Wintry Winter 25-26 Winter Battle Zone

[Webberweather53]

Getting an MJO event to orbit into the Western Hemisphere (phase 8-1) a majority of the time relies on the extratropical circulation carrying the signal along, because the SSTs aren't warm enough outside of the Indo-Pacific to couple directly with the ocean, except perhaps in big El Niño events.

Having a negative NAO makes these western hemisphere MJO orbits more likely to occur because the extratropical waves penetrate deeper into the tropics during -NAO:

You can basically think of this as a positive feedback, where the presence of a -NAO makes a phase 8-1 MJO more likely to occur, which also favors -NAO, etc.
https://journals.ametsoc.org/view/journals/clim/34/23/JCLI-D-21-0153.1.xml

 

[SnowNiner]

Need that look January … not December

I used to think that way, but last December gave me a quick inch of cold powder mood event. Gone by lunch but it was fun and cold.

Just to me a complete unknown how this winter shakes out. -EPO/+TNH worked great last year. Can we do it again? I have no idea but my eyes are on the pacific, pacific, pacific as it makes or breaks us every year it seems.

 

[griteater]

I used to think that way, but last December gave me a quick inch of cold powder mood event. Gone by lunch but it was fun and cold.

Just to me a complete unknown how this winter shakes out. -EPO/+TNH worked great last year. Can we do it again? I have no idea but my eyes are on the pacific, pacific, pacific as it makes or breaks us every year it seems.

We want to see that MJO continue on into 8-1 and out of the Maritime Continent to get the Pacific side rolling

 

[1300m]

I used to think that way, but last December gave me a quick inch of cold powder mood event. Gone by lunch but it was fun and cold.

Just to me a complete unknown how this winter shakes out. -EPO/+TNH worked great last year. Can we do it again? I have no idea but my eyes are on the pacific, pacific, pacific as it makes or breaks us every year it seems.

I still believe as much as ever that the -NAO is the most directly influential circulation on eastern U.S. winter weather, but I also agree that without Pacific cooperation we still struggle. It's just too hard to snow here with any destructive elements to the flow as we've seen time and time again.

 

[Webberweather53]

A few other things I think that are playing into our favor at least for December

Being in a La Niña with a slower-moving and more amplified MJO (due in part to the easterly QBO) makes a subsequent -NAO and weaker polar vortex/-NAM more likely.

Fig from Lee et al (2019)




The current global tropics SSTa are also almost the exact opposite of the MJO phase speed & SST correlation pattern derived from Suematsu & Miura (2021), favoring slower MJO events that typically have stronger and more consistent extratropical teleconnections as Yadav et al (2024) + Yadav & Straus (2017) and Tseng et al (2020) have argued respectively.

 

[griteater]

I think our best hope analog for Nov-Dec comes from year 2000.




Note the central North Pac low and NW Asia / E Europe high in the Nov image. That's a precursor to Strat PV weakening as shown here (from https://journals.ametsoc.org/view/journals/clim/23/12/2010jcli3010.1.xml)



From paper conclusions, "...The regional tropospheric anomalies that are best correlated with vortex weakening are found to be those that are in phase with (and thus amplify the magnitude of) the climatological extratropical planetary waves, strongly suggesting (though simplified modeling work is certainly necessary) that regional anomalies that amplify the climatological stationary waves will, on average, affect the vortex. The two regional anomalies that can most effectively modulate the vortex are the North Pacific low and the eastern European high. A low over the North Pacific tends to result in a dramatic increase in wave 1 leaving the troposphere and converging at the vortex, and a high over eastern Europe tends to result in a dramatic increase in wave 2 leaving the troposphere and converging at the vortex. A low over the northwestern Pacific (possibly associated with October Eurasian snow) has a similar, but weaker, effect than that of a low over the central Pacific."


Current Euro Weekly for Nov 5 - Dec 5...



Here's the Strat PV weakening that occurred in Nov-Dec 2000 at 10mb (upper strat) and 100mb (lower strat)


Was also going to post the image that Eric did about the MJO Phase 7 / Nina / NAO connection




Here was the MJO in Dec 2000 - it went into Phase 7 the 2nd week of Dec



Solar and QBO this year are good comparisons to 2000-2001 as well - max phase of the solar cycle and QBO is in the negative phase





Early and late winter strat warmings are favored in -QBO (East) / Solar Max winters

(From: https://journals.ametsoc.org/view/journals/atsc/61/23/jas-3297.1.xml)

 

[Webberweather53]

I have pretty high confidence December is gonna try to make things real interesting this year.

