Extreme October Blocking Event Hints at AO- Winter

[WEATHER53]

Yup, and it looks absolutely horrific.  Binning ENSO into "El Nino" and "La Nina", regardless of your index (3.4 SSTA, MEI, their new index), as they do in that write-up is about the worst thing one can do.  Even the "weenies" on this board know that the strength of the ENSO signal can totally alter the pattern (e.g., both strong El Ninos and La Ninas yield warm North American patterns, in general; a weak La Nina up through a low-end moderate El Nino is the best cold signal).

 

To be clear, I'm not saying their new index is bunk.  I have no idea.  Perhaps it does, in fact, capture the atmospheric state - in ENSO terms - better than anything else we have.  But their blog write-up on it, where they simply differentiate between El Nino and La Nina states, is just a horrific misrepresentation of ENSO forcing.  I'd say that any meteorologist should be ashamed to attach their name to that, but, hey, what the heck... I, very sadly, see that done all the time.  I still hear/read that "El Nino = warm winter" all the time, without any regard for the strength of the event.  Sorry to get all revved up over this... but it's perhaps my biggest pet peeve in this entire field.  I'm astonished how many mets go to the ESRL site, look at the LINEAR correlation maps (which get tilted positive because the strong El Ninos outweight the strong La Ninas) and then blindly jump to the conclusion that "El Nino = warm winter".  The correlation is NON-linear.  Arrrgg!  Ok, off my soapbox.

Too many cooks in the kitchen already and some more alphabet soup indexes get introduced each year with most fading away or inconclusive. Try the analog method, assess the hand that mother nature has already played earlier in the year, study the resultant history behind that for the last 40 years and mother nature will tell you where she is headed if you are willing to learn how to read it.  But, that seems to not satisfy the science quest for numerics and indexes and thus the search goes on.

[GaWx]

 Followup post regarding strength of correlation of sub -1 Nov. with strong -AO in subsequent DJF:

 

 Regarding the 12 sub -1 Nov. AO's since 1950-1, a whopping 7 of these 12 (58%) had a DJF averaged sub -1.2 in DJF! Compare that to a very paltry 6 of the other 52 DJF's (only 12%) having a sub -1.2. That's indicative of a very strong AO correlation between Nov. and DJF.

 

 Interestingly, four of those other six that had a sub -1.2 DJF were during a Nino. Four of the five highest Nov. AO's that were also followed by a sub -1.2 DJF AO were Nino's. Three of those four Nino Nov.'s that were followed by a sub -1.2 DJF AO had a +AO. There were 3 of 10 (30%) Nino +AO Nov.'s attaining a subsequent sub -1.2 DJF AO. Compare that to only 1 out of 22 (5%) of non-Nino +AO Nov.'s attaining a subsequent sub -1.2 DJF AO. So, that tells me that having a Nino helps the chance to some extent of still getting a strongly -AO in DJF when there is a +Nov. AO. This is something to keep in mind in case Nov. of 2014's AO is positive (assuming we actually get a Nino). Regardless, the best bet to get a strongly -AO in DJF is to get a sub -1 Nov. AO for any ENSO.

[pbweather]

After studying and following teleconnections virtually every day in the last 6-7 years and many years before this less intensely, I have found it intriguing that people come up with a "new" wonder teleconnection that will revolutionise long term weather forecasting. However, the reality is always a lot different when averaged over a period of years.

 

My view is that there are multiple pattern drivers, some though are just being markers for some other process going on in the atmosphere and by these I mean the AO, NAO, SAI etc.  All of these are caused by some other driver or process to cause these anomalies, yet I see time and time again people use them as though they are living breathing individual drivers of weather patterns.

 

I think many teleconnections that have been identified are, as said above, just indicators and very little is understood as fact as to what drives the changes in them. Sure there is theory that may explain things, but none are proven fact apart from a perhaps a few exceptions.

 

One of those exceptions which I think is partially explained in observations is the sunspot theory. Higher UV radiation during high sunspots has been measured and observed. This increases ozone production in the stratosphere and a relationship with pattern change can be theorised from this, but here is where again theory kicks in rather than fact again.

 

Take this current El Nino. In the spring there was a massive kelvin wave that was near similar strength to the 1997 event that travelled across the Pacific, but persistent trade winds killed it at the surface. Why?  What allowed the 1997 event to rise to the surface unhindered compared to this year? I would argue that some other teleconnection dominated the ENSO signal this year.

 

I think of teleconnections as a balance scale.  If in the case of the 1997 Nino event that there was no other driver to hinder the kelvin wave warming the tropical Pacific to record levels then you end up with a hundred year event. Most other occasions there is always some process or driver that opposes what ever teleconnection you are looking at. And on that note, which teleconnection is a stronger driver than others and does this change from year to year and season to season?

