2025 ENSO/Winter Speculation

[weatherwiz]

5 minutes ago, Typhoon Tip said:

It depends what is meant by the bold ( for me - )

Snow advances ... that's just seasonally unavoidable.  But, not all years observe this normalcy the same way.  They all tend ( or used to before perhaps 25 years ago), end up around the same cryospheric state by mid Februaries ... but the autumnal d(cryo)/dt (speed of recovery) I have found is more correlated to ensuing winter temperature biases over Canada ( and by circumstance of proximity ... affecting the U.S.)

Faster tended to be colder Mt-WI-NY-NS

Slower tended to be more variable .. ( don't wanna say "warm" here because that word is very relative circa Jan 25th at Tower Minnesota)

So stating the obvious... cold is intrinsic to snow.  Gee ya think-

But what's interesting about this is that the correlation has been not as good over the last decade ... It's complex, but I suspect the warming polar summer states are setting favorable frameworks abrupt behavior in recovery times - so it's artificially ( so to speak...) lending to impressive d(cryo)/dt.  

... Like everything being effected by the CC one-eyed monster, the predictability of any domain in question tends to be the first aspects to get f'ed.

So the simplest version of all this, yes the d(cryo)/dt is impressive, this year, but - for me - it could be construed as more impressive in say, 1995 than it really is in 2025.

*But* ( ... to add even more to this "popcycle" headache - ), it's not just the land snow.  I noticed, back mid to late August that that he rate of sea-ice loss was slower than the last several years...  That was unexpected, particularly when we just came off the 2023 piss in the oceanic jacuzzi historic globally historic year so recently.  Interesting...  Anyway, the seasonal nadir appeared to also happen about 10 days to 2 weeks earlier than the last several years ( using Climate Reanalyzer), and has shown also that seasonal recovery behaves to do so more meaningfully, sooner and perhaps faster.   This below is an example of how the scalar value, still being low, belies the character/behavior of the system, which is perhaps better exposed by evaluating the deltas

What adds more interest to this IMO is it seems a lot of "correlations" we had been very familiar with have diminished over the past decade-plus as well. Now, the easy answer here is that is just a product of increasing our sample size (data set). This is likely certainly a factor, but how strong of a factor? But I suspect something else is going on too...and the way to come to that conclusion is when you break everything down into how we understand things and basic principles and you're getting results that don't make sense. 

also, if I understand correctly, the correlation is geared more towards the evolution of the AO? Lots of influences on the state and evolution of the AO, especially stratospheric processes. 

[MJO812]

https://x.com/weatherwilly/status/1978632840305631546?s=19

Winter outlook

[Snowcrazed71]

2 hours ago, MJO812 said:

https://x.com/weatherwilly/status/1978632840305631546?s=19

Winter outlook

There are so many contradicting forecasts going on this year. Of course, I would like the one that shows us getting a better winter this year, but there are some that show below average. Was very confusing. Is that these forecasts are by meteorologists and some of them are calling for dryer and less snow for the Northeast and some are calling for above normal for the Northeast. Just like every year ( in regards to the last 5 to 7 at least ), it feels like a crap shoot.

[MJO812]

58 minutes ago, Snowcrazed71 said:

There are so many contradicting forecasts going on this year. Of course, I would like the one that shows us getting a better winter this year, but there are some that show below average. Was very confusing. Is that these forecasts are by meteorologists and some of them are calling for dryer and less snow for the Northeast and some are calling for above normal for the Northeast. Just like every year ( in regards to the last 5 to 7 at least ), it feels like a crap shoot.

Winter outlooks this far out are crapshoots.

[cleetussnow]

2 hours ago, MJO812 said:

Winter outlooks this far out are crapshoots.

One of them will be right.  Google AI basically says all options are on the table.  Which is correct!  I’m going with that.

 

[mahk_webstah]

11 hours ago, CoastalWx said:

More voodoo.

I’m just focused on the development of blocking later this month

[CoastalWx]

52 minutes ago, mahk_webstah said:

I’m just focused on the development of blocking later this month

Meh. Late October blocking? Let’s get that in January.

