WHY the +AO = WARM WINTER argument is in deep Doo

[HM]

No, I'm not suggesting that any more than those who are looking at the effects and correlations related to the AO are suggesting the AO is "its own entity". 

 

Just as there are correlations associated with the AO and what happens in the fall, there are also correlations with the EPO. It's all blocking and location of blocking, and there are forcings that play into that.

 

Well, if you are not saying that then I don't why you asked the original question you did. If the EPO is merely an effect of multiple known forcings, shouldn't the forcings be what we discuss for general circulation?

 

As for the AO, any cold season we can rely on a PV forming in the autumn. There is a constant behind the AO and that is the formation of the PV. Yes, we do measure things that affect its strength and if it will be more susceptible to disturbances. So the real discussion we have is usually on those forcings that we know of for NAM strength. My argument to Howard was not to say a +AO Nov=+winter but that if we took the conditions in Nov now and had them again in winter (huge ++AO in DJF) that it would bias things in a warm direction.

[CoastalWx]

The OLR and VP do point to a more Aleutian ridge give or take the usual 10-20 degrees longitude. From a forcing argument you can see that. This whole thing seemed to get kick started with the recurves in the west pac and the increase and 50mb temps across nrn Siberia. This warmer pocket may have migrated east and perhaps propagated or through conduction, made its way to the higher levels of the tropopause.

[CoastalWx]

The OLR and VP do point to a more Aleutian ridge give or take the usual 10-20 degrees longitude. From a forcing argument you can see that. This whole thing seemed to get kick started with the recurves in the west pac and the increase and 50mb temps across nrn Siberia. This warmer pocket may have migrated east and perhaps propagated or through conduction, made its way to the higher levels of the tropopause.

 

We also have had a pretty good -PNA at times which is expected, but this time around the PV or pieces of it have resided in Canada and thus have been allowed to permeate the lower 48.

[CoastalWx]

BTW HM, I think you mean Dave, not Howard?

[HM]

Sure, I see what you are saying about the WPO. I just think it's worth considering what the EPO is doing in regards to the WPO/AO as well. This year is somewhat unusual in that a persistent -WP/-EP regime has been pretty dominant. Regardless of what the AO looks like, above normal heights keep popping up in the NE Pacific, Alaska, and NW Canada.

 

We agree that you should always consider the EPO. The point of my posts was to counter the claims made in the 2 original posts by DT. He showed a big December WP correlation over the eastern CONUS and said this is why the +AO forecasts are wrong. But when you look closer, you see that the -WPO years are made up of mostly -AO years. When you actually find the -WPO/+AO Decembers, they don't look that the general WPO correlation at all; and in fact, they are rather warm across the CONUS.

[tacoman25]

Well, if you are not saying that then I don't why you asked the original question you did. If the EPO is merely an effect of multiple known forcings, shouldn't the forcings be what we discuss for general circulation?

 

As for the AO, any cold season we can rely on a PV forming in the autumn. There is a constant behind the AO and that is the formation of the PV. Yes, we do measure things that affect its strength and if it will be more susceptible to disturbances. So the real discussion we have is usually on those forcings that we know of for NAM strength. My argument to Howard was not to say a +AO Nov=+winter but that if we took the conditions in Nov now and had them again in winter (huge ++AO in DJF) that it would bias things in a warm direction.

 

Sure, I get all that. But I think some of us are trying to ask other questions which shouldn't be overlooked when considering how the dominant patterns might play out going forward.

 

The fact is, no one knows exactly how all of the forcings work in regards to blocking. So while it's fine to discuss the possible forcings behind things, why not look at how this sort of pattern has played out in the past?

[HM]

BTW HM, I think you mean Dave, not Howard?

