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Science

Rare South Atlantic Hurricane Heads Toward Brazil 52

Posted by michael from the batten-the-hatches dept.
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."
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Rare South Atlantic Hurricane Heads Toward Brazil More

Rare South Atlantic Hurricane Heads Toward Brazil

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  • Better picture of it here... (Score:5, Informative)

    by shiwala ( 93327 ) on Friday March 26, 2004 @09:44PM (#8686675)
    Here's a nicer image of the cyclone [nasa.gov].

  • hurricanes in California (Score:4, Interesting)

    by bobbozzo ( 622815 ) on Friday March 26, 2004 @09:47PM (#8686698)
    We had the tail end of a hurricane from baja hit southern California about 2 years ago... a very rare event.
    It didn't do a whole lot of damage; many areas get 80-90mph Santa Ana winds occasionally.

  • Interesting? (Score:2, Interesting)

    by OC_Wanderer ( 729511 )
    Interesting isn't a word I'd choose to use for storms which are people killers.
  • Until the first post blaming this on "global warming" *cough*cough*?

    • Approximately thirty-six seconds.
    • As a climate change researcher, I wouldn't dare make the leap that the storm in the south atlantic is caused by global climate change (Although it has never has occured in recorded history). An enormous amount of research would have to be done to make a connection between the two events. What is dishartening to me is the fact the so many people can cast aside the enormous amount of evidence that global climate change is occuring. Is it just because your in denial that some of the choices that we all make
      • What is dishartening to me is the fact the so many people can cast aside the enormous amount of evidence that global climate change is occuring. Is it just because your in denial that some of the choices that we all make when it comes to energy use has detrimental effects on the environment?

        I think it's pretty well documented that climate change is occuring (though still, the heteroskedasticity of the data makes this hard to prove). However, the link that's never been made is that our actions are what's

        • I know that it is extremely difficult to link human activities to climate change. The complexity of global climate is so vast that no mathmatical model could ever come close to approximating it. That said, I believe that the connection not being made between human activity and climate change is due to a construct of our limited mathmatical abilities to model such a relationship. We still work with linear relationships in modeling as it is. No one as of yet has invented a way to model exponential relatio

  • Historical Occurances (Score:5, Interesting)

    by VoiceOfSanity ( 716713 ) on Friday March 26, 2004 @10:29PM (#8686894)
    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.
  • ....global warming....and all who thrive in her... ;-)

    -psy

  • Maybe (Score:5, Interesting)

    by Molina the Bofh ( 99621 ) on Friday March 26, 2004 @10:47PM (#8686971) Homepage
    Maybe it's one of the first signs that this prediction [guardian.co.uk] may be accurate.

    And, as the article says, Bush thinks Global Warmin is a hoax. Typical.

    • The extreme rapid change described in that article brings up my skeptic meter a bit. I really wonder if that report is one of the many disaster case studies that the government does for planning purposes. They do lots of fictional thought-experiments for things like biological attack, what happens if russian scientists sell everything to Iran, etc. Before I believe that article, I would need to see corroberating information.

      • Re:Maybe (Score:3, Interesting)

        by 2marcus ( 704338 )
        If you go to the original study [kelber.de] you can see that it is in fact well-caveated. It was a hypothetical scenario - designed to look at unlikely and extreme outliers of what climate scientists are studying.

        Note that I am a believer in reducing greenhouse gas emissions in order to reduce the likelihood of extreme negative climate change events. However, the Pentagon report should really not be used as an example of mainstream climate science (I believe the authors themselves do not work in the field). And t

  • The OSEI image looks like it was hastily assembled.....

  • Atlantic anomalously COOL right now (Score:4, Interesting)

    by mc6809e ( 214243 ) on Saturday March 27, 2004 @02:50AM (#8687841)
    Most of the South Atlantic is actually cooler than average, [noaa.gov] so it seems unlikely that global warming is to blame.

    • Re:Atlantic anomalously COOL right now (Score:4, Insightful)

      by BigBadBri ( 595126 ) on Saturday March 27, 2004 @07:25AM (#8688396)
      Why unlikely?

      Global warming is just that - a warming, on average, of the globe.

      The fact that the majority of the South Atlantic is cooler than average could reflect any one of a number of causes, one of the most likely of which is a warming of the Antarctic leading to increased melting of the icecap, thus releasing lots of cold water into the South Atlantic.