I can’t quite figure out what’s going to happen in the heart of the winter this year.

Do we get a mid winter thaw as we get an Indian Ocean to Maritime Continent orbit with another favorable S2S look later in January or do we keep the good times rolling throughout most of this period?

If the tropospheric circulation anomalies can get anchored into the stratosphere (a stratospheric warming event for ex), that’s probably how we can keep the good times rolling well into January.

The stratosphere likely won’t matter much for this first round of mjo forcing in December, but it probably will be an important factor in January and February

I.e. could help keep the -NAO/-AO going beyond the timescale of the initial mjo forcing (as mentioned previously) or enhancing wave reflection Feb (+TNH) if its strong by then.

 

[Webberweather53]

I think our best hope analog for Nov-Dec comes from year 2000.

View attachment 175824


Note the central North Pac low and NW Asia / E Europe high in the Nov image. That's a precursor to Strat PV weakening as shown here (from https://journals.ametsoc.org/view/journals/clim/23/12/2010jcli3010.1.xml)

View attachment 175827

From paper conclusions, "...The regional tropospheric anomalies that are best correlated with vortex weakening are found to be those that are in phase with (and thus amplify the magnitude of) the climatological extratropical planetary waves, strongly suggesting (though simplified modeling work is certainly necessary) that regional anomalies that amplify the climatological stationary waves will, on average, affect the vortex. The two regional anomalies that can most effectively modulate the vortex are the North Pacific low and the eastern European high. A low over the North Pacific tends to result in a dramatic increase in wave 1 leaving the troposphere and converging at the vortex, and a high over eastern Europe tends to result in a dramatic increase in wave 2 leaving the troposphere and converging at the vortex. A low over the northwestern Pacific (possibly associated with October Eurasian snow) has a similar, but weaker, effect than that of a low over the central Pacific."


Current Euro Weekly for Nov 5 - Dec 5...
View attachment 175828


Here's the Strat PV weakening that occurred in Nov-Dec 2000 at 10mb (upper strat) and 100mb (lower strat)
View attachment 175829

Was also going to post the image that Eric did about the MJO Phase 7 / Nina / NAO connection

View attachment 175830


Here was the MJO in Dec 2000 - it went into Phase 7 the 2nd week of Dec

View attachment 175831

Solar and QBO this year are good comparisons to 2000-2001 as well - max phase of the solar cycle and QBO is in the negative phase

View attachment 175832

View attachment 175833

Early and late winter strat warmings are favored in -QBO (East) / Solar Max winters

(From: https://journals.ametsoc.org/view/journals/atsc/61/23/jas-3297.1.xml)
View attachment 175834

What’s interesting about the latter linked study you showed is that during solar max/east QBO years (like this winter), the polar vortex does weaken in early winter but they note that this doesn’t often carry over into subsequent months (Jan-Feb).

What’s interesting is the polar vortex in solar max/east QBO winters starts out weaker in December then actually becomes significantly strong in January (less significantly positive in Feb), then weakens again in March.

Hmm

 

[griteater]

What’s interesting about the latter linked study you showed is that during solar max/east QBO years (like this winter), the polar vortex does weaken in early winter but they note that this doesn’t often carry over into subsequent months (Jan-Feb).

What’s interesting is the polar vortex in solar max/east QBO winters starts out weaker in December then actually becomes significantly strong in January (less significantly positive in Feb), then weakens again in March.

Hmm

Yeah, I think the hopeful goal would be to get things going in Dec and have that carry over into Jan via weakened SPV and slow moving MJO.

81-82 was also solar cycle max / -QBO (E) / cool enso and had an early warming

 

[MRKEVIN7575]

Yeah, I think the hopeful goal would be to get things going in Dec and have that carry over into Jan via weakened SPV and slow moving MJO.

81-82 was also solar cycle max / -QBO (E) / cool enso and had an early warming

View attachment 175841

With climate change we really need alot more to go right than wrong for a pattern that supports cold and winter weather

 

[Rain Cold]

Heading into winter with a weaker SPV is found money. Parlay the bet and let the cards fall. We've seen a tendency for blocking already. And while we know past results don't guarantee future returns, I'm hopeful the phrase "atmospheric memory" holds water...or frozen water, as we get into and through December.

If we have a couple of events to track in December and a cold Christmas period, I won't complain all that much about a January thaw, as long as it's, how shall we say, appropriately aware of its manners, resigning to not overstay its welcome.