 

Do you mean my AO comments? If so, then I did mean Howard. He said my statements about the current forcings not meaning the same thing in winter as they do now is BS. So, in other words, that severely +AO this month wouldn't mean anything if it were the DJF average. lol

[tacoman25]

We agree that you should always consider the EPO. The point of my posts was to counter the claims made in the 2 original posts by DT. He showed a big December WP correlation over the eastern CONUS and said this is why the +AO forecasts are wrong. But when you look closer, you see that the -WPO years are made up of mostly -AO years. When you actually find the -WPO/+AO Decembers, they don't look that the general WPO correlation at all; and in fact, they are rather warm across the CONUS.

 

Gotcha.

[The_Global_Warmer]

And so nobody even tries to come back to this after say Dec is over, and claim "my forecast was wrong", please get it through your head now, there has been NO FORECAST of mine thrown out in this thread via any arguments laid out here. I'm not saying Dec wont be cold or have a

-EPO...Simply chiming in on how the forcing tends to affect the patterns here as the fall-->winter transition unfolds... And i can speak for HM there as well. This all in response of challenging a baseless claim made by a couple in this thread

 

Well.  Basically we have this data helping us predict the winter AO state.  The data is very accurate.  So we know the AO will overall positive this DJF.  We also know more often that not that leads to above normal temps.

 

But in these threads no one is saying a AO+ means a cold and snowy winter won't happen. So many folks come and ignore all of it. Except that a AO+ leans warm for most of us the majority of AO+ regimes. 

 

 

The first reaction was to try and discredit the SAI.  By claiming October or the dates are way to subjective.  Then it was shown moving the dates doesn't change much.  It was also shown that October is not arbitrary itself.  Maybe the 30 days period could be moved to Sept 24th to Oct 24th. Maybe it could be a 20 day period or 40 day.  But the SAI correlation is real to the AO state. 

 

I am sure we didn't see this kind of scrutiny of the SAI last year by anyone who is doing it this year.

 

 

Then there is the OPI.  Less known.  But based off the SAI.  Like literally based off it.  They just took it further adjusting for more factors and have gotten it to a 91 percent up from the SAI 83 percent.  While yes the OPI has not been formally published. The creator or co-creator has given us more than enough to know it's legit. 

 

So this OPI not only backs the SAI it says we get a 1.64 AO+ for DJF.  So the same crowd can't try to bash the OPI since it's based off the SAI.  Instead they go after RICCARDO personally.

 

It's lovely that our weather community is so awesome that a guy from Italy finds our little American weather community so he can share there knowledge with us.  He also takes time to make up forecasts for NA when he has ZERO obligation too.  He has come back with data or predictions and responded to everyone who has asked things of him.

 

But his work shows a major AO++.  Snow lover equates major AO++ with SE ridge and lack of cold and snow.  So the OPI is totally dismissed.

 

 

And Al's proprietary method that predicts the 3rd most negative NAO on record since the mid to late 70s become the snow lovers choice.

 

 

It's kind of like the SAI and OPI are the EURO and GFS and the Proprietary is the KURO.

 

 

All of this crap is because snow lovers perceive that their drug of choice(SNOW) may not come through.  Snow chasing addiction is a really hard one.  Because you are not in control of getting your fix.  You have to hope and wait Mother Nature comes through for you.

 

So the natural inherent human nature of denial begins.  So to fix the pain from the worry that the drug(snow) won't come through they have to change the paradigm. 

 

In this case changing the paradigm is unfortunately changing ones perception of reality. 

 

For the snow addict its better to believe in Oct, Nov, Dec that snow is coming than it is to accept the odds could be lower this year vs another or whatever and be ok with less.  When they believe the snow is coming in Oct, Nov, Dec and it doesn't work out like they hoped.  Only Jan, Feb, and March are a let down.  Instead of the entire period.

 

hope can be cruel at times.

 

The next issue is.  Meteorology is a science. 

 

 

"The National Weather Service (NWS) provides weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas, for the protection of life and property and the enhancement of the national economy. NWS data and products form a national information database and infrastructure which can be used by other governmental agencies, the private sector, the public, and the global community."

