2025-2026 ENSO

[EastonSN+]

Seems the difference between the GEFS dumping the trough out west as opposed to the EPS is the handling of the MJO. While the EPS is essentially in the COD, GEFS is moving to phase 6.

[GaWx]

3 hours ago, EastonSN+ said:

Seems the difference between the GEFS dumping the trough out west as opposed to the EPS is the handling of the MJO. While the EPS is essentially in the COD, GEFS is moving to phase 6.

 
 Today’s EPS and CFS are also going to ph 6 mid Jan. BAMwx posted that phase 6 in -AAM during Jan has been very cold in the E US, with the most intense cold in the interior SE (see lower right in image just below), which to me was very counterintuitive. So, I needed to know the answer.

 

  Now it’s even more important to know as the move to ph 6 midmonth now has increasing model support. The following are results of my research done on Tue, which looked at GSP, a station in that coldest (pink) area, during La Niña:

 

Niña Year….# phase 6 days…avg anomaly

1975…3…-8 M

1976…13…-9 W-S

1989…3…+8 M

1999…3…+2 M

2000…3…-4 W

2006…6…+3 S

2008…3…+8 S

2009…6…+1 W-M

2011…12…-7 W-S

2012…19…+1 W-S

2017…2…0 W

2018…3…-2 S

2021…8…-1 M-S

2022…4…-9 W

2025…2…-5 W

W weak (mainly in or near circle), M mod., S strong

91 total days (big sample)

—————

So, 15 cases of ph 6 during Nina Jans:

3 MBN

3 BN

6 NN

1 AN

2 MAN

——————— 

- These La Nina Jan results weren’t at all what I would have expected for phase 6, one of the 3 mild Jan phases in the SE averaged out over all years:

 

- Though there’s not surprisingly lots of variability, GSP did average 2 BN. Before seeing BAMwx’s post I never would have expected this. However, it should also be noted that BAM’s -6 to -7 for GSP is at the same time significantly too cold. 

- Only 3 of the 15 Jan cases were AN to MAN: 1989, 2006, and 2008. These were all M to S intensity (intuitive).

- So, none of the last 8 were mild as there were 5 NN and 3 BN (2011, 2022, and 2025). These also averaged 2 BN. The weakest 3 averaged a solid cold 6 BN.

- Thus if phase 6 continues to look more likely for midmonth, it will be interesting to see whether or not the NN to cold dominance works out in the SE (and E overall by association), especially if the bulk of ph 6 turns out to be anywhere from inside the circle to near/just outside the circle.

@donsutherland1

[PhiEaglesfan712]

3 hours ago, bluewave said:

A large portion of the West had their warmest December on record. But none of the areas in the East that were cold approached their coldest December on record. This has been a common theme in recent years with the warm departures being more impressive than the cold departures on a month to month basis. 
 

 

 

Climatologist49

 

‪@climatologist49.bsky.social‬

 

Follow

December 2025 temperature ranking (since 1895). A lot of the West had their warmest December on record and nearly everywhere out west had a top 5 warmest December. 

 

10:26 PM · Jan 1, 2026

Everybody can

 

Climatologist49

 

‪@climatologist49.bsky.social‬

 

Follow

The month-to-date temperature departure from normal for the Contiguous U.S. is +3.9F. If this is how the month ends, December 2025 would finish as the 4th warmest December on record (1895-present). 4 of the top 5 would include 2021, 2023, 2024, and 2025. It's as if something has changed.

11:47 AM · Dec 29, 2025

Everybody can

lol, this looks more like an el nino or a +PDO than a typical -ENSO/-PDO.

[GaWx]

4 hours ago, bluewave said:

A large portion of the West had their warmest December on record. But none of the areas in the East that were cold approached their coldest December on record. This has been a common theme in recent years with the warm departures being more impressive than the cold departures on a month to month basis. 
 

 

 

Climatologist49

 

‪@climatologist49.bsky.social‬

 

Follow

December 2025 temperature ranking (since 1895). A lot of the West had their warmest December on record and nearly everywhere out west had a top 5 warmest December. 

