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Atlantic Tropical Action 2011 - Part III


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I'm not sure the research is at a point where we can say without a doubt that it is a plus/minus to development from a microphysical standpoint...Yes, dust is a good CCN, but if you have too many CCNs you have too many small droplets, a scenario which doesn't lend itself to efficient precipitation development.

Also, studies have shown that dust can have a large enough radiative effect leading to cooler SSTs in the equatorial Atlantic, during particularly dry years in the Sahel region of Africa.

I thought we lost correlation of Sahel rainfall to TC activity once we switched to the positive AMO.

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Yeah, the last time I can recall this kind of consistency so far out was Dean 2007. I just remember the models showing a monster Caribbean Cruiser more than a week in advance. Do I remember that correctly?

Moving beyond the NATL...

Cyclone Yasi-- the big one that hit Australia this year-- was modeled with almost creepy accuracy and consistency more than a week out.

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The GFS is definitely showing a large amount of consistency on this pouch P17L possibility. Latest run shows a whopper of a storm hitting the FL panhandle in the same area as Ivan and Opal in about ten days or so. The same run has the storm going over Hispaniola and getting disrupted but then bombing out once it gets near Florida and into the eastern Gulf. The SST in the Gulf certainly support a rapid intensification if this all plays out. Just have to watch and see what happens.

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Yeah, the last time I can recall this kind of consistency so far out was Dean 2007. I just remember the models showing a monster Caribbean Cruiser more than a week in advance. Do I remember that correctly?

I do recall Dean 2007 being modeled quite accurately at least a week in advance. Wasn't Felix 2007 also modeled reasonably well pretty far in advance?

I doubt that there has been a hurricane consistently modeled to hit about the same region of the U.S. from the same wave this far in advance since at least 2008. Scarey!

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Even the GFS ensemble means have shown at least a weak sfc low...not easy to do. The 0Z GFS version has a weak sfc low centered just west of S FL in the extreme eastern Gulf on 8/26, which is almost right on top of the 0Z GFS operational's position for the same time!

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The past several runs have shown a large storm hitting the US or coming close. This thing could be a big one. For entertainment purposes and also because the consistent nature of the runs for the past 36 hours or so have shown the system as a hurricane I am posting this GFS pic.

00zgfs500mbHGHTPMSLtropical264.gif

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Pouch 17 FL panhandle hit late on 8/27. Still another U.S. hurricane hit modeled on the GFS from this same pouch! This is pretty unusual consistency.

Yea, I've rarely seen such run to run consistency this far out. Very strange.

Yeah, the last time I can recall this kind of consistency so far out was Dean 2007. I just remember the models showing a monster Caribbean Cruiser more than a week in advance. Do I remember that correctly?

Moving beyond the NATL...

Cyclone Yasi-- the big one that hit Australia this year-- was modeled with almost creepy accuracy and consistency more than a week out.

The GFS is definitely showing a large amount of consistency on this pouch P17L possibility. Latest run shows a whopper of a storm hitting the FL panhandle in the same area as Ivan and Opal in about ten days or so. The same run has the storm going over Hispaniola and getting disrupted but then bombing out once it gets near Florida and into the eastern Gulf. The SST in the Gulf certainly support a rapid intensification if this all plays out. Just have to watch and see what happens.

It really is amazing the consistency here. I don't think I've seen it since Dean either.

So great we have consistency... the problem is its still for a system that the GFS indicates will undergo tropical cyclogenesis by day 4. I know you guys are all excited with the Dean consistency compairisons, but its important to note that Dean formed pretty early on in the Atlantic at 31W and most of that consistency you guys are alluding to was related to tracking a large and well organized feature throughout the Atlantic in an arguably easy to forecast track regime.

We don't have that yet at all... nor do we have all the models on board for a strong system (the 12z ECWMF was noticeably less bullish). If you guys can also remember back say four or five days ago the GFS had a string of 5-6 runs showing 93L as a pretty potent tropical cyclone traveling on a similar track that it now shows this feature in the most recent modeling. It still hasn't developed yet. The GFS also had a pretty significant string of runs where it had a very strongly modeled Emily, and that forecast busted pretty horribly. So despite the consistency exhibited by the recent runs of the GFS, that shouldn't make you automatically think this is going to be a big system. Lets see how the SAL interacts with the environment of the pouch and come back in about 4-5 days to see if this system is actually ready to develop like the GFS is expecting. I think it will be much more obvious then whether or not we have a dud or a robust cyclone worth tracking.

