Dean = Global Warming?

[x-y-no]

GW could lead to more enhanced TCs

However, if the tropics heat up faster than the poles, thermal wind balance would imply greater wind shear. That may confine TCs to the tropics where the horizontal temperature gradients are less

But the projected (and observed) pattern is the opposite - the poles (particularly in the northern hemisphere) are warming faster than the tropics.

[Downdraft]

I think we are agreeing but saying it differently. We have seen many storms in high ocean heat never develop because of other factors inhibiting them. Dean was a classic case of perfect fuel and almost perfect environment to develop and maintain. Of and by itself it can't be seen as evidence of GW and its affect on tropical cyclones.

[Sanibel]

2 days ago NYC tied their all time coldest August daytime mex temps at 59ºF, and I don't think that implies a glaciation episode is about to occur.

First, those who cite the fact that a single weather event can't determine global warming don't speak up when someone uses a single weather event to dismiss GW as is done above.

Next, this is something I've been emphasizing in these threads. It's called "amplitude". It's a GW phenomenon where troughs and weather patterns become enhanced because there's more energy in the atmosphere from GW. When you add heat to something it energizes it. This energy manifests in the form of stronger weather patterns. One example is the extreme rain seen in India from single storms. The monsoon has worse downpours that rain huge amounts per rain event. This is the extra energy showing itself in the form of harder rains. All documented. The weather event cited above could be due to that extra energy being able to pull cooler air down from the north in the form of stronger fronts (higher amplitude troughs). All due to amplitude. So, indeed, cooler weather could very well be directly related to a warming atmosphere - as counterintuitive as it is. In the meantime the south baked under 100 degree temperatures and drought.

[Downdraft]

2 days ago NYC tied their all time coldest August daytime mex temps at 59ºF, and I don't think that implies a glaciation episode is about to occur.

First, those who cite the fact that a single weather event can't determine global warming don't speak up when someone uses a single weather event to dismiss GW as is done above.

Next, this is something I've been emphasizing in these threads. It's called "amplitude". It's a GW phenomenon where troughs and weather patterns become enhanced because there's more energy in the atmosphere from GW. When you add heat to something it energizes it. This energy manifests in the form of stronger weather patterns. One example is the extreme rain seen in India from single storms. The monsoon has worse downpours that rain huge amounts per rain event. This is the extra energy showing itself in the form of harder rains. All documented. The weather event cited above could be due to that extra energy being able to pull cooler air down from the north in the form of stronger fronts (higher amplitude troughs). All due to amplitude. So, indeed, cooler weather could very well be directly related to a warming atmosphere - as counterintuitive as it is. In the meantime the south baked under 100 degree temperatures and drought.

I don't think anyone is arguing that GW isn't happening. What gets debated with passion is how much and man's contribution to it. What we were discussing in this thread is the affect upon tropical cyclones specifically in the Atlantic Basin. I believe there is a point of agreement that GW may inhibit or negatively affect cyclone formation but positively enhance cyclone intensity. Your quite right that although counterintuitive GW could produce much colder weather on parts of the planet. If you start interrupting or shutting down some of the great ocean loop currents I'd shudder to think its impact upon global climate. No matter what your opinion it's a good debate!

[KWT]

That makes sense Sanibel if you didn't overmiss one huge thing, and thats the earth is warming and therefore while there is more inthe way of extreme warm events the cold events are become less extreme simply because the poles aren't quite as cold as they used to be. So how can you get cool spells getting more extreme when the cold pools that feed us that cold in the N.hemisphere are slowly decaying?

As for Dean, can't balme GW on that one really, we've seen several sub-900mbs in the western Caribbean as well as any other strong hurricanes as well, who knows though its hard to say.

[Sanibel]

That makes sense Sanibel if you didn't overmiss one huge thing, and thats the earth is warming and therefore while there is more inthe way of extreme warm events the cold events are become less extreme simply because the poles aren't quite as cold as they used to be. So how can you get cool spells getting more extreme when the cold pools that feed us that cold in the N.hemisphere are slowly decaying?

It's a sophisticated science I don't want to pretend I myself have a studied knowledge of. But you have to be careful with general assumptions. By your own example deserts should very hot places because the mean of 114* daytime temperatures should be high. But they get downright cold at night because of other factors like, humidity, heat radiation etc.

