2025-2026 ENSO

[Spartman]

6 hours ago, snowman19 said:

I’m starting to wonder if we see a weak La Niña develop. I’ve been saying cold-neutral and I still think that’s the favored outcome but the door seems to be opening for a possible weak Nina to develop this summer/fall. It appears a strong -IOD is taking shape, that, along with a continued -PDO, -PMM and the surface/subsurface/trade wind/SOI trends are seemingly opening the door for a possible weak Niña
 

 

 

 

 

Might as well

[Stormchaserchuck1]

Really nice cold 500mb +NAO for the next 7 days. That's what I want to see more of through the late Spring/Summer to have more -EPO next Winter. 

[Stormchaserchuck1]

19 hours ago, 40/70 Benchmark said:

-PDO has been steadily weakning...not saying that will defiinitely continue, but I feel like the trend of the PDO is more highly correlated to the weather pattern than the index itself. Maybe someone like @Stormchaserchuck1 can chime in on that, but I feel like the PDO is a bit lagged from the atmosphere.

I think it's more after the fact. Now, I think in a long term PDO phase, the subsurface moves to the state, and the thermocline does have impact on the H5 pattern (subsurface takes longer to change, longer to move back). However, that didn't work out so good last Winter, when we were coming off of a record 4-year -PDO period and the +PNA was mostly present. Since November, the only strong Aleutian High pattern that we have seen was Jan 15 - Feb 10. Just 1 example. A shift has generally occurred. It will be interesting to see how that progresses in the Summer. The PDO doesn't have real high year-to-year correlations believe it or not, and even +several months its correlation wanes. A lot of the high-correlation-PDO composites that you see are because the PNA impacts it in now-time. 

[40/70 Benchmark]

11 hours ago, Stormchaserchuck1 said:

Really nice cold 500mb +NAO for the next 7 days. That's what I want to see more of through the late Spring/Summer to have more -EPO next Winter. 

The WPO and the NAO were the main issue last season....EPO/PNA supplied seasonal cold, but major storms still either tracked inland, or failed to phase because the PNA ridge would get throttled. Only time the NAO played ball in January it ended up a suppressive detriment.

[Typhoon Tip]

2 hours ago, 40/70 Benchmark said:

The WPO and the NAO were the main issue last season....EPO/PNA supplied seasonal cold, but major storms still either tracked inland, or failed to phase because the PNA ridge would get throttled. Only time the NAO played ball in January it ended up a suppressive detriment.

pretty good assessment here overall, yup.

I mean I like to deeper dive into why these larger identified resonances behaved the way they did, but just as a step back recognition, agreed.

[40/70 Benchmark]

19 hours ago, Typhoon Tip said:

pretty good assessment here overall, yup.

I mean I like to deeper dive into why these larger identified resonances behaved the way they did, but just as a step back recognition, agreed.

I definitely dive pretty deeply into it in the blog...but I think the predominant +WPO is tied into the west PAC warm pool. I think the NAO is being impacted by CC because we hardly ever have DM seasons that average -NAO anymore. Last season was predicatable due to solar max, but even beyond that...the ceiling is like one month averaging neg NAO lol. This century, only 2000-2001, 2010-2011 and 2020-2021 have pulled it off.

[GaWx]

3 hours ago, 40/70 Benchmark said:

I definitely dive pretty deeply into it in the blog...but I think the predomianat +WPO is tied into the west PAC warm pool. I think the NAO is being impacted by CC because we hardly ever have DM seasons that average -NAO anymore. Last season was predicatable due to solar max, but even beyond that...the ceiling is like one month averaging neg NAO lol. This century, only 2000-2001, 2010-2011 and 2020-2021 have pulled it off.

Thanks, Ray. I also wonder about CC’s effect.
-Don’t forget 2009-10

-Including March actually brings 2012-13 into the list due to the -1.61 in March making DM average -0.39

-Including March would take 2020-1 out for me because DM averaged only -0.14, which I call neutral

-Based on DJF, I have 2009-10, 2010-11, and 2020-21. Based on DJFM, I have 2000-01, 2009-10, 2010-11, and 2012-13.

[40/70 Benchmark]

15 hours ago, GaWx said:

Thanks, Ray. I also wonder about CC’s effect.
-Don’t forget 2009-10

-Including March actually brings 2012-13 into the list due to the -1.61 in March making DM average -0.39

-Including March would take 2020-1 out for me because DM averaged only -0.14, which I call neutral

-Based on DJF, I have 2009-10, 2010-11, and 2020-21. Based on DJFM, I have 2000-01, 2009-10, 2010-11, and 2012-13.

