2025-2026 ENSO

[GaWx]

12Z EPS held into the cold partially because of this:

[stadiumwave]

MJO Phases 7 & 8 & both really good as you move into DEC. 

Phase 6 is good in DEC until 2nd half of DEC. 

Phase 7 & 8 gets better each week as you progress into DEC. Phase 7 starts getting worse as you get into JAN. 

 

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

 

[GaWx]

1. EW 12/15-21: large change in just 3 days: will it hold?

11/25 run:

 

11/28 run:

——————

2. EW 12/8-14: huge change in just 3 days: will it hold?

11/25 run:

 

11/28 run:

 

—————

3. EW 12/1-7: huge change in just 3 days

11/25 run:

 

11/28 run:

—————-

-NYC has cooled from +1F to -4F for the 3 week period in just 3 days.

-They now have NYC at -3F for Dec as a whole, which is ~36-37F. 
Similar cold ENSO Decs were in 1954, 1964, 1966, 1975, 1981, 1988, and 2007.

 

[EastonSN+]

59 minutes ago, GaWx said:

1. EW 12/15-21: large change in just 3 days: will it hold?

11/25 run:

 

11/28 run:

——————

2. EW 12/8-14: huge change in just 3 days: will it hold?

11/25 run:

 

11/28 run:

 

—————

3. EW 12/1-7: huge change in just 3 days

11/25 run:

 

11/28 run:

—————-

-NYC has cooled from +1F to -4F for the 3 week period in just 3 days.

-They now have NYC at -3F for Dec as a whole, which is ~36-37F. 
Similar cold ENSO Decs were in 1954, 1964, 1966, 1975, 1981, 1988, and 2007.

 

Thanks for this. The only good snowfall winter on the list for CPK is 64/65. 

[MJO812]

Looping in 8. Insane. 

[snowman19]

The EPS and and GEPS caved to the GEFS on the +EPO/Alaskan vortex by the 2nd week of December, but they go +PNA/-NAO so it keeps the east under a trough
 

GEFS:  https://www.pivotalweather.com/model.php?m=gfs&p=500h_anom&rh=2025112900&fh=288&r=na&dpdt=&mc=&pwplus=1

GEPS, EPS: 

 

[GaWx]

Back down to neutral NAO/AO week 2 similar to 2 days ago:

[snowman19]

@donsutherland1 Out of curiosity, do you have any temp/precip composites for +EPO, +PNA, -AO, -NAO Decembers?

[GaWx]

MJO from today’s 2 week runs: both now have 11+ day long phase 8s, longest since Feb 2010 and longest Dec since 1975. Lots of potential in 1st half of Dec and beyond!
 

GEFS is all in 8 12/3-13 vs yesterday’s 7 for same period:

EPS is same as yesterday:

 

[mitchnick]

Yesterday's PV forecast has it impotent thru early January again.

[MJO812]

38 minutes ago, snowman19 said:

@donsutherland1 Out of curiosity, do you have any temp/precip composites for +EPO, +PNA, -AO, -NAO Decembers?

The EPS is starting to pick up on the negative NAO.

[donsutherland1]

1 hour ago, snowman19 said:

@donsutherland1 Out of curiosity, do you have any temp/precip composites for +EPO, +PNA, -AO, -NAO Decembers?

I will check when I get home this evening.

[40/70 Benchmark]

2 hours ago, snowman19 said:

The EPS and and GEPS caved to the GEFS on the +EPO/Alaskan vortex by the 2nd week of December, but they go +PNA/-NAO so it keeps the east under a trough
 

GEFS:  https://www.pivotalweather.com/model.php?m=gfs&p=500h_anom&rh=2025112900&fh=288&r=na&dpdt=&mc=&pwplus=1

GEPS, EPS: 

 

I probably rushed the PV recovery, which I can live with...the bigger deal is getting the Pacific trough transition correct.

[Stormchaserchuck1]

13 minutes ago, 40/70 Benchmark said:

I probably rushed the PV recovery, which I can live with...the bigger deal is getting the Pacific trough transition correct.

You going to get 3"? Glad I didn't bet you. The strong -PNA/+NAO being modeled didn't really happen. 

