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Winter 13-14' Med/Long Range Discussion


Chicago Storm

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GFS in serious troll mode. From sub -20c 850 temps to a driving rainstorm within 48 hours in the LR.

 

Very extreme and by the looks of it another cold shot is likely to follow once the storm passes with sub -20Cs all across the Prairies. Active storm track developing in the Pacific by the looks of it. 

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Much of Canada stays very cold and much below normal through the entire GFS run. Bodes well for when storms do develop and move north. A very tight gradient pattern is in place with an active storm track. Lets see how the month progresses. Alot of extreme temperature variations across the subforum on the GFS LOL. 

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Very extreme and by the looks of it another cold shot is likely to follow once the storm passes with sub -20Cs all across the Prairies. Active storm track developing in the Pacific by the looks of it. 

 

If we get a more active storm track it'll likely be tied in with a +EPO/-PNA. We'll need some of the non-Pacific teleconnections to help out if we want to to stay cold enough for snow.

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If we get a more active storm track it'll likely be tied in with a +EPO/-PNA. We'll need some of the non-Pacific teleconnections to help out if we want to to stay cold enough for snow.

 

I admit that I can't see Allan's model page, but I hope the Euro ensemble agrees with the PDS map room's depiction of the strong -PNA coupled with the weakening of the -EPO around the middle of the month.  With that strong of a -PNA it should pop the SE ridge and thus end the suppression idea.  With the EPO trending towards neutral but still in the negative range there should be enough cold air around for a decent system around that time frame, and the OP GFS seems to be showing it.  For once could the op GFS be well linked to the ensemble pattern?  If anyone can see the Euro ensembles is it all right if you let me know by text in this thread?

 

http://www.esrl.noaa.gov/psd/map/

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I admit that I can't see Allan's model page, but I hope the Euro ensemble agrees with the PDS map room's depiction of the strong -PNA coupled with the weakening of the -EPO around the middle of the month.  With that strong of a -PNA it should pop the SE ridge and thus end the suppression idea.  With the EPO trending towards neutral but still in the negative range there should be enough cold air around for a decent system around that time frame, and the OP GFS seems to be showing it.  For once could the op GFS be well linked to the ensemble pattern?  If anyone can see the Euro ensembles is it all right if you let me know by text in this thread?

 

http://www.esrl.noaa.gov/psd/map/

 

+EPO/-PNA may not be so bad for Minnesota, especially with the PV on our side of the pole, but for most of us, without blocking over the Atlantic, we're going to warm. Contrasting the 0z EURO with the 12z EURO is interesting. They're reasonably similar. Both retrograde the EPO ridge, both lower heights in Alaska but don't really dig a GOA trough, both keep the PV around Hudson Bay. However, the 12z/4 run popped a mini +PNA ridge and managed to keep the Lakes colder. 0z lost that ridge, and we warm.

 

Beyond Day 7 I get the feeling we'll be in thread the needle mode. It may turn out ok but it's going to be a razor's edge. Latitude will help.

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+EPO/-PNA may not be so bad for Minnesota, especially with the PV on our side of the pole, but for most of us, without blocking over the Atlantic, we're going to warm. Contrasting the 0z EURO with the 12z EURO is interesting. They're reasonably similar. Both retrograde the EPO ridge, both lower heights in Alaska but don't really dig a GOA trough, both keep the PV around Hudson Bay. However, the 12z/4 run popped a mini +PNA ridge and managed to keep the Lakes colder. 0z lost that ridge, and we warm.

Beyond Day 7 I get the feeling we'll be in thread the needle mode. It may turn out ok but it's going to be a razor's edge. Latitude will help.

Its going to be a tight gradient pattern with the SE ridge trying to fight back against the PV. Previous analogs that did weaken the EPO ridge didnt last very long so were going to have to see if its just transient or consistent. With such a strong gradient in place the possibility of storms increases coupled with the enhanced STJ.

For cold air to stay in place across the Lakes area while this retrogradation is taking place we would need help from the Atlantic. By edging out a ridge across Eastern Greenland we can keep the effects of the SE ridge just south of us. And some models do try and create a -NAO around this same time.

Interesting pattern. Its a battle of the Oceans.

Such a pattern would produce a stormy period from about Dec 15 to around Dec 28.

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Temps will certainly moderate and there will probably be some above average days but I'm not ready to buy into a persistent torch at this point.  If the EPO trends toward neutral or slightly positive it might not be much different than if it were weakly negative. 

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Might only be one model run, but the 06z GFS completely gets rid of any idea of warmth in this region through out the entire run minus a day or two. Plus areas north of I-80 get plenty of snow, would certainly be a pleasant change from what could potentially come. The EPO looks to remain in the tank for a while which should keep things cold, only this time we will have clippers traversing the region.

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