 

So with respect to this winter, yes we can all see the AO is more negative this year in Oct with near record values, but the EC model has the AO going +ve by the 20th of Oct probably finishing off the month with +ve values for the last 10 days. So net AO values are probably going to struggle to get much lower than -1 in the end, and with reference to the post earlier about Nov being a more correlated AO month, then if we start Nov with +ve AO does this make the -ve Oct AO redundant?

 

And what about sunspots? Scaife et al has shown a strong relationship with peak solar cycle sunspots like we are in now and more +AO type winters. So on one hand we have the OPI probably going to say -ve AO winter and sunspots say otherwise. Which is the stronger indicator? The OPI is just a marker. Sunspots has been observed to change the stratospheric chemistry which according to theory should alter the weather patterns. I think I would put more weight on observations rather than a statistical marker.

 

So to summarise, I think this winter is one of those that has too many opposing teleconnection drivers to be an extreme winter. If we had the current -ve AO back in the low sunspot period of 2010 then we may have a different story, but this year I think not. A mix of this and that will end up a not too far from normal winter when averaged out over not just N America but much of the N Hemisphere land masses.  I guess we will only find out in the Spring.

[griteater]

And what about sunspots? Scaife et al has shown a strong relationship with peak solar cycle sunspots like we are in now and more +AO type winters. So on one hand we have the OPI probably going to say -ve AO winter and sunspots say otherwise. Which is the stronger indicator? The OPI is just a marker. Sunspots has been observed to change the stratospheric chemistry which according to theory should alter the weather patterns. I think I would put more weight on observations rather than a statistical marker.

 

I see this mentioned a lot...i.e. peak in solar cycle.  But this is a relatively weak solar cycle.  Many of the papers that cover the QBO-Solar relationship use solar flux values as opposed to sunspot numbers.  Since May, the 90 day solar flux has fallen into the neutral zone, not solar max, not solar min.  Does the Scaife et al paper talk about actual sunspot numbers or is it more focused on solar max regardless of the strength of the solar cycle?

[millwx]

Well thanks for being straightforward and brutally honest about your thoughts. I agree with you in the sense that binning El Nino and La Nina events is a poor thing to do, as ENSO is a spectrum, not A or B. The purpose of the index was to identify times where the low-frequency forcing is coming from the West Pacific (hence why I call La Nina), verses the East Pacific (El Nino). It's just a label, but may be more beneficial to put West Pacific where the "La Nina" string is and East Pacific where the "El Nino" string is. This analysis is a bit more in depth than your typical ESRL analysis but the methodology is simple, I get that. The difference is the index is completely independent of what is occurring in the Ocean, and only cares what is going on in the atmosphere. Thanks again for your thoughts.

Mike, I did not mean to seem to be trashing the index. I'm not. I've not analyzed it myself enough to speak intelligently on it. It may be the best analytical index to come along for ENSO... or maybe not. I don't know.

That's not my problem. My issue comes in the fact that the blog write-up states clearly and unequivocally (though I am paraphrasing here) that a warm ENSO event equals a warm winter. That is just very simply factually incorrect. And I hear that "warm ENSO = warm winter" even from fellow mets on a semi-regular basis. Even CPC uttered it earlier this year. I've just become tremendously frustrated by this! Go look at all winters back to 1950, break them down by ENSO phase and check out the results. Now, because the WSI index is different, perhaps the signal is as well. But I'd seriously doubt it gets a COMPLETELY different signal as other ENSO indices indicate. So, I can say with extremely high confidence that even this new index probably shows at least a similar signal. As such... the blog post concluding warm ENSO events lead, generally, to warm winters is simply wrong.

THAT is my critique. Not the index. The index may be fine. The application of it in the blog posting is, flatly, terrible.

[Ginx snewx]

Mike, I did not mean to seem to be trashing the index. I'm not. I've not analyzed it myself enough to speak intelligently on it. It may be the best analytical index to come along for ENSO... or maybe not. I don't know.

That's not my problem. My issue comes in the fact that the blog write-up states clearly and unequivocally (though I am paraphrasing here) that a warm ENSO event equals a warm winter. That is just very simply factually incorrect. And I hear that "warm ENSO = warm winter" even from fellow mets on a semi-regular basis. Even CPC uttered it earlier this year. I've just become tremendously frustrated by this! Go look at all winters back to 1950, break them down by ENSO phase and check out the results. Now, because the WSI index is different, perhaps the signal is as well. But I'd seriously doubt it gets a COMPLETELY different signal as other ENSO indices indicate. So, I can say with extremely high confidence that even this new index probably shows at least a similar signal. As such... the blog post concluding warm ENSO events lead, generally, to warm winters is simply wrong.