 

[Rain Cold]

With climate change we really need alot more to go right than wrong for a pattern that supports cold and winter weather

I think it's made it harder to snow for sure, which is hard enough to begin with. Good patterns seem to result in marginal events, with a whole lot of cold rain falling down.

It's sad when a 1040 high pressure is hard-pressed to get the job done. But c'est la vie, I guess.

 

[MRKEVIN7575]

Heading into winter with a weaker SPV is found money. Parlay the bet and let the cards fall. We've seen a tendency for blocking already. And while we know past results don't guarantee future returns, I'm hopeful the phrase "atmospheric memory" holds water...or frozen water, as we get into and through December.

If we have a couple of events to track in December and a cold Christmas period, I won't complain all that much about a January thaw, as long as it's, how shall we say, appropriately aware of its manners, resigning to not overstay its welcome.

It could be a front loaded winter, which 2010-11 was if i remember correctly. My area had 12.5 inches snow that winter. Each winter may have similarities to past winters, but every winter is different

 

[GaWx]

Today’s Euro Weeklies update:

1) 4th run in a row with a very weak SPV late Nov/early Dec with today’s having ~25% of members with a very early major SSW, the highest yet of any run!


2) After having warmed up significantly in the E US the last 3 runs for most of November/early Dec from the cold Nov 2-9 and then mainly NN Nov 10-Dec 7 of the Oct 26 run, today’s has cooled back down notably for much of Nov 10-Dec 7 and is downright cold for the new week (Dec 8-14) with a solid -AO for Nov 24-Dec 14. Keep in mind that the Euro often has trouble seeing cold too far out. So, seeing BN all the way out at weeks 5-6 in today’s run is noteworthy and will be followed closely for future trends.

 

[Rain Cold]

Today’s Euro Weeklies update:

1) 4th run in a row with a very weak SPV late Nov/early Dec with today’s having ~25% of members with a very early major SSW, the highest yet of any run!
View attachment 175847

2) After having warmed up significantly in the E US the last 3 runs for most of November/early Dec from the cold Nov 2-9 and then mainly NN Nov 10-Dec 7 of the Oct 26 run, today’s has cooled back down notably for much of Nov 10-Dec 7 and is downright cold for the new week (Dec 8-14) with a solid -AO for Nov 24-Dec 14. Keep in mind that the Euro often has trouble seeing cold too far out. So, seeing BN all the way out at weeks 5-6 in today’s run is noteworthy and will be followed closely for future trends.

What site do you go to for that?

 

[griteater]

What site do you go to for that?

Try this link It's toward the bottom of this page (and you can of course use the filtering on the left to get specific charts)

https://charts.ecmwf.int/?facets={"...:[],"Range":["Extended (42 days)"],"Type":[]}

 

[griteater]

Note the central North Pac low and NW Asia / E Europe high in the Nov image. That's a precursor to Strat PV weakening as shown here (from https://journals.ametsoc.org/view/journals/clim/23/12/2010jcli3010.1.xml)

View attachment 175827

From paper conclusions, "...The regional tropospheric anomalies that are best correlated with vortex weakening are found to be those that are in phase with (and thus amplify the magnitude of) the climatological extratropical planetary waves, strongly suggesting (though simplified modeling work is certainly necessary) that regional anomalies that amplify the climatological stationary waves will, on average, affect the vortex. The two regional anomalies that can most effectively modulate the vortex are the North Pacific low and the eastern European high. A low over the North Pacific tends to result in a dramatic increase in wave 1 leaving the troposphere and converging at the vortex, and a high over eastern Europe tends to result in a dramatic increase in wave 2 leaving the troposphere and converging at the vortex. A low over the northwestern Pacific (possibly associated with October Eurasian snow) has a similar, but weaker, effect than that of a low over the central Pacific."

The CFS for November is a banger for weakening the Strat PV

 

[SD]

Anyone know the last winter that had a weak spv? I feel like that suckers been wound up tight since 2010

 

[griteater]

Anyone know the last winter that had a weak spv? I feel like that suckers been wound up tight since 2010

Here's a link to a good list of SSWs (from Amy Butler)

https://csl.noaa.gov/groups/csl8/sswcompendium/majorevents.html

 

[griteater]

Dec 2020 also had the N Pac Low / E Euro High configuration prior to the Jan 5, 2021 SSW that crushed Brent and Texas with cold

 

[GaWx]

What site do you go to for that?

