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Winter 2014-2015 Pattern Discussion Thread I

LithiaWx

By LithiaWx,
in Southeastern States

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Bob Chill

Bob Chill

Posted
Posted

Good points, Bob.  The answer to that last question is NO.  Of course, if those flies in the ointment occur, it means that virtually everyone has missed something important (or maybe missed isn't the right word...maybe instead it would something not known, as opposed to missed).

 

Don't get me wrong, I think the seasonals are out to lunch.  But it's going to be a pretty spectacular bust if they're not.

 

We could face a hostile pattern for an annoying period. That can happen any winter regardless of any index/tc/ssta config. But if we don't get several very wintry periods this winter I will be shocked. Snow is a wildcard of course but several persistent cold periods seems quite likely this year. 

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GaWx

GaWx

Posted
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Wait what? You mean having a weak nino with a +PDO....and a -AO's never happened?  Ever?  Maybe there's a meteorological reason for that and that's what the models are seeing.  They look like they're seeing the +PDO and the Nino....maybe the -AO don't mix for some reason.

No, I said I don't think you'll find any warm winters when there is a weakish Niño/+PDO/-AO.

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Bob Chill

Bob Chill

Posted
Posted

Wait what? You mean having a weak nino with a +PDO....and a -AO's never happened?  Ever?  Maybe there's a meteorological reason for that and that's what the models are seeing.  They look like they're seeing the +PDO and the Nino....maybe the -AO don't mix for some reason. 

 

76-77 and 77-78 fit that combination. So does 03-04 as far as warm neutral goes. 

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BNAwx

BNAwx

Posted
Posted

Sometimes I think seasonals and long range models beyond 30 days causes more harm than good. They did awful with Enso for months on end. I'm not saying they have no use because they do. But if we lined up a year of seasonal runs, what is the verfication accuracy? Lately it has seemed pretty bad but I don't have proof and I really don't pay too much attention to them. 

 

Looking at what we know from tracking everything this fall, the human consensus is quite different than the seasonal model consensus. If the AO ends up positive this year on the means it will be an unprecedented bust based on quite a bit of research. A -ao doesn't guaranty cold in the east but other factors in conjunction with a -ao sure seem to favor cold in the east. The +PDO looks great and the pattern will support a continuation of improving that region. Enso is looking quite good now as well. 

 

If we go warm this winter is can really happen only a couple ways. +AO/NAO  or -pna/pac flood or nasty vortex setting up shop around AK/bearing sea or combination of any of those. Is that really favored from all available data? 

 

I agree with all of this.  Based on the setup we currently see (and have seen) leading up to this winter, I think anyone putting out a winter forecast for an above normal winter temp wise would have more explaining to do than the person putting out a colder than normal outlook.  I guess I could see a "normal" outlook but it would simply be because someone's being conservative.  I certainly won't fault anyone if their winter forecast busts because they called for colder or even snowier than normal.

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LithiaWx

LithiaWx

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Brett Anderson's interpretation of the Long range models :  Here is a key quote to keep in mind : Keep in mind,

the European weeklies have been going through a rough stretch lately in terms of pattern recognition, thus confidence in the model remains lower than average, especially for the December panels.

 

 

http://www.accuweather.com/en/weather-blogs/anderson/cold-retreats-later-in-the-month/37333774

 

 

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Bob Chill

Bob Chill

Posted
Posted

He misunderstood what I said. I said that I'm not aware of any WARM weakish Nino/+PDO/-AO winter.

 

I should have added that to my post. You've clearly outlined this through a pile of data several times this fall. 

 

December may scare us a little. Nino's can start off slow in Dec. Also, the -AO response from the SAI is typically sometime in Dec. I think the blocking pattern we are in now isn't connected to the SAI but more of the shockwave that Nuri sent through the high latitudes. I'm not sure we would have hit such an anomalous pattern without Nuri. 

 

If we revert back to neutralish ao/nao conditions and lower heights centered in the west during the first half of Dec I wouldn't be surprised. In some ways I'm expecting it. It's not really that big a deal. The real scare would come if we have a +AO period of +1-2sd's during the first half of Dec. I don't think that outcome is favored but if it happens the weenie hotline will need to hire some extra staff. 

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Cold Rain

Cold Rain

Posted
Posted

I guess as the pattern relaxes and we lose our blocking some, it becomes time to keep an eye on the Stratosphere and track the strength of the vortex.  That seems to be the thing to watch for the reemergence of December blocking and an -AO/-NAO.

 

If I'm reading recent posts correctly, Coastalwx, HM, and ORH_wxman (I believe) have indicated that things are looking really good from a stratosphere perspective.  So we can put that on our side too.