Oh yes...I was focused on cool ENSO.

Yea, I was being generous, so I included anything with a mean negative value. Yes, missed 2012-2013, as well....I listed those seasons based on a very cursory glance, so thanks for the corrections

[40/70 Benchmark]

That is quite a run there early last decade considering the strong modern predisposition towards +NAO....3/4 years with a mean DM -NAO. Hopefully due for another stretch like that soon. Approaching solar min near the turn of the decade should help.

[bluewave]

On 5/6/2025 at 6:16 AM, snowman19 said:

I’m starting to wonder if we see a weak La Niña develop. I’ve been saying cold-neutral and I still think that’s the favored outcome but the door seems to be opening for a possible weak Nina to develop this summer/fall. It appears a strong -IOD is taking shape, that, along with a continued -PDO, -PMM and the surface/subsurface/trade wind/SOI trends are seemingly opening the door for a possible weak Niña

It may turn out to be another case of the record WPAC warm pool driving the La Niña background more than what is occurring in the traditional ENSO regions east of the Dateline. 
 

 

[40/70 Benchmark]

1 hour ago, bluewave said:

It may turn out to be another case of the record WPAC warm pool driving the La Niña background more than what is occurring in the traditional ENSO regions east of the Dateline. 
 

 

Yea, need to weight the RONI heavily.

[mitchnick]

4 hours ago, bluewave said:

It may turn out to be another case of the record WPAC warm pool driving the La Niña background more than what is occurring in the traditional ENSO regions east of the Dateline. 
 

 

And it may not.

[bluewave]

2 hours ago, mitchnick said:

And it may not.

It already has. The very strong 500mb ridge has returned to the east of Japan and south of the Aleutians this spring. Also notice the Southeast Ridge or Western Atlantic Ridge linking up again with the Greenland to Iceland blocking. 
 

 

[mitchnick]

2 hours ago, bluewave said:

It already has. The very strong 500mb ridge has returned to the east of Japan and south of the Aleutians this spring. Also notice the Southeast Ridge or Western Atlantic Ridge linking up again with the Greenland to Iceland blocking. 
 

 

Well if it is, why didn't say it was presently ongoing instead of saying it "may" occur, or were you just setting yourself up for a future "I told you so?" What else could be the reason? Honestly, I  don't get it.

[Stormchaserchuck1]

Pretty nice Aleutian High pattern getting going at Day 13+ on the GEFS. Let's see what happens, that is associated with possibly some cooling in the ENSO subsurface, and a short term trend to more -PDO.  Could pop a nice ridge in the Midwest, too. 

[LibertyBell]

On 5/7/2025 at 3:29 PM, GaWx said:

Thanks, Ray. I also wonder about CC’s effect.
-Don’t forget 2009-10

-Including March actually brings 2012-13 into the list due to the -1.61 in March making DM average -0.39

-Including March would take 2020-1 out for me because DM averaged only -0.14, which I call neutral

-Based on DJF, I have 2009-10, 2010-11, and 2020-21. Based on DJFM, I have 2000-01, 2009-10, 2010-11, and 2012-13.

remember we don't really need a -NAO, 2002-03 was better than any of those winters and had a near neutral NAO.

[LibertyBell]

14 hours ago, bluewave said:

It may turn out to be another case of the record WPAC warm pool driving the La Niña background more than what is occurring in the traditional ENSO regions east of the Dateline. 
 

 

isn't this why we've been having so many multiyear la ninas?

[Stormchaserchuck1]

1 hour ago, LibertyBell said:

remember we don't really need a -NAO, 2002-03 was better than any of those winters and had a near neutral NAO.

I would take -NAO though. It's about a 0.5 or 75% correlation. Since 11-12, the lowest Winter NAO (DJFM) we have had is -0.14! And in that time there have been 18 Winter months >+1.12 NAO and 0 Winter months <-1.12 NAO. Remember, the NAO is a SLP measurement, so it's not always aligned with 500mb.  We know about the record snow drought for PHL-NYC the last 7-8 years.. and every one of them has been +NAO. Not a perfect correlation, but a good one.. 

