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.

Re:Better picture of it here...

[dnahelix]

Did you try the 250m pixel size link[4.5M image] from the same page?
Incredible resolution!

Re:Hurricane or Cyclone

[2marcus]

Actually, the the NOAA FAQ lists hurricane/cyclone terminology, and oddly there is no approved name for a South Atlantic hurricane... which may testify further to the rareness of the event. Quote follows:

Tropical cyclones with maximum sustained surface winds of less than 17 m/s (34 kt, 39 mph) are called "tropical depressions". (This is not to be confused with the condition mid-latitude people get during a long, cold and grey winter wishing they could be closer to the equator ;-)) Once the tropical cyclone reaches winds of at least 17 m/s they are typically called a "tropical storm" and assigned a name. If winds reach 33 m/s (64 kt, 74 mph)), then they are called: a "hurricane" (the North Atlantic Ocean, the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E); a "typhoon" (the Northwest Pacific Ocean west of the dateline); a "severe tropical cyclone" (the Southwest Pacific Ocean west of 160E or Southeast Indian Ocean east of 90E); a "severe cyclonic storm" (the North Indian Ocean); and a "tropical cyclone" (the Southwest Indian Ocean) (Neumann 1993).

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. ;)