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Winter 2013-14 Pattern Discussion


CAD_Wedge_NC

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Oh, don't get me wrong; I'd rather have it negative. What I don't know is why sometimes, like last year, the -AO didn't help, and like this year, a ++AO isn't hurting too bad. This year, we have the -EPO and -WPO, so apparently, they're negating the ++AO to a large degree. That leads me to *believe* that when other specific signals are present, that it's effects are somewhat negated. Is that a wrong idea? In general, assuming no overriding factors are present, it is an important signal for the SE.

 

My thoughts exactly. Of course, my thoughts on this really aren't worth that much. I would much rather have the a -AO, but it appears that it is not a necessity for cold especially if the other factors mentioned are in our favor. I think the folks in Texas will tell you that it does not take a -AO for the cold to get to them. As has been mentioned previously, we had some pretty steep dips in the AO last winter, but did not have much t show for it.

 

I think the most encouraging thing I see right now is agreement of all of the members on the rise of the PNA. This, if true,  could lead to a deeper dip in the jet in the SE. Now if we could just get some Atlantic blocking to show up, maybe we could hold it for awhile.

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Still a good bit of variability on the 12z GFS mems for the upcomg weekend, with a general consensus towards interaction between the streams, drawing the leading surface wave up the TN Valley, and possible transfer to a more potent storm off N NE. Big difference from 24 hours ago is the HP yesterday's Euro had SE Canada is now coming down into the Plains. Source region is very cold, >-30C at 850, so there could be a sig artic outbreak in the northern plains to Lakes. Pattern looks to remain active through at-least Christmas, and this weekend is still a ways from being fully resolved.

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My thoughts exactly. Of course, my thoughts on this really aren't worth that much. I would much rather have the a -AO, but it appears that it is not a necessity for cold especially if the other factors mentioned are in our favor. I think the folks in Texas will tell you that it does not take a -AO for the cold to get to them. As has been mentioned previously, we had some pretty steep dips in the AO last winter, but did not have much t show for it.

 

I think the most encouraging thing I see right now is agreement of all of the members on the rise of the PNA. This, if true,  could lead to a deeper dip in the jet in the SE. Now if we could just get some Atlantic blocking to show up, maybe we could hold it for awhile.

Not on this run of the Euro unfortunately.  About as ++ as it gets the way it looks to me.

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This is close for us upstate and N GA folks for end of next weekend! But we know how it will change this far out!

 

All that map is showing is typical post frontal flurries in Middle Tennessee and Northern Alabama. The GFS is nowhere close to showing snow for anywhere outside of the mountains in the Carolinas through Day 16. 

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Cold is bottled up in Canada. Zonal.

 

Wouldn't be there long with that -WPO block in place.   That's your driving force right there.  Jet is already tightening on the front end of the lobe.  And dare I see abv normal heights over N greenland and Santa's house?

 

I predict that kind of setup would build a nice PV over SE Canada.  Fingers crossed for a change in the AO/NAO by Christmas.

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Looks to me like it's showing ZR in NE GA

Words of advice...don't go by those maps 99.9% of the time they are useless. Read and listen to what these folks say when they break down the model runs. If NC isn't all wound up about a "system/frontal passage" then you/me/burrell and Ne Ga folks have zilch to look forward to.
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Words of advice...don't go by those maps 99.9% of the time they are useless. Read and listen to what these folks say when they break down the model runs. If NC isn't all wound up about a "system/frontal passage" then you/me/burrell and Ne Ga folks have zilch to look forward to.

I disagree to and extent, I've known us at times well quite a few times that we've seen winter precip and NC see nothing! Not saying that happens often but it does happen

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Of course, that could be a temporary zonal pattern but there is no driving force to get the cold air down to us. 

Yeah I'm thinking temporary, only because so far this winter it doesn't seem to be a problem of eventual cold getting shot down to us...regardless of the means, we'll see what the ens says but I don't give much credit to that 240hr frame on the 12z.

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Just based on some analogs of -EPO winters, in which the EPO bottomed out in December. The preceding January was cold in the east in with a pretty strong signal for high latitude blocking in Feb. Really confident with a back loaded winter.

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Just based on some analogs of -EPO winters, in which the EPO bottomed out in December. The preceding January was cold in the east in with a pretty strong signal for high latitude blocking in Feb. Really confident with a back loaded winter.

I don't know if you have heard of Joe D Aleo, but he has shown some nice analogs for the January Feb, timeframe.

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Wouldn't be there long with that -WPO block in place.   That's your driving force right there.  Jet is already tightening on the front end of the lobe.  And dare I see abv normal heights over N greenland and Santa's house?

