2025-2026 ENSO

[bluewave]

3 hours ago, 40/70 Benchmark said:

I think there is some value in honing in on how much temperature maxes have warmed, since I don't think the warmer mins are as detrimental to snowfall.

The main detriment to snowfall in general for the I-95 corridor since 18-19 has been the warm storm tracks. So while this winter averaged 34.8° in NYC, the 11 days on which .25+ of precipitation fell averaged 41.0°.

For 50”+ snowfall seasons and La Niña background NYC needs to average closer to 32.0° and have cold storm tracks and storm days when the bulk of the precipitation falls.

Even during the warmer winters of 15-16, 16-17, 17-18, and 20-21,the colder storm tracks and storm days allowed NYC to finish in the respectable 30-40” range for snowfall. But the lack of cold for a DJF average near 32.0° was too warm to go 50”+.

Since 18-19 we have had both a warm background pattern and warm storm tracks. So this is why the 7 year snowfall totals have been at record low levels. I am hoping for the remainder of the 2020s we can see some bounce off these extreme low values. But expecting a repeat of 2010-2018 is probably a very low probability outcome absent some major volcanic event.

[snowman19]

This is shaping up to be the strongest -IOD event since 16-17

[mitchnick]

I noticed over in the MA Medium Range thread that the Euro weeklies have been getting progressively cooler as the forecast periods approach.

Interestingly, while searching for any tidbits for early winter thoughts on YouTube, I  found a September forecast from Bam Weather. It looks like I'm not the only one who noticed the changes on the weeklies. According to Bam, both the regular Eps products and Gefs have been too warm lately. Otoh, the EPS AI has been much better. 

I put the link to the video below and it's got some decent info in addition to the comments on the EPS AI. Take a look if you get a chance. More importantly, the performance of the EPS AI should probably be followed through the Fall to see if it holds any edge come winter.

 

[Stormchaserchuck1]

^Yeah the Great Lakes trough for around 9/4 was not even on models 7-10 days ago. Now it's expected to be -400dm and actually closes off for a little while. I've been noticing weak projections on ensemble means >11 days out. I wonder why that is. 

[Stormchaserchuck1]

14 hours ago, snowman19 said:

@Stormchaserchuck1

Actually the cold waters off of New Foundland have turned my N. Atlantic SST indicator for Winter NAO negative on the daily. Of course, it's an average of May-Sept, but Erin really did cool that -NAO area a bit.. if you want to make a correlation between ACE and following Winter NAO, like a lot of people do... 

It's been pretty rare lately to have that whole area from the Davis strait to N. Atlantic below average, but there has been persistent -H5 over the region this Summer. I've found that since 2012 it correlates with a following Winter ridge at 90N. 

[snowman19]

41 minutes ago, Stormchaserchuck1 said:

^Yeah the Great Lakes trough for around 9/4 was not even on models 7-10 days ago. Now it's expected to be -400dm and actually closes off for a little while. I've been noticing weak projections on ensemble means >11 days out. I wonder why that is. 

EURO/EPS hasn’t been what it used to be for awhile now

@Stormchaserchuck1 In regards to your last post: 

“Actually the cold waters off of New Foundland have turned my N. Atlantic SST indicator for Winter NAO negative on the daily. Of course, it's an average of May-Sept, but Erin really did cool that -NAO area a bit.. if you want to make a correlation between ACE and following Winter NAO, like a lot of people do... 

It's been pretty rare lately to have that whole area from the Davis strait to N. Atlantic below average, but there has been persistent -H5 over the region this Summer. I've found that since 2012 it correlates with a following Winter ridge at 90N.”

The last time I remember the North Atlantic being this cold was 2013-14

[Stormchaserchuck1]

^I don't think it's going to be as much of a blowout +NAO Winter as we previously thought, but there is still strong tendency for us to pattern change 10 days to a few weeks after a cold period, that has been in effect for a while now. I don't see 13-14 style cold happening this Winter. -NAO/-AO/+PNA hasn't been staying in a strong state for more than a short time. Last Feb it went from -31F in Valentine, Nebraska to 60s a few days later. Some places had a 3-day change of 100 degrees. It's not sustaining. 

[Stormchaserchuck1]

I saw bluewave posted in the climate change forum, The Arctic circle trough that I had been tracking ended up maxing out at 4980dm yesterday, which is the lowest 500mb height on record in the Northern Hemisphere for August. It's akin to the 10" of snow that fell in Florida last Winter happening again. 

[snowman19]

10 hours ago, Stormchaserchuck1 said:

^I don't think it's going to be as much of a blowout +NAO Winter as we previously thought, but there is still strong tendency for us to pattern change 10 days to a few weeks after a cold period, that has been in effect for a while now. I don't see 13-14 style cold happening this Winter. -NAO/-AO/+PNA hasn't been staying in a strong state for more than a short time. Last Feb it went from -31F in Valentine, Nebraska to 60s a few days later. Some places had a 3-day change of 100 degrees. It's not sustaining. 

13-14 was one of the strongest ++AO/++NAO winters in history, I believe it was second only to the 88-89 winter. It was 100%, all Pacific driven. We went into a Victoria mode PDO (psuedo +PDO) and had relentless strong +PNA/-EPO/-WPO all winter long. The PAC side behaved like an El Niño despite the cold-neutral ENSO that was in place

[mitchnick]

8 hours ago, Stormchaserchuck1 said:

I saw bluewave posted in the climate change forum, The Arctic circle trough that I had been tracking ended up maxing out at 4980dm yesterday, which is the lowest 500mb height on record in the Northern Hemisphere for August. It's akin to the 10" of snow that fell in Florida last Winter happening again. 