You have to look at global warming energy as a wind or force acting on a great body of water. The more energy you put into that body of water the higher the waves get. Weather troughs are simply "waves" in the atmosphere. The more energy the higher the waves. So, even if the global mean is rising deeper amplitude is capable of bringing unseasonably cooler temperatures further south because the weather systems have the energy to yank that cool air down from further north. Just as warm air can be pulled from the south. The second dimension at which this occurs is the vertical axis where deeper layered airmasses can result from this extra energy. It is possible the strong Highs that guided Dean were enhanced by this energy. A bigger "wave," so to speak, of High pressure. But you have to be careful in your analogy above, since the total change, so far, is only around 1 degree in the mid-latitudes so far. So the air hasn't been warmed that much, yet, to carry your theory.

As for the sub-900 storms. Those records being broken are a red flag that warm oceans are supporting a higher level of instability allowing for stronger storms as seen in the record pressures. You can't easily rationalize away the GOM low pressure record being broken twice in the same year as well as the Atlantic record. What is that crying out?

[Derek Ortt]

if the poles are warming up faster, that would mean lower wind shear. However, there would be less need for heat transfer between the tropics and the poles. This could lead to more intense hurricanes, but more that stay within the tropics and fewer at higher latitudes (unless they form at the high latitudes)

[x-y-no]

if the poles are warming up faster, that would mean lower wind shear. However, there would be less need for heat transfer between the tropics and the poles. This could lead to more intense hurricanes, but more that stay within the tropics and fewer at higher latitudes (unless they form at the high latitudes)

Yes. This seems like a very plausible hypothesis to me.

[KWT]

Yep in the mid-latitudes its not much Sanibel but the Arctic is running decently above that.

Prehaps this is where our decently locations come into play here Sanibel. i'm at 52N roughly whilst your way south of that. In a decent northerly we'll drag down air from the Arctic and you really can't source from much colder, bar W.Russia maybe. A deeper digging upper low won't make us any colder.

As for the hurricanes of 2005, thats impressive but could just as easily be a seasonal fluke, if we have another season like it in terms of intense hurricanes then we have to consider something different, I do have to admit the fact we've seen so many top 15 hurricanes over the last few years is interesting. Dean would have been strong GW or no GW given the set-up it had, Janet got down to 914mbs years before global warming became an issue and given it strengthened while heading towards Yucatan I'd bet Janet was close to 900mbs at its peak...at the same place Janet was at 914mbs Dean was at 926mbs just starting its strengthening towards peak. I'd bet there are others that were strong enough to be top 10 right now but deepest pressure wasn't recorded.

[Jim Hughes]

if the poles are warming up faster, that would mean lower wind shear. However, there would be less need for heat transfer between the tropics and the poles. This could lead to more intense hurricanes, but more that stay within the tropics and fewer at higher latitudes (unless they form at the high latitudes)

This would make sense if you considered what these storms are doing in regards to the troposphere's pole to tropical relationship but not the stratosphere. An increase of intense storms would help make the Brewer Dobson Circulation stronger (Which I believe this positive AMO run has done).

This increase would bring more ozone levels to the poles, hence an even warmer polar stratosphere. So the temperature gradient between the tropics and the poles would still be getting smaller up above. And this DOES have an influence upon our climate.

Of course you have to consider what the QBO and space weather variables are like also in regards to all of this.

[Sanibel]

As for the hurricanes of 2005, thats impressive but could just as easily be a seasonal fluke

Keep in mind that the "seasonal fluke" of which you speak entailed a record number of storms and several record storms themselves. The little extra possibly coming from global warming. Especially if you consider warm seas to be the source. 2005 was well above and beyond the previous Atlantic Oscillation peak year of 1933. You can see them scrambling for excuses like missed storms etc - but that's what they are doing, that is, scrambling around the obvious.

We'll see what happens in statistics. For all we know global warming will enhance the SAL flow, ENSO, etc - disrupting Atlantic storms rather than enhancing them.

[terstorm1012]

But Sanibel, it is still entirely possible that there's been seasons with missed storms. 1933 could still have a storm or two undetected, or more. That said, we'll never know.

I don't consider that reaching for straws when done without an agenda.

hey this is a great discussion by the way. It is so nice to discuss this calmly and scientifically.

[KWT]

I seem to remember one of the pro-mets here saying that there could have been as many as 5-7 storms missed in 1933 in the east Atlantic.

for example i'm sure Delta woul have not been picked up and considered extra-tropical, as there do tend to be extra-tropical cyclones that far south at that itme of year. Lee would have been missed as well given it was very weak and lasted 6hrs, Zeta may have been missed or considered extratropical. Unless a ship went thorugh Vince's and Epsilon's small inner core those two would have also been missed in 33 or considered as powerful extra tropical cyclones.
Thats 5 I'm convinced would have been missed in 33.

