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Who Needs Hazel When You Have Sandy


CT Rain

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Ridging to the northeast of potential Sandy is much weaker with the 0z and 18z GFS than the 12z and 6z GFS, which is also related to the difference with how the low SE of Newfoundland is handled, as the 0z/18z runs have it completely separated from the main flow, unlike the 2 earlier runs. Just like any other part of the forecast this can still change but it also proves that it's not a lock that Sandy will be blocked from staying offshore.

gfs_namer_126_500_vort_ht.gif

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Eh haheh .. he makes a good point.

The bigger question is whether the runs are right in developing he tropical entity.

Yes the beta drift effect would favor more ridging to the northeast of the cyclone than the GFS is showing, there's nothing to knock that ridge down hence the 50/50 low should be the one that moves east, not Sandy.

12z GGEM track is possible though, the storm goes just far enough east to avoid a direct hit, but not SE of Bermuda.

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If you compare the 12z run to the 00z run you can see the ridge immediately east of Sandy (not north) is quite a bit weaker. That weakness allows the storm to drift east and keeps it too far east to phase with the developing NEUS trough.

I also think the models are going to struggle with fujiwhara interaction between the big ocean low off Newfoundland and the expanding wind field associated with Sandy.

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If you compare the 12z run to the 00z run you can see the ridge immediately east of Sandy (not north) is quite a bit weaker. That weakness allows the storm to drift east and keeps it too far east to phase with the developing NEUS trough.

I also think the models are going to struggle with fujiwhara interaction between the big ocean low off Newfoundland and the expanding wind field associated with Sandy.

Yeah the reaches of the NATL low sort of weaken that ridge and it drifts east.

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Yeah the reaches of the NATL low sort of weaken that ridge and it drifts east.

Yeah the big Newfoundland low is farther west now and that weakens the ridge a bit opening up the escape hatch. The 12z run was the near perfect location for the pseudo 50/50 low that was east enough to keep the omega block/ridge in place.

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Even at 72 hours or so it was evident that there were huge changes from the 12z run in the North Atlantic with that upper level low. A good example as to why its not usually a good idea to get worked up over any solution at 180+ hours out -- the changes from run to run can be huge because even the main players in the pattern can be jumping around on the the models at that range.

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Yeah the big Newfoundland low is farther west now and that weakens the ridge a bit opening up the escape hatch. The 12z run was the near perfect location for the pseudo 50/50 low that was east enough to keep the omega block/ridge in place.

It's funny though, because the trough in the Plains was sharper...more amplified with that and the ridge just off the west coast. So one part looked better, the other obviously worse.

To the accuweather weenies, this is why it always isn't a good idea to run with the most anomalous solutions. While it can happen, you need a synergistic appeal to the happen where all the moving parts need to work in harmony.

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It's funny though, because the trough in the Plains was sharper...more amplified with that and the ridge just off the west coast. So one part looked better, the other obviously worse.

To the accuweather weenies, this is why it always isn't a good idea to run with the most anomalous solutions. While it can happen, you need a synergistic appeal to the happen where all the moving parts need to work in harmony.

Yeah you need to thread the needle to get the most extreme/anomalous solution to occur in any given geographc area lol. More often than not the countless different and moving pieces don't come together perfectly and you're left with a flop.

While the pattern is interesting that's about all you could reasonably say with this morning's 12z runs. If it was a 96 or 120 hour forecast... that would be one thing... but 180+ hours you're really in weenie land out there.

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The set up over the eastern US and Atlantic certainly creates a classic environment for high sensitivity to initial conditions with this storm, and a bifurcation of forecast solutions. In general, this results in all or nothing. Obviously not quite that severe in reality, but we're certainly not looking at a nice Gaussian distribution of solutions

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Yeah you need to thread the needle to get the most extreme/anomalous solution to occur in any given geographc area lol. More often than not the countless different and moving pieces don't come together perfectly and you're left with a flop.

While the pattern is interesting that's about all you could reasonably say with this morning's 12z runs. If it was a 96 or 120 hour forecast... that would be one thing... but 180+ hours you're really in weenie land out there.

< 72 hour forecast ;)

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Anyone remember January 2-4 this year? There was plenty of hype after only a few hour 192-240 ECM runs that showed a developing blizzard, and nothing came out of it at the end. There was also a similar case in February 2011 when the GFS had a very strong storm developing 192 hours out and the only thing that came out of it was a light Mid Atlantic snow event.

This is a reminder of why no one should be taking hour 180+ solutions seriously. As the latest model runs are suggesting, especially with the different handling of the Atlantic low and the ridging NE of Sandy, there's so much that can go wrong with these long range extreme scenarios; not to say it is impossible, but it could just as easily fail to verify.

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You can also see some other differences to the op run and as you get towards 168 h there is considerable spread in the ensembles to get to the mean. I do notice a more amplified trough and maybe stronger blocking in the Atlantic however. All this is saying is dont buy into any one solution yet.

GEFS have that wave along the trough developing as a possibility we talked about earlier.

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You can also see some other differences to the op run and as you get towards 168 h there is considerable spread in the ensembles to get to the mean. I do notice a more amplified trough and maybe stronger blocking in the Atlantic however. All this is saying is dont buy into any one solution yet.

I was gonna comment on that too. The overall pattern seemed a little more favorable than the op fwiw. Just another example of how complicated things are....but aren't they always for fun events? LOL.

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One other thing to mention is the far superior tropical vortex assimilation on the Euro versus the GFS. No :weenie: 's, I am not saying the euro will be right, all I am saying is we dont really know if the GFS is getting the tropical wave right at its assimilation so it could be throwing off the track later on. This does not mean a big bomb will happen because it may not see the vortex right yet, just that there is another problem to the equation this far out.

I was gonna comment on that too. The overall pattern seemed a little more favorable than the op fwiw. Just another example of how complicated things are....but aren't they always for fun events? LOL.

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