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When will the pattern change to cold occur?


Isotherm

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HM in the main thread just gave the East Coast a possible dire outlook for snow lovers. In a nutshell, he stated that the QBO just peaked at a very positive value; and that the solar flux values are high also. This does not bode well for warming up the stratosphere to favorable levels. Also, with the positive +AAM and +EPO values, this may keep the MJO moving very quickly and weakly thorough all of the phases through early January. :(

You left out some parts:

"This will pay off down the road because the same factors causing the warmth now will become favorable for split flow / +PNA/-NAO."

"While ending November on a warm note seems like a given, the North Pacific will be in the process of retrograding. This may give rise to the PNA in early December. So while a full blown Arctic Attack may not be in the cards, a general PNA pattern is very possible as the overall N PAC continues to retrograde. Perhaps this ends up being brief as the<br style="color: rgb(28, 40, 55); font-family: Arial; line-height: 18px; background-color: rgb(251, 253, 254); ">MJO continues to send us "bad signals" through mid-December. Maybe the SE ridge returns for a while before the development of a -NAO takes the heights down. "

http://www.cpc.ncep.noaa.gov/data/indices/qbo.u30.index

This shows 30 MB zonal wind index @ -3.05

Anomaly @ 1.57

Standarized data @ 0.13

And then this one

http://www.esrl.noaa.gov/psd/data/correlation/qbo.data

Shows it at -3.05 for October 2011...

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You left out some parts:

"This will pay off down the road because the same factors causing the warmth now will become favorable for split flow / +PNA/-NAO."

"While ending November on a warm note seems like a given, the North Pacific will be in the process of retrograding. This may give rise to the PNA in early December. So while a full blown Arctic Attack may not be in the cards, a general PNA pattern is very possible as the overall N PAC continues to retrograde. Perhaps this ends up being brief as the<br style="color: rgb(28, 40, 55); font-family: Arial; line-height: 18px; background-color: rgb(251, 253, 254); ">MJO continues to send us "bad signals" through mid-December. Maybe the SE ridge returns for a while before the development of a -NAO takes the heights down. "

http://www.cpc.ncep....s/qbo.u30.index

This shows 30 MB zonal wind index @ -3.05

Anomaly @ 1.57

Standarized data @ 0.13

And then this one

http://www.esrl.noaa...lation/qbo.data

Shows it at -3.05 for October 2011...

I pretty much agree with HM. I think we might see things improve temporarily in early Dec. Before things go downhill again by mid Dec. Particularly, if the Euro and UK MJO forecasts are correct, with the stronger MJO impulse in phases 3-5 by then. I think a real major pattern change to sustained cold is unlikely to happen before Dec. 20.

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The problem is after that 288h panel, the vortex just reasserts itself over AK and the pattern hasn't really changed. This is fairly consistent with the Euro ensembles as well. It tries to retrograde again at the very end of the run which puts us at about Dec 5...so perhaps things could change for the better by the 10th if that happens. My guess is its a little later than that.

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The problem is after that 288h panel, the vortex just reasserts itself over AK and the pattern hasn't really changed. This is fairly consistent with the Euro ensembles as well. It tries to retrograde again at the very end of the run which puts us at about Dec 5...so perhaps things could change for the better by the 10th if that happens. My guess is its a little later than that.

Agree. I still think any cold air in the East will be transient in nature prior to December 15th. The arctic/north atlantic patterns also look wretched for the next 2-3 weeks with no indication of -AO/NAO development. It should happen by mid month but we've got a lot of work to do with this pattern.

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Agree. I still think any cold air in the East will be transient in nature prior to December 15th. The arctic/north atlantic patterns also look wretched for the next 2-3 weeks with no indication of -AO/NAO development. It should happen by mid month but we've got a lot of work to do with this pattern.

I think that we are both in the delayed but not denied camp. Even if December doesn't work out too well, I think that there should be some degree of blocking by January.

Just look at the two winters after a winter monthly -2.0 or lower AO reading like we first saw back in 2010.

http://www.cpc.ncep....ent.ascii.table

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I think that we are both in the delayed but not denied camp. Even if December doesn't work out too well, I think that there should be some degree of blocking by January.

Just look at the two winters after a winter monthly -2.0 or lower AO reading like we first saw back in 2010.

http://www.cpc.ncep....ent.ascii.table

Bluewave -- agreed. I've always been on board for a 30-40 day sustained period of good blocking and cold/snowy weather this winter. I thought it'd be Dec 1-Jan 10 a month ago, but all this delay means to me is the period will likely be about Dec 15 through mid to perhaps most of January now, which if it works out, ends up being more favorable for us in terms of coinciding with superior snowfall climatology. If I had to pick a 15 day period of winter that I'd agree to throw down the crapper, it'd be Dec 1-15. Any other 15 day period is historically better for our area (Dec-Feb).