[Stormchaserchuck1]

The +EPO and cold probably isn't going to happen like that.. it's going to be one or another. If the negative 500mb over Alaska holds in the next few days, models will probably trend warmer in the CONUS. CPC yesterday put out a cold 3-4 week forecast though, with above average precip

[40/70 Benchmark]

5 minutes ago, Stormchaserchuck1 said:

You going to get 3"? Glad I didn't bet you. The strong -PNA/+NAO being modeled didn't really happen. 

I think so...which is why I wanted you to bet. I was very confident in a fast start to the month based on my analogs.

[Stormchaserchuck1]

4 minutes ago, 40/70 Benchmark said:

I think so...which is why I wanted you to bet. I was very confident in a fast start to the month based on my analogs.

I'm liking the cold tendency (-AO tendency) this cold season. Something like 97-98 and 01-02 are the farthest thing from right now. Notice how the modeled 500mb maps have more cold than warm anomalies in the N. Hemisphere.. we haven't seen that in like 10 years. When I researched snowfall in Winter the N. Hemisphere negative 500mb (general) was the strongest thing preceding. I'm trepidacious about an above average snowfall Winter down here, but we do have a better pattern coming compared to the last 10 years imo. Anyway, good job on your analog outlook. 

[leo2000]

28 minutes ago, Stormchaserchuck1 said:

The +EPO and cold probably isn't going to happen like that.. it's going to be one or another. If the negative 500mb over Alaska holds in the next few days, models will probably trend warmer in the CONUS. CPC yesterday put out a cold 3-4 week forecast though, with above average precip

I don't buy the +EPO with MJO going in phase 8 along with the weak polar vortex. I do think a +PNA is coming. 

[brooklynwx99]

quite the trend with the AO… almost getting a -WPO/-NAO ridge bridge at this point. makes sense with the weak SPV

[snowman19]

39 minutes ago, Stormchaserchuck1 said:

The +EPO and cold probably isn't going to happen like that.. it's going to be one or another. If the negative 500mb over Alaska holds in the next few days, models will probably trend warmer in the CONUS. CPC yesterday put out a cold 3-4 week forecast though, with above average precip

If the +EPO/AK vortex happens then yea, it’s eventually going to scour out the arctic cold from Canada and the CONUS and we’re going to get Pacific origin air. The +PNA and -NAO would prevent it from getting really warm in the east, but since we are at the mercy of the PAC, the -NAO block would trap the PAC air underneath

[brooklynwx99]

1 minute ago, snowman19 said:

If the +EPO/AK vortex happens then yea, it’s eventually going to scour out the arctic cold from Canada and the CONUS and we’re going to get Pacific origin air. The +PNA and -NAO would prevent it from getting warm in the east, but since we are at the mercy of the PAC, the -NAO block would trap the PAC air underneath

if a transient AK vortex does develop, it would be due to a strongly negative WPO… you’d be getting modified Siberian air, not a true Pacific onslaught 

sure, you’d modify eventually, but it wouldn’t be all that bad

[Stormchaserchuck1]

5 minutes ago, snowman19 said:

If the +EPO/AK vortex happens then yea, it’s eventually going to scour out the arctic cold from Canada and the CONUS and we’re going to get Pacific origin air. The +PNA and -NAO would prevent it from getting warm in the east, but since we are at the mercy of the PAC, the -NAO block would trap the PAC air underneath

It may just be a brief pattern though, like a few days. I think 36 hours ago the ensemble mean had the coldest anomalies over the PNW, where it's now Alaska so it's been moving around a little bit. A +EPO can overwhelm +PNA/-NAO.. btw, NAO is SLP between ~Iceland and the Azores. That's +NAO being shown, but -AO (High pressure over the arctic circle). Not really a strong anomaly pattern coming up.. hard to make a forecast in all that neutrality. I do like the overall cold 500mb in the N. Hemisphere though. 

[40/70 Benchmark]

6 minutes ago, brooklynwx99 said:

quite the trend with the AO… almost getting a -WPO/-NAO ridge bridge at this point. makes sense with the weak SPV

I still think there will be some sort of break prior to Xmas....also not huge on mid atlantic snowfall this month...at least not in the lower terrain on the coastal plane.

