2025-2026 ENSO

[snowman19]

[donsutherland1]

The EPS and long-range ECMWF continue to suggest that an EPO-/WPO-/PNA-/AO- pattern will develop to open December. Such a pattern typically favors a trough's being anchored in the West and extending mainly across Canada. Although some cold could periodically push into the eastern U.S., the coldest anomalies would stay in the west (both in Canada and the U.S.).

December 1-10, 1980-2024:

Composite 500 mb Anomalies:

Composite Temperature Anomalies:

December 1-8, 2025 ECMWF Weekly Forecasts:

500 mb Anomalies:

Temperature anomalies:

[donsutherland1]

Below are the four major clusters for the EPO-/WPO-/PNA-/AO- (91% of all cases):

Currently, the guidance favors the most common cluster.

[snowman19]

9 minutes ago, donsutherland1 said:

Below are the four major clusters for the EPO-/WPO-/PNA-/AO- (91% of all cases):

Currently, the guidance favors the most common cluster.

Another case of the NAO/AO disconnect that we’ve been seeing more frequently the last 10 years….the NAO/AO used to almost always go positive or negative together and you rarely saw a disconnect between the two

[MJO812]

1 hour ago, snowman19 said:

 

How about the other MJO plots ? November was always supposed to be mild towards the end. Its the end of Novenber into December when the pattern flips favorable .

[snowman19]

7 minutes ago, MJO812 said:

Hopefully it goes to 8 like the majority hae been saying 

It’s certainly possible that it goes into phase 8 in December. However, the earlier idea that it would propagate into phase 8 by the end of this month appears to be dead in the water right now. The progression has slowed considerably 

[MJO812]

1 minute ago, snowman19 said:

It’s certainly possible that it goes into phase 8 in December. However, the earlier idea that it would propagate into phase 8 by the end of this month appears to be dead in the water right now. The progression has slowed considerably 

The slowdown has happened a few times in the past as it got closer. Sometimes models are too gungho in the long range just to tame it back.

[donsutherland1]

Social media version of the ECMWF weekly forecast for December 1-8:

[bncho]

27 minutes ago, donsutherland1 said:

Social media version of the ECMWF weekly forecast for December 1-8:

you forgot the "PREPARE NOW" 

[donsutherland1]

14 minutes ago, bncho said:

you forgot the "PREPARE NOW" 

True. Fixed:

[MJO812]

1 hour ago, donsutherland1 said:

Social media version of the ECMWF weekly forecast for December 1-8:

There are plenty of meteorologists who are really amazed at this upcoming pattern for next month. 

Maybe they are just trying to impress people but we are only in November.  Lets see how the models respond towards December .

[donsutherland1]

7 minutes ago, MJO812 said:

There are plenty of meteorologists who are really amazed at this upcoming pattern for next month. 

Maybe they are just trying to impress people but we are only in November.  Lets see how the models respond towards December .

I think we’ll get opportunities. I suspect winter will get off to a good start, as often happens with La Niña.

[jm1220]

20 minutes ago, donsutherland1 said:

I think we’ll get opportunities. I suspect winter will get off to a good start, as often happens with La Niña.

Fingers crossed, it does look like the pattern could be favorable to at least get us on the board. It might be an overrunning scenario with the SE ridge where NYC changes to rain, but we’d be on the board at least. 

[MJO812]

11 minutes ago, jm1220 said:

Fingers crossed, it does look like the pattern could be favorable to at least get us on the board. It might be an overrunning scenario with the SE ridge where NYC changes to rain, but we’d be on the board at least. 

I will take a few inches of snow to rain in a heartbeat. Old fashion winters.

[qg_omega]

40 minutes ago, MJO812 said:

There are plenty of meteorologists who are really amazed at this upcoming pattern for next month. 

Maybe they are just trying to impress people but we are only in November.  Lets see how the models respond towards December .

Looks very warm in the East starting Thanksgiving week

[EastonSN+]

2 hours ago, snowman19 said:

Another case of the NAO/AO disconnect that we’ve been seeing more frequently the last 10 years….the NAO/AO used to almost always go positive or negative together and you rarely saw a disconnect between the two

How much more frequently has this been happening (i.e. 20% more often than the previous 50 year average)? 

Not arguing, just want to get an idea.

[EastonSN+]

1 hour ago, donsutherland1 said:

True. Fixed:

This is a quote from USA tday online:

"La Niña vs. polar vortex? Forecast warns of 'extraordinary' winter weather.

A sudden, dramatic shift in temperatures high in the atmosphere will dance with the La Niña weather pattern. There won't be a clear winner, and forecasters are still determining how cold it could get."

 

Epic battle shaping up.