THAT is my critique. Not the index. The index may be fine. The application of it in the blog posting is, flatly, terrible.

you know that's Mike's blog right

[pbweather]

I see this mentioned a lot...i.e. peak in solar cycle.  But this is a relatively weak solar cycle.  Many of the papers that cover the QBO-Solar relationship use solar flux values as opposed to sunspot numbers.  Since May, the 90 day solar flux has fallen into the neutral zone, not solar max, not solar min.  Does the Scaife et al paper talk about actual sunspot numbers or is it more focused on solar max regardless of the strength of the solar cycle?

My understanding is that the 8 fold UV radiation increase during higher sunspot periods was previously hidden withing the broad spectrum of the UV radiation band and it only came to light (excuse the pun) when a new satellite was sent up to observe the Solar spectrum in finer detail. So the total solar radiation incident on the upper atmosphere changes very little through the sunspot cycles, but some important wavelengths do change significantly and these are the ones that are active at producing Ozone and hence change the stratosphere.

 

As far as this being a weak cycle in concerned, I think this is overplayed by many who want the next mini iceage to start. Sunspot activity now is on a par with early 2000s and I think with plenty of sunspot activity to generate increased ozone which statistically has been found to favour increased westerly flow around the polar vortex and therefore less blocking.

[millwx]

you know that's Mike's blog right

Didn't know and doesn't matter. I'd say the same if I knew. I'm usually far less blunt and far more diplomatic. I'm not a bomb thrower like some mets who we all know, I don't need to name names. Vitriol and nastiness gets one nowhere. I see some folks defend those bomb throwers by saying, "well, they're still good mets" or "it adds color to the discussion". Bull. Being rude, arrogant or nasty is just counterproductive, anti-social behavior.

So, if my comments to Mike come off as such, I apologize. The seeming "ire" in my post comes from years of seeing this false conclusion drawn between ENSO and it's resultant effects. It was born out of 1980s strong El Niño events. Yeah, I'm getting old, I guess... I remember the early years when an understanding of ENSO was only just beginning. But that's 30 years ago now! We know much more now and have long since retired that ENSO myth to the dustbin. Yet, I still see many mets - even at CPC, where they REALLY should know better - cart it out EVERY time an El Niño event is predicted.

And in the case of Mike's WSI blog it really got under my skin because I think it actually does his work a disservice. I actually disagree with the commenters on this thread who think another index is just too much. We are always gaining more and better understanding of how the atmosphere works. From those new insights there may be a way to quantify any new findings into a convenient index value which allows us to further our analyses and use the indices going forward to help improve our forecasting. So, I have ZERO problem with the index itself and love that WSI/Mike is trying to advance things along like this. I commend them for that.

My concern is the application of it. If one misapplies an index it undermines it's usefulness. And, as noted above, this ENSO myth (warm yields warm) has been debunked long, long ago. So, it's a source of endless frustration for me. I don't mean to seem so ire-filled as if I'm attacking Mike personally, as he is far, FAR from the only met to make the warm-warm connection. I'm just supremely frustrated because I simply don't know WHY. And that's not a subtle additional dig. Honestly, I really don't know why this myth is perpetuated even amongst professional mets. As I mentioned earlier, even CPC rolled it out a few months ago. I'm not one of those ppl who always bash the govt. I used to work with those folks. Most of them are VERY smart. I don't know Mike personally but I'd bet, since WSI gives him that space for his blog posting, he's also probably pretty top notch. So, these are not meteorological lightweights we're talking about. Why, then, does the ENSO myth perpetuate?

Anyway, enough of my soapbox. I apologize to Mike if my tirade was too personal and vitriolic - just very frustrated with this issue. No offense was intended and I commend the actual work towards developing a new/better index. I'd simply advise more care in the application of it. Now...

We should return to the subject of the topic of this thread... the AO (in my defense, I didn't introduce this off-topic tangent, lol). I find the Oct-Winter AO correlation fascinating and would like to delve further into why that's the case. Obviously, whatever pattern sets up a good -AO in Oct is either a stable pattern (persisting into winter) or produces an effect which has a feedback mechanism that reinforces the -AO signal come winter. Really, I don't know which is the correct answer. Off the top of my head, I could see an argument for either. There is a long-term cycle in both the AO and NAO (albeit VERY noisy - it takes some pretty extreme smoothing to see the signal). That backs the stability argument. On the feedback argument one could use Eurasian snow cover. I'd need to investigate the typical October -AO pattern over Eurasia, but IF it is supportive of snow then this would support the feedback argument (I know some argue that Eurasian snow is an effect, not a cause, but there are at least some theories and studies that argue otherwise). And I'm sure other "feedback" theories could be put forth. So, it would be very interesting to gain further understanding as to what's going on here... why this relationship exists. Very intriguing.