 

I predict that kind of setup would build a nice PV over SE Canada.  Fingers crossed for a change in the AO/NAO by Christmas.

That would be a great present from Santa  :wub: 

 

Looks to me like it's showing ZR in NE GA

Cold chasing moisture.....it's not gonna happen

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Wouldn't be there long with that -WPO block in place.   That's your driving force right there.  Jet is already tightening on the front end of the lobe.  And dare I see abv normal heights over N greenland and Santa's house?

 

I predict that kind of setup would build a nice PV over SE Canada.  Fingers crossed for a change in the AO/NAO by Christmas.

 

And it has been the catalyst thus far.  We've been zonal. That hasn't really changed.  The -WPO has been effective at giving me more cold days than warm, as well as 2 rounds of wintry precip. I'd say it's done a decent job so far.

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Not sure exactly where, but I was thinking the same.

TW

Just to clarify guys, I was looking at 240 and thinking it looked decent for hp over New England/SE Canada and some cold air east of the Apps for possible ice.  I agree that the maps for late weekend show frontal rain followed by clearing and essentially no snow (except maybe some flurries in the mountains).

TW

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The lack of AO hasn't been so bad for us because we've had such a strong PV over on our side of the world this year. An +AO gives us a more zonal flow, which is pretty much what we've been seeing lately in the upper atmosphere. Surface temps were able to penetrate south due to the very dense cold air. Imagine if we had a -AO and -NAO at the same time that air came in, we'd be jumping up and down for joy!  :snowing:

Cold is bottled up in Canada. Zonal.

 

Agree with these.  We have this perma, west-based +NAO signature going on (+AO too).  Maybe you can sneak in a marginal wintry event, but hard to get a good-un in this kind of pattern. 

 

W6dbQ63.gif

 

 

The Euro looks to be headed in a decent direction past day 7.  Certainly not seeing a torch in our future.

 

It does look like we will see the eastern and north pacific ridging, with a trough in the east as we move into next week following the weekend storm.  Looks to me like a northern stream dominated pattern that would be slightly below normal temp wise, with possible clipper system / mtn upslope chances.

 

 

From CPC Disco:

6-10 DAY OUTLOOK FOR DEC 15 - 19 2013  TODAY'S MODEL SOLUTIONS ARE IN VERY GOOD AGREEMENT ON THE OVERALL CIRCULATION  PATTERN PREDICTED OVER NORTH AMERICA FOR THE 6-10 DAY PERIOD. A STRONG RIDGE IS  PREDICTED TO BE OVER THE NORTH PACIFIC WITH ABOVE NORMAL 500 HPA HEIGHTS  EXTENDING INTO THE WESTERN CONUS. A DEEP TROUGH IS FORECAST TO EXTEND FROM  HUDSON BAY INTO THE EASTERN CONUS. OVERALL, THERE IS GOOD CONSENSUS AMONG  ENSEMBLE MEMBERS AND HIGH-RESOLUTION OPERATIONAL MODELS. HOWEVER, THE RECENT  ECMWF HIGH RESOLUTION RUNS INDICATE A DEEPER TROUGH OVER THE EAST, AS DO A  GREATER FRACTION OF ENSEMBLE MEMBERS OF THE 00Z ECMWF ENSEMBLE COMPARED TO  RECENT GEFS RUNS AND THE GFS OPERATIONAL RUNS.
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Seems to me that the CPC probability scheme is minimizing the depth of the trough in the east in the 6-10 day range. They may be right, but it appears they are hedging on the probability the troughing does not go deep into the SE. I think sometimes I also look at their 6-10 and 8-14 probabilities and weight them too heavily. If they say my area has a 35-40% probability of above average, you could also argue that we have a 55-60% probability of not being above average. Anyway, these maps have not exactly nailed the actual weather the last couple months. I don't think we are going into the ice box next week, but I would say we are as likely to be below average as we are above. Models have been missing temps from 2 days out. I would not put a whole lot of stock on their 6-10 day. Real cold air to the north and real warm are to the south. Hard to tell how the "battleground is going to shake out.

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The big -WPO signature we've had recently got me to run a composite for January for years with average December WPO readings less than -100. We're currently at -234 for the month so far and image we have a good shot at keeping it under -100 by the end of the month given what we're seeing on the model forecasts.

 

The January composite indicates a continued -WPO signal with above avg heights over AK, as well as below avg heights over the east and most of Europe.  The AO/NAO regions are neutral.  P.S. - While '78 was technically above -100, it was close.. at -97.

 

tEeg5q8.png

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