 

10:26 PM · Jan 1, 2026

Everybody can

 

Climatologist49

 

‪@climatologist49.bsky.social‬

 

Follow

The month-to-date temperature departure from normal for the Contiguous U.S. is +3.9F. If this is how the month ends, December 2025 would finish as the 4th warmest December on record (1895-present). 4 of the top 5 would include 2021, 2023, 2024, and 2025. It's as if something has changed.

11:47 AM · Dec 29, 2025

Everybody can

Dec ‘25 will end up cooler than +3.9F once Dec 29-31 are added. Why? Because Dec 29-31 averaged NN to slightly BN vs 1991-2020 climo overall based on my rough est. That could be as cold as ~30 for those 3 days.

 So, the question isn’t if it will end up cooler because it has to based on the above. The question is how much will it bring down the +3.9. Roughly, you’d be adding a 10% weighting with as cold as ~-1 (based on 1991-2020 anomaly) to a 28 day of +3.9. That would come out to ~+3.4 IF the last 3 days were really -1. If it goes back down to ~+3.4, then it could also end up cooler than 1939, something @TheClimateChangerand I have been discussing. Even if Dec 29-31 averaged near 0 anomaly, that would still bring Dec as a whole down to +3.5, still quite possibly cooler than 1939 in the absolute and definitely much cooler for the anomaly vs appropriate climo for each period as 1939 was >+5.5.

 Also, 2015 may turn out warmer. So, 2025 could come in 6th or so.

 This chart only goes through 2021:

Edit: note that per this chart that 1939 was >+5.5 F vs its climo and 1957 was ~+3.9. So, 2025 anomaly also could come in cooler than 1957’s anomaly.

 So, 2025’s anomaly vs its climo could come in 7th.

[SnowGoose69]

28 minutes ago, PhiEaglesfan712 said:

lol, this looks more like an el nino or a +PDO than a typical -ENSO/-PDO.

A strong El Nino December would rarely have those anomalies from ND into the Lakes, they'd normally  be above normal.  Sometimes the immediate EC can be below but El Nino Decembers, even weak to moderate ones often are not cold anywhere except the Deep South and SE and that is often just a relativity thing where a place like ATL/BNA might average -1 largely due to lots of overcast and rainy days but not exactly have a ton of days in the 40s or below or nights below 32.  An El Nino January or February can have that type of departure map though

[donsutherland1]

Today is the 32nd consecutive day on which the PNA is < 0. Despite the EPS and GEFS currently showing only a brief turn to positive, the historic evidence since 1980 suggests that a regime change to an extended period of a predominantly positive PNA is likely once the current stretch of PNA- concludes. Until one is in the short-range of the teleconnection forecasts, the base case remains a regime shift in the PNA, not a temporary fluctuation to positive values. 

All 10 prior streaks of 30 or more consecutive days since 1980 ended with a regime change in the PNA.

[jaxjagman]

5 hours ago, SnowGoose69 said:

A strong El Nino December would rarely have those anomalies from ND into the Lakes, they'd normally  be above normal.  Sometimes the immediate EC can be below but El Nino Decembers, even weak to moderate ones often are not cold anywhere except the Deep South and SE and that is often just a relativity thing where a place like ATL/BNA might average -1 largely due to lots of overcast and rainy days but not exactly have a ton of days in the 40s or below or nights below 32.  An El Nino January or February can have that type of departure map though

In Mid Tn some of most catastrophic ice storms happen during a  more or less in a moderate NINO.I.E 1951 and 1994,we in general in Tn have have two distinct weather patterns east and west of the Cumberland Plateau.In a NINA a ice storm is more common east of the Cumberland,during a NINO its west.

We get some of our best winter storms in a NINO than compared to a NINA around Nashville.Though in general it starts out with ZR and/or IP before the columns cool to become all SN

Edit:I'm not trying to dispute you if what i said,just adding to climo here,what you said is in general is right around BNA,cold surface temps and WAA is a recipe for ice