Brazilian tropical disturbance, and tornado damage surveys
The season's second South Atlantic tropical/sub-tropical disturbance has formed off of the coast of Brazil today. The disturbance formed from the remains of a cold-core low, which sat over warm waters of 27 degrees C long enough to start acquiring tropical characteristics. We saw this same behavior this past hurricane season with the Greek storms Delta, Epsilon, and Zeta. The disturbance is mostly just a swirl of low clouds, but has seen two bursts of deep convection today. The most recent burst of convection, seen in the satellite photo below, formed in a spiral band well removed from the center. Early this morning, a more impressive burst of deep convection formed near the storm's center, but was quickly ripped away by strong westerly upper-level winds. These strong winds are expected to continue to bring high levels of wind shear over the disturbance over the next few days, and likely keep it from forming into a tropical depression. The system is expected to move slowly southwest, parallel to the Brazilian coast, and get absorbed into a frontal system to the south by Friday. No threat to land is likely, and this storm is mostly just of academic interest.

Figure 1. Tropical/subtropical disturbance off the coast of Brazil. Image credit: NASA Global Hydrology and Climate Center.
So, the academic question to ask is, does this second tropical system of the year off the coast of Brazil show that climate change is affecting the Atlantic? Only one hurricane and two tropical depressions have been observed in the South Atlantic since 1970, when accurate tracking methods became available with the advent of weather satellites. There is usually too much wind shear to allow a tropical cyclone to form, and the South Atlantic lacks an active "Intertropical Convergence Zone" (ITCZ)--that stormy band of weather that stretches along the Equator and acts as a source region for many of the disturbances that grow into Northern Atlantic hurricanes. With Hurricane Catarina of March 2004, another tropical depression in January 2004, a "near miss" tropical cyclone February 24 of this year, and now another tropical or subtropical system trying to form in the South Atlantic today, it is quite possible that climate change might be to blame. It may also be that we are seeing an active period in the South Atlantic that has a long cycle, and last repeated itself before satellites were around. Given the Atlantic Multi-decadal Oscillation (AMO) that affects hurricane activity in the North Atlantic, it is reasonable to think we might see a similar pattern in the South Atlantic.
In either case, I believe is it time that the NHC considered adopting a naming system for the South Atlantic. Had today's system intensified into a tropical storm, it would not have been given a name, since there is no naming system in place for the South Atlantic Ocean. Given the current trends we're seeing, it would be no surprise if we saw more tropical systems here in the next few years.
Tornado damage surveys from the weekend's outbreak
More damage surveys are complete from the weekend's major tornado outbreak, and it now appears that the strongest tornadoes were of F3 intensity on the Fujita scale. There were at least four F3 tornadoes in the outbreak, and these tornadoes had winds in the 158 - 206 mph range (roughly the same winds as found in a Category 5 hurricane). The Springfield, MO NWS office has posted a detailed summary of the the three F3 tornadoes that affected the southwestern portion of Missouri over the weekend, and the Central Illinois NWS office has posted a nice summary of the two F2 tornadoes that slammed Springfield, IL on Sunday, March 12. Included are zoom radar animations of the impressive hook echo, plus many damage photos. Not all the tornado-like damage from the weekend's wild weather was due to tornadoes, though--a storm survey done in along the west side of the Quad City Airport in Moline from Sunday concluded that the damage from a 107 mph wind gust done to homes, trees, and power lines on the west side of the airport was due to a severe thunderstorm downdraft (microburst).
Jeff Masters
Reader Comments
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It is important to recognize that one has to compare apples with apples and not apples and oranges to substantiate a claim.
Specifically, two tropical disturbances identified recently in the South Atlantic doesnot constitute a tropical cyclone which still has not formed this year, despite the two tropical disturbances identified in the South Atlantic that some want to use to support as possiible evidence of global warming.
Think about this objectively, we compare increases in Atlantic hurricane activity based solely upon the actual development of a tropical storm or subtropical one, and not tropical depressions and certainly not the number of tropical disturbances that originate.
So can those who wish to blame every new big snow storm, tornado outbreak, hurricane landfall, UFO in their own backyard, etc. on global warming, please keep things in their proper perspective.