 

 

 

No where does the advancement of this field of science have to do with wanting or getting snow.  And if someone starts denying science because it doesn't favor their addiction to snow then the are compromised.

 

 

 

When a snow lover becomes irrational.  You can't reason with them to stay inline with the truth.  Telling them that all this means is that your chances of this much cold or snow goes from say 63 percent to 47 percent means nothing.  They don't want to hear that.  They want that 63 percent or whatever the best chances are for them to get the snow.  Accepting that the odds are just lower for the amount of snow and cold they want is not neccesary.

 

Because there are folks in your profession who have sold there soul to the devil to make money on the snow lovers obsession.  And they can turn to them(FOR A MARGINAL MONTHLY FEE OF COURSE.)  To get the real facts on things.  Of course the guys who wont tell you how they come up with their "methods" not to mention make you pay for their opinion.  All you are paying for is for someone to reinforce the reality you wish to see.

 

 

 

Does this really matter?  No.  Not at all but when this irrational stuff is interjected into discussion that requires scientific integrity to not be compromised at all then it's an issue.

 

 

So you will end up wasting time defending the facts that have already been established instead of progressing the conversation/field of Science at hand.

[CoastalWx]

Do you mean my AO comments? If so, then I did mean Howard. He said my statements about the current forcings not meaning the same thing in winter as they do now is BS. So, in other words, that severely +AO this month wouldn't mean anything if it were the DJF average. lol

 

Sorry, wasn't sure who you was who there.

[The_Global_Warmer]

Why was my comment deleted about Al's propriety blend? 

 

We are censoring truth now huh?

 

It seems to me the OP wanted to talk about such things?

[NJwinter23]

That may be correct, but then why has the EPO/WPO been so predominantly negative for so long, regardless of tropical forcing (which I believe was pretty dormant for awhile)? I mean, I understand that tropical forcing becomes more important as we move deeper into fall, but I also know that especially in ENSO neutral years, it tends to cycle through different phases quite a bit. So I guess I'm just trying to understand the emphasis on "well, if we have this same tropical forcing in DJF, the result will be opposite".

 

The November to DJF EPO correlations exist, and there must be a reason for that as well right?

 

Well I posted OLR as well and you can see that there has been greater convection than normal over Indonesia for the last 30 days, and variability in  other regions as well at times (and boy has this pattern been variable).. so clearly trop forcing has not been dormant. Sometimes it can appear that way though when just glancing at the MJO Phase diagrams and they are in the circle. And the point is not that trop forcing becomes more important  deeper into the cold season, it has different influence on the long-wave pattern eventually downstream into the u.s., because the wavelengths are changing through the fall and into the cold season. In this case, Indonesian forcing is a classic warm East signal in the winter months, but if you check out phase 4-5 maps in the Fall months it actually can provide a cold pattwern in the East.

[CoastalWx]

Well I posted OLR as well and you can see that there has been greater convection than normal over Indonesia for the last 30 days, and variability in  other regions as well at times (and boy has this pattern been variable).. so clearly trop forcing has not been dormant. Sometimes it can appear that way though when just glancing at the MJO Phase diagrams and they are in the circle. And the point is not that trop forcing becomes more important  deeper into the cold season, it has different influence on the long-wave pattern eventually downstream into the u.s., because the wavelengths are changing through the fall and into the cold season. In this case, Indonesian forcing is a classic warm East signal in the winter months, but if you check out phase 4-5 maps in the Fall months it actually can provide a cold pattwern in the East.

 

And that's what I'm more concerned with...how is this going to behave in the coming months? I do like seeing some warmer water near and below the surface to at least help the MJO move east should it do so...but that doesn't always last. Looks like it may be a Kelvin wave.

