2025-2026 ENSO

[bluewave]

This has to be the most extreme -WPO +EPO dipole that we have seen in December. Lead to the unusually strong ridge out West with the -PNA for such a strong -WPO. Record Pacific Jet and historic flooding in the Pacific Northwest. 
 

Strong December -WPO 500 mb composite more -EPO snd weaker Western U.S. ridge 

[Terpeast]

8 hours ago, 40/70 Benchmark said:

Doubt at your own peril.

Wdym?

All I was saying that I’m waiting until the weeklies are more consistent for at least a few days instead of flip flopping. Only then I’ll think there’s some credibility to their forecasts. 

[donsutherland1]

As is often the case during La Niña, winter arrived abruptly. It came on fast, cold, and at times snowy, especially across the Upper Midwest, the Great Lakes, and the Northeast.

But the PNA turned increasingly and persistently negative. As its negative state grew stronger, it began to consume winter.

Voices quickly rose to declare winter finished before it had truly begun. Some had even pronounced it stillborn from the outset. As Hanukkah arrived and Christmas drew near, fatalism spread like the unwelcome Influenza virus. The earlier December snows faded into memory. What remained were only fragments of seemed to be a winter that nearly was.

Others, however, saw something different. They treated the shift not as an ending, but as an invitation. They saw the pause as an opportunity to reflect on moments that failed to fully arrive yet still left their mark. They recognized how seasons, like ideas or paths, often shape us not through completion, but through incompleteness. They held onto their dreams of snow, their faith in winter intact even as it was tested and surrounded by a growing chorus of voices whose belief had long since shattered.

Then, on the heels of the winter solstice, the 12/21/2025 0z EPS arrived.

12/20 0z run:

12/21 0z run:

Although it was one cycle of an Ensemble at a distant timeframe, it bore a message. It did not guarantee that an epic winter period lay ahead. However, with its smaller Southeast ridge, it whispered that perhaps the worst fears expressed by some might never come to pass. 

The journey continues.

[Terpeast]

4 minutes ago, donsutherland1 said:

As is often the case during La Niña, winter arrived abruptly. It came on fast, cold, and at times snowy, especially across the Upper Midwest, the Great Lakes, and the Northeast.

But the PNA turned increasingly and persistently negative. As its negative state grew stronger, it began to consume winter.

Voices quickly rose to declare winter finished before it had truly begun. Some had even pronounced it stillborn from the outset. As Hanukkah arrived and Christmas drew near, fatalism spread like the unwelcome Influenza virus. The earlier December snows faded into memory. What remained were only fragments of seemed to be a winter that nearly was.

Others, however, saw something different. They treated the shift not as an ending, but as an invitation. They saw the pause as an opportunity to reflect on moments that failed to fully arrive yet still left their mark. They recognized how seasons, like ideas or paths, often shape us not through completion, but through incompleteness. They held onto their dreams of snow, their faith in winter intact even as it was tested and surrounded by a growing chorus of voices whose belief had long since shattered.

Then, on the heels of the winter solstice, the 12/21/2025 0z EPS arrived.

12/20 0z run:

12/21 0z run:

Although it was one cycle of an Ensemble at a distant timeframe, it bore a message. It did not guarantee that an epic winter period lay ahead. However, with its smaller Southeast ridge, it whispered that perhaps the worst fears expressed by some might never come to pass. 

The journey continues.

You’re quite the story teller! No cap. 

I noticed the EPS fading the SE ridge this morning as well. GEFS did the same thing.

[yoda]

Webb says we're screwed

https://x.com/webberweather/status/2002755646454993016

https://x.com/webberweather/status/2002759593269792869

 

[donsutherland1]

21 minutes ago, yoda said:

Webb says we're screwed

https://x.com/webberweather/status/2002755646454993016

https://x.com/webberweather/status/2002759593269792869

 

Webb describes a plausible scenario. It's not the only possibility, despite his skill and expertise.

Prior to about 1980, December PNA- cases (-0.500 or below average) were typically followed by January PNA- cases. Since 1980, most cases have seen the PNA flip in January. The difference in PNA persistence could reflect the changes that have taken place due to Arctic amplification rather than statistical factors e.g., sample size. With Arctic sea ice extent continuing to set new daily record lows, the risk of a fairly abrupt change can't be ruled out.

That there has been a strong clustering of December-January cases prior to and after 1980 (Dec PNA-/Jan PNA- prior to 1980 and Dec PNA-/Jan PNA+ since 1980) suggests that more than random variability is involved. That does not guarantee a flip to positive for January, but model skill at such a timeframe is essentially non-existent. 

Yes, both the EPS and GEFS paint a picture of a perpetual PNA-. But that's current modeling. The long-range isn't cast in stone, at least as far as January is concerned. Assuming a canonical La Niña winter, I think things are tilted toward a warm February, especially in the East.

 

[GaWx]

4 hours ago, bluewave said:

This has to be the most extreme -WPO +EPO dipole that we have seen in December. Lead to the unusually strong ridge out West with the -PNA for such a strong -WPO. Record Pacific Jet and historic flooding in the Pacific Northwest. 
 

