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AO Winter Analogs When December Reaches +3.5


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I really don't know what the policy on profanities are on the board, but I don't know of any other way to say this:

You're ****ing depressing, man. Educational. But, depressing.

If it's a no-no, I'm sure a mod will be along shortly to edit...

Last winter was a lot more fun. I hate the possible warm outcome as much as anyone here. This morning's 60° temperatures were as depressing as it can get in December.

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If we are able to do a flip like we did last year, it's still is going to take time.

The AO dropped below -5 on 12/18/10 and didn't rebound positive until

later in January. So if we get lucky this year, maybe by early January

we will see a pattern change?

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don, do you see any hope in the near future, maybe, mid-january/febuary?

Thunderbolt,

I don't know if I would call January or February the near future. That's still quite far out. Also, I don't know what area you are referring to, but will assume that it is perhaps somewhere in the Mid-Atlantic/southern New England areas currently suffering from excessive warmth.

Right now, if I had to venture a guess, either January or February (but not both) could have enough cold weather that one of the months might have a near normal temperature anomaly. If everything worked out, one of those months might even have a somewhat below normal anomaly. None of the months will likely be persistently cold, but the cold could match or somewhat exceed the warmth in one of them. The other month could well wind up being much warmer than normal. Presently, I lean toward January as being the coldest month relative to normal based on when the ongoing AO+ regime began.

Snowfall opportunities will be hit or miss. I don't expect any KU storms this winter and that will be a trying experience given the frequent KU events of the past two winters. However, a "near miss" where a small area receives a > 10" snowfall or, perhaps more likely, interior cities (Pittsburgh, Allentown, Albany, or Burlington) have a 10" or greater snowfall, is a possibility. I do believe the Great Lakes' cities Chicago, Detroit, Toronto, etc., could see one big event with 10" or more snow at some point.

The big cities of the East (Washington to Boston) will probably experience a moderate snowfall (2"-4:/3"-6" type) at some point later this winter. Boston might have the best chance out of the big cities to see a 10" or greater snowfall, but that isn't assured. Changeover cases may predominate. December's snowfall data could add or reduce confidence in these scenarios and, unfortunately, a worse case (<10" seasonal snowfall, inclusive of October's snowfall, in such cities as New York and Philadelphia) is still on the table.

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Thunderbolt,

I don't know if I would call January or February the near future. That's still quite far out. Also, I don't know what area you are referring to, but will assume that it is perhaps somewhere in the Mid-Atlantic/southern New England areas currently suffering from excessive warmth.

Right now, if I had to venture a guess, either January or February (but not both) could have enough cold weather that one of the months might have a near normal temperature anomaly. If everything worked out, one of those months might even have a somewhat below normal anomaly. None of the months will likely be persistently cold, but the cold could match or somewhat exceed the warmth in one of them. The other month could well wind up being much warmer than normal. Presently, I lean toward January as being the coldest month relative to normal based on when the ongoing AO+ regime began.

Snowfall opportunities will be hit or miss. I don't expect any KU storms this winter and that will be a trying experience given the frequent KU events of the past two winters. However, a "near miss" where a small area receives a > 10" snowfall or, perhaps more likely, interior cities (Pittsburgh, Allentown, Albany, or Burlington) have a 10" or greater snowfall, is a possibility. I do believe the Great Lakes' cities Chicago, Detroit, Toronto, etc., could see one big event with 10" or more snow at some point.

The big cities of the East (Washington to Boston) will probably experience a moderate snowfall (2"-4:/3"-6" type) at some point later this winter. Boston might have the best chance out of the big cities to see a 10" or greater snowfall, but that isn't assured. Changeover cases may predominate. December's snowfall data could add or reduce confidence in these scenarios and, unfortunately, a worse case (<10" seasonal snowfall, inclusive of October's snowfall, in such cities as New York and Philadelphia) is still on the table.

There already has been a KU storm this season... not this winter though.

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Just gets more and more depressing the more I read. I feel like I'm back in the late '90s. We all knew we'd have to pay for the slew of awesome winters at some point though, right? Hopefully, this'll just be one crappy one that precedes a few blockbuster ones (Don, please say saomething about my hopes having some merit ;) ).

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If we are able to do a flip like we did last year, it's still is going to take time.

The AO dropped below -5 on 12/18/10 and didn't rebound positive until

later in January. So if we get lucky this year, maybe by early January

we will see a pattern change?

Blue wave, that's what I'm hoping for but would be happy if it occurred by mid Jan. However, without help I'm not sure how long it would last.

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this winter had a record cold February with a KU storm...