[WEATHER53]

Do you mean my AO comments? If so, then I did mean Howard. He said my statements about the current forcings not meaning the same thing in winter as they do now is BS. So, in other words, that severely +AO this month wouldn't mean anything if it were the DJF average. lol

No. What is BS is to state that "what made November cold will make Dec and Jan warm" and then tap dance when questioned on it. It's also a statement that has no way to dissect no matter what the outcome is.

[donsutherland1]

And if someone starts denying science because it doesn't favor their addiction to snow then the are compromised.

 

I love the snow, but I try to separate my sentiments from what the data shows when looking at situations (both meteorologically and in terms of climate). As noted previously, in spite of what the OPI is signaling, I hope Ricardo and his team are as accurate as possible. In the bigger picture, the OPI could be an important breakthrough in improving winter season forecasts. Better seasonal forecasts can have large economic and social benefits even if the opportunity cost is some loss of "mystery" or uncertainty about what lies ahead.

[ORH_wxman]

There are years where the SCE did better than the SAI. The SAI did better in more years, which is why it has a higher correlation, but it is not strange or unheard of for SCE to outforecast the AO versus SAI.

 

1977 was a year where the SAI was hurt by very high early October snow cover. The SCE predicted a fairly robust -AO while the SAI forecasted a +AO. The winter had a fairly robust -AO. 2002 had another similar discrepency in a year that had high early October snow cover, however, this time it was more of a push. The SAI predicted a modest +AO and the SCE predicted a robust -AO...the AO ended up in the middle at modestly negative.

 

If someone can identify years where the SCE did better and have a reason on why, then it wouldn't be all that difficult to sell a -AO idea. I do not think I would play those odds, but there is enough uncertainty that it doesn't deserve some of the hostile remarks.

[OKpowdah]

There could be some improvement of understanding, if we dropped the one dimensional indices and actually looked at the pattern. My guess is some people would be helpless without their three letter acronyms

[Jonger]

Well.  Basically we have this data helping us predict the winter AO state.  The data is very accurate.  So we know the AO will overall positive this DJF.  We also know more often that not that leads to above normal temps.

 

But in these threads no one is saying a AO+ means a cold and snowy winter won't happen. So many folks come and ignore all of it. Except that a AO+ leans warm for most of us the majority of AO+ regimes. 

 

 

The first reaction was to try and discredit the SAI.  By claiming October or the dates are way to subjective.  Then it was shown moving the dates doesn't change much.  It was also shown that October is not arbitrary itself.  Maybe the 30 days period could be moved to Sept 24th to Oct 24th. Maybe it could be a 20 day period or 40 day.  But the SAI correlation is real to the AO state. 

 

I am sure we didn't see this kind of scrutiny of the SAI last year by anyone who is doing it this year.

 

 

Then there is the OPI.  Less known.  But based off the SAI.  Like literally based off it.  They just took it further adjusting for more factors and have gotten it to a 91 percent up from the SAI 83 percent.  While yes the OPI has not been formally published. The creator or co-creator has given us more than enough to know it's legit. 

 

So this OPI not only backs the SAI it says we get a 1.64 AO+ for DJF.  So the same crowd can't try to bash the OPI since it's based off the SAI.  Instead they go after RICCARDO personally.

 

It's lovely that our weather community is so awesome that a guy from Italy finds our little American weather community so he can share there knowledge with us.  He also takes time to make up forecasts for NA when he has ZERO obligation too.  He has come back with data or predictions and responded to everyone who has asked things of him.

 

But his work shows a major AO++.  Snow lover equates major AO++ with SE ridge and lack of cold and snow.  So the OPI is totally dismissed.

 

 

And Al's proprietary method that predicts the 3rd most negative NAO on record since the mid to late 70s become the snow lovers choice.

 

 

It's kind of like the SAI and OPI are the EURO and GFS and the Proprietary is the KURO.

 

 

All of this crap is because snow lovers perceive that their drug of choice(SNOW) may not come through.  Snow chasing addiction is a really hard one.  Because you are not in control of getting your fix.  You have to hope and wait Mother Nature comes through for you.