[Stormchaserchuck1]

On 5/7/2025 at 11:51 AM, 40/70 Benchmark said:

I definitely dive pretty deeply into it in the blog...but I think the predominant +WPO is tied into the west PAC warm pool. I think the NAO is being impacted by CC because we hardly ever have DM seasons that average -NAO anymore. Last season was predicatable due to solar max, but even beyond that...the ceiling is like one month averaging neg NAO lol. This century, only 2000-2001, 2010-2011 and 2020-2021 have pulled it off.

I'm not so sure the NAO is tied to CC. Why have other seasons had -NAO's, some strong -NAO? The Winter NAO state for the last 14 years is a bit of an anomaly, because it hasn't happened that way in other seasons. 

Don't get me wrong, I would say the trend is warmer and less snowy, but that N. Atlantic pressure index has not been favorable. 

With more global precipitable water now though, I think a -NAO these days would be less dry than several decades ago. 

[GaWx]

17 minutes ago, Stormchaserchuck1 said:

I'm not so sure the NAO is tied to CC. Why have other seasons had -NAO's, some strong -NAO? The Winter NAO state for the last 14 years is a bit of an anomaly, because it hasn't happened that way in other seasons. 

Don't get me wrong, I would say the trend is warmer and less snowy, but that N. Atlantic pressure index has not been favorable. 

With more global precipitable water now though, I think a -NAO these days would be less dry than several decades ago. 

Thanks, Chuck.
 

Winters (DJF) with avg of sub -0.25 NAO:

-16 of 25 (64%) of 1954-5 through 1978-9 

-6 of 45 (13%) of 1979-80 through 2024-5 (1984-5, 1986-7, 1995-6, 2009-10, 2010-11, 2020-1)

[Stormchaserchuck1]

11 minutes ago, GaWx said:

Thanks, Chuck.
 

Winters (DJF) with avg of sub -0.25 NAO:

-16 of 25 (64%) of 1954-5 through 1978-9 

-6 of 45 (13%) of 1979-80 through 2024-5 (1984-5, 1986-7, 1995-6, 2009-10, 2010-11, 2020-1)

I was using DJFM, but it's interesting to see that there's still only 1 example in 14 years, using DJF. +0.25 is not that much. 

There isn't NAO data from the 1930s, but imo the 1930s through early 1950s were probably more +NAO. 

[Stormchaserchuck1]

After a quick review, it looks like the early-1900s were more +NAO. This looks more cyclical since the 1890s, and although 3 swings is not much, it may even run in 50-year cycles, which we could actually be in the middle of. 

[snowman19]

It may turn out to be another case of the record WPAC warm pool driving the La Niña background more than what is occurring in the traditional ENSO regions east of the Dateline. 
 
 

It’s starting to look like we see, at minimum, a cold-neutral ENSO, with a weak La Niña becoming a distinct possibility

[bluewave]

22 minutes ago, snowman19 said:

It’s starting to look like we see, at minimum, a cold-neutral ENSO, with a weak La Niña becoming a distinct possibility

My guess is that next winter will be warmer than this last one was from Philly to Boston. Every La Nina with such a strong +PNA in December had winters around it which were warmer. But since the snowfall was so low anyway, there is a chance that one larger snowstorm if it should occur could rival or exceed last winter from Philly to Boston. I will update again after we see what clues we get in October. 

[mitchnick]

Euro's May Enso update taking the shotgun approach.

[LibertyBell]

9 hours ago, Stormchaserchuck1 said:

I'm not so sure the NAO is tied to CC. Why have other seasons had -NAO's, some strong -NAO? The Winter NAO state for the last 14 years is a bit of an anomaly, because it hasn't happened that way in other seasons. 

Don't get me wrong, I would say the trend is warmer and less snowy, but that N. Atlantic pressure index has not been favorable. 

With more global precipitable water now though, I think a -NAO these days would be less dry than several decades ago. 

-NAO is now shifting to MAM while +NAO predominates in DJF.

Actually scratch March, now DJFM are all +NAO while -NAO is now AM

[mitchnick]

May's Euro does favor a Niño for 26/27. But that's got to be low skill.

[LibertyBell]

9 hours ago, Stormchaserchuck1 said:

I was using DJFM, but it's interesting to see that there's still only 1 example in 14 years, using DJF. +0.25 is not that much. 

There isn't NAO data from the 1930s, but imo the 1930s through early 1950s were probably more +NAO. 

with some small exceptions like 1933-34, 1942-43, 1947-48.  Those were some very cold/snowy winters!!