[Mike.Ventrice]

Mike, I did not mean to seem to be trashing the index. I'm not. I've not analyzed it myself enough to speak intelligently on it. It may be the best analytical index to come along for ENSO... or maybe not. I don't know.

That's not my problem. My issue comes in the fact that the blog write-up states clearly and unequivocally (though I am paraphrasing here) that a warm ENSO event equals a warm winter. That is just very simply factually incorrect. And I hear that "warm ENSO = warm winter" even from fellow mets on a semi-regular basis. Even CPC uttered it earlier this year. I've just become tremendously frustrated by this! Go look at all winters back to 1950, break them down by ENSO phase and check out the results. Now, because the WSI index is different, perhaps the signal is as well. But I'd seriously doubt it gets a COMPLETELY different signal as other ENSO indices indicate. So, I can say with extremely high confidence that even this new index probably shows at least a similar signal. As such... the blog post concluding warm ENSO events lead, generally, to warm winters is simply wrong.

THAT is my critique. Not the index. The index may be fine. The application of it in the blog posting is, flatly, terrible.

 

Again, the purpose of the index was to tell whether the atmosphere is feeling El Nino. It is just a simple means to state whether the forcing in the upper-troposphere is coming from the West Pacific verses the East Pacific, regardless of SSTA information. You often get large signals at lower frequencies in the upper-troposphere. Here is an archive that highlights such variability: http://www.atmos.albany.edu/student/ventrice/documents/enso/

 

Now the index is simple in it's construction. Just a 120day running average of unfiltered VP200 anomalies averaged over two boxes, which are then subtracted. From my work is VP200 with regards to the MJO, it's a very useful field to isolate intraseasonal and interannual signals. I wanted to construct an index that could monitor the strength of the atmospheric response to ENSO, as it is likely one of the best predictors we have at seasonal time scales.

 

From my blog, yes the signal is "Warm" over the US for both El Nino and La Nina. But these are just composites. The true signal is what is occurring over western Canada in each state. La Nina pools the cold air up in western Canada, which then needs something to kick it down across the U.S. Might that be a strong MJO event, or a developing -NAO block.

 

It sounds like you have a solid understanding and are passionate about your thoughts regarding El Nino. My recommendation is instead of simply stating your thoughts in a very strong opinionated fashion, to do the research and write an article to share it with the field to prove it. We often are emotional as meteorologists and can come across arrogant, especially if someone goes against the grain and begins touting things that do not line up with your thoughts. I've come across many in the field like that and the best way is to remain professional and logical.

 

Thanks again for you sharing your thoughts, as well as others on this thread. The beauty of science.

[griteater]

As far as this being a weak cycle in concerned, I think this is overplayed by many who want the next mini iceage to start. Sunspot activity now is on a par with early 2000s and I think with plenty of sunspot activity to generate increased ozone which statistically has been found to favour increased westerly flow around the polar vortex and therefore less blocking.

 

That's a topic for climate change, but again, the current solar flux values are in the range of solar neutral conditions, not solar maximum.

 

On the topic of ozone, my understanding is that increasing ozone in the polar stratosphere aids in UV radiation absorption and warming of the stratosphere...thus, a weaker polar vortex.

[GaWx]

As far as this being a weak cycle in concerned, I think this is overplayed by many who want the next mini iceage to start. Sunspot activity now is on a par with early 2000s and I think with plenty of sunspot activity to generate increased ozone which statistically has been found to favour increased westerly flow around the polar vortex and therefore less blocking.

pbweather,

I disagree with the idea that we're on par with early 2000's sunspot activity. We're most certainly in a much weaker cycle. Also, the chances of an even weaker cycle or cycles ahead are there and they are not low chances. We appear to be in the early states of a multidecade long grand minimum, which could easily end up rivaling the Dalton Minimum of 200 years ago. Now, regarding how much cooling impact that would likely have, we'll see as there are varying ideas. It could still end up minor but that isn't yet known by any means.

[donsutherland1]

A new atmospheric ENSO index is introduced to WSI clients, showing current state and what this may mean for winter:

 

http://www.wsi.com/blog/energy/introducing-a-new-atmospheric-el-nino-southern-oscillation-index-its-current-state-and-upcoming-winter-implications/

Thanks for posting this link. I look forward to reading it. WSI has come up with some really good analytical products, so a tool on how the atmosphere is behaving should add value and perhaps provide possible insights for going forward.