 

So the natural inherent human nature of denial begins.  So to fix the pain from the worry that the drug(snow) won't come through they have to change the paradigm. 

 

In this case changing the paradigm is unfortunately changing ones perception of reality. 

 

For the snow addict its better to believe in Oct, Nov, Dec that snow is coming than it is to accept the odds could be lower this year vs another or whatever and be ok with less.  When they believe the snow is coming in Oct, Nov, Dec and it doesn't work out like they hoped.  Only Jan, Feb, and March are a let down.  Instead of the entire period.

 

hope can be cruel at times.

 

The next issue is.  Meteorology is a science. 

 

 

 

No where does the advancement of this field of science have to do with wanting or getting snow.  And if someone starts denying science because it doesn't favor their addiction to snow then the are compromised.

 

 

 

When a snow lover becomes irrational.  You can't reason with them to stay inline with the truth.  Telling them that all this means is that your chances of this much cold or snow goes from say 63 percent to 47 percent means nothing.  They don't want to hear that.  They want that 63 percent or whatever the best chances are for them to get the snow.  Accepting that the odds are just lower for the amount of snow and cold they want is not neccesary.

 

Because there are folks in your profession who have sold there soul to the devil to make money on the snow lovers obsession.  And they can turn to them(FOR A MARGINAL MONTHLY FEE OF COURSE.)  To get the real facts on things.  Of course the guys who wont tell you how they come up with their "methods" not to mention make you pay for their opinion.  All you are paying for is for someone to reinforce the reality you wish to see.

 

 

 

Does this really matter?  No.  Not at all but when this irrational stuff is interjected into discussion that requires scientific integrity to not be compromised at all then it's an issue.

 

 

So you will end up wasting time defending the facts that have already been established instead of progressing the conversation/field of Science at hand.

 

AO looks to turn southward.

 

Calls for a warm November looks awful.

 

This is like trying to pitch out of a inning and the lead-off hitter just got on first already. 

[The_Global_Warmer]

There are years where the SCE did better than the SAI. The SAI did better in more years, which is why it has a higher correlation, but it is not strange or unheard of for SCE to outforecast the AO versus SAI.

 

1977 was a year where the SAI was hurt by very high early October snow cover. The SCE predicted a fairly robust -AO while the SAI forecasted a +AO. The winter had a fairly robust -AO. 2002 had another similar discrepency in a year that had high early October snow cover, however, this time it was more of a push. The SAI predicted a modest +AO and the SCE predicted a robust -AO...the AO ended up in the middle at modestly negative.

 

If someone can identify years where the SCE did better and have a reason on why, then it wouldn't be all that difficult to sell a -AO idea. I do not think I would play those odds, but there is enough uncertainty that it doesn't deserve some of the hostile remarks.

 

Except in both scenarios you described the OPI wasn't in line with the SAI.

In the 1977 one the OPI was about 0.3 higher than the actual AO.

In the 2002 one the OPI was about 0.2 lower than the actual AO.

 

I agree that there is no need for hostility.  But I can't agree that an -AO is possible.  It's technically not impossible.  But with the OPI forecast of 1.64.  The math shows the OPI index would have to be wrong by a margin almost 50% more than the most off years in it's times series.

 

And all of those years had extreme ENSO events.  This year doesn't.

 

The question then for me is.  Why did the OPI which is based off the SAI do so much better in those years where the SAI failed dramatically?

 

Clearly the OPI creators have found ways to account for more than the SAI can account for.

 

 

 

[The_Global_Warmer]

AO looks to turn southward.

 

Calls for a warm November looks awful.

 

This is like trying to pitch out of a inning and the lead-off hitter just got on first already. 

 

 

 

Which means what?  Who the hell is discussing the November AO?  What does failed predictions about the November monthly temperatures have to do with anything relevant to this topic?

[Jonger]

AO looks to turn southward.