10 mb zonal winds found here:

ECMWF | Charts

charts.ecmwf.int

 

[Rain Cold]

Try this link It's toward the bottom of this page (and you can of course use the filtering on the left to get specific charts)

https://charts.ecmwf.int/?facets={"Product type":[],"Parameters":[],"Range":["Extended (42 days)"],"Type":[]}

10 mb zonal winds found here:

ECMWF | Charts

charts.ecmwf.int

Thank you both. I thought it may be from one of those pay sites. I don't spend nearly as much time as I probably should looking at strat PV data.

 

[GaWx]

Anyone know the last winter that had a weak spv? I feel like that suckers been wound up tight since 2010

Weak SPV for DJF as a whole since 2009-10:

-2023-4 (and that wasn’t a cold winter)

-2020-1:


-2018-9


-2012-3


-2011-2


-2009-10



Last weak SPV in early Dec: 2019-20 but was strong much of rest of winter:

 

[GaWx]

Weak SPV for DJF as a whole since 2009-10:

-2023-4 (and that wasn’t a cold winter)

-2020-1:
View attachment 175850

-2018-9
View attachment 175851

-2012-3
View attachment 175852

-2011-2
View attachment 175857

-2009-10
View attachment 175854


Last weak SPV in early Dec: 2019-20 but was strong much of rest of winter:
View attachment 175855

Followup on the 6 winters since 2009-10 with a weak SPV when averaged out over DJF:

What’s interesting is that only 2009-10 was a cold winter in the E US! And none of the last 5 were cold! Does anyone know why?

2023-4: NN SE, AN NE
2020-1: NN
2018-9: AN SE, NN NE
2012-3: AN
2011-2: AN

2009-10: BN
————-
Now I’ll look at weak SPV winters further back (to 1990-1) to see if the pattern differs but I’ll start with 2009-10:

2009-10: BN
2005-6: NN
2003-4: BN
2002-3: BN
2001-2: NN SE, AN NE
2000-1: BN
1998-9: AN
1997-8: NN SE, AN NE

So, unlike 2011-2+, which were all NN to AN, 1997-8 through 2009-10 averaged slightly BN in the SE and NN in the NE.

Being that 1997-8 through 2009-10 was more inline with what is intuitive regarding weak SPVs, I wonder if CC has messed up the relationship between a weak SPV and cold in the E US.

Any thoughts? Or were the 5 weak SPV winters between 2011-2 and 2023-4 not being cold somehow just flukes? That’s a lot of flukes though.

 

[GaWx]

I’ll now look at strong SPV winters since 2010-1:

-2024-5: NN SE, BN NE
-2021-2: AN
-2019-20: AN
-2015-6: AN
-2013-4: BN
-2010-1: BN

These 6 strong SPV winters averaged NN, which is colder than the 5 during that period that had a weak SPV! How can that be explained?

Now, what were the strong SPV winters between 1990-1 and 2008-9?

-2004-5: NN
-1999-0: NN
-1995-6: BN
-1992-3: NN SE, BN NE

These 4 strong SPV winters averaged NN. Compared to the weak SPV winters, they’re a little warmer in the SE (intuitive) and ~same in NE.

 

[tennessee storm]

It could be a front loaded winter, which 2010-11 was if i remember correctly. My area had 12.5 inches snow that winter. Each winter may have similarities to past winters, but every winter is different

Yeah hopefully most the coldest air stays locked up in csnada

 

[Myfrotho704_]

Latest Euro weeklies showing an absolutely loaded pattern that supports cross polar flow in early Dec with a very notable signal of a -AO, likely in part due to a weaker SPV. Also a stout +PNA/-EPO and -NAO. This pattern fits past looks of Arctic outbreaks across the U.S. and notable southern snow events. We are on track, especially with the pattern moving forward over the next couple of weeks that favors keeping that strat PV weaker (strong AK/Bering sea troughing)

 

[Myfrotho704_]

 

[Tarheel1]

Today’s Euro Weeklies update:

1) 4th run in a row with a very weak SPV late Nov/early Dec with today’s having ~25% of members with a very early major SSW, the highest yet of any run!
View attachment 175847

2) After having warmed up significantly in the E US the last 3 runs for most of November/early Dec from the cold Nov 2-9 and then mainly NN Nov 10-Dec 7 of the Oct 26 run, today’s has cooled back down notably for much of Nov 10-Dec 7 and is downright cold for the new week (Dec 8-14) with a solid -AO for Nov 24-Dec 14. Keep in mind that the Euro often has trouble seeing cold too far out. So, seeing BN all the way out at weeks 5-6 in today’s run is noteworthy and will be followed closely for future trends.