      Looking at the chart, this seems plausible, as the concentration of colder water is away from the continental shelf of South America, and appears to skirt around the South Atlantic islands (notice the finger of yellow / orange sticking out from the coast of Argentina).

      Cyclone formation is driven by temperature gradients, rather than average temperature, and the fact that the (normally slightly warmer) water on the continental shelf is warmer than usual, whereas the deepwater areas are colder, leads to the conclusion that the temperature gradient is much higher than usual.

      So it's not surprising that a cyclone has formed, and the anomalous temperature gradients are perfectly consistent with global warming.

      One thing from the map - I'd love to be in a boat off Namibia right now, watching the dolphins and whales - that extra cold water will be full of food, and it'll be a bumper autumn's fishing all along the South-West coast of Africa.

      • Cyclone formation is driven by temperature gradients, rather than average temperature, and the fact that the (normally slightly warmer) water on the continental shelf is warmer than usual, whereas the deepwater areas are colder, leads to the conclusion that the temperature gradient is much higher than usual.

        However, tropical cyclones result from a vertical temperature gradient - rising warm, moist air over warm water - not a horizontal one.
        • What warms the air and causes it to rise?

          A horizontal temperature gradient, starting from a steady state, will warm the air over the warm water more than the air over the cold, causing the warm air to rise and to suck in the air from the cold end of the gradient.

          Coriolis does the rest, causing the incoming air to rotate and form the cyclone.

          It is the horizontal gradient in the water that provides the differential heating in the air, and leads to the end result that you claim as a cause.

    • I thought the prevailing hypothesis about global warming was that it would result in some nonintuitive weather and temperature changes - i.e. the Gulf Stream stopping would make things become actually colder in places.

      Not to say that you are wrong and this does have anything to do with global warming, just that I think only looking at water temperature is not enough to be conclusive.

      • s/global warming/climate change (Score:5, Informative)

        by 2marcus ( 704338 ) on Saturday March 27, 2004 @09:57AM (#8688776)
        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.

  • FAQ on South Atlantic Tropical Events (Score:4, Informative)

    by 2marcus ( 704338 ) on Saturday March 27, 2004 @10:03AM (#8688794)
    From the NOAA FAQ [noaa.gov]:

    Subject: G7) Why doesn't the South Atlantic Ocean experience tropical cyclones?

    Though many people might speculate that the sea surface temperatures are too cold, the primary reasons that the South Atlantic Ocean gets no 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.

    However, in rare occasions it may be possible to have tropical cyclones form in the South Atlantic. In McAdie and Rappaport (1991), the US National Hurricane Center documented the occurrence of a strong tropical depression/weak tropical storm that formed off the coast of Congo in mid-April 1991. The storm lasted about five days and drifted toward the west-southwest into the central South Atlantic. So far, there has not been a systematic study as to the conditions that accompanied this rare event.

  • Pasted from the local oglobo.globo.com, free reg. required.

    Ciclone Catarina ganha forca e deve atingir Santa Catarina neste domingo

    ClicRBS
    CBN

    RIO - Batizado de Catarina, o ciclone extratropical que se formou a 440 quilometros da costa sul do pais ganhou forca durante a madrugada deste sabado e deve chegar ao continente na madrugada deste domingo, se for mantido este ritmo de deslocamento.

    O ciclone, que tem ventos de 118 a 152 quilometros por hora, deve entrar no continente brasileiro entre Itajai, no lit
    • Wow! Did babelfish improved that much since the last time I used it? Apart from calling Rio "River" :), it's a reasonable translation, for a machine:

      Cyclone Catherine gains force and must reach Santa Catarina in this sunday ClicRBS CBN

      RIVER - Baptized of Catherine, the extratropical cyclone that if formed the 440 kilometers of the south coast of the country gained force during the dawn of this Saturday and must arrive at the continent in the dawn of this sunday, will have remained this rhythm of displac

  • More Links & Information on the Storm... (Score:5, Informative)

    by cwolfsheep ( 685385 ) on Saturday March 27, 2004 @11:44AM (#8689231) Homepage
    1. I first found out about the storm on Weather Underground [wunderground.com].
    2. Dvorak Source [wisc.edu]
    3. CNN's 1st page on it. [cnn.com] 4. CNN's follow-up page on it. [cnn.com]

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

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