Winter 2020-21 Discussion

[frd]

@CAPE  remember what we learned the last two years........ no matter the perceived clue and no matter the head fake , especially good ones that might entice your positive winter vibes, don't be fooled!  Ha ha...... I know you know this,  but here we go again. 

And we are talking it is September 22 nd. How things evolve remain uncertain. Saw this last year in October and especially that November period,  when postings here commented and reflected that maybe we would get - AO periods and HL blocking, even though the NAO look was not that great.

  

[40/70 Benchmark]

3 hours ago, CAPE said:

^Nice writeup with helpful supporting/background data. That last analog composite is generally in line with the h5 pattern the seasonal/climate models have been depicting for winter, with the possible exception of Dec, fwiw.

Not a good look for this region, but we are getting used to the pig EPAC ridge parking in an 'unfavorable' location with little to no help in the AO/NAO space.

Yea, unless something changes, not a good look for you guys....even our better years from that composite still sucked for you. But hey....its not my final call, and the way my last two outlooks have done, it will be good new for you guys if it does end up being my final call.

[George BM]

19 minutes ago, 40/70 Benchmark said:

Yea, unless something changes, not a good look for you guys....even our better years from that composite still sucked for you. But hey....its not my final call, and the way my last two outlooks have done, it will be good new for you guys if it does end up being my final call.

This is just me being 'Curious George' but what would the winter weather pattern look like if there was ever a "super" la nina (ONI < -2.0C)? - TIA

[Eskimo Joe]

 

[40/70 Benchmark]

23 minutes ago, George BM said:

This is just me being 'Curious George' but what would the winter weather pattern look like if there was ever a "super" la nina (ONI < -2.0C)? - TIA

 

[40/70 Benchmark]

On 9/15/2020 at 5:44 AM, CAPE said:

Latest CFS runs continue to depict h5 +height anomalies over the high latitudes for late Fall into the first part of winter.

Agree with that.

[40/70 Benchmark]

On 9/9/2020 at 6:30 PM, frd said:

 

As many here already know, the QBO is currently positive and looks to continue to become more so in the months ahead.

There is some research that points out a tendency for a more poleward based and oriented North Pacific Ridge during  +QBO winters. HM mentioned that, along with a couple other mets as well. @griteater recently mentioned it  too in a detailed and revealing post. I found it so interesting as to share it here. Nice job with this ! 

Here is the post below :

. 

The QBO is utilized in various ways with respect to seasonal forecasting, but IMO, it's best use with winter forecasting is not so much with the AO/NAO, but rather, with the configuration of the North Pacific High/Ridge that is common during La Nina winters.  A North Pacific ridge is almost certain to be present in the mean pattern during Cool ENSO / La Nina winters when the Jul-Oct averaged AAM is negative (which has been the case thus far for Jul-early Sep).

 

Anthony Masiello's findings from 2012 showed that more poleward north pacific ridges were favored during +QBO winters, while north pacific ridges that were suppressed to the south were more favored during -QBO winters.  A key element here is that the designation of the QBO for this purpose was in the lower stratosphere (roughly Nov-Feb averaged at 45mb) as opposed to the typical level used with QBO analysis which is at 30mb. 

 

While the QBO began to behave much more erratic than normal at the first part of 2020, it appears to have resumed with a more typical progression as the positive QBO has more firmly established itself in recent months in the middle stratosphere and descending into the lower stratosphere.  For the upcoming winter, I would anticipate the QBO to average positive for Nov-Feb averaged at 45mb - most similar to the winter of 2010-2011 when compared to other cool ENSO winters. 

 

See QBO Charts:

NASA QBO Chart

Free Univ of Berlin QBO Chart

 

Below is a list of what I have for the last 11 La Nina winters that followed El Nino, along with the Nov-Feb avg 45mb QBO, then the placement of the north pacific ridge averaged for Dec-Mar.

 

La Nina Winter That Followed El Nino Winter / Jan-Feb avg QBO at 45mb / Placement of North Pacific Ridge avg for Dec-Mar

2010-2011 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

2007-2008 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

2005-2006 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

1998-1999 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

1995-1996 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1988-1989 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NE)

1983-1984 / Neutral QBO / no clear distinction overall in the north pacific

1973-1974 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1970-1971 / Negative QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1964-1965 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1954-1955 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

 

Of the 11 winters, the only one that didn't follow the QBO/North Pacific Ridge placement theory was the winter of 1970-1971.