Always fun!

 

[Bigedd09]

Always fun! View attachment 175865

I believe this because everyone East of the APPS get screwed lol

 

[Mitch West]

That is a solid look through December 14th. I've seen worse looking 1104 hours out in late December.

 

[Webberweather53]

The current negative Indian Ocean Dipole (-IOD) event is approaching record territory in the modern era.

https://pulse.climate.copernicus.eu

https://www.bom.gov.au/climate/enso/?ninoIndex=nino3.4&index=iod&period=weekly#overview-section=Monitoring-graphs

 

[GaWx]

The current negative Indian Ocean Dipole (-IOD) event is approaching record territory in the modern era.

https://pulse.climate.copernicus.eu

https://www.bom.gov.au/climate/enso/?ninoIndex=nino3.4&index=iod&period=weekly#overview-section=Monitoring-graphs

View attachment 175867


View attachment 175868

Hey Eric,
Thanks. Do you know of any specific forecasting implications of this very strong Oct -IOD for the upcoming December in the E US?

Edit: I know the IOD will rise substantially by Dec and likely even by Nov from where it is now to at least a much less negative. Climo/history shows that has happened virtually 100% of the time.

 

[Webberweather53]

Hey Eric,
Thanks. Do you know of any specific forecasting implications of this very strong Oct -IOD for the upcoming December in the E US?

Edit: I know the IOD will rise substantially by Dec and likely even by Nov from where it is now to at least a much less negative. Climo/history shows that has happened virtually 100% of the time.

There's lots of co-variability between ENSO and the IOD, and there's a positive correlation between ENSO & IOD intensity. Oth, when you try to isolate the influence of the IOD alone here in the context of weak to moderate La Ninas, this is what happens:

The Nov-Dec 500mb & SLP difference composite of +IOD & -IOD years with weak to moderate La Niña captures some of the things we're currently seeing like the very extended Pacific Jet/+EPO, +PNA, and even perhaps the -SAM/-AAO. The NAO is completely different this year though.

 

[Webberweather53]

This is what happens if you take that difference composite through the winter.

The big takeaway I glean from this is the transition from an early winter +PNA type pattern to a canonical Nina look w/ a +NAM/AO is much sharper in these winters with a bigger -IOD in the preceding fall.

Also, the classic Seasonal Footprinting Mechanism (SFM) pattern is more prominent in Feb-Mar in the -IOD years, which would hasten the development of +PMM in the spring and be more favorable for El Niño development later next year.

Jan




February




March

 

[Tarheel1]

This is a good look for me and the mountains of NC! The pattern is going to flip pretty quickly, for this to be possible, as next week atleast looks toasty!

 

[Rain Cold]

There's lots of co-variability between ENSO and the IOD, and there's a positive correlation between ENSO & IOD intensity. Oth, when you try to isolate the influence of the IOD alone here in the context of weak to moderate La Ninas, this is what happens:

The Nov-Dec 500mb & SLP difference composite of +IOD & -IOD years with weak to moderate La Niña captures some of the things we're currently seeing like the very extended Pacific Jet/+EPO, +PNA, and even perhaps the -SAM/-AAO. The NAO is completely different this year though.

View attachment 175870


View attachment 175871


View attachment 175872

View attachment 175873

This sounds bad

 

[Webberweather53]

Much like last year, the very warm Tropical Indo-Pacific Warm Pool (IPWP) is going to play a major role in this coming winter.

Last 15 days (global mean removed) SST anomalies




This matches up well over the Tropical Indo-Pacific w/ the difference composite for IPWP warm pool strength for cool ENSO & east QBO winters. Here that is measured as the 40-year removed SST anomaly for Oct-Nov in the following bounding box: [20S-20N, 90E-150E]




The resulting 500mb pattern difference yields this in ERA-5 (1940-Present). A pattern we've become all too familiar with over the last decade or so.




This is almost exactly what the long-term multidecadal 500mb height trend looks like in winter. This is not surprising at all as the IPWP is warming at a faster rate than the adjacent areas of the tropics, likely because it is a fast/ocean dynamical thermostat response (Clement et al (1996)) to the warming climate during this period.

 

[Webberweather53]

Yummy

 

[MRKEVIN7575]

Yummy

View attachment 175894

Eric, i think it would be safe to say that it will probably be a front loaded winter, which typically are part of niñas. IF the spv or tpv are weaker than normal then winter may extend past December but it's only speculation since I'm not a meteorologist lol