[donsutherland1]

Don/folks,

Very nice work, Don, as usual.

1. One thing that I think can be easily overlooked by some is the -AO bias for DJF. For all DJF's since 1950-1, the mean AO has been -0.35 and the median has been -0.41 as opposed to near 0. So, the index is sort of tilted in the negative direction. So, a DJF's average AO of, say, -0.25 would actually mean that winter would be favored to get slightly less AO type blocking than average. What I'm getting at is that I feel that a DJF AO # of ~-0.40 should be treated as neutral rather than 0.

 

2. Related to this -AO bias, 62% of DJF months 1950-2014 had a -AO and only 38% had a +AO. Also, 33% of DJF months had an AO under -1 while only 17% had it over +1.

 

3. Even after taking this bias into account, the DJF mean of -0.779 in Don's analysis still suggests a pretty good -AO signal vs. -0.35. However, the median of -0.414 is totally neutral. The % of winter months less than 0 (75%) is still a pretty good signal vs. 62% though the 39% for -1 or lower seems pretty modest to me vs. 33%.

 

4. I realize the advantage of looking at Oct. vs. Nov. since it gives one more month of lead time in analyzing winter AO probabilities. However, and probably not surprisingly, Nov. gives a much stronger signal than Oct. Whereas the mean is -0.75 (vs. -0.35) and the median is -0.50 (vs. -0.41) for the DJF AO when the preceding Oct. AO is <-1, the mean is a whopping -1.14 (vs. -0.35) and the median is a whopping -1.25 (vs. -0.41) for the DJF AO when the preceding Nov. AO is <-1. So, the correlation with November is much stronger than that with October.

 

**Edit: I forgot to mention that the actuals as well as the GEFS mean forecast out two weeks strongly suggest a good bit better than 50% chance for a sub -1 Oct AO as I'm estimating a sub -1 average for 10/1-27 based on it.

Thanks for this additional information. I didn't post about the wintertime average AO tendency (somewhat negative), but am looking only at the general tendency from this far out. November's AO could confirm whether things are on course for a more blocky winter as your statistics point out. Right now, I'm leaning in that direction, but want to see additional data.

[donsutherland1]

After studying and following teleconnections virtually every day in the last 6-7 years and many years before this less intensely, I have found it intriguing that people come up with a "new" wonder teleconnection that will revolutionise long term weather forecasting. However, the reality is always a lot different when averaged over a period of years.

 

My view is that there are multiple pattern drivers, some though are just being markers for some other process going on in the atmosphere and by these I mean the AO, NAO, SAI etc.  All of these are caused by some other driver or process to cause these anomalies, yet I see time and time again people use them as though they are living breathing individual drivers of weather patterns.

 

I think many teleconnections that have been identified are, as said above, just indicators and very little is understood as fact as to what drives the changes in them. Sure there is theory that may explain things, but none are proven fact apart from a perhaps a few exceptions.

 

One of those exceptions which I think is partially explained in observations is the sunspot theory. Higher UV radiation during high sunspots has been measured and observed. This increases ozone production in the stratosphere and a relationship with pattern change can be theorised from this, but here is where again theory kicks in rather than fact again.

 

Take this current El Nino. In the spring there was a massive kelvin wave that was near similar strength to the 1997 event that travelled across the Pacific, but persistent trade winds killed it at the surface. Why?  What allowed the 1997 event to rise to the surface unhindered compared to this year? I would argue that some other teleconnection dominated the ENSO signal this year.

 

I think of teleconnections as a balance scale.  If in the case of the 1997 Nino event that there was no other driver to hinder the kelvin wave warming the tropical Pacific to record levels then you end up with a hundred year event. Most other occasions there is always some process or driver that opposes what ever teleconnection you are looking at. And on that note, which teleconnection is a stronger driver than others and does this change from year to year and season to season?

 

So with respect to this winter, yes we can all see the AO is more negative this year in Oct with near record values, but the EC model has the AO going +ve by the 20th of Oct probably finishing off the month with +ve values for the last 10 days. So net AO values are probably going to struggle to get much lower than -1 in the end, and with reference to the post earlier about Nov being a more correlated AO month, then if we start Nov with +ve AO does this make the -ve Oct AO redundant?

 

And what about sunspots? Scaife et al has shown a strong relationship with peak solar cycle sunspots like we are in now and more +AO type winters. So on one hand we have the OPI probably going to say -ve AO winter and sunspots say otherwise. Which is the stronger indicator? The OPI is just a marker. Sunspots has been observed to change the stratospheric chemistry which according to theory should alter the weather patterns. I think I would put more weight on observations rather than a statistical marker.

