2025-2026 ENSO

[mitchnick]

2 hours ago, MJO812 said:

This looks great. More members further south  this run.

Mean is livin' with the termites. I don't recall ever seeing such an extended, weak period of 10mb winds. Still decently below average into January and lower at that point than several days ago.

[snowman19]

Lowest Nino 3.4 SSTs this fall (since Sept 1st)

[michsnowfreak]

4 hours ago, MJO812 said:

That doesnt mean this winter will not be good.  Its only November 17.

Jeez people are already jumping off ledges.

In Michigan we get more winter than the east coast and we get it noticeably earlier. I would never be worried about a winter if I wasn't seeing lots of snow on models by the start of December. If anyone SERIOUSLY (and not trolling) is jumping off a ledge on the east coast in mid November...Just wow. Especially when so many have pointed out many good signs. 

[GaWx]

4 hours ago, MJO812 said:

Weeklies are awesome if you like winter weather 

Per this EW run’s weekly 2m maps directly from the source, it remains a step down process from a mild E US start:

Dec 1-7: mild

 

Dec 8-14: cools some to slightly mild to normal

 

Dec 15-21: cools to normal

 

Dec 22-28: cold comes in around Christmas!

[GaWx]

4 hours ago, MJO812 said:

This looks great. More members further south  this run.

This is by a good margin the weakest SPV on any run. If this verifies closely, this would be the weakest late Nov to early Dec SPV by a good margin since way back in 1987! We know that one month later there was a historic SE winter storm, which gave Atlanta 4” of sleet, very heavy snowfall in some other areas, and ZR down all of the way down here.

[Stormchaserchuck1]

5 minutes ago, GaWx said:

Per this EW run’s weekly 2m maps directly from the source, it remains a step down process from a mild E US start:

Dec 1-7: mild

Dec 8-14: cools some to slightly mild to normal
Dec 15-21: cools to normal

Dec 22-28: cold comes in around Christmas!

They are catching onto the time-lagged -NAO from November Stratosphere warming (late Dec -NAO). 

Still, that Dec 1-7 map is pretty significantly different from a few weeks ago.. the seasonal models don't fluctuate that much. 

[stadiumwave]

3 hours ago, snowman19 said:

Lowest Nino 3.4 SSTs this fall (since Sept 1st)

Look at Region 1 & 2

 

 

[snowman19]

4 minutes ago, stadiumwave said:

Look at Region 1 & 2

 

 

Region 4. Looks basin-wide

[GaWx]

 From JB today:

Euro MJO closest analogs 1983 and 1989

The severe cold Decembers of 1983 and 1989 

both raise the spectre of a cold shot letting loose into the Texas Citrus areas, with Fla secondary concern

 

had a major stratwarm in mid to late November, almost identical to now

—————-

 The only problem with this is that there was no major stratwarm in mid to late Nov of 1983 or 1989 or anytime during early to mid winter for both for that matter:

https://www.researchgate.net/figure/The-SSW-and-SFW-event-onset-date-year-and-type-identified-in-the-NCEP-NCAR-dataset-The_tbl1_267063738

———-
 Also, I checked to see if the 60-90N temperatures in the strat. in mid to late Nov were notably warm and they weren’t. Lastly, I checked the zonal winds at 60N in both Novs to see if they were weak despite no actual reversal. They weren’t as they were pretty close to normal. 
 

https://acd-ext.gsfc.nasa.gov/Data_services/met/ann_data.html#ncep_clim_stats_nh

[Stormchaserchuck1]

This is the pattern that a lot of us were talking about this Summer and Fall, showing itself in the first few days of December already! @40/70 Benchmark -AO/+NAO

It has still shown difficult for an Aleutian ridge to get established and hold persistent.. notice how the Pacific is +PNA there. Could be the MJO passing through 7-8, too. Kind of a "Neutral ENSO" type thing in the N. Pacific, imo. 

-AO near 90N does correlate with cold around 45N, but it doesn't actually usually go south of 40N, unless the ridge moves over the Davis Strait or northern Canada. We saw this pattern last February. We'll need that +PNA to get going, amping a ridge over the West Coast to get a far SE pushing cold shot, at least in the first part of December. 

[stadiumwave]

[BlizzardWx]

00z ECMWF at 50 hPa has a full PV split with 3 daughter vortices, one right over the US. That'll help heading into December. 