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franklin NCwx

franklin NCwx

Posted
Posted

Not only do we have the Nino/PDO combo which are looking better every day, but the Oct indicators were excellent - snow advance, OPI, Aleutian Low, early stratosphere conditioning. I've never been a big fan of the seasonal models, but hey, maybe they get it right - would prefer to have them in agreement.

and the qbo phase which favors bkocking.
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LithiaWx

LithiaWx

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The first half of December doesn't have a good look as it stands now.  Mr.Bob thinks it has to do with the Pac jet slamming into the West coast.  The models are picking up on that and if they are right, we won't get the look we want downstream. 

 

Models are wrong! How about some more reasoning rather than just one liners? Euro ens have a strong Pac jet driving into the west coast in the 11-15 day period.....you are not going to get any cold air into the lower 48 until that pattern switches up so perhaps the weeklies have some logic behind them right now....not to mention that would be more following the ENSO climo going into December..I am inclined to give them some credence...how about you?

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SnowNiner

SnowNiner

Posted
Posted

If I'm reading recent posts correctly, Coastalwx, HM, and ORH_wxman (I believe) have indicated that things are looking really good from a stratosphere perspective.  So we can put that on our side too.

 

I wonder if we or they would mind creating a thread on that...kind of a count down to glory type thing?!

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BullCityWx

BullCityWx

Posted
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Not only do we have the Nino/PDO combo which are looking better every day, but the Oct indicators were excellent - snow advance, OPI, Aleutian Low, early stratosphere conditioning.  I've never been a big fan of the seasonal models, but hey, maybe they get it right - would prefer to have them in agreement.

 

I'd be lying if I wasnt a little concerned, given the weeklies seem to be showing practically the same thing the LR Euro is showing.

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GaWx

GaWx

Posted
Posted

Oh, geez.  Yeah sorry misread that.  Bout gave me a heart attack.  Thanks.

 

So it's history, indices, analogs, mets......versus the long range models.  I'll take the former FTW. 

 

 You're welcome. I'll add still another favorable (at least imo) indicator: barring some very unforeseen development, we're going to end up with a chilly November in Atlanta (as well as much of the SE US..say 1.5 or more below normal). Looking at my list of anything from high end neutral positive ENSO to low end moderate Nino, the top 10 coldest Novembers there (all 1.5 or more colder than normal) were followed by non-cold winters there (warmer than 43) only three times: the warm 1951-2 and 1936-7 as well as the near normal 1923-4. Well, 1951-2 is no surprise as it had a strongly -PDO as well as a +AO and +NAO averaged over DJF. The polar opposite of that combo is expected this winter by all indications. Now, 1923-4 was not a warm winter at ATL as its DJF averaged very slightly below normal...I'm calling it near normal. Its PDO was +0.55 averaged over DJF (per Univ. of Washington), a fairly solid +PDO. Per my notes from 2009, the NAO averaged +0.27 as per this link:

 

http://www.cgd.ucar.edu/cas/jhurrell/indices.data.html#naostatdjfm

 

 So, the only data I have suggests it wasn't a -NAO winter. However, that link is now dead. So, I know longer can locate pre 1950 NAO's and I have nothing about that winter's AO. Does anyone have access to pre 1950 AO's or NAO's?

 

 Now, 1936-7 had a +0.26 PDO. One could argue that it isn't a solidly +PDO. I would say that is the case. Regarding AO or NAO, I have nothing.

 

 Regardless, what I'm saying is that this being a chilly November is supportive of a cold winter, if anything. It certainly isn't supportive of a warm winter. So, when this is added to the expected weakish Nino/solid-AO/solid +PDO, it would be mind boggling if this winter is warm! If the AO isn't solidly negative, the SAI and OPI would bust horribly. If the PDO isn't positive, it would be the first time of 18 cases back to 1900 for a -PDO after a PDO of  +0.70+ in Sep. The Sep. PDO was over +1.0.

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GaWx

GaWx

Posted
Posted

I'd be lying if I wasnt a little concerned, given the weeklies seem to be showing practically the same thing the LR Euro is showing.

 

Jeremy,

1) In all fairness, that is still only one model (weeklies and LR Euro).

2) Even if the first half of Dec is mild, we of course can still have quite a cold winter. When I get time, I'm going to look back at my daily KATL data (back to 1930) and see what I can find about this.

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griteater

griteater

Posted
Posted

So, the only data I have suggests it wasn't a -NAO winter. However, that link is now dead. So, I know longer can locate pre 1950 NAO's and I have nothing about that winter's AO. Does anyone have access to pre 1950 AO's or NAO's?