 

Here are 500mb Height / U.S. Temperature composites of the Positive QBO winters from the list: 

 

 

 

And here are 500mb Height / U.S. Temperature composites of the Negative QBO winters from the list (I left off the 70-71 winter):

 

 

Clearly, the Positive QBO composite with the more poleward north pacific ridge offers more potential for cold air intrusion into the lower 48 east of the Rockies compared with the Negative QBO composite.

 

One other thing to look for is the Oct-Nov 500mb pattern over the NE Pacific / Alaska / NW Canada.  Winters with a more poleward north pacific ridge tend to be absent of negative height anomalies in the Bering Sea, Alaska, and NW Canada during Oct-Nov....while, winters with a more southward displaced north pacific ridge tend to contain solid negative height anomalies in the eastern Gulf of Alaska extending up into portions of the Bering Sea, Alaska, and/or NW Canada.

 

Bottom Line: I would expect the upcoming winter to exhibit a more poleward north pacific ridge in the mean pattern as long as: 1) the QBO progression continues in a more typical manner as seen in the past few months, and 2) the Oct-Nov averaged 500mb pattern doesn't contain negative height anomalies in the eastern Gulf of Alaska extending up into portions of the Bering Sea, Alaska, and/or NW Canada  

Wow....GREAT stuff.

Food for thought, and it makes sense in that we use the QBO as a predictor for the polar fields, however, I have aways known the +QBO to favor less blocking (+NAO/AO). But, if it were to favor more N PAC blocking during la nina seasons, then that could change things.

Only thing with 2010-2011 is that we also had some NAO assist.

Interesting...

The question I have is why is the dataset limited to la nina seasons following el nino seasons?

[frd]

58 minutes ago, 40/70 Benchmark said:

Interesting...

The question I have is why is the dataset limited to la nina seasons following el nino seasons?

I could be mistaken, but I believe he was attempting to match the progression that could be possible this late fall and the upcoming winter .

Granted it was a feeble Nino last winter, but I believe that was his goal. Future QBO numbers will be very interesting as we move deeper into the Fall season.

Are you looking at where the IO forcing set ups later this month, and in October,  for any winter clues? 

I ask because bluewave posted a week or so back that depending where the forcing sets up, it has a role in the upcoming winter's temperatures and I imagine the background state.  I have to go back and locate it .  Well worth the read. 

I found it , here you go :

<

We would need to see all that IO forcing shift east toward the Maritime Continent in October. The big amped up MJO 5 in October 2017 came before the snowy La Niña 17-18 winter.  The strong IO MJO 1 in October 2011 preceded the 11-12 La Niña winter. There is some research that early IO forcing can excite the PV like we saw last winter.

>

 

 

[jlh]

On 9/20/2020 at 9:22 AM, WinterWxLuvr said:

I don’t disagree but when you’re looking at 100 year trends you also have to take into consideration the differences in urban areas along that 100 year journey. Lot more concrete and asphalt now vs then. The March 2013 storm is a great example. Just a few miles outside of that heat island was heavy snow. A degree or two made all the difference.

I think to draw conclusions on the 100 year trend with snowfall you’d have to get away from urban locations and look at a small regional collection of data. I know that I’ve looked at the data for Winchester and the thing that stands out the most is the randomness of the high and low snowfall totals.

I definitely think the climate will be a factor, just not sure that’s necessarily gonna show up in snow totals, or what that factor will be. Now if we get 10 of the next 15 winters as warm as last year, I might be singing a different tune.

That is a very valid point. I'll have to take a look at some of the more remote locations...

[Maestrobjwa]

2 hours ago, 40/70 Benchmark said:

Only thing with 2010-2011 is that we also had some NAO assist.

Interesting...

Was that why we were able to pull off Commutagedon (late Jan 2011) down here?

[40/70 Benchmark]

28 minutes ago, Maestrobjwa said:

Was that why we were able to pull off Commutagedon (late Jan 2011) down here?

It wasn't a "block", per se....but we did time some NAO assist very well for the 1/11 blizzard. Not sure about latter January. @Ginx snewx can tell you all about transient NAO assist haha

He loves it.

[CAPE]

2 hours ago, 40/70 Benchmark said:

It wasn't a "block", per se....but we did time some NAO assist very well for the 1/11 blizzard. Not sure about latter January. @Ginx snewx can tell you all about transient NAO assist haha

He loves it.