[Stormchaserchuck1]

Yeah, the 0z Euro looks really good for Stratosphere warming, coming in 3 bursts, and holding strong through December 4. Dec 4th has a +30-35 day normal lag as a secondary event to the troposphere, so we're correlating with -AO conditions to the 1st week of January. 

[BlizzardWx]

Pretty deep vertically for areas with a wind reversal too. 

[40/70 Benchmark]

5 hours ago, Stormchaserchuck1 said:

This is the pattern that a lot of us were talking about this Summer and Fall, showing itself in the first few days of December already! @40/70 Benchmark -AO/+NAO

It has still shown difficult for an Aleutian ridge to get established and hold persistent.. notice how the Pacific is +PNA there. Could be the MJO passing through 7-8, too. Kind of a "Neutral ENSO" type thing in the N. Pacific, imo. 

-AO near 90N does correlate with cold around 45N, but it doesn't actually usually go south of 40N, unless the ridge moves over the Davis Strait or northern Canada. We saw this pattern last February. We'll need that +PNA to get going, amping a ridge over the West Coast to get a far SE pushing cold shot, at least in the first part of December. 

I expect December significant snows to largely be relegated to 40N along the east coast.

[40/70 Benchmark]

10 hours ago, snowman19 said:

Region 4. Looks basin-wide

Basin-wide, but east-based, nonetheless.

[40/70 Benchmark]

My primary concern with respect to the first third of the winter season is that I rushed the recovery of the PV due to a dearth of appreciation for just how protracted the relaxation of the zonal winds would be. I went with something falling short of a full reversal, but even if we do see a reversal, I think that is largely immaterial to how the forecast will evolve. Another factor that played into my hasty recovery of the PV is that I operated on the assumption of a reflection event in mid January, which occurs during a stronger PV and entails a hasty recovery from the early season disruption. My guess is that my timing may be off, but I'll have the right idea in the seasonal mean. Reflection event may just be more towards the back end of my range, in latter January or early February. I also wish I had paid more attention to the behavior of the MJO in my primary analog of December 2000, which hit phase 8 mid month. I focused so much on using it as an analog for the disruption of the PV that I totally brain-cramped on the behavior of the MJO.

 

 

***********************************************************************

Balance of November-December 2025 Outlook

December Analogs: 2021, 2017,2008, 2007, 2000, 1981, 1970

Here is how the analog composite fared versus reality for the month of October: 

 

 

 And versus current seasonal guidance for November (CFS):

 

The MJO is currently crossing from phase 5 into phase 6, which is triggering the abrupt transition to a much blockier and colder weather pattern that is currently underway.

 

The progress of the wave is then forecast to stagnate as it approaches phase 7 and essentially decays around mid-month. 

 

While the cold will moderate for a time, however, the pattern will remain stormier than average, with the first snowfall likely across the higher terrain of northern New England next weekend.

 

High latitude blocking will be consistent as the polar vortex remains weak throughout the balance of November into early December, as the arctic high regime will be prevalent.

 

Arctic High Regime Courtesy Lee et al (2019)

 

 

Here is the December composite data versus the latest CFS temperature anomaly forecast:

 

 

 

Expect this sale style of deviation from the MC forcing during the early portion of the season.

 

December 2017-January 2018:

December 2024-January 2025:

 

 

An official SSW as defined by the reversal of the mean H85mb zonal westerly winds is unlikely, however, there is a low probability of one as suggested both by the minority of guidance, and the December 4, 1981 analog. Should there be a reversal of the H85mb zonal winds, December 4th is a good estimation of the when the PV will reach its weakest point before the split, and subsequent recovery begins.

 

As per the expectation of a significantly weakened vortex resulting from bonafide warming that will fall short of a full zonal wind reversal, the December 2000 event is the preferred analog.

This is appropriate since 2000-2001 is also the top analog from the seasonal composite.

Accordingly, the polar vortex should have consolidated back to at least something approaching climatological levels prior to Christmas (18th-24th). It will then continue to strengthen with moderating temperatures in the east, per research conducted Lee et al (2019), which indicates that the arctic high regime is favored for less than 20 days following a weak PV. This is also consistent with the onset of a reflection event on December 21,1981, just over two weeks after the December 4th SSW.  There is a slight chance of Ku event between the first and 15th of the month.  The PNA should average negative during what will be active month, with numerous SWFE and overrunning events commencing by approximately the 10th. The probability for a White Christmas is above climatological levels given the active pattern and at least seasonable cold throughout the first half of the month, but it remains dubious for the coastal plane given the milder turn prior to the holidays. In fact, the proverbial "Grinch Storm" is more likely than not. A Pacific trough should begin to evolve towards the end of the month in conjunction with a rather stout PV, as a mild pattern ensues to ring in 2026.