1978 10 10 1.562

1978 10 11 1.925

1978 10 12 1.330

1978 10 13 0.828

1978 10 14 0.730

1978 10 15 0.634

1978 10 16 0.487

1978 10 17 0.529

1978 10 18 0.974

1978 10 19 1.615

1978 10 20 1.508

1978 10 21 1.486

1978 10 22 1.220

1978 10 23 1.243

1978 10 24 1.672

1978 10 25 1.822

1978 10 26 2.336

1978 10 27 2.547

1978 10 28 2.549

1978 10 29 2.909

1978 10 30 3.091

1978 10 31 3.294

1978 11 1 3.925

1978 11 2 4.544

1978 11 3 3.921

1978 11 4 3.105

1978 11 5 2.566

1978 11 6 2.307

1978 11 7 2.254

1978 11 8 2.940

1978 11 9 3.256

1978 11 10 3.509

1978 11 11 3.941

1978 11 12 3.825

1978 11 13 3.596

1978 11 14 3.392

1978 11 15 2.997

1978 11 16 2.803

1978 11 17 2.623

1978 11 18 2.776

1978 11 19 3.242

1978 11 20 4.009

1978 11 21 3.690

1978 11 22 3.348

1978 11 23 2.310

1978 11 24 0.581

1978 11 25 -1.222

1978 11 26 -2.138

1978 11 27 -1.428

1978 11 28 -0.018

1978 11 29 0.619

1978 11 30 0.174

1978 12 1 0.239

1978 12 2 0.390

1978 12 3 0.653

1978 12 4 0.540

1978 12 5 -0.483

1978 12 6 -1.686

1978 12 7 -2.057

1978 12 8 -1.255

1978 12 9 -0.298

1978 12 10 -0.266

1978 12 11 -0.166

1978 12 12 0.383

1978 12 13 1.064

1978 12 14 1.445

1978 12 15 0.541

1978 12 16 0.503

1978 12 17 0.674

1978 12 18 0.960

1978 12 19 -0.125

1978 12 20 -0.937

1978 12 21 -1.192

1978 12 22 -1.522

1978 12 23 -1.551

1978 12 24 -1.573

1978 12 25 -2.607

1978 12 26 -3.588

1978 12 27 -4.292

1978 12 28 -4.184

1978 12 29 -3.693

1978 12 30 -3.103

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Previously, the GFS ensembles hinted that the AO could dip below 0 for a short time in the near-term. IMO, that forecast was, in part, the result of initialization errors of > 1 standard deviation. Historic experience with super AO+ regimes argued against such a development.

Since that time, the GFS ensembles have adjusted and now show the AO staying positive for the foreseeable future. That is consistent with a composite based on past occasions when the AO peaked at +5 or above. In fact, the GFS ensembles are forecasting a scenario that is very close to that of the 1989 AO+ regime (the single La Niña case when the AO peaked at +5 or above) when transposed on the current month.

AO12082011.jpg

In conclusion, the current AO+ regime, which has now lasted 19 days, is likely to continue through the foreseeable future. It will likely continue into at least a part of January. For perspective, the 1989 AO+ regime lasted 68 days.

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What is interesting with the 1989 AO analogy was the record cold that followed in Texas. Significant freeze damage occured throughout the Lower Rio Grande Valley from that event. It will certainly be something I'll monitor as the month of December moves along. Thanks for the input as always, Don.

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There has been a lot of talk about the persistence of this +AO scenario, but what is going to have to change for it to go away?

comet, nuclear explosion, or sun dramatically going back to sleep

our only hope is #3, but solar cycle 24 is still progressing towards its peak, so don't hold your breath

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this winter had a record cold February with a KU storm...

1978 10 10 1.562

1978 10 11 1.925

1978 10 12 1.330

1978 10 13 0.828

1978 10 14 0.730

1978 10 15 0.634

1978 10 16 0.487

1978 10 17 0.529

1978 10 18 0.974

1978 10 19 1.615

1978 10 20 1.508

1978 10 21 1.486

1978 10 22 1.220

1978 10 23 1.243

1978 10 24 1.672

1978 10 25 1.822

1978 10 26 2.336

1978 10 27 2.547

1978 10 28 2.549

1978 10 29 2.909

1978 10 30 3.091

1978 10 31 3.294

1978 11 1 3.925

1978 11 2 4.544

1978 11 3 3.921

1978 11 4 3.105

1978 11 5 2.566

1978 11 6 2.307

1978 11 7 2.254

1978 11 8 2.940

1978 11 9 3.256

1978 11 10 3.509

1978 11 11 3.941

1978 11 12 3.825

1978 11 13 3.596

1978 11 14 3.392

1978 11 15 2.997

1978 11 16 2.803

1978 11 17 2.623

1978 11 18 2.776

1978 11 19 3.242

1978 11 20 4.009

1978 11 21 3.690

1978 11 22 3.348

1978 11 23 2.310

1978 11 24 0.581

1978 11 25 -1.222

1978 11 26 -2.138

1978 11 27 -1.428

1978 11 28 -0.018

1978 11 29 0.619

1978 11 30 0.174

1978 12 1 0.239

1978 12 2 0.390

1978 12 3 0.653

1978 12 4 0.540

1978 12 5 -0.483

1978 12 6 -1.686

1978 12 7 -2.057

1978 12 8 -1.255

1978 12 9 -0.298

1978 12 10 -0.266

1978 12 11 -0.166

1978 12 12 0.383

1978 12 13 1.064

1978 12 14 1.445

1978 12 15 0.541

1978 12 16 0.503

1978 12 17 0.674

1978 12 18 0.960

1978 12 19 -0.125

1978 12 20 -0.937

1978 12 21 -1.192

1978 12 22 -1.522

1978 12 23 -1.551

1978 12 24 -1.573

1978 12 25 -2.607

1978 12 26 -3.588

1978 12 27 -4.292

1978 12 28 -4.184

1978 12 29 -3.693

1978 12 30 -3.103

Unc, That's the one I had brought up to you a month or so ago in regards to a possible winter analogue. It was a -PDO neutral enso( as opposed to la nina now) that went from a strongly positive ao to negative ao/nao January/February.