Transient ridging in the NAO domain is tricky. It is clearly not a block, and to get any benefit from it takes great timing. Many times it looks "good" when it shows up on a mean, but it ends up being useless and/or nothing more than a ridge passing through that space out in front of a digging trough. There are varying degrees of actual blocking, but the premise is the same- the storm track is forced underneath, and it persists for some appreciable amount of time such that we don't have to thread the needle.

[poolz1]

Besides the 50/50 ridge...Id take this any month Nov-March.

That's one heck of a LR signal. It's nice to actually have a fall....and it looks to continue.

[nj2va]

1 hour ago, poolz1 said:

Besides the 50/50 ridge...Id take this any month Nov-March.

That's one heck of a LR signal. It's nice to actually have a fall....and it looks to continue.

 

If that look persists into mid-October, it could easily lead to early flakes for the mountains.  The later the month goes with that look, it opens the door for the far NW exurbs too (your area, etc).  

[CAPE]

19 hours ago, 40/70 Benchmark said:

Wow....GREAT stuff.

Food for thought, and it makes sense in that we use the QBO as a predictor for the polar fields, however, I have aways known the +QBO to favor less blocking (+NAO/AO). But, if it were to favor more N PAC blocking during la nina seasons, then that could change things.

Only thing with 2010-2011 is that we also had some NAO assist.

Interesting...

The question I have is why is the dataset limited to la nina seasons following el nino seasons?

Assuming we are looking at a CP based, low end moderate Nina, where is the most likely location for the N/EPAC ridge to park? Given the current state and trend of the QBO, significant HL blocking episodes(AO/NAO) would appear an unlikely prospect once we get into the heart of winter, so it looks like the most critical element is the exact placement of that ridge. If it is further NE, that would seem to lessen the chances of a persistent SER.

[Rhino16]

1 hour ago, CAPE said:

Assuming we are looking at a CP based, low end moderate Nina, where is the most likely location for the N/EPAC ridge to park? Given the current state and trend of the QBO, significant HL blocking episodes(AO/NAO) would appear an unlikely prospect once we get into the heart of winter, so it looks like the most critical element is the exact placement of that ridge. If it is further NE, that would seem to lessen the chances of a persistent SER.

Are people saying it’s likely to be a CP (Central Pacific?) event Based on models?

[CAPE]

6 minutes ago, Rhino16 said:

Are people saying it’s likely to be a CP (Central Pacific?) event Based on models?

Based on recent/current observations, it appears to be headed in that direction. 40/70 Benchmark made a post on his preliminary thoughts for winter a page or so back and discussed it in detail.

[frd]

2 hours ago, CAPE said:

Given the current state and trend of the QBO, significant HL blocking episodes(AO/NAO) would appear an unlikely prospect once we get into the heart of winter,

We are getting our winter now and in early October. By the way,  Western fires are not the only location in the NH spewing aerosol and other elements into the atmosphere. 

 

 

 

[CAPE]

1 minute ago, frd said:

We are getting our winter now and in early October. By the way,  Western fires are not the only location in the NH spewing aerosol and other elements into the atmosphere. 

 

Maybe Cohen will be right for the wrong reason again. 

[frd]

2 minutes ago, CAPE said:

Maybe Cohen will be right for the wrong reason again. 

Speculation on my part that maybe the pattern is possibly showing a tendency for a different outcome at times during the winter regarding the North Pac ridge and Western ridging.  Again not sure how things evolve as we get deeper into the Fall season. It seems the last 3 years were all November and EARLY December head fakes,  as the real winter pattern did not take hold until post December 20th. 

[JakkelWx]

All the smoke from the wildfires is so widespread globally (massive fires in California but also even bigger fires in Siberia that arent getting enough media attention) that it's gotta be cooling the Earth by a tenth of a degree celsius or so. Maybe even more.

[frd]

 

@CAPE  Interesting 

 

 

 

[frd]

 

Great post by @bluewave this morning, I wanted to share it here. As mentioned in the post here, a very small sample size indeed,  but still worth following to see what  transpires with the Western Ridge during the month of October. I wonder if we enter a feedback loop and how the evolving Nina will effect long term Western ridging later in the year.    