 

The month of December will average anywhere near normal, anywhere to -1F to +2F, except near normal to +2F across the middle Atlantic.

[anthonymm]

19 hours ago, FPizz said:

Are you like 15 years old or something and don't remember past 4 years ago?  Central park from 1970-2002 only had 4 winters above 30".  Go look up some stats.

Sorry lived in FL before 2022. Thus I have not seen first hand evidence that this place can be snowy.

[MJO812]

1 minute ago, anthonymm said:

Sorry lived in FL before 2022. Thus I have not seen first hand evidence that this place can be snowy.

Its not a snowy climate but we do get big snowstorms once in a while.

[GaWx]

28 minutes ago, MJO812 said:

It’s not a snowy climate but we do get big snowstorms once in a while.

To me, NYC has a very snowy climate. Then again, my avg annual snow is only 0.2” with most winters getting none. My area hasn’t received a foot+ of snow for an entire season since 1800. I’ve also lived in Atlanta, where their avg is still “only” 2”. So, when I see a city’s average at 20”+, ten+ times as much as ATL and 100+ times as much as SAV, that there is very snowy! Atlanta’s never even gotten close to 20” in a season!

 Aside: Cloudflare problems had been causing widespread outages this morning, including here.

[FPizz]

17 minutes ago, anthonymm said:

Sorry lived in FL before 2022. Thus I have not seen first hand evidence that this place can be snowy.

Ok that explains it.  From 2002 to now, NYC has had 12 winters above 30", but the prior 32 winters, only 4.  I think that stretch from 2002-present, but really 2002-2016, really skewed peoples expectations.  

 

17 minutes ago, MJO812 said:

Its not a snowy climate but we do get big snowstorms once in a while.

This is correct.  Often the area is between 15-25", but those bigger winters is what we crave.

[anthonymm]

22 minutes ago, FPizz said:

Ok that explains it.  From 2002 to now, NYC has had 12 winters above 30", but the prior 32 winters, only 4.  I think that stretch from 2002-present, but really 2002-2016, really skewed peoples expectations.  

 

This is correct.  Often the area is between 15-25", but those bigger winters is what we crave.

Yea my reference is the last 3 winters which were 2.5", 7"ish, and 13" ish. Naturally I'm skeptical when people say this area is gonna have 20"+. Though I've seen the numbers from the past and I realize I just got here during a profoundly unwintery stretch.

[GaWx]

MJO model progs:

-11/18 GEFS/EPS runs similar to yesterday day by day along with good progression into 7(GEFS) and well into 7 (EPS).

-11/17 extended EPS remains consistent with recent runs with it getting into 8 on 12/14. But the big news is that the extended GEFS is its most progressive yet and with it actually moving into 8 a day earlier than the EPS (12/13).

 At RDU/BWI since 1974 for the 23 three+ day long Dec phase 8 periods averaged out: lots of variation but with solid tendencies

-78%/61% of Dec phase 8 were cold

-Compare that to only 22%/13% that were mild

-Phase 8’s three+ day long periods have averaged 5 days with the longest being 13 days

-Phases 1 and 2 have also averaged cold at BWI but with again lots of variation but with solid tendencies

 Based on all of this as well as a typical couple of weeks+ lag of cold in the E US after an SSWE, I’m hoping for E US cold domination to start around Dec 15th. Until then, I expect mild to dominate much of the E US, especially mid-Atlantic south.

 

11/17 GEFS extended:

 

11/17 EPS extended:

[jm1220]

1 hour ago, FPizz said:

Ok that explains it.  From 2002 to now, NYC has had 12 winters above 30", but the prior 32 winters, only 4.  I think that stretch from 2002-present, but really 2002-2016, really skewed peoples expectations.  

 

This is correct.  Often the area is between 15-25", but those bigger winters is what we crave.

Said it many times, there’s no way in the long run NYC can get away with repeated 40” winters without reversion to the mean of mid-20s snow averages. Add CC and it gets worse.