[40/70 Benchmark]

Looks like Wxbell is beeffing up this season...soundings and faster load times, among other things.

[mahk_webstah]

11 hours ago, CoastalWx said:

Meh. Late October blocking? Let’s get that in January.

Totally but we’ve had such a warm fall that I wouldn’t mind a quick turn to winter and that pattern could probably yield some early snow

[MJO812]

2 hours ago, 40/70 Benchmark said:

Looks like Wxbell is beeffing up this season...soundings and faster load times, among other things.

I like Pivotal and Stormvista better.

[George001]

I am all in. I believe something big is going to happen this winter. 

[Snowcrazed71]

9 minutes ago, George001 said:

I am all in. I believe something big is going to happen this winter. 

Well... Statistics and time is on our side as we haven't really had anything too big region wide in quite some time. I'm excited to get the season going. Bring out the weenies... Kev? Kev? 

[MJO812]

Meteorologist Bobby Martrich from EPAWA likes a +TNH pattern with a  -EPO  for this winter.  

[cleetussnow]

5 hours ago, George001 said:

I am all in. I believe something big is going to happen this winter. 

Big heat wave starting December 24th until January 2nd. Set your watch to it.  

[sebastiaan1973]

Mysterious 'warm blob' breaks records in the North Pacific Ocean

 https://www.bbc.com/news/articles/ce3xynwwx4yo

[40/70 Benchmark]

On 10/17/2025 at 10:28 AM, MJO812 said:

I like Pivotal and Stormvista better.

I like Wxbell's graphics the best....SV has just always had the best loading time, but that gap maybe closing.

[Snowcrazed71]

https://x.com/WeatherNut27/status/1979519862406893835?t=55aZXekPcWl4KPXZd3eBZA&s=19

Is it me or does NOAA always tend to have a warm bias on their winter forecasts? 

[WxWatcher007]

2 hours ago, Snowcrazed71 said:

https://x.com/WeatherNut27/status/1979519862406893835?t=55aZXekPcWl4KPXZd3eBZA&s=19

Is it me or does NOAA always tend to have a warm bias on their winter forecasts? 

I’m not sure it’s a true warm bias as much as there have been some absolute blowtorches in parts of the CONUS the last decade or so, and those are hard to pin down when ENSO seems to have a more muted impact?

That said, the easiest call in wx seems to be winter warmth. I mean based on that graphic the last “cool” winter prior to last season was 2014-15. Ugly. 

[Typhoon Tip]

Yeeeeah, put another way even simpler… As long as the climate curve is pointed up that intrinsically favors warmer than normal at all times. And so without any contravening indicator that are sufficiently loud even reasonable… they’re probably just gonna operate on that former basis

[wokeupthisam]

1 hour ago, Typhoon Tip said:

Yeeeeah, put another way even simpler… As long as the climate curve is pointed up that intrinsically favors warmer than normal at all times. And so without any contravening indicator that are sufficiently loud even reasonable… they’re probably just gonna operate on that former basis

IOW, "persistence forecasting"?

[Met1985]

So seems like we are canceling winter before it starts? Glad I don't have to wait on heartbreak later on but can just get it out of the way.

[WxWatcher007]

56 minutes ago, Met1985 said:

So seems like we are canceling winter before it starts? Glad I don't have to wait on heartbreak later on but can just get it out of the way.

I don’t track winter particularly closely until I need to but I’m actually cautiously optimistic. Just not sure it’s another cool one—though things look pretty similar to last year at this time. 

[MJO812]

8 hours ago, Met1985 said:

So seems like we are canceling winter before it starts? Glad I don't have to wait on heartbreak later on but can just get it out of the way.

Who is ? Its only October . No one can get anything accurate this far out.

[SJonesWX]

8 hours ago, Met1985 said:

So seems like we are canceling winter before it starts? Glad I don't have to wait on heartbreak later on but can just get it out of the way.

Beer?

[Met1985]

2 hours ago, MJO812 said:

Who is ? Its only October . No one can get anything accurate this far out.

 

1 hour ago, SJonesWX said:

Beer?

No I've just seen several posters in and around the forum say that this winter is looking bleak because of the ENSO, the record water temperature of the coast of China, and global warming.  