One last thing... the GFS operational runs have been way out in left field against its ensembles and ECWMF forecasting a surge in upper level divergence beyond the 4-5 day period. The other models show a much more subdued amplification of the MJO in phase 1/2. This might be the reason why its been too bullish as of late with the recent string of invests. This should also throw caution in the wind to what the GFS wants to depict in the mid and long range with this current pouch in the East Atlantic.

nq4785.gif

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Good points, Phil-- and I'm glad you made them. But please note, I hardly think anyone is "banking" on this scenario to play out. I don't think anyone here is that naive.

What's cool, either way, is that the modeling suggests 1) a better environment and 2) a better steering trend than what we've seen up to now.

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Good points, Phil-- and I'm glad you made them. But please note, I hardly think anyone is "banking" on this scenario to play out. I don't think anyone here is that naive.

What's cool, either way, is that the modeling suggests 1) a better environment and 2) a better steering trend than what we've seen up to now.

I hate to play the role as the wet blanket, but after watching all the high expectations with 93L get wiped away from a strong dose of SAL, its worth mentioning that SAL looks rather robust with this system too, both in front and above the pouch. Just take caution guitar.gif

skw2nb.jpg

Consistency is sometimes worth something, but not when the model is poorly examining the environment. Look at the analyzed 500mb RH by the 00z GFS and compaire it to the IR Satellite and SAL tracker above. I'm pretty sure the GFS is being quite a bit too bullish with the swath of higher relative humidity in the SAL.

mrwqzb.gif

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I hate to play the role as the wet blanket, but after watching all the high expectations with 93L get wiped away from a strong dose of SAL, its worth mentioning that SAL looks rather robust with this system too, both in front and above the pouch. Just take caution guitar.gif

I can understand why forecasters here are being bearish right now-- y'all have been getting burned hard this season, so it makes sense.

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I can understand why forecasters here are being bearish right now-- y'all have been getting burned hard this season, so it makes sense.

I think Adam can echo these thoughts as well... but I've been somewhat disappointed that the GFS has done as poorly as it has in the last couple of weeks with TCG and TC tracking. The ECWMF is back to schooling it again it seems.

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I do recall Dean 2007 being modeled quite accurately at least a week in advance. Wasn't Felix 2007 also modeled reasonably well pretty far in advance?

I doubt that there has been a hurricane consistently modeled to hit about the same region of the U.S. from the same wave this far in advance since at least 2008. Scarey!

Felix as I recall was missed by almost all of the global model guidance up until the day before genesis. It's pretty unusual that the models miss such a robust TC so badly, which is why I didn't think Felix would develop at the time, and it still sticks out to me.

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I hate to play the role as the wet blanket, but after watching all the high expectations with 93L get wiped away from a strong dose of SAL, its worth mentioning that SAL looks rather robust with this system too, both in front and above the pouch. Just take caution guitar.gif

Consistency is sometimes worth something, but not when the model is poorly examining the environment. Look at the analyzed 500mb RH by the 00z GFS and compaire it to the IR Satellite and SAL tracker above. I'm pretty sure the GFS is being quite a bit too bullish with the swath of higher relative humidity in the SAL.

GFS always seems to perform poorly with the SAL or other dry layers that ruin nascent systems... it was way too bullish with Gustav last year and 93L in the Caribbean, and did not foresee the effect of the dry air on those two systems.

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I think Adam can echo these thoughts as well... but I've been somewhat disappointed that the GFS has done as poorly as it has in the last couple of weeks with TCG and TC tracking. The ECWMF is back to schooling it again it seems.

Completely agree. Also strongly agree with your SAL/dry air hypothesis.

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Why hasnt NOAA started initiated an Invest for P17L? The 72 hour total precipitable water loop shows a clearly defined circulation. The visible shows this too. Perhaps the lack of convection?

I personally think it is because long term models are projecting a hurricane with possible impact on US. If the models were projected nothing, I would venture to say that there would be an Invest.

No one wants to be the forecaster who starts the hype machine going when long term models are projecting something big because the chances of it not panning out are extroidinarily high. Think about it.

I could be wrong... does anyone no if there is a minimum criteria set based upon scientific observation that a disturbance must meet before an Invest is inititiated. And if such criteria exist, does NOAA really follow it?

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