 

So to summarise, I think this winter is one of those that has too many opposing teleconnection drivers to be an extreme winter. If we had the current -ve AO back in the low sunspot period of 2010 then we may have a different story, but this year I think not. A mix of this and that will end up a not too far from normal winter when averaged out over not just N America but much of the N Hemisphere land masses.  I guess we will only find out in the Spring.

A few points:

 

1. There is no "wonder teleconnection." We agree on that point. However, the predominant state of the major teleconnections (EPO, PNA, AO, etc.) provides insight into the temperature anomalies. In recent years, more effort has been devoted to trying to predict some of these teleconnections i.e. the Siberian Snow Advance Index (SAI) and October Pattern Index (OPI).

 

2. How the atmosphere responds to SSTAs (ENSO and other areas) is also crucial. The abnormally warm SSTAs signaled a predominantly EPO- winter last year and forecasters who picked up on that tendency early last year did a good job in anticipating a cold winter (I didn't see this until later). The ocean-atmosphere response is complex and SSTAs can influence the state of the atmosphere, but the state of the atmosphere can also exert influence on SSTAs. A similar phenomenon exists with regard to sudden stratospheric warming events (SSWs). Sometimes the SSWs are precursors to blocking. At other times, they are a response to earlier blocking and may not necessarily indicate renewed blocking lies ahead.

 

3. The solar activity-AO hypothesis deals with longer-term tendencies, not seasonal ones. I use the term "hypothesis," because as far as I have seen, the literature is not definitive. In any case, the number of sunspots was high during winter 1968-69, yet that was one of the blockier winters on record.

 

In short, a lot is involved. Nevertheless, I suspect that some of the recent work that has been done may be paving the way for more accurate seasonal forecasts than had been possible even a decade ago.

[GaWx]

 I forgot to mention that the actuals as well as the GEFS mean forecast out two weeks strongly suggest a good bit better than 50% chance for a sub -1 Oct AO as I'm estimating a sub -1 average for 10/1-27 based on it.

 

 The 10/1-14 averaged AO is at an impressive ~-1.6. Today's GEFS mean forecast out two weeks looks similar to, if not a touch more negative than, yesterday through the two week forecast fwiw. I'm estimating that the combo of that and the actuals through 10/14 is giving a 10/1-28 projected averaged AO of a very impressive ~-1.5. So, something close to -1.5 for the entire month is not at all far-fetched. If it were to be near -1.5, only 2009's -1.540, 2012's -1.514, and 2002's -1.489 would be nearby going back to 1950! The next one is the not even close -1.243 of 1979.

 

 What happened in the subsequent DJF's AO for these three years (vs. mean of -0.35)?

- 2002: -0.65

- 2009: -3.42 (lowest AO since at least 1950)

- 2012: -1.12

 

 So, we got a record low AO, a strongly -AO, and a modest -AO (vs. -0.35 mean). So, this would be encouraging for the chances at a solid -AO this winter. If Nov. were to also have a strong -AO and if we get El Nino, it would be looking extremely encouraging for strong -AO chances for DJF.

[Isotherm]

My understanding is that the 8 fold UV radiation increase during higher sunspot periods was previously hidden withing the broad spectrum of the UV radiation band and it only came to light (excuse the pun) when a new satellite was sent up to observe the Solar spectrum in finer detail. So the total solar radiation incident on the upper atmosphere changes very little through the sunspot cycles, but some important wavelengths do change significantly and these are the ones that are active at producing Ozone and hence change the stratosphere.

 

As far as this being a weak cycle in concerned, I think this is overplayed by many who want the next mini iceage to start. Sunspot activity now is on a par with early 2000s and I think with plenty of sunspot activity to generate increased ozone which statistically has been found to favour increased westerly flow around the polar vortex and therefore less blocking.

 

 

In addition to Larry (GaWx's) post, solar UV variation plays a significant role in modulation of stratospheric circulation through ozone production which in turn can impact the tropospheric vortex / northern annular mode. There's a good deal of research ongoing which continues to investigate the indirect links between tropospheric circulation and solar variability. If one were to conduct a simple sunspot --> tropospheric circulation correlation, you wouldn't find as much as if you examined other variables such as UV radiation, geomagnetic activity and the solar wind, etc. And their relationship to tropospheric circulation may not necessary show up in linear correlations. The effect is more indirect. Since solar activity and Earth's troposphere is separated by the stratosphere, mesosphere, etc., other variables can modulate, enhance or mute the background solar signal, such as the QBO for example. However, there's no doubt that solar variability plays an enormous role in creating a domino effect and exerting influence gradually downward through the atmospheric layers.