[Baroclinic Zone]

On 10/16/2025 at 9:15 PM, CoastalWx said:

Meh. Late October blocking? Let’s get that in January.

Nah, let’s get our annual blocking period out of the way now so we can look forward to zonal PAC warmth.

[Snowcrazed71]

Interesting read

https://www.facebook.com/share/p/1Zn5LKmxi3/

[sebastiaan1973]

http://AO PV Blog

Summary

• The Arctic Oscillation (AO) is currently negative to near neutral and is predicted to oscillate around neutral and possibly go negative again the next two weeks as pressure/geopotential height anomalies across the Arctic are currently mostly mixed and are predicted to remain mostly mixed to mostly positive the next two weeks. The North Atlantic Oscillation (NAO) is currently negative as positive pressure/geopotential height anomalies dominate across Greenland, and the NAO is predicted to oscillate around neutral the next two weeks as pressure/geopotential height anomalies are predicted to mostly mixed to positive across Greenland.
• The next two weeks, weak ridging/positive geopotential height anomalies across Greenland will support transient troughing/negative geopotential height anomalies downstream across much of Europe. The progressive flow pattern will support normal to above normal temperatures across Europe including the United Kingdom (UK) with a brief flip to normal to below normal temperatures first across much of Europe including the UK next week.
• Ridging/positive geopotential height anomalies are predicted to dominate Asia with the exception of troughing/negative geopotential height anomalies across Eastern Asia the next two weeks. This pattern favors normal to above normal temperatures across most of Asia with the exception of normal to below normal temperatures regionally across Eastern Asia the next two weeks.
• The general predicted pattern across North America the next two weeks is widespread ridging/positive geopotential height anomalies centered on Eastern Canada with troughing/negative geopotential height anomalies along the west coast of North America and the Eastern United States (US). This patten will favor widespread normal to above normal temperatures across Alaska, much of Canada and the US with the exceptions of normal to below normal temperatures in the Eastern US this week and then next week normal to below normal temperatures will sweep into the West Coasts of Canada and the US and then eventually in the Eastern US.
• I continue discussing my thoughts about the upcoming pattern across the Northern Hemisphere (NH) and continue with some preliminary predictors for the upcoming winter polar vortex (PV) and weather.

Plain Language Summary

So far for October, it is a tale of two continents, extremely mild in North America and fairly widespread cold across Eurasia, especially in Southeast Asia, Siberia and focused now in Mongolia (see Figure). It has also been chilly in Central Asia and in Europe, especially in Southeast Europe (see Figure). No joke but Mongolia has the most resilient winter weather in the Northern Hemisphere. It has been a forgettable month of October for me here in Boston but at least for me the cold is where it should be in October. And the forecast can be summarized as mild weather reigns supreme (see Figures 3, 6 and 9). Longer term Greenland blocking could become established in early November that could finally bring cooler weather to North America and re-establish some colder weather across northern Eurasia. I am also closely watching the snow cover advance across Siberia this month, a rapid advance suggests a more severe winter and a slower advance a milder winter.

[MJO812]

https://x.com/bam_weather/status/1981050021589000365?s=19

[40/70 Benchmark]

Last update from me prior to go-time. Confidence is high.

 

Official La Niña Now Appears Likely for Winter '25-26'

Subsurface Yields Invaluable Clues

October IRI Update

There have been no major changes to the October suite of the International Research Institute (IRI) ENSO guidance. In fact, the consensus seems to be coming into exceptionally good agreement, as the dynamical guidance has warmed ever so slightly, and the statistical guidance cooled with both settling in around a peak of about -0.6C.

 

While intensity guidance has remained rather consistent, there have been a couple notable changes both with respect to the surface and the subsurface of the equatorial Pacific.

 

Recent ENSO Developments

During the month of September, Eastern Mass Weather anticipated that another round of trades near the close of the month and into the month of October would trigger significant cooling over the eastern half of the ENSO regions.

 

 This is indeed evident in the recent data.

