Rare South Atlantic Hurricane Heads Toward Brazil

jellisky writes "An unprecendented sort of weather event has been occuring recently, without much fanfare at all. A tropical cyclone in the south Atlantic is slowly drifting toward Brazil. The southern Atlantic ocean isn't exactly a hurricane hotbed, as pointed out by National Hurricane Center forecaster Jack Beven, "We know there hasn't been a hurricane in that area since at least the satellite era, the mid-60s at the minimum." The storm is a small one, though, but has estimated winds near minimal hurricane strength (74-95 mph). It's quite an interesting sight, perfect for piquing the weather curiousity that many of us have."

Comments

Better picture of it here...

[shiwala]

Here's a nicer image of the cyclone.

Historical Occurances

[VoiceOfSanity]

Over the last year there have been several unusual hurricane events. The first recorded hurricane in the Atlantic to occur in April was in 2003, along with the first recorded hurricane in December, both breaking long-standing records. This one however is most unusual because of the weather patterns in that part of the world. While they have most of the necessary conditions (warm water, weather systems) the prevailing winds blow from west to east (as opposed to east to west for the North Atlantic tropics), usually tearing systems that could develop into shreads.

This becomes a problem because unlike areas that are used to hurricanes (US, Carribbean, Pacific, Australia, Madagascar) the Brazilians have no experience with tropical systems, so they have no way of knowing what to expect. Having lived through 16 of them (including Betsy in 1965, Camille in 1969 and Andrew in 1992) all I can say is that anyone living in the potential landfall area might want to consider going inland a ways.

A good site to look at is the Naval Research Labs Monterey hurricane page located here:

http://www.nrlmry.navy.mil/tc_pages/tc_home.html

It lists all of the systems they are following, along with a very good collection of satellite images.

s/global warming/climate change

[2marcus]

In fact, those of us who do climate science use the term "climate change" rather than "global warming". As MrWa stated, thermohaline circulation (gulf stream) collapse would lead to anomalous cooling in the northern Atlantic (unlikely in the near term according to the models I've seen), but we also study aerosol effects (sulfate cooling, the effect of the Pinatubo eruption, etc), and so on. And in general regional changes in temperature, while hard to predict, can be either positive or negative even if global mean surface temperatures are increasing.

In any case, most models do not predict large warming of the equatorial band, partially because evaporation over tropical oceans keeps the atmosphere from heating. Of course, this increased evaporation leads to increased latent heat, which is a possible cause of extreme weather.

Having said that, one extreme event does not proof of climate change make. Climate change is about long term trends, not short term weather. If we see more South Atlantic hurricanes over the next decade, then there would be an indication that they could be a result of climate change.

Then we could look for the proximate cause: increased latent heat, ocean temperature patterns, change in winds, salinity changes, all of the above concurrent or consecutive, whatever. Then we would ask, is this change something we would expect from human induced change, eg increased greenhouse gas forcing or aerosols or something else.

More Links & Information on the Storm...

[cwolfsheep]

1. I first found out about the storm on Weather Underground.
2. Dvorak Source
3. CNN's 1st page on it. 4. CNN's follow-up page on it.

*. Hats off to the person that beat me to a first post. ;)