 

Calls for a warm November looks awful.

 

This is like trying to pitch out of a inning and the lead-off hitter just got on first already. 

 

Which means what?  Who the hell is discussing the November AO?  What does failed predictions about the November monthly temperatures have to do with anything relevant to this topic?

Most outlets are changing December calls to cold, that's 1/3rd of the winter.... So this is relevant to the OP.

[heavy_wx]

There could be some improvement of understanding, if we dropped the one dimensional indices and actually looked at the pattern. My guess is some people would be helpless without their three letter acronyms

 

Definitely. I don't think some people understand that different height patterns can produce the same value of a given teleconnection index.

[Ginx snewx]

Global warmer meltdown. Great cold outlook for Decembers first couple of weeks. Good discussion here from most. Happy to see myself actually that no one has really found the elusive key to consistent LR forecasting. Some things are better left unpredictable. Good stuff being discussed and the meltdown itself was worth the visit.

[griteater]

The question then for me is.  Why did the OPI which is based off the SAI do so much better in those years where the SAI failed dramatically?

 

Clearly the OPI creators have found ways to account for more than the SAI can account for.

 

I posted this previously, but the OPI is not based off the SAI.  The way the OPI is calculated has nothing to do with snow advance in Siberia (i.e. SAI).  It is calculated based off the 500mb wave pattern that occurs during the entire month of October.  I think the concepts in the OPI are sound, but let's see how it turns out this year given that this will be the first season in which the group will be making a forward based forecast.  Personally, I think it will perform well this winter...but who knows, it could fail and the OPI group would have to make adjustments (i.e. it could fail where the OPI team has to come back and say "we didn't account for this, and will build this into our model going forward").

[Absolute Humidity]

I posted this previously, but the OPI is not based off the SAI.  The way the OPI is calculated has nothing to do with snow advance in Siberia (i.e. SAI).  It is calculated based off the 500mb wave pattern that occurs during the entire month of October.  I think the concepts in the OPI are sound, but let's see how it turns out this year given that this will be the first season in which the group will be making a forward based forecast.  Personally, I think it will perform well this winter...but who knows, it could fail and the OPI group would have to make adjustments (i.e. it could fail where the OPI team has to come back and say "we didn't account for this, and will build this into our model going forward").

Well said. Let's see how this plays out.

[Harry]

I posted this previously, but the OPI is not based off the SAI.  The way the OPI is calculated has nothing to do with snow advance in Siberia (i.e. SAI).  It is calculated based off the 500mb wave pattern that occurs during the entire month of October.  I think the concepts in the OPI are sound, but let's see how it turns out this year given that this will be the first season in which the group will be making a forward based forecast.  Personally, I think it will perform well this winter...but who knows, it could fail and the OPI group would have to make adjustments (i.e. it could fail where the OPI team has to come back and say "we didn't account for this, and will build this into our model going forward").

 

GREAT POST.. It is amazing how some have forgotten what transpired here ( well Eastern back then )  back in 2006 when someone came along with this big breakthrough involving seasonal outlooks ( then their own winter call based off of it )  that had much to do about the Pacific if i recall correctly?

 

Thus yeah it IS best to wait. Always great to have a new tool especially in this realm of wx forecasting so yeah it will be great if it works out. If it does fail then yeah hopefully some adjustments can be made to improve it vs canning the whole thing. No need to get hyper sensitive over it as a few have done in this thread.

[The_Global_Warmer]

I posted this previously, but the OPI is not based off the SAI.  The way the OPI is calculated has nothing to do with snow advance in Siberia (i.e. SAI).  It is calculated based off the 500mb wave pattern that occurs during the entire month of October.  I think the concepts in the OPI are sound, but let's see how it turns out this year given that this will be the first season in which the group will be making a forward based forecast.  Personally, I think it will perform well this winter...but who knows, it could fail and the OPI group would have to make adjustments (i.e. it could fail where the OPI team has to come back and say "we didn't account for this, and will build this into our model going forward").