 

GA -

 

DJFM AO since 1899 (don't have monthly)

https://climatedataguide.ucar.edu/climate-data/hurrell-wintertime-slp-based-northern-annular-mode-nam-index

Click on Data Access

 

NAO - Principal Component Based

https://climatedataguide.ucar.edu/climate-data/hurrell-north-atlantic-oscillation-nao-index-pc-based

Click on Data Access

 

NAO - Station Based

https://climatedataguide.ucar.edu/climate-data/hurrell-north-atlantic-oscillation-nao-index-station-based

Click on Data Access

 

Alternate site for old NAO data 

http://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/

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Mr Bob

Mr Bob

Posted
Posted

This whole index matching seasonal forecasting process is full of flaws...I would like to see the skill scores of any individual forecaster over the last 5 ,10,15 years and then tell me if climo is not a better forecast.....The indices are not static and any number of things can change over the course of a winter. In hindsight, what Larry shows us certainly has some credence, but as much as anything it is an IF this happens this way, then the result will be a cold winter. The same process is followed by almost every forecaster on here hence the groupthink, especially this year...

 

Climo says, however, that back to back winters of last year's magnitude probably are not going to happen, and I also believe that pattern trends over the last six months do play a role. So I am not so gung ho this winter. (That and $3 will get you a cup of Starbuck's coffee.)

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GaWx

GaWx

Posted
Posted

 

Grit,

 Wow, thanks very much!

 

1923-4: According to Grit's links, 2 of the 3 have a neutralish NAO (slightly positive) for 1923-4. The other one had a -NAO but for DJFM. March appears to be skewing things to the heavily -NAO direction in this DJFM -NAO. The only place I could find AO had it moderately negative (-0.77) but again that was for DJFM. March very likely had a solid -AO based on the very strong March -NAO, which would skew DJFM too far negative vs. DJF. It had a +0.55 PDO, which I'd call moderately positive. I have it as a weak to possibly low end moderate Nino. It was preceded by a cold November. This winter was near normal in ATL (technically very slightly cooler than normal at 43.9).

 So, 1923-4 was a +PDO/weakish Nino following a cold November but the AO/NAO is murky. The mix of indicators suggest it was probably neutralish for DJF. Keep in mind that it wasn't a warm winter by any means. So, to summarize, I don't see 1923-4 as being a good analog for 2014-5 even though ENSO appears quite similar, the PDO is fairly similar, and there was a cold KATL November. The AO/NAO probably doesn't fit from all I can tell and seems to be the main DQer.

 

1936-7: According to Grit's links, all data suggest this was very likely a neutral to positive NAO and AO. The PDO was +0.26, which arguably could be called fairly neutral. I have the ENSO as neutral positive. So, despite 1936-7 having a cold November and neutral positive ENSO, it is definitely not a good analog since the AO/NAO apparently weren't negative and the PDO was only slightly positive.

 

 So, back to the 10 coldest KATL Novembers, where does this leave us? As I said, only 3 of the 10 coldest KATL Novembers in the ballpark of the current ENSO weren't followed by a cold KATL winter: 1951-2 (warm), 1936-7 (warm), and 1923-4 (near normal). 1951-2 (warm) is not at all an analog since the PDO was strongly negative and the AO/NAO were positive. 1936-7 is not a good analog since the AO/NAO apparently weren't negative and the PDO was only slightly positive. Finally, 1923-4 likely isn't a good analog because the AO/NAO probably doesn't fit from all I can tell.

 

 The remaining 7 coldest KATL Novembers in same ENSO ballpark were all followed by cold KATL winters (DJF):

 

1880-1: ~2 colder than normal

1885-6: ~4 colder than normal

1911-2: ~3 colder than normal

1939-0: ~5.5 colder than normal

1968-9: ~3.5 colder than normal

1969-0: ~4 colder than normal

1976-7: ~7.5 colder than normal (coldest on record)

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packbacker

packbacker

Posted
Posted

Lot of good signals out there but that -QBO/solar max signal is still there.

Solar flux around 145 the last 75 days and still creeping up.

 

We'll see.

 

What is the relationship to a -QBO/solar max?  Lots of thoughts on the -QBO being good for blocking but DT believes a falling -QBO to neutral gives the best relationship to a -NAO.  And of course nobody knows if the -QBO will rise to neutral range in the next 6-12 weeks.  What's the deal with solar max?

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BullCityWx

BullCityWx

Posted
Posted

Jeremy,

1) In all fairness, that is still only one model (weeklies and LR Euro).

2) Even if the first half of Dec is mild, we of course can still have quite a cold winter. When I get time, I'm going to look back at my daily KATL data (back to 1930) and see what I can find about this.

 

We certainly can. I'm concerned, though, if we go warm for a majority of December that we wont be able to pull a second rabbit out of the hat with January and February. 

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