                   

                           1.2        3       3.4        4

 17SEP2025     -0.0     -0.4     -0.4     -0.3

 24SEP2025     -0.1     -0.4     -0.5     -0.3

 01OCT2025    -0.1     -0.3     -0.5    -0.4

 08OCT2025    -0.1     -0.1     -0.3     -0.3

 15OCT2025    -0.4    -0.5     -0.6      -0.2

 

Note the drop from 0.0 in region 1.2 on September 17, to -0.4 as of October 15th, which has reenforced the east-based configuration. 

 

This cooling will slow or even halt over the next week, before resuming near the end of the month and culminating in a likely peak of the weeklies during the month of November.

 

 What is also evident is not only the lack of cooling in the western flank of region 4, but in fact slight warming, from -0.3 to -0.2. This is the result of the second noteworthy trend in that a considerable subsurface warm pool has been working into the western half of region 3.4 to the west of 150W.

 

The ramifications of this are twofold; firstly, it is now a virtual certainty that this event will indeed remain eastern biased, which has been the supposition all summer and into the fall. The primary El Niño Modoki analogs have and will remain 1995, 2017 and 2021.

 

In fact, the subsurface bias to the east in 2025 is even more drastic than it was in all 3 primary EMI analog years.

 

The second implication of this is that there is a limit to just how potent La Niña can grow given that the end is in sight, but perhaps not as restrictive as one may perceive.

Western Subsurface Warmth is Telling

The logical assumption is that the encroachment of the subsurface warm pool into the western flank of the developing La Niña will limit it's additional growth, thus confirming the climatology based assertion made by Eastern Mass Weather in July, that this event would not achieve official La Niña status as designated by the Climate Prediction Center (CPC). However, when considering the degree of cooling that has already occurred over region 3.4 in conjunction with two notable past instances of developing western subsurface warmth, it is now clear that this is a position worth reconsidering. There are two evident analogs when considering this development and they are the years 1967 and 2008, respectively, the latter of which also represented a very good analog for the late development of cool ENSO event that occurred last season.  The similarities in the subsurface are clear:

 

The July-August-September 90 day SOI are as follows, from most favorable to least favorable for development of La Niña:

 

2008: 23.92

2025: 8.64

1967: 5.8

 

The trade winds were as one would expect given the respective 90 day SOI values, as 2008 features the strongest trades and 1967 the weakest by far.

 

 

When considering all of the above data, 2008 was best poised for further cooling of La Nina and 1967, which failed to be officially designated, the least. Thus given that the ONI in 2008 dropped another 0.6 from the JAS value of -0.2, and 1967 another 0.5 from the JAS value of -0.2, it is prudent to anticipate a peak in 2025 in the -0.7 to -0.9 range when considering the current JAS value of -0.3, despite the considerable incursion of subsurface warmth lurking to the west. This update to the anticipated peak ONI range of -0.7 to -0.9 is crucial because since 1950, the only event to reach an ONI value of -0.7 and not go on to be officially designated a La Niña is......1967, which as previously illustrated, occurred during a season in which the hemisphere was not as conducive to it's development as it is in 2025. Applying the expected rate of growth of the current JAS RONI value of -0.63 yields a peak value in the -1 to -1.2 range, thus it appears that the recent La Niña Advisory issued by the CPC on October 9th was indeed warranted and the advancement of subsurface warmth if not necessarily prohibitive. It is also important to remain mindful that an even more pronounced expansion of subsurface warmth took place over the summer, when the vast majority of the ENSO subsurface had warmed considerably only to recover in August.

 

Furthermore, although the event is expected to evolve into an east-based fashion, the latest Jamstec guidance does imply a brief pullback into a more central-based, or basin-wide configuration given the forecast brief spike in the EMI value during the month of November. 

 

This is feasible given the anticipated lull in the cooling over the eastern region owed to the brief relaxation of the trades during the coming week, in conjunction with a potential reemergence of a cool eddy in the subsurface of region 4 amid the continued presence of ample trades.

 

 

While it is unlikely that the developing warm pool over the western half of ENSO will recede as much as did during the month of August, it does in fact serve as a reminder of the capricious nature of the subsurface.

 

Winter Outlook 2025-2026 will be the next publication during the second week of November-