In terms of strength, well yeah in that regards the 05 season does offer some questions and I think its probably true at least in the Atlantic that peak strength of storms is slowly increasing, or in the case of pressure, decreasing, though its hard to know the true strength of some of those hurricanes given away from land data would be limited and is probably nothing more then an educated guess, though even then it doesn't really compare to 05.

[Jim Hughes]

As for the hurricanes of 2005, thats impressive but could just as easily be a seasonal fluke

Keep in mind that the "seasonal fluke" of which you speak entailed a record number of storms and several record storms themselves. The little extra possibly coming from global warming. Especially if you consider warm seas to be the source. 2005 was well above and beyond the previous Atlantic Oscillation peak year of 1933. You can see them scrambling for excuses like missed storms etc - but that's what they are doing, that is, scrambling around the obvious.

We'll see what happens in statistics. For all we know global warming will enhance the SAL flow, ENSO, etc - disrupting Atlantic storms rather than enhancing them.

I am sorry Sanibel but you and everybody else are missing the bigger picture here. This activity level is actually serving a purpose. I would be more worried about our climate system if it was absent.

[Sanibel]

It is very hard to draw a specific conclusion since there are so many variables that could be responsible. But it would be interesting, in this negative 2007 environment, if the next storm went big category again. We would start seeing a higher average intensity.

I am sorry Sanibel but you and everybody else are missing the bigger picture here. This activity level is actually serving a purpose. I would be more worried about our climate system if it was absent.

Well last year had all the positive factors needed for an active year and failed. The Nino wasn't really a real Nino since none of the regular Nino effects happened - like storms into California and a wet cool winter in Florida. You can get to the point where you are blaming everything on global warming - but you have to watch out for the signs. What is causing this year to be inactive so far is beyond me. It's just a general, vague negativity that seems to prevail around the entire basin. Like an intangible atmospheric. What I'd be worried about is another Dean coming off Africa and not being held south. But that goes unsaid.

[mitchell]

I don't think anyone is arguing that GW isn't happening. What gets debated with passion is how much and man's contribution to it.

Maybe on this forum it doesn't but I constantly hear people on the news arguing that global warming is nothing more than a left wing invention aimed at regulating you even more. I actually heard Rush Limbaugh passionately arguing the other day, after dismissing global warming as a bunch of nonsense, that even if you are foolish enough to believe it, how it was "pompous and arrogant" that this generation would claim that the current climate is the one we should try to maintain by limiting our contributions of greenhouse gasses. Essentially he was saying "who are we to say what climate is the right one."

It was rich. But my point is that many many people of influence argue in all sorts of ways that GW isn't happening.

[KWT]

Sanibel, all the global signs for El Nino were in palce by September (-ve SOI, etc) and several as early as April/May, as for your winter, lest we forget we had one of the strongest +ve AO ever at the start, it over-ruled eeverything, even the El nino signal, but we very much had El nino by early Autumn in 06. As for this year, well thats for another debate though I do have an idea its more guesswork then anything else without looking into it further.

[terstorm1012]

Also keep in mind that the delayed freezing of the Arctic last year ended up delaying winter across much of North America (and when it froze, Winter got back at us with a vengence).

Jeff Masters wrote about it in the winter or spring but I forget exactly when. That is where I'm pulling that information from.

[Matt-hurricanewatcher]

If the new updated data for the United states is right. Then most of the hottest years fall in the 30s. In some more spread out over the last hundred or more years, that makes it hard to say if global warming occuring in the united states. Even so in Portlands snow fall has droped by 200 percent+ in the last 30-40 years with possibly as much as 1+ degree warmer by charts I've looked at since the 70s. Much much less snow and more rainy warm winters. I don't get it, makes me wonder if I should trust anything. You would expect to see a soild trend to warmer in the US.

As for the hurricane more warm sst's. Which form by the sun/Atmosphere warming the surface of the ocean over the spring and summer. As time go's by this area of warm water go's deeper making for the level of TCHP. So yes a warmer overall atmopshere would mean more TCHP=stronger hurricanes.

[hial2]

http://abcnews.go.com/Technology/CSM/st ... 859&page=1

Just to add more fuel to the fire............