Here is bluewaves's post: 

<

The sample size for La Niña Octobers with a Western Ridge and Eastern Trough is very small. So we will have to see if the strong ridge to start the month persists like it has in September. There was only 1 La Niña year since 1950 with a pattern like this. It was October 1988. The dominant Pacific feature that winter was that the NEPAC ridge extended north into Alaska. Main problem for us in 88-89 was the very strong +NAO. 08-09 had an almost identical Pacific La Niña pattern with a better Atlantic and more snowfall. So maybe a strong ridge out West in October would be hinting that the Pacific Ridge will extend into Alaska.This would be unlike the last 2 winters with the flat La Niña Ridge North of Hawaii.  But we would have to wait and see how the NAO evolves . Still too early to know if any of this pans out. Just something to think about.

 

>

[snowman19]

2 hours ago, JakkelWx said:

All the smoke from the wildfires is so widespread globally (massive fires in California but also even bigger fires in Siberia that arent getting enough media attention) that it's gotta be cooling the Earth by a tenth of a degree celsius or so. Maybe even more.

All these wildfires punching smoke up into the stratosphere are not what you want to see. It is increasing the chances of seeing another +AO winter. HM posted 2 articles last week explaining in detail why this is

[JakkelWx]

Yes, that may be true but wouldn't the smoke dissolve and get mixed out before it has a chance to affect the winter? What if the wildfires stop a month before the winter?

[snowman19]

1 minute ago, JakkelWx said:

Yes, that may be true but wouldn't the smoke dissolve and get mixed out before it has a chance to affect the winter? What if the wildfires stop a month before the winter?

No, they have just begun to affect the stratosphere. The effects will continue through winter. This is going to have long lasting effects for many months even after they end

[40/70 Benchmark]

2 hours ago, frd said:

 

Great post by @bluewave this morning, I wanted to share it here. As mentioned in the post here, a very small sample size indeed,  but still worth following to see what  transpires with the Western Ridge during the month of October. I wonder if we enter a feedback loop and how the evolving Nina will effect long term Western ridging later in the year.    

Here is bluewaves's post: 

<

The sample size for La Niña Octobers with a Western Ridge and Eastern Trough is very small. So we will have to see if the strong ridge to start the month persists like it has in September. There was only 1 La Niña year since 1950 with a pattern like this. It was October 1988. The dominant Pacific feature that winter was that the NEPAC ridge extended north into Alaska. Main problem for us in 88-89 was the very strong +NAO. 08-09 had an almost identical Pacific La Niña pattern with a better Atlantic and more snowfall. So maybe a strong ridge out West in October would be hinting that the Pacific Ridge will extend into Alaska.This would be unlike the last 2 winters with the flat La Niña Ridge North of Hawaii.  But we would have to wait and see how the NAO evolves . Still too early to know if any of this pans out. Just something to think about.

 

>

I don't view this post as good news.

[frd]

26 minutes ago, 40/70 Benchmark said:

I don't view this post as good news.

Sample size is small and we would require a - NAO , especially in our region here for any hopes of significant snowfall. But, the idea of a poleward High during the winter and even extending into the EPO regions has been mentioned by a few pros and mets.  Of course, as you know,  being in  a Nina combined with the location of the Northern Mid Atlantic will take some divine intervention for significant snowfall opportunities.  

[40/70 Benchmark]

15 minutes ago, frd said:

Sample size is small and we would require a - NAO , especially in our region here for any hopes of significant snowfall. But, the idea of a poleward High during the winter and even extending into the EPO regions has been mentioned by a few pros and mets.  Of course, as you know,  being in  a Nina combined with the location of the Northern Mid Atlantic will take some divine intervention for significant snowfall opportunities.  

That to me implies that you even with the N PAC ridging positioned well, you still need an NAO. I don't like the odds of that. I may be able to get away with it...but most won't.

[CAPE]

6 minutes ago, 40/70 Benchmark said:

That to me implies that you even with the N PAC ridging positioned well, you still need an NAO. I don't like the odds of that. I may be able to get away with it...but most won't.

We can snow here with a favorable Pacific(PNA/EPO) and a +NAO. Its not always easy and there is a higher risk of bigger storms tracking inland, but we did pretty well in the winter of 13-14. Gotta have the cold available and that pattern delivered consistently. Ofc that winter was not a Nina. A -NAO definitely improves the odds of a favorable storm track down here though. It is pretty much a requirement for a big snow producer, especially for the coastal plain.