One must realize that we most likely know far less about the immense complexities of our Atmosphere, than we do currently understand, despite how much we in the scientific field or anyone else for that matter, likes to think we do.
My posts in here will be very far and in between but some of these unfounded claims needed to be clarified and kept in their proper perspective. Naturally, I don't expect to change anyones mind who wants to try and support a global warming argument with the aforementioned for they are entitled to their own personal opinions as well.
That being said, the unusual development of a real tropical cyclone in 2003 (hurricane)in the South Atlantic can be accunted for just as easily by what we do not know about that region (i.e. Natural climate cycles like the AMO Dr. Masters mentioned) amongst the prospect others went unnoticed without satewllite detection capability.
Moreover, one unusual event does not legitimately consitute climate change by its very definition.
Thanks,
Tony
I noticed a typo in my previous post, it was a hurricane in the South Atlantic during the 2004 season not 2003.
To further substantiate my previous point in the aforementioned post below.
Dr. Masters stated the following:
"So, the academic question to ask is, does this second tropical system of the year off the coast of Brazil show that climate change is affecting the Atlantic?"
"Only one hurricane and two tropical depressions have been observed in the South Atlantic since 1970, when accurate tracking methods became available with the advent of weather satellites."
To reiterate, there still has not been one tropical cyclone to develop since the one hurricane in 2004, despite the two tropical disturbances noted in Dr. Masters comments.
Once again, a tropical disturbance is not a tropical cyclone.
So, the answer to the question is a respectful "no" in regards to whether the two identified tropical disturbances this year give evidence of climate change based on the current data.
However, if we see real tropical cyclones develop on a consistent basis, then and only then, can one legitimately suggest it to be a result of climate change. Furthermore, if that indeed did occur, the direct cause would still be unknown as to whether it was related to Natural climate cycles or human activities that some would like to think regardless.
I hope everyone has a great weekend.:)
Thanks,
Tony
yep, La Nina is bad for the hurricanes. It is very unlikely this year.
ForecasterColby, there is evidence that a full-force hurricane hit San Diego in the 1850s and maybe another one earlier than that. Also a tropical storm hit in the 1930s. Propability alone says a hurricane will hit again in the next 50 to 100 years even if climate does not change at all. However, if the recent upturn in hurricanes is not limited to the North Atlantic/Gulf, it only increases the chances. I still say it will happen, but not during a La Nina year. NY has a much greater chance to get hit this year.
Remember, as this year has shown, hurricanes CAN maintain strength on waters <80 degrees and cover quite a bit of distance before they dissipate if they are moving fast.
Perhaps one day a Cat 1 hurricane will hit southern California. Maybe even a Cat 2 if global warming is stronger than forecast and everything else is just right. But I doubt I will see a major hurricane hit southern California in my lifetime.
major hurricane? very unlikely. However, catergory 1 hurricanes have hit southern California before, and this was long before 'global warming' was even a factor.
Posted By: atmosweather at 4:07 AM GMT on March 16, 2006.
So the same amount of damage as Hurricane Andrew? I think not...
Wind damage would be minor. On the other hand, Florida doesnt have a wall of 7000-10,000 foot mountains behind it to double or even triple the rainfall. 30 inches of rain in a day will mess up any city... and the fact that it would fall on dry soil would probably only make it worse.
Also, LA by nature is not really possible to evacuate...
hurricanechaser, i would just like to point out that Dr Masters only said 'climate change' might add to these odd storms, and didnt even mention 'greenhouse warming'. Since we all agree the climate is changing now (as it pretty much always is), and by any standard a fluxuation that lasts 100s of years is a sort of climate change in and of itself, i don't think the statement is invalid even if the cause may not be anthropomorphic.
I was specifically referring to other posts here that picked up on Dr. Masters comments and the question he posed regarding the development of South Atlantic tropical disturbances and its correlation to climate change. In your comments you missed the central premise of my posts which I will clarify after posting your comments below.
