atlantic ocean form. In the last 20 years 320 systems have developed into tropical storm status in this area, an average of 16 storms every single year. Last year a record high 30 systems formed.

But what about the South Atlantic? South of the equator between Africa and South America, tropical activity is very rare, and is typically limited to just off the South American coast. Only one system ever is known to have formed off of western Africa. This is because wind shear in this portion of the world is typically always very high. Wind shear, of course, is a killer of tropical systems. But more than wind shear is water temperature. Water temps in the South Atlantic are a lot cooler than they are north of the equator, thanks to flows coming from the Antartic. Warm water is what feeds tropical systems and gives them their juice. So the South Atlantic's cooler temps keep tropical formation from happening.

As mentioned, 320 storms have formed in the Atlantic, north of the equator, the part of the world that concerns us the most, in the last 20 years. In the South Atlantic, only 85 storms are suspected to have formed since 1957. Only one of those 85 potential storms have ever formed into a hurricane. That was hurricane Catarina in 2004. Almost all of these systems start out as a front coming off the coast of Brazil, that stalls in the open waters. It starts to pick up some tropical characteristics, and in rare instances, becomes fully tropical. The South Atlantic also doesn't have the tropical convergence zone helping to produce systems like we have in the North Atlantic.

Because of advancements in satellite technology, the ability to have eyes in all parts of the world now, help in pointing these systems out. They even have the ability to look at images from the past and make determinations if there's been systems organized enough to have possibly become at least subtropical. That is why the suspected number of storms in the South Atlantic is 85 since 1957.

And the advanced satellites recently are showing us that storm formation in the South Atlantic may not be as rare as we once thought. Now, a majority of these storms are subtropical, which means it has both warm and cold core features. Fully warm core tropical systems are a lot more rare. Of the last 15 known named storms in the South Atlantic since 2004, only 4 have become fully tropical. Since January of 2020, there's been 5 named storms in the South Atlantic. Two have already formed this year. The most recent is subtropical storm Potira forming off the coast of Brazil this week. Shear is taking it's toll on Potira so it's not expected to transition to a full tropical system, never mind strengthen into anything of significance.

So tropical systems in the South Atlantic are something we never have to deal with, unless we're vacationing in Rio, and even then, it would be a rare occurance for it to happen as very few make landfall, but the South Atlantic does have tropical activity. Not quite enough to make it one of the worlds tropical cyclone basins, of which there are 7, but enough to where the Brazilian Navy came out with a storm list to name these systems in 2011.