Strong December -WPO 500 mb composite more -EPO snd weaker Western U.S. ridge 

 Indeed, this combo has been a rarity in at least Dec. Looking at history for Dec, I looked to see the last time there was a strong -WPO dominating with a neutral or +EPO. It looks per the current December’s numbers that there will end up a strong -WPO while there will probably be a weak +EPO average (with the 3 +EPO periods averaging longer than the 3 -EPO periods).

 The last half month+ long period within Decs when there was anything similar was the first half of 1995 (extreme -WPO and weak +EPO), the first half of 1966 (very strong -EPO and neutral EPO), and Dec 7-23, 1956 (extreme -WPO and moderate +EPO).

 Over a shorter timeframe, Dec 1-10 of 2012 had a very strong -WPO while there was a moderate +EPO.

[snowman19]

1 hour ago, yoda said:

Webb says we're screwed
https://x.com/webberweather/status/2002755646454993016
https://x.com/webberweather/status/2002759593269792869
 

His earlier forecast was predicted on the warm pool being moved east, which he says is starting to look unlikely. He says a weak SPV is actually a detriment 

 

 

 

 

 

 

 

 

[snowman19]

His earlier forecast was predicted on the warm pool being moved east, which he says is starting to look unlikely

[/url]

[bncho]

3 hours ago, donsutherland1 said:

As is often the case during La Niña, winter arrived abruptly. It came on fast, cold, and at times snowy, especially across the Upper Midwest, the Great Lakes, and the Northeast.

But the PNA turned increasingly and persistently negative. As its negative state grew stronger, it began to consume winter.

Voices quickly rose to declare winter finished before it had truly begun. Some had even pronounced it stillborn from the outset. As Hanukkah arrived and Christmas drew near, fatalism spread like the unwelcome Influenza virus. The earlier December snows faded into memory. What remained were only fragments of seemed to be a winter that nearly was.

Others, however, saw something different. They treated the shift not as an ending, but as an invitation. They saw the pause as an opportunity to reflect on moments that failed to fully arrive yet still left their mark. They recognized how seasons, like ideas or paths, often shape us not through completion, but through incompleteness. They held onto their dreams of snow, their faith in winter intact even as it was tested and surrounded by a growing chorus of voices whose belief had long since shattered.

Then, on the heels of the winter solstice, the 12/21/2025 0z EPS arrived.

12/20 0z run:

12/21 0z run:

Although it was one cycle of an Ensemble at a distant timeframe, it bore a message. It did not guarantee that an epic winter period lay ahead. However, with its smaller Southeast ridge, it whispered that perhaps the worst fears expressed by some might never come to pass. 

The journey continues.

One of the best posts I've ever seen on the entire forum from one of the best posters on this entire forum.

Kudos to you. Winter still has a chance.

[donsutherland1]

1 minute ago, bncho said:

One of the best posts I've ever seen on the entire forum from one of the best posters on this entire forum.

Kudos to you. Winter still has a chance.

Thank you for the kind words, Bncho.

[michsnowfreak]

4 hours ago, Terpeast said:

Wdym?

All I was saying that I’m waiting until the weeklies are more consistent for at least a few days instead of flip flopping. Only then I’ll think there’s some credibility to their forecasts. 

I agree. They change daily. When they stop flip flopping is when you can be more confident in a scenario. 

[michsnowfreak]

Also....a canonical la nina is a VERY roller coaster ride- more roller coaster than typical climo. So expect tons of model chaos the rest of the winter.

[40/70 Benchmark]

5 hours ago, Terpeast said:

Wdym?

All I was saying that I’m waiting until the weeklies are more consistent for at least a few days instead of flip flopping. Only then I’ll think there’s some credibility to their forecasts. 

If you are basing analysis off of the weekly output, I get it...all I'm saying is they are probably right given the Pacific trough regime that has become established and a probable reflection event looming later in January.

I like to use those as probabilistic tools, rather than deterministic.

[40/70 Benchmark]

1 hour ago, snowman19 said:

 

 

 

 

 

 

I don't understand why he feels as though the warm pool needs to shift to allow for +TNH??? We have had intervals of it in this regime previously both last year and in 2022 ...

The data indicates that -WPO this severe in December is very likely to yield a -WPO in the seasonal mean moving forward, furthermore, we haven't had sn issue establishing -EPO ridges in this west warm pool regime.

[bluewave]

2 hours ago, GaWx said:

 Indeed, this combo has been a rarity in at least Dec. Looking at history for Dec, I looked to see the last time there was a strong -WPO dominating with a neutral or +EPO. It looks per the current December’s numbers that there will end up a strong -WPO while there will probably be a weak +EPO average (with the 3 +EPO periods averaging longer than the 3 -EPO periods).

 The last half month+ long period within Decs when there was anything similar was the first half of 1995 (extreme -WPO and weak +EPO), the first half of 1966 (very strong -EPO and neutral EPO), and Dec 7-23, 1956 (extreme -WPO and moderate +EPO).

 Over a shorter timeframe, Dec 1-10 of 2012 had a very strong -WPO while there was a moderate +EPO.

This is one of the most extreme December patterns that we have experienced in terms of temperature and precipitation volatility across the CONUS.

 

[MJO812]

Eps again was too torchy in the long range.  Take the long range with a grain of salt. 

 

New run is colder