You said:
"hurricanechaser, i would just like to point out that Dr Masters only said 'climate change' might add to these odd storms, and didnt even mention 'greenhouse warming'. Since we all agree the climate is changing now (as it pretty much always is), and by any standard a fluxuation that lasts 100s of years is a sort of climate change in and of itself, i don't think the statement is invalid even if the cause may not be anthropomorphic."
You left off the most important distinction I made, which is there is nothing "odd" as you put it, about two formations of tropical disturbances, which don't even compare equally with actual tropical cyclones (depressions, storms, and hurricanes) that have actually formed in the past.
Now lets review how he phrased the "climate change" question.
He said:
"it is quite possible that climate change might be to blame."
"It may also be that we are seeing an active period in the South Atlantic that has a long cycle, and last repeated itself before satellites were around."
"Given the Atlantic Multi-decadal Oscillation (AMO) that affects hurricane activity in the North Atlantic, it is reasonable to think we might see a similar pattern in the South Atlantic."em>
Ok, please look at these statements objectively, he is making a distinction between the term "climate change" in the first comment and the Natural climate cycles in the two succeeding ones that he said could "also" be to blame.
Since a Natural climate cycle like the AMO is part of climate change and he is referring to another form of climate change in his comments, what other form of climate change can we presume he is referring to, since you and I both know he is a big believer in anthropomorphic global warming as you are unapologetically as well (which is not something I take issue with for I can respectfully disagree about that, as we all should do on that issue).
Regarding the global warming debate and its correlation with Atlantic Basin activity, there are many proponents of anthropomorphic global warming that say that the increase in our recent activity is due to human induced causes and not the Natural climate variability of the AMO cycles which I support.
Therefore, it seems pretty obvious that one doesn't have to use the term global warming to state the obvious insinuation, when a definite distinction is made between it and natural climate variability.
To be specific, my comments are notto rehash the direct cause of global warming debate, but to suggest everyone legitimately compare the historical record objectively, which hasn't been done by some of the comments that are posted in this blog that preceded my own.
In short, there is nothing unusual about two tropical disturbances being identified in the South Atlantic when in the past we have actually had one hurricane other than the one in 2004 and two real tropical depressions as well.
Consequently, it is safe to say there were most likely many tropical disturbances that formed not in the too distant past that simply went unnoticed because they in itself aren't a big event.
In regards to my view on global warming, please see my two most recent posts in fshheads blog as to "why" I don't feel a need to continue to debate that issue.
Thanks,
Tony
I am sorry that I somehow totally messed up that last post with all the bold and italics.
Please understand that my comments are in no way reflective on any problems I have with Dr. Masters and his personal opinions about climate change or anyone elses for that matter. In reality, we all have a fundemental right to our own opinions.
My central premise was comparing tropical cyclone development with true tropical cyclone development which tropical disturbances are not and don't legitimately consitute a real anamoly since there has been one identified hurricane and two tropical depressions observed in the past at a time our technology and most likely interest wasn't as focused on that region.
It was not meant to be a debate about the direct cause of global warming, because none of us truly knows that answer as to how much an effect human activities have or will have on global temperature increases, no matter how much we like to think we do. This applies to everyone of us regardless of our own personal opinions on the direct cause of it.
Thanks,
Tony
So, how do those events tie to global warming? I'm wondering what the mechanism might be.
you and I both know he is a big believer in anthropomorphic global warming as you are unapologetically as well
hmm, i dunno if i would say i am a 'big believer; in anthropomorphic warming as the entire cause of global warming.. i think it is part of the cause but i think natural fluxuations are also part of the cause, and i don't pretend to know which factors are the most prevalent.
Thanks for your responses to my posts.:)
"hmm, i dunno if i would say i am a 'big believer; in anthropomorphic warming as the entire cause of global warming.. i think it is part of the cause but i think natural fluxuations are also part of the cause, and i don't pretend to know which factors are the most prevalent."
Just a quick post to clarify that I didn't say either you or Dr. Masters thought it was the entire cause but the direct cause...huge difference there.
Just like I believe Natural Climate variability is the direct cause, but most likely not the entire cause, meaning human activity may and probably has had some minimal effect.
These are simply my opinions at this point based on the current data available.:)
I hope you have a great night.:)
Thanks,
Tony
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