 

With regards to the current cycle, solar flux peaked generally around 1600-1700, while the early 2000s flux peaked around 2400. Additionally, geomagnetic activity is consistently at much lower levels than it was back in the early 2000s. There's no doubt the intensity of this current cycle is quite a bit less than the cycle 23 climax. Flux right now has fallen to around 1200-1250, which is essentially 50% of peak cycle 23 conditions. I'm not making any claims about the upcoming winter, but in terms of any comparison with the early 2000s solar activity - it's apples and oranges - much different right now.

[uncle W]

1957-58 was during a high solar output and it was a great winter...the ao/nao is on its way down again...they are forecast to rise near neutral later in the month...

[Wow]

 The 10/1-14 averaged AO is at an impressive ~-1.6. Today's GEFS mean forecast out two weeks looks similar to, if not a touch more negative than, yesterday through the two week forecast fwiw. I'm estimating that the combo of that and the actuals through 10/14 is giving a 10/1-28 projected averaged AO of a very impressive ~-1.5. So, something close to -1.5 for the entire month is not at all far-fetched. If it were to be near -1.5, only 2009's -1.540, 2012's -1.514, and 2002's -1.489 would be nearby going back to 1950! The next one is the not even close -1.243 of 1979.

 

 What happened in the subsequent DJF's AO for these three years (vs. mean of -0.35)?

- 2002: -0.65

- 2009: -3.42 (lowest AO since at least 1950)

- 2012: -1.12

 

 So, we got a record low AO, a strongly -AO, and a modest -AO (vs. -0.35 mean). So, this would be encouraging for the chances at a solid -AO this winter. If Nov. were to also have a strong -AO and if we get El Nino, it would be looking extremely encouraging for strong -AO chances for DJF.

 

Day 1-16 500mb anomaly avg for the GEFS...

 

[GaWx]

 The 10/1-14 averaged AO is at an impressive ~-1.6. Today's GEFS mean forecast out two weeks looks similar to, if not a touch more negative than, yesterday through the two week forecast fwiw. I'm estimating that the combo of that and the actuals through 10/14 is giving a 10/1-28 projected averaged AO of a very impressive ~-1.5. So, something close to -1.5 for the entire month is not at all far-fetched. If it were to be near -1.5, only 2009's -1.540, 2012's -1.514, and 2002's -1.489 would be nearby going back to 1950! The next one is the not even close -1.243 of 1979.

 

 What happened in the subsequent DJF's AO for these three years (vs. mean of -0.35)?

- 2002: -0.65

- 2009: -3.42 (lowest AO since at least 1950)

- 2012: -1.12

 

 So, we got a record low AO, a strongly -AO, and a modest -AO (vs. -0.35 mean). So, this would be encouraging for the chances at a solid -AO this winter. If Nov. were to also have a strong -AO and if we get El Nino, it would be looking extremely encouraging for strong -AO chances for DJF.

 

 The 10/15 GEFS mean has gone a good bit more in the +AO direction for 10/20+ since the last two days' runs. As of them, it was forecasting near a -1.5 for 10/1-27/28. Today, it is forecasting only down at -1.0 for 10/1-29. With this kind of volatility for day 5+, the GEFS mean AO prediction past about one week should be taken with a grain of salt. Regardless, the near record low AO that was suggested as a realistic possibility by the GEFS of the past two days would appear to be virtually impossible if you believe today's run. Also, apparently the Euro ensemble is similar, if not even less negative, per another post. I don't have access to it as far as I know.

 Bottom line: getting a sub -1.0 AO for October as a whole looks a whole lot less likely than it appeared the prior two days based strictly on the GEFS though a sub -1.0 is still quite possible, especially when considering a rather sig. +bias for the GEFS in week two. Regardless, the Nov. AO will be weighted quite a bit more than Oct. by me as regards winter AO possibilities for reasons stated in other very recent posts.

 

**EDITED**

[Mike.Ventrice]

 The 10/15 GEFS mean has gone a good bit more in the +AO direction for 10/20+ since the last two days' runs. As of them, it was forecasting near a -1.5 for 10/1-27/28. Today, it is forecasting only down at -1.0 for 10/1-29. With this kind of volatility for day 5+, the GEFS mean AO prediction past about one week should be taken with a grain of salt. Regardless, the near record low AO that was suggested as a realistic possibility by the GEFS of the past two days would appear to be virtually impossible if you believe today's run. Also, apparently the Euro ensemble is similar, if not even less negative, per another post. I don't have access to it as far as I know.

 Bottom line: getting a sub -1.0 AO for October as a whole looks a whole lot less likely than it appeared the prior two days based strictly on the GEFS though a sub -1.0 is still quite possible, especially when considering a rather sig. +bias for the GEFS in week two. Regardless, the Nov. AO will be weighted quite a bit more than Oct. by me as regards winter AO possibilities for reasons stated in other very recent posts.

