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Tropical Storm Isaac, Part 1: Moving Through The Eastern Caribbean Sea


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Circulation seems to be tightening up despite some dry air interaction. Could also argue theres a bit of a WSW movement.

Vorticity disruption may not be hampering this too much at the moment. Maybe its just the models not handling this process well.

GFS EnKF control has a much more organized system than the OP GFS FWIW

2012AL94_AMSUSR89_201208191432.GIF

What's its track?

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FWIW, the someone less trusted CMC and NoGaps are showing or suggesting fish,,,.

So that tells us it won't be, LOL. :P

Serious note, new 12Z ECMWF, while not showing the deep system that it was a couple of days ago, looks quite a bit better organized on this run. It takes a strong, well organized 850 mb vorticity maximum that looks well correlated with a MLC (at least as it gets farther west) due west through the Islands and into the central Caribbean by Saturday morning. In any event, it is no longer showing the shearing/weakening trend in the Caribbean that it was showing the last couple of runs, at least trough day 5.

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So that tells us it won't be, LOL. :P

Serious note, new 12Z ECMWF, while not showing the deep system that it was a couple of days ago, looks quite a bit better organized on this run. It takes a strong, well organized 850 mb vorticity maximum that looks well correlated with a MLC (at least as it gets farther west) due west through the Islands and into the central Caribbean by Saturday morning. In any event, it is no longer showing the shearing/weakening trend in the Caribbean that it was showing the last couple of runs, at least trough day 5.

:wub:

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Not disappoint who? LOL ;)

Scratch that. Somehow, people always find a way to get disappointed.

TIME (HR)		  0	 6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    25    26    30    34    39    52    66    78    90    99   105   107   108
V (KT) LAND	   25    26    30    34    39    52    66    78    90    99   105   107   108
V (KT) LGE mod    25    24    25    27    29    37    49    65    83    99   109   112   109
FORECAST TRACK FROM OFPI 

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Josh. ;-)

:D

Bingo.

ECMWF has a Yucatan "hit"

The 12Z Euro track is red-hawt. Admit it-- even you guys like it.

It never really gets going on the euro, hardly anything you could put alot of confidence into; also believe the euro is too fast.

Yeah, but the indication of general W motion-- as opposed to Shredderola or Fishville-- is encouraging.

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It never really gets going on the euro, hardly anything you could put alot of confidence into; also believe the euro is too fast.

As I mentioned above, I would disagree with this characterization of the EC. Just because it only has a 1008 mb surface low doesn't mean it doesn't develop. It shows a very well developed vorticity maximum at 850 mb that looks pretty well correlated with a surface and 500 mb feature (see below). It did something very similar with Gordon several days out - it did not show a low surface pressure, but yet had a well organized looking system.

12zeurotropical850mbVortSLP168.gif

12zeurotropical500mbSLP168.gif

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In choosing weenie modes, I still have somewhat of a preference for 1938 over 1900. The differences in the GFS ensemble means between runs seems to be shrinking.

I don't know what year to use for the Carolinas weenie storm, since Hazel wasn't an MDR long tracker.

post-138-0-26939000-1345405101_thumb.gif

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As I mentioned above, I would disagree with this characterization of the EC. Just because it only has a 1008 mb surface low doesn't mean it doesn't develop. It shows a very well developed vorticity maximum at 850 mb that looks pretty well correlated with a surface and 500 mb feature (see below). It did something very similar with Gordon several days out - it did not show a low surface pressure, but yet had a well organized looking system.

I'm going to take a guess and say that the multiple vort maxes at 500 mb at 156 hrs is to blame for the lack of sfc and wind organization on the Euro. during that time frame. Having two regions fighting for center of circulation dominance I would assume would induce areas of convection that would interfere with one another hindering a nice area of central organization that would promote intensification. Later on at 180 the vort max consolidates at 500 mb though. post-3697-0-32808700-1345405134_thumb.pn

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I'm going to take a guess and say that the multiple vort maxes at 500 mb at 156 hrs is to blame for the lack of sfc and wind organization on the Euro. during that time frame. Having two regions fighting for center of circulation dominance I would assume would induce areas of convection that would interfere with one another hindering a nice area of central organization that would promote intensification. Later on at 180 the vort max consolidates at 500 mb though. post-3697-0-32808700-1345405134_thumb.pn

Here at home all I have is what I can see on the web, so I don't have that kind of detail. My point really just was that the previous few runs have had more of a strung out wave looking feature, while this runs has more of a look of intense vorticity center indicative of a TC. While I am definitely in the camp of believing that the global models are an excellent tool in forecasting tropical cyclone intensity trends, I just did not want to leave the idea that just because the low center is only 1008 mb that means it's not showing much development. I think it is better to look at the vorticity, its trends, and how aligned it is vertically. Gordon was a good example of that.

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After a hand full of GFS runs showing a weak system in the Western Carib...the 12z GFS maintains a stronger core and then explodes in the GOM around 240 heading for Texas...

Man that thing is bombing the freak out, then again it's hard not to imagine with the hot tub water sitting in the Gulf if it does make it there (although that would be really bad for gas prices). :wub:

Despite issues with outside influences (other vort maxes, the TUTT, etc.), one cannot deny that these verbatims are churning out some interesting tracks.

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