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Bluewave -- agreed. I've always been on board for a 30-40 day sustained period of good blocking and cold/snowy weather this winter. I thought it'd be Dec 1-Jan 10 a month ago, but all this delay means to me is the period will likely be about Dec 15 through mid to perhaps most of January now, which if it works out, ends up being more favorable for us in terms of coinciding with superior snowfall climatology. If I had to pick a 15 day period of winter that I'd agree to throw down the crapper, it'd be Dec 1-15. Any other 15 day period is historically better for our area (Dec-Feb).

Sounds kind of like last winter. I certainly agree with your thoughts, it's just that I'm still kind of nervous because you never really know with these semi-permanent Alaskan vortexes...I don't recall that really being a huge problem in the past two winters. A transient PNA pattern won't do us much good if the EPO is still essentially very positive. I'm getting worried that this vortex is going to be stubborn all winter...

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Sounds kind of like last winter. I certainly agree with your thoughts, it's just that I'm still kind of nervous because you never really know with these semi-permanent Alaskan vortexes...I don't recall that really being a huge problem in the past two winters. A transient PNA pattern won't do us much good if the EPO is still essentially very positive. I'm getting worried that this vortex is going to be stubborn all winter...

No doubt; if this vortex continues to be a major player in mid December, then it may be time to start rethinking the winter as a whole. But as of right now, most indications are that the north pacific pattern will gradually improve over the coming 2-3 weeks. GFS ensembles actually shoot the PNA slightly positive for early december, but the NAO/AO continue to be solidly positive thereafter.

Snow cover across the nern hemisphere this past week is second highest on record, so there's a bit of good news. Additionally, solar ap values have fallen off the cliff since early November, which should also aid in getting the block going by mid dec.

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The MJO is really going to be a detriment to getting this pattern reversal complete, especially if the Euro based modelling is correct. Don't look at the latest Euro ensembles. I think they're too slow, but if correct, we'd have a potent MJO wave slowing down in phase 3-5 through late dec, aka shoot me in the foot.

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back in August we had the 3rd lowest August AO monthly reading since 1950...Here is a list of years with the lowest August monthly index and the following winters lowest monthly index...14 of 16 years listed had a winter month with a lower index...Two of the five la nina years had a higher index...reds are El nino years and blue la Nina years...Black's are neutral...The AO is now positive since August...1974 and 1999 are the only years the AO index was higher during the winter months...Some other years saw a positive AO after August...1977 was one...that was an el nino year though...1964 went positive for a month in October but slipped back negative by November...

year......August AO....low winter AO

1977..........-1.412..........-3.014 Feb...

1964..........-1.207..........-2.084 Feb...

2011..........-1.063..........????

1960..........-1.008..........-1.506 Jan...

1966..........-0.945..........-1.401 Dec...

1950..........-0.851..........-1.928 Dec...

1987..........-0.836..........-1.066 Feb...

1986..........-0.826..........-1.473 Feb...

1958..........-0.755..........-2.013 Jan...

1959..........-0.745..........-2.484 Jan...

1969..........-0.728..........-2.412 Jan...

2004..........-0.720..........-1.271 Feb...

1999..........-0.672.........+1.076 Feb...

1968..........-0.671..........-3.114 Feb...

1956..........-0.652..........-1.513 Feb...

1963..........-0.625..........-1.178 Dec...

1974..........-0.533.........+0.194 Feb...

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Is that ridging showing up north of the Caspian? scooter.gif

GEFS not as favorable, verbatim, but these are OP runs at a certain frame..so those 10 day graphics are a little deceiving. Once the black hole vortex erodes (looking better to do so around early Dec)..the MJO impulse should respond and the global indexes will begin cooperating. When we get blocking after that is up the air (I favor late Dec)...but Dec 15 still looks like the magic date as to when this thing turns around.

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That looks somewhat hopeful; however, there's still a pronounced trough in the Desert Southwest which causes the SE ridge to flex its muscles a bit. Moreover, the Alaskan vortex is still kind of strong but noticeably weaker. There's not any hint of a ridge south of Greenland which would induce some kind of east- or west- based block. I have to say that the big positives here are that the positive anomalies in the West Coast like you said; plus, the ridge below Alaska has been eroded away. Northern Europe is also turning colder instead of Southern Europe, which is typical of more of a -NAO.

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That looks somewhat hopeful; however, there's still a pronounced trough in the Desert Southwest which causes the SE ridge to flex its muscles a bit. Moreover, the Alaskan vortex is still kind of strong but noticeably weaker. There's not any hint of a ridge south of Greenland which would induce some kind of east- or west- based block. I have to say that the big positives here are that the positive anomalies in the West Coast like you said; plus, the ridge below Alaska has been eroded away. Northern Europe is also turning colder instead of Southern Europe, which is typical of more of a -NAO.

Agreed on all counts. It's more indicative of a changing pattern than anything, not a flipped pattern. The steps are beginning on that frame...it's going to take another week or more after that to get everything lined up correctly. But it's a huge step in the positive direction compared to what we had been seeing for several weeks now.

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