[donsutherland1]

18 minutes ago, EastonSN+ said:

How much more frequently has this been happening (i.e. 20% more often than the previous 50 year average)? 

Not arguing, just want to get an idea.

Here's some data:

[michsnowfreak]

1 hour ago, donsutherland1 said:

I think we’ll get opportunities. I suspect winter will get off to a good start, as often happens with La Niña.

Ive been suspecting that for months for here in the Great Lakes, and im getting more confident now that we have hit mid November.

[MJO812]

1 hour ago, qg_omega said:

Looks very warm in the East starting Thanksgiving week

Until the start of December 

[GaWx]

 From our member @griteaterposted elsewhere: my take on him is that he isn’t a baseless hyping forecaster. Instead, he generally uses his intelligence and immense knowledge in an objective manner and thus is well worth following. Yes, he’s an optimist in the sense that his winter posts are mainly when the prospects for E US cold are good and is usually quiet(er) when prospects aren’t good. I think of him as the opposite of @snowman19. Both smart/knowledgeable and neither are baseless hypsters as they back up their posts well. One loves to predict cold and the other mild.

Predicting the future is hard in any business or hobby, but I have higher than normal confidence that the Dec 15 to Jan 15 period is going to be active and fun in here. Get the load testing done early boys!

 My own feeling is that the combo of a weak SPV in late Nov/early Dec along with a weak to moderate MJO since that’s on average when it’s coldest (preferably slow moving <1.5 amp phase 8 followed by slow moving near or inside COD phases 1-2-3) combined with Nina climo would give a good chance at a cold dominated E US 12/15-1/15. A lot is up to the MJO, which has struggled to get into phase 8 at all in Dec since 2010.

[stadiumwave]

7 hours ago, snowman19 said:

 

 

Phase 6-8 in DEC are not bad at all. 6 turns bad in JAN/FEB. A lot of misconceptions about MJO phases. Use Roundy's RMM:

https://www.atmos.albany.edu/facstaff/roundy/waves/rmmcyc/index200reg.html

[BlizzardWx]

7 hours ago, donsutherland1 said:

The EPS and long-range ECMWF continue to suggest that an EPO-/WPO-/PNA-/AO- pattern will develop to open December. Such a pattern typically favors a trough's being anchored in the West and extending mainly across Canada. Although some cold could periodically push into the eastern U.S., the coldest anomalies would stay in the west (both in Canada and the U.S.).

December 1-10, 1980-2024:

Composite 500 mb Anomalies:

Composite Temperature Anomalies:

December 1-8, 2025 ECMWF Weekly Forecasts:

500 mb Anomalies:

Temperature anomalies:

Might be an ice storm pattern for my part of the world with cold air under cutting mild SW flow aloft 

[SnowGoose69]

6 hours ago, snowman19 said:

Another case of the NAO/AO disconnect that we’ve been seeing more frequently the last 10 years….the NAO/AO used to almost always go positive or negative together and you rarely saw a disconnect between the two

Its common in the TNH pattern...93-94, 14-15 winters saw the -AO/+NAO often.

[qg_omega]

3 hours ago, michsnowfreak said:

Ive been suspecting that for months for here in the Great Lakes, and im getting more confident now that we have hit mid November.

https://x.com/p_simmswx/status/1989685215497752663?s=46&t=m4Eqkekadb-JCXTm7k-Txg

[MJO812]

Weeklies still look good for December . We just have to be patient.

[donsutherland1]

1 hour ago, GaWx said:

 From our member @griteaterposted elsewhere: my take on him is that he isn’t a baseless hyping forecaster. Instead, he generally uses his intelligence and immense knowledge in an objective manner and thus is well worth following. Yes, he’s an optimist in the sense that his winter posts are mainly when the prospects for E US cold are good and is usually quiet(er) when prospects aren’t good. I think of him as the opposite of @snowman19. Both smart/knowledgeable and neither are baseless hypsters as they back up their posts well. One loves to predict cold and the other mild.

Predicting the future is hard in any business or hobby, but I have higher than normal confidence that the Dec 15 to Jan 15 period is going to be active and fun in here. Get the load testing done early boys!

 My own feeling is that the combo of a weak SPV in late Nov/early Dec along with a weak to moderate MJO since that’s on average when it’s coldest (preferably slow moving <1.5 amp phase 8 followed by slow moving near or inside COD phases 1-2-3) combined with Nina climo would give a good chance at a cold dominated E US 12/15-1/15. A lot is up to the MJO, which has struggled to get into phase 8 at all in Dec since 2010.

Griteater is very knowledgeable. It will be fasinating to see how things evolve.

[qg_omega]

10 hours ago, snowman19 said:

 

December is cooked