40/70 Benchmark

I don't think the super El Nino in-and-of itself is an absolute death knell for December, but it is when combined with descending solar and +QBO.

Yes...this weekend is when I consider summer, and 80s over.

Yea, I used that chart in my last blog....likely explains the continuation of the warm pool east of Japan.

Basically, high AAM means that the hemisphere is more representative of warm ENSO, low AAM cool ENSO.

The most glaring commonality between the QBO composite and both the solar and intense El Niño composites is the pronounced ridging stretching from the northeastern CONUS and into central Canada, which obviously is a rather mild signal for the forecast area in the seasonal mean. However, it has been mentioned on numerous occasions that neither of these winter composites are entirely bereft of high latitude blocking or even shorts bursts of severe winter weather. This is evident in the bifurcation of the composite below. This is a signal that is emergent among some seasonal guidance. What is clear is that as El Niño begins to wane and perhaps shift somewhat to the west as the season evolves, the Gulf of Alaska low begins to retrograde, which allows the central Canadian-Northeastern CONUS ridge to lift up into the NAO domain. This mid-to-latter season progression is the crux of the volatility and Modoki-like episode(s) that have been referenced with the respect the overall characterization of the polar domain. The primary risk here for a transition to a significantly colder pattern is that the block is more oriented towards the Eastern portion of the NAO domain, which is especially evident in the more meager El Niño analogs that did not have the very cohesive Gulf of Alaska low that is synonymous with El Niño. The inference is that the development of the more Modoki like intervals during the second half of the season is contingent on the progression of the mid latitudes of the northern Hemisphere growing more redolent of traditional El Niño as boreal winter ensues, which should take place given the forecast for this warm ENSO event to reach an unprecedented magnitude as Mother Nature gives her best shot at the redistribution of that stagnant west Pacific warm pool

Totally reasonable....that ridge should lift up towards the NAO domain in January, as the GOA low retrogrades and forces the ridge away from the Aleutians.

Conclusions Concerning the Extra Tropical Pacific It will be the volatility of the northern Pacific that will dictate the mercurial nature of winter 2026-2027, and an unprecedentedly powerful El Niño will be the primary catalyst. The barrage of immense WWBs responsible for the extreme magnitude of El Niño will also ensure that winter is mild in the mean due to the initial eastern orientation of the warm ENSO event. Ironically enough, it is these same WWBs that will also preclude winter 2026-2027 from being as warm as many within weather circles who have been conditioned by climate change may think, as it will also act to reduce the heavy MC flavor that we have become so accustomed to in modern versions of El Niño. There are no "silver bullets" with respect to seasonal forecasting, but perhaps the closest notion is the ability to hone in on the most anomalous pattern driver and simply follow its' lead. In case it hasn't been mentioned, El Niño is about to set the record for just about every measurement used to assess its' intensity, and the 4.1C anomaly measured in region 1.2 the weeks of July 29th and August 5th are the greatest ever recorded within any ENSO region. Excuse this forecaster for not being surprised that the winter 2026-2027 Extra tropical Pacific composite just so happens to be a carbon copy of the ENSO region 1.2 correlation with the winter pattern. In closing, forecast symmetry for winter 2026-2027 continues to strengthen with he addition of the extra tropical Pacific to the consensus. Polar Analog Composite, Solar Analog Composite QBO Analog Composite, Extra Tropical Pacific Composite Intense El Niño Composite, Basin-Wide El Niño Composite:

Primary Polar Analogs: 1982-1983, 2015-2016 2026-2027 Polar Analog Composite: The mean DJFM AO value of the polar composite near neutral and barely positive, at .09, and the NAO is moderately positive at .49, with high latitude blocking heavily weighted towards February and March, all of which represent a reasonable preliminary seasonal forecast for winter 2026-2027.

I was thinking similar to 2015 as far as residual MC influence when I did my early polar and Pacific work this summer in an effort to start conservative and err on the side of caution, but I am starting to lean less than that now.

This makes sense, though, if you consider that the N hemisphere was not at all redolent of El Nino throughout the summer, likely due in large part to the antecedent state of the extra tropical Pacific. If that were to begin to change, this is what it would look like. I think October will be the month that will really be telling, which I know you have posted data to the same effect.

I think he needs to do a better job of emphasizing that a full reversal is less likely than a stretch and/or reflection event, as he completely neglects the solar and QBO aspects, which are pretty hostile. I could see something like the scenario he laid out from January 2016 (I used this season as a strong polar analog), but I don't think a full reversal is as likely as he seems to intimate.

Uh oh....Larry is aroused

You also have to consider potential hybrid patterns and what that may look like. I think it's safe to assume that there will be more of a traditional El Nino response than 2023 and even 2015.

Great stuff in here today.

Yea, major El Niño season's are very high stakes....the dice are loaded towards huge events, but opportunities for more quotidian, or pedestrian snowfalls are limited by a dearth of cold in the seasonal mean, so it can be tough to sniff climo snowfall if you whiff on the big dogs.

Well, I was referring to "favor" within a forecasting context....

Well, latter December is more palatable....but what I specifically meant is the latter November/early December type of deal we saw this past season....that is exceedingly rare. Once nearing the new year it's much more common. For instance, I count five prior to the ides of December between 1958 and 2012 in this table.

Just as an aside, SSW climo time frame isn't late autumn and early winter.... mid winter, okay....last season was very rare in that regard.

It's more +NAO....AO is pretty much a push, but I would hedge towards subtle negative given my composite. I think we will def. have some -NAO periods....I just don't think it will be a mean DJFM -NAO. I also don't expect a SSW....it will be triggered more by strat reflection, etc...

There is some validity to that, but it's more useful during cool ENSO. There probably is some statistical connection between very inactive hurricane seasons and poor subsequent winters due to super El Nino.

There will undoubtedly be less MC influence this season relative to 2016.

You don't think +EPO has been historically favored during super El Nino with a huge GOA low?? The seasonal mean will be +EPO, but I think we can have some fleeting periods of cross polar flow.

I think your thought process is intentionally linear here.....you know damn well how chaotic snowfall is and the bar that year is pretty damn low...I'll take the over.

Eh...I see what you're saying, but ENSO doesn't operate in a vacuum. I get the sample size limitation, but we also need to consider that 3/4 Super El Ninos have occurred during the descending portion of the solar cycle, which is pretty hostile towards sustained high latitude blocking. I don't think that connection between descending solar and super El Nino is a coincidence, either.

I feel like Allison would rather not find out....