Stop reading the CC forum or you'll go blind!

Seriously, Euro weeklies have winds at 10mb dying down if that forecast can be trusted. 

[snowman19]

@GaWx

As expected, geomag is picking up again
 
 

[GaWx]

1 hour ago, snowman19 said:

@GaWx

As expected, geomag is picking up again
 
 

2025 08 22 2025.640  55   7.1  27  31
2025 08 23 2025.642  75   6.9  25  31
2025 08 24 2025.645 109   8.7  34  41
2025 08 25 2025.648 142  15.2  37  45
2025 08 26 2025.651 192  21.8  36  40
2025 08 27 2025.653 211  23.0  26  33
2025 08 28 2025.656 204  15.8  23  29
2025 08 29 2025.659 209  24.9  31  34
2025 08 30 2025.662 196  18.9  24  30
2025 08 31 2025.664 195  12.7  18  21

[GaWx]

 Per Joe Bastardi yesterday in the free video, this is and will likely end up being the quietest Labor Day weekend for the globe as a whole tropically (not Atlantic specifically as 2024, for one, was equally quiet) of most of our lifetimes. There was just an Invest in the EPAC and the remnants of a TD in SE Asia. That was it, which is fascinating!

[snowman19]

1 hour ago, GaWx said:

 Per Joe Bastardi yesterday in the free video, this is and will likely end up being the quietest Labor Day weekend for the globe as a whole tropically (not Atlantic specifically as 2024, for one, was equally quiet) of most of our lifetimes. There was just an Invest in the EPAC and the remnants of a TD in SE Asia. That was it, which is fascinating!

If I had to pick out the things in the PAC that are different from last year at this time besides the obvious (-IOD, earlier developing La Niña, -PMM, -AAM), it would be the total lack of a parade of recurving tropical cyclones and extratropical systems coming off the coast, upwelling and cooling the marine heatwave around Japan like we had last year. 
 

[snowman19]

Well defined tropical instability waves showing up in the Nino regions on the SST anomaly charts…..a sign of a rapidly developing La Niña. SSTs in region 3.4 are starting to pass the Niña threshold of -0.5C. EWBs are continuing. I think it’s all but a given that we are going to be in a La Niña this fall into at least the early part of the winter as the models have been projecting for some time now

@FPizz Weak

[FPizz]

1 hour ago, snowman19 said:

Well defined tropical instability waves showing up in the Nino regions on the SST anomaly charts…..a sign of a rapidly developing La Niña. SSTs in region 3.4 are starting to pass the Niña threshold of -0.5C. EWBs are continuing. I think it’s all but a given that we are going to be in a La Niña this fall into at least the early part of the winter as the models have been projecting for some time now

What are you thinking, weak or mod la Nina? 

[raindancewx]

The Canadian update shows a cool Fall for the East (Sept-Nov) with La Nina dead by February, likely dying mid-January. May not last long enough to be official, but will be La Nina in practice. Cold winter for the Northern US.

I suspect the cool Fall idea is right but overdone. Canadian had the right idea for August but it was a bit too cold. Wet Junes locally often precede a fluke/heavy out of winter snow events. So cold availability in the transitions to/from Winter, but not Winter itself is consistent with my expectations for seasonal behavior locally. I'm expecting a small number of very powerful lows with a lot of cold and moisture in the Fall here (likely mid-Oct to mid-Nov if I had to guess) and then again in Spring (mid-Feb to early Apr). Actual winter should be warm, although I do think the models are overdoing the dryness nationally for winter right now.

If the hurricane season remains inactive, I'd also expect a pretty major cold wave again when or just after the La Nina collapses, likely focused on the Northern and Western US. ACE is about to dip below average again and low La Nina ACE is correlated with more frequent cold days in the Southwest in Nov-Feb.

[Stormchaserchuck1]

I expect a warmer than average Oct-Nov, as the PDO has really high correlation in these months for above average CONUS. It even correlates higher than the PNA if you can believe it, and much higher than Nino 3.4 in the Fall, although both are generally above average.  

[Stormchaserchuck1]

15 hours ago, snowman19 said:

13-14 was one of the strongest ++AO/++NAO winters in history, I believe it was second only to the 88-89 winter. It was 100%, all Pacific driven. We went into a Victoria mode PDO (psuedo +PDO) and had relentless strong +PNA/-EPO/-WPO all winter long. The PAC side behaved like an El Niño despite the cold-neutral ENSO that was in place

13-14 was a really rare N. Hemisphere 500mb is very unlikely to happen again for a long time. Probably >1/100 year occurrence with such a strong +NAO and cold. For variance, we've never come close to having a strong -NAO with such above average temps, although since 2013 there has been a weaker -NAO/warm EC correlation.

[Stormchaserchuck1]

August finishes the 13th straight month with +SOI, albeit weak

[Stormchaserchuck1]

16 hours ago, mitchnick said:

Seriously, Euro weeklies have winds at 10mb dying down if that forecast can be trusted. 

When I was researching 10mb events, about Sept 25 is when bigger things start to occur. In late Sept/Oct the correlation with warm Stratosphere to -NAO is actually +60 days! So a warming event would predict a -NAO in late November or December. Cold Stratosphere/+AO is +0 days, right to the surface, as it is the whole cold season. 

[PhiEaglesfan712]

7 hours ago, FPizz said:

What are you thinking, weak or mod la Nina? 

If there is a la nina, then hope for something weak (like 17-18). A moderate la nina is not going to be favorable for the winter (like 11-12 and 22-23).