 

 

I thought I remember reading Riccardo saying it was based off the SAI.  But I think he uses a translation when he writes or I may have misread it.

 

That actually would give a lot of credence to why the SAI failed in those years but the OPI didn't. 

 

Unless I am mis-reading the SAI on the near 40 year timescale like the OPI is only at 63 percent correlation.  And the SCE is 51 percent.  The OPI in the same range is 91 percent.

 

 

However in figure B We see the most recent period at 60 percent for the SAI but on the bottom it is at 84 percent.  It looks like they have much better results once they had reliable daily data to use instead of weekly. 

 

The biggest thing I see is that the SCE can be way off.  In 2009 the SCE was off by almost a 2.5 deviation while the weekly data for the SAI was only off by 0.3 or 0.4.  Using the daily data for 2009 the SAI is less than 0.1 off from the AO.

 

The OPI being at 97% since 2000 is just remarkable.  Hell the OPI being at 91 percent for almost 40 years is as well.  To me it's exciting.  It's almost hard to believe just because it's accuracy is so remarkable. 

 

 

 As long as they didn't do any fudging during the hindcast when the created the data set after the fact there shouldn't be an issue. 

 

 

I am rooting for the OPI because humans will eventually completely unlock the Earths Atmospheric puzzle in relation to everything including outer space.  I just want it to be sooner than later so it's before I die.  I am 31.  So if I can make it another 50 years it will be 2063.  Overall with this kind of progress I have a feeling we are close to some massive breakthroughs in medium to long range forecasting.

 

 

 

 

 

 

 

 

[skierinvermont]

The OPI + AO are a strong correlation. Even if it didn't work out this year, no adjustment would be necessary. One year doesn't negate a strong long-term correlation.

 

That said I do want to read the paper in English and pass peer-review and see how it plays out because as of now I don't fully understand what is being done to produce the OPI and so I am retaining a slight bit of skepticism. But if the OPI correlation is legitimate as described then even if the AO were somehow negative this winter, it would not negate a strong long-term correlation.

 

The correlation is far stronger than some of the SST correlations being used on eastern (by Chuck for example). 

[N. OF PIKE]

I would like to hear Will's reply to the comment wrt to OPI not being off on the years he cited the SAI being off.

[Dsnowx53]

Well I posted OLR as well and you can see that there has been greater convection than normal over Indonesia for the last 30 days, and variability in  other regions as well at times (and boy has this pattern been variable).. so clearly trop forcing has not been dormant. Sometimes it can appear that way though when just glancing at the MJO Phase diagrams and they are in the circle. And the point is not that trop forcing becomes more important  deeper into the cold season, it has different influence on the long-wave pattern eventually downstream into the u.s., because the wavelengths are changing through the fall and into the cold season. In this case, Indonesian forcing is a classic warm East signal in the winter months, but if you check out phase 4-5 maps in the Fall months it actually can provide a cold pattwern in the East.

 

 

Perhaps I'm a bit misguided with this, but how much different are the wavelengths in mid and late November vs December, anyway? The wavelengths are a tad longer in December, so even if the forcing is a tad too far west, perhaps larger wavelengths would help any subsequent ridging "move" eastward a bit into a more favorable position Plus, there are +SST anomalies in the west-based ENSO regions, which could lead forcing to migrate east a bit into a more favorable location to help out with better EPO ridging to begin with. 

 

Based on the wavelengths and current regime, I would actually favor a cold December. But perhaps in January when the wavelengths begin to shorten again, the east could be quite mild given the +AO and potential EPO ridging being too far west because of the shorter wavelengths. 

 

February would be a bit more uncertain...but maybe some weak +ENSO effects could set in, hopefully leading to blocking at some point along with a split flow and hopefully a continued -EPO regime...perhaps this favors a cold month. 

 

Long-range forecasting is not my forte, but those are my leanings.