 

**EDITED**

 

Just put this out on our WSI_Energy twitter handle:

 

https://twitter.com/WSI_Energy/status/522418934679879681

[GaWx]

Just put this out on our WSI_Energy twitter handle:

 

https://twitter.com/WSI_Energy/status/522418934679879681

 

Mike,

 Thanks. That's even more positive than what I'm seeing, including only getting down to ~-2.6 rather than the ~-2.8 today's GEFS is suggesting. On what model is that based and what is the date of the model's forecast? Is it 10/13? Is it the Euro ens?

 

Edit: example: your linked forecast has it down only to ~-1.3 on 10/19 vs. today's GEFS' -2.2!

[Mike.Ventrice]

Mike,

 Thanks. That's even more positive than what I'm seeing, including only getting down to ~-2.6 rather than the ~-2.8 today's GEFS is suggesting. On what model is that based and what is the date of the model's forecast? Is it 10/13? Is it the Euro ens?

 

Edit: example: your linked forecast has it down only to ~-1.3 on 10/19 vs. today's GEFS' -2.2!

 

It's the ECMWF ensembles, but I suspect slight differences in EOF construction are resulting in differences in the index as a whole.

[GaWx]

It's the ECMWF ensembles, but I suspect slight differences in EOF construction are resulting in differences in the index as a whole.

 

Mike,

 Thank you. So, it must be the 10/13 forecast. Do you have the 10/15 forecast? Also, does the Euro ens. have a bias? Even the GEFS has had a +AO bias for week 2 as of the last few months overall.

[Mike.Ventrice]

Mike,

 Thank you. So, it must be the 10/13 forecast. Do you have the 10/15 forecast? Also, does the Euro ens. have a bias? Even the GEFS has had a +AO bias for week 2 as of the last few monhts overall.

 

I apologize... this was made from the European weekly* model, not the ensembles. I'm not sure about the biases- but a new forecast will be made tomorrow night.

[stadiumwave]

My excitement at the beginning of the month for this winter is fading fast.  Looking at the ensembles & the pattern being projected doesn't exactly make this winter weather lover very optimistic.

[Cold Rain]

My excitement at the beginning of the month for this winter is fading fast.  Looking at the ensembles & the pattern being projected doesn't exactly make this winter weather lover very optimistic.

Wait, what? Why?

[Bob Chill]

My excitement at the beginning of the month for this winter is fading fast. Looking at the ensembles & the pattern being projected doesn't exactly make this winter weather lover very optimistic.

I think you're jumping the gun. Everything is going as well as we can ask for Oct. Just because we are losing blocking at the end of Oct means basically nothing as far as winter goes. Showing ridging on the means going forward south of the Aleutians is no big deal either. Assuming the SAI works out, we won't really see the AO response until sometime in Nov at the earliest. Most high extent years don't respond until Dec and that's what we want for a best case scenario. I have a lot of seasonal graphs I put together that show this.

If you look at the positives so far you can only think we stand a fair chance at not having a bust or torch in the east:

1. Extreme Oct blocking event

2. Large area of low height anomalies south of the Aleutians that likely can't be erased by what ensemble guidance is showing

3. PDO region continuing to improve and take on a +PDO look

4. October snow cover increase in eurasia is off to the races

5. 3.4 is improving at a critical time

What is it you're seeing that is so negative?

[WidreMann]

My excitement at the beginning of the month for this winter is fading fast.  Looking at the ensembles & the pattern being projected doesn't exactly make this winter weather lover very optimistic.

He's channeling me. Since I don't post as much, somebody has to play this role.

[stadiumwave]

I think you're jumping the gun. Everything is going as well as we can ask for Oct. Just because we are losing blocking at the end of Oct means basically nothing as far as winter goes. Showing ridging on the means going forward south of the Aleutians is no big deal either. Assuming the SAI works out, we won't really see the AO response until sometime in Nov at the earliest. Most high extent years don't respond until Dec and that's what we want for a best case scenario. I have a lot of seasonal graphs I put together that show this.

If you look at the positives so far you can only think we stand a fair chance at not having a bust or torch in the east:

1. Extreme Oct blocking event

2. Large area of low height anomalies south of the Aleutians that likely can't be erased by what ensemble guidance is showing

3. PDO region continuing to improve and take on a +PDO look

4. October snow cover increase in eurasia is off to the races

5. 3.4 is improving at a critical time

What is it you're seeing that is so negative?

 

I know there have been some very strong reasons to be optimistic & you've also addressed a couple of my concerns. I posted that on a bad day in which my pessimism rather than science took over my fingers.