Stormchaserchuck1

It's been pretty constant central-subsurface cold since the 23-24 El Nino. You can see how the surface has been running much warmer than the subsurface (more credence to RONI), which makes me think that when we finally do shift to El Nino, it will be warmer than the subsurface Kelvin Waves would indicate. Pretty good chance we go to El Nino in 2026 or 2027.

Which ones? I have been below average every Winter since 15-16, and there have been 6 La Nina's in that time (RONI).

+NAO's run wetter, so when that phases with the northern stream, as rare as it is, it produces a lot of good snowfall.

A lot of disparity in the forecasts this month. Even the CPC's outlook released today looks crazy based on how the 1st half of the month will likely turn out (especially in the NW).

DCA: -2.6 NYC: -2.0 BOS: -1.6 ORD: -3.5 ATL: -0.8 IAH: -0.1 DEN: +0.5 PHX: +0.4 SEA: +3.0

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.

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

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.

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.

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.

^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.

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.

^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.

Interesting that the pattern usually flips one year after a 2nd year La Nina minus 2nd year El Nino (Winter 26-27)

Another trough hitting the Great Lakes around 9/4.. it will be interesting to see where we go after that, it might start warming.. October is the month of the year where the PDO correlation really picks up, and is the highest correlated PDO month of the year, in terms of non-0-time based happening: But in September the PDO correlation is still weak

Nice post. I love subsurface data, as the thermocline probably has a better correlation to our pattern than surface SSTs, which are variable from the pattern (look at how much Erin cooled SSTs). Subsurface data is spotty, so any info on that is great info. That updated image to July 2025 is cool. I would think in a more classic -PDO it wouldn't be as warm from the top down, and you would have more consistency about 200m deep. I've always said I think it's more of a decadal La Nina state in effect.

Highest daily SOI today since May.. +24. I think a Weaker La Nina state is more likely for the Winter. 2nd year La Nina's and -PDO's tend to have a more classic cold season -PNA pattern, but we haven't had as strong of a -PNA generally since the 23-24 Strong El Nino. It's very likely that August 2025 will be the 11th consecutive month with +SOI Top 20 best matches since 1948 to 2nd year La Nina vs 2nd year El Nino for the cold season (Nov-March) Dec-Feb

505dm over the Arctic circle today! It phases into a +NAO/+AO in the next few days, which is usual for the pattern this year since May. Cold +AO/+NAO H5 continues..

I'm so interested to see if we get a cold December this year, because strong -QBO/weak -ENSO analogs strongly support it. I remember those similar 2 conditions in the Fall of 2005, we used the 1989 analog, and it worked out great that Winter. Besides that, there is nothing strongly anomalously warm about the global pattern right now, wrt to previous years. I am going to be in the 70s for highs something like 13/14 August days, which is unusual. We had a warm up in June, but cold H5 was overtop of it, so it was a strong +NAO driven warm up. We aren't just popping ridging out of nowhere, like we did a lot 2020-2024. For all this about 2nd year El Nino's being so warm in the global pattern, you don't hear much about 2nd year La Nina's, and the cooling effect. I think since late November last year it's been a cooler US pattern, relative to global warming and all. Will be interesting to see if it lasts into the Winter. Analogs say that odds are starting to become in that favor, the more we get these cooler patterns through the Fall.

Sub 5100dm over the Artic circle tomorrow! Areas of cold 500mb >60N continues to be a theme for the warm season since May 2024, and May this year. I say for cold Winter prospects, give me cold upper latitude 500mb earlier in the year. I think it correlates to more -EPO conditions down the road. Hopefully the trend of cold 500mb continues in the Fall. It shut off after September last year, and in the Fall of the last several years.

Pretty cool to watch the N. Pacific warm pool shift north with the Summer pattern. It's aligned right now with the Hadley/mid-latitude Cell.

^Winter NAO prediction based on May-Sept N. Atlantic SSTAs will probably come in weakly positive. Add to it that we are in the period of 0 to +4 years after a Solar Max, which has a +0.2 Winter NAO correlation, or 55% of the time. Then the NAO has run positive 6 straight months, and the AO has run positive 5 straight months.. that rolls forward to a +0.2 Winter +NAO correlation. All-in-all, that gives us about a +0.3-4 correlation right now for +NAO Winter (DJFM), or 60-62% chance of happening, based on those 3 indicators. Because of the decadal cycle, and 83% of Winter months have been +NAO since 11-12, I would say the current odds are more like 65% chance it is a +NAO Winter.

18-19 and 20-21 through 22-23 -NAO's were really not getting cold at all. The last 2 Winters, there has been cold under -NAO patterns in the east, and the Mid Atlantic has done better in those times.

Down below 5190dm over the Arctic circle Aug 22-25. It's doing exactly what that +AO roll-forward showed, in the exact location, albeit a few months early. I thought this was impressive because the Polar Vortex was 2000 miles from where the base +AO period had negative H5.

Down below 5190dm over the Arctic circle Aug 22-25