That winter followed two brutal winters and the buzz was the opposite of the spectru may be the case the upcoming one as November was so mild throughout the East that ski resorts were concerned and at one point , (late November/early December) snow was shipped via rail to some of the NE resorts. You remember that?

I don't think that type of flip will occur this year, as some other pattern players are on the field this year of which the experts, Wes, Don etc.; have exposed and detailed.

However, there is that glimmer of hope, though it be dim, that something similar could occur this go around.

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Today, the AO reached +5.647. That demolishes the December record of +5.040 set on December 2, 1979 and is the second highest AO reading on record. Recordkeeping began in 1950.

Not sure if maybe there were some recent adjustments to the AO readings, but the highest value I see now is +4.394 on Dec. 3rd. That would be a noteworthy difference.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/daily.index.ascii

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Not sure if maybe there were some recent adjustments to the AO readings, but the highest value I see now is +4.394 on Dec. 3rd. That would be a noteworthy difference.

http://www.cpc.ncep....ily.index.ascii

I have some reservations about those revisions. They appear to put the AO into line with the initialization of the GFS ensembles, which had been off by 1-2 standard deviations around that time. However, on the re-analysis data, the area of 500 mb height anomalies < -300 mb was larger than that for a number of the AO +5 dates e.g. 2/25/1990. It fell short of the 2/26/1990 record value (+5.911). The ECMWF ensembles also initialized at greater than +4 around that time and that initialization was the basis of my suggesting that the AO had dropped below +4 after four consecutive days at or above +4.

Given the above, I'm still comfortable with the idea that the current AO+ regime will continue for the time being before ending in January.

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To Add to Don's Discussion on the AO index, Using all the last daily occurrences in December as analogs that had a value of +3.5 or higher, and rolling them forward equals the graphic below.

10 Dates:

19511225

19711220

19751221

19791206

19831228

19841209

19901226

19911219

19991225

20061231

5xly1j.gif

The last 3.5+ AO value was on Dec 6th,2011.

Here are composite plots of the mean daily 500mb pattern right after the AO peaks at 3.5 Standard Deviations above normal in December. As of now, December 6th was the last date the AO got above +3.5 (That could change). Here is an animated gif of the initial analogs all the way out to 35 days after (5 day increments), as you can see, there is quite a change. That would mean in general 25-35 days (Lines up with Don's timing) from the 6th of December, things would begin to turn around as far as the cold pattern. But, if the AO peaks again past +3.5, this would reset back to a later initial date.

50 days after (Not Shown), there is also a hell of a signal for a -NAO pattern, I guess thats a plus, wouldn't happen Till Late January though, barring a more positive trend in the +AO again of course...

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This morning's AO was +0.313. This is the 27th consecutive day on which the AO has been positive. Per the discussions earlier in this thread, odds favor the current AO+ regime lasting at least 30 days, and I believe it will. Even if the AO briefly dips into negative territory (indicated by a few ensemble members), the guidance strongly points to the AO's rising and remain stable at positive levels. In short, the Atlantic pattern remains relatively persistent. What is forecast to change is that the GFS ensembles are pointing to the PNA's going positive albeit not strongly positive.

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This morning's AO was +0.313. This is the 27th consecutive day on which the AO has been positive. Per the discussions earlier in this thread, odds favor the current AO+ regime lasting at least 30 days, and I believe it will. Even if the AO briefly dips into negative territory (indicated by a few ensemble members), the guidance strongly points to the AO's rising and remain stable at positive levels. In short, the Atlantic pattern remains relatively persistent. What is forecast to change is that the GFS ensembles are pointing to the PNA's going positive albeit not strongly positive.

a hint of 70/71?

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This morning, the AO was +0.719, the 28th consecutive day on which it has been positive. Yesterday likely marked the lowest the AO will fall for the foreseeable future. The AO is forecast to continue to rise in coming days.

Don, you beat me to it. The NAO is more positive than the AO and both are forecast to remain positive into the new year. Makse me feel good about the AO call that we made earlier in the month. I don't know whether you saw Jason's post showing a graph of seasonal snowfall based on enso state and the nao but la nina winters with a positive nao were the pits. It was a cool graph.

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I don't know whether you saw Jason's post showing a graph of seasonal snowfall based on enso state and the nao but la nina winters with a positive nao were the pits. It was a cool graph.

I did. It's a very nice graph, even if the outcome is ugly.

P.S. For those who haven't seen Jason's graphs, they can be found at: http://www.washingtonpost.com/blogs/capital-weather-gang/post/two-devastating-graphs-for-dc-snow-lovers/2011/12/15/gIQAASxOwO_blog.html

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