[40/70 Benchmark]

2 minutes ago, Stormchaserchuck1 said:

It may just be a brief pattern though, like a few days. I think 36 hours ago the ensemble mean had the coldest anomalies over the PNW, where it's now Alaska so it's been moving around a little bit. A +EPO can overwhelm +PNA/-NAO.. btw, NAO is SLP between ~Iceland and the Azores. That's +NAO being shown, but -AO (High pressure over the arctic circle). Not really a strong anomaly pattern coming up.. hard to make a forecast in all that neutrality. I do like the overall cold 500mb in the N. Hemisphere though. 

Yea, the cold 500mb is what I was getting at by "cold in se Canda", which I was supremely confident would be in play this year, in sharp contrast to the past decade.

[40/70 Benchmark]

8 minutes ago, snowman19 said:

If the +EPO/AK vortex happens then yea, it’s eventually going to scour out the arctic cold from Canada and the CONUS and we’re going to get Pacific origin air. The +PNA and -NAO would prevent it from getting really warm in the east, but since we are at the mercy of the PAC, the -NAO block would trap the PAC air underneath

It would probably be a pattern that would still stack snow in NNE, but my area points southward would struggle on the cp.

[Terpeast]

7 minutes ago, Stormchaserchuck1 said:

It may just be a brief pattern though, like a few days. I think 36 hours ago the ensemble mean had the coldest anomalies over the PNW, where it's now Alaska so it's been moving around a little bit. A +EPO can overwhelm +PNA/-NAO.. btw, NAO is SLP between ~Iceland and the Azores. That's +NAO being shown, but -AO (High pressure over the arctic circle). Not really a strong anomaly pattern coming up.. hard to make a forecast in all that neutrality. I do like the overall cold 500mb in the N. Hemisphere though. 

The mid month warm up was to be expected. However the +epo is projected to wane at the end of the 15 day forecast period. 

[MJO812]

7 minutes ago, 40/70 Benchmark said:

It would probably be a pattern that would still stack snow in NNE, but my area points southward would struggle on the cp.

I think the coast also does well in December.  Phase 8 promotes blocking . I dont know why people are still talking about the possibility of warmth in the modeling when they have backed off of it. Embrace the pattern ahead.

Expect below normal temps in NYC for December with above normal snowfall . Same goes with other coastal cities in the Northeast. 

This is not hard forecast with the pattern coming up. We haven't seen phase 8 in years.

[40/70 Benchmark]

15 minutes ago, MJO812 said:

I think the coast also does well in December.  Phase 8 promotes blocking . I dont know why people are still talking about the possibility of warmth in the modeling when they have backed off of it. Embrace the pattern ahead.

Expect below normal temps in NYC for December with above normal snowfall . Same goes with other coastal cities in the Northeast. 

This is not hard forecast with the pattern coming up. We haven't seen phase 8 in years.

I have explained my forecast rationale in quite vivid detail, so if the logic is still lost on you, the issue is not mine. I will be sure to pay particularly close attention to how much the I 95 cities south of Boston receive in December.

Good luck-

[MJO812]

15 minutes ago, 40/70 Benchmark said:

I have explained my forecast rationale in quite vivid detail, so if the logic is still lost on you, the issue is not mine. I will be sure to pay particularly close attention to how much the I 95 cities south of Boston receive in December.

Good luck-

I read your forecast and I completely disagree .So far you missed the 10mb and 50mb warming .You incorrectly strengthened the PV too quickly. Your 500 where the mean trough sitting through Manitoba will be wrong. The polar vortex placement where you errored will be the reason we snow to the coast in phase 8 which you believe died in phase 7.

How am I lost when I have been right about the pattern while you and others were counting on the warmth ? Alot of you were too quick with the warmth. 

Good luck with your forecast.  You do w great job but in this case you will most likely be wrong for December. 

[40/70 Benchmark]

2 minutes ago, MJO812 said:

I read your forecast and I completely disagree .So far you missed the 10mb and 50mb warming .You incorrectly strengthened the PV too quickly. Your 500 where the mean trough sitting through Manitoba will be wrong. The polar vortex placement where you errored will be the reason we snow to the coast in phase 8 which you believe died in phase 7.

How am I lost when I have been right about the pattern while you and others were counting on the warmth ? Alot of you were too quick with the warmth. 

Good luck with your forecast.  You do w great job but in this case you will most likely be wrong for December. 

I stopped reading your response right there. Either you didn't actually read my outlook, or you're illiterate to some extent.