George001

I don’t see 15-16 as a good example of the SAI being complete BS, but I do see it as a good example of it being overrated in that it did what it was supposed to do, but other factors (mainly ENSO) were stronger drivers. It did what it was supposed to do, in Jan and Feb of that winter the PV was displaced south with periods of blocking. But again, the super Nino was the primary driver that winter. I do agree with you that the hype should not have been off the charts. I have no idea why Cohen forecasted an arctic cold winter during the 2015-2016 winter regardless of what the SAI did. 2015-2016 was the strongest El Niño winter on record, when ENSO gets that strong that trumps SAI every time. Even if last winter had a record high SAI, I still would have gone mild with below normal snowfall for my area due to the high end strong Nino, -PDO, and the parade of storms crashing into the Pacific Northwest during the fall.

To an extent yes, but I don’t think it’s completely meaningless. In my opinion it was overrated in the mid 2010s when some were considering it to be a silver bullet to winter forecasting where more Siberian snow cover = colder and snowier winters in the east. It isn’t that simple, never is. The takeaway I’m getting from it is an increased risk of the polar vortex being displaced south rather than consolidated over the North Pole. Yet, there are conflicting signals. The high solar and high geomag supports a +NAO pattern with a stronger polar vortex. The reason this interests me is what other years with rapid Siberian snow cover advance did during high solar/geomag years in the polar region. In 14-15, we had the rare combination of a strong polar vortex that was also displaced south. Make no mistake, these were still +NAO winters so it didn’t exactly prove Cohens theory correct (rapid Siberian snow cover advance = weaker polar vortex and -NAO/-AO). The big takeaway for me is while this is not a reason to go all Joe Bastardi and forecast well BN temps in the east with 200% of normal snow up and down 1-95 (cannot just ignore what’s going on with the pacific. I have gotten burned doing that one too many times and won’t make the same mistake again) its still worth looking at. I wouldn’t take this as a reason to forecast a -NAO (especially given that previous examples of high Siberian snow cover advancement with high solar/geomag were still +NAO winters, some even strongly +NAO). I’m thinking more along the lines of an +NAO winter with the vortex displaced more south than usual (this happened in 07-08, 14-15, 13-14, 92-93, and 93-94). Now…. All of this may not matter if the Siberian snow cover advance slows down and finishes around average. The month is not over so that’s still very possible. Just a week ago the Siberian snow cover advance was running below normal.

Siberian snow cover is advancing rapidly, the quickest pace since October 2014. According to Cohens research, rapid advance of the Siberian snow cover is linked to -AO pattern during winter and a weaker polar vortex. It is especially interesting that this is happening in a year with a fairly strong +NAO and +AO signal (high solar, high geomag, etc).

The big thing with the fall pattern is it has been fairly dry for most of the US. It has also been warmer than average throughout the CONUS, with most of the warmth centered over the plains. So I plan to look to falls that have a similar temp profile and precip profile across the conus and adjust my analogs accordingly. I’m actually not sure what it will look like yet. I do want to see the 1st half of November first though.

The MJO often is a big driver, especially at higher amplitudes. Over the next couple weeks, the MJO is expected to pass through phases 4-6 which is warm for the east. It is unclear how long the MJO will remain in those phases, whether it goes into the COD or into 7,8 and then 1, what the amplitude is, etc. Just way too many unknowns right now and that is just with the MJO.

I have seen (I believe it was Eric Fisher who posted this graph) graphs showing that there is a decent correlation between November temps and seasonal snowfall in Boston (I suspect this is related to the November pattern persisting into December and potentially early Jan). Personally, I do believe it matters. There are exceptions to every rule and it’s not a death sentence for winter if November is warm, but I would rather have a cold November than a warm one. It’s October temps that don’t have much correlation one way or another. It would be a bad sign if the long range guidance for November ends up being correct, but fortunately for winter enthusiasts long range guidance is extremely unreliable.

I would go 2 warm and 2 cool, Dec-Jan BN and Feb-Mar AN. I would not forecast below normal temps though unless the signal for a cold/snowy winter was extreme like it was going into the 2014-2015 winter. I don’t think it’s bad luck or anything that we had 9 AN winters in a row, it’s climate change. This more than just me bitching about how horrible it’s been since the super Nino, even the good winters we had were AN temp wise. 2017-2018 is considered to be a severe winter with periods of extreme cold and snow by many, and it really was. It was downright frigid during that Dec-mid Jan stretch. March was an all out snow blitz, I got so much snow during that month that a big tree collapsed under the weight of the snow and had to be removed. yet, even the severe 2017-2018 winter averaged AN temps simply due to the extreme magnitude of the warm periods when the pattern became unfavorable in Feb. What may have been +3 or +4 anomalies decades ago are now +7 to +8, and you see extreme shit like 70+ degrees in Feb. So even in an “average” up and down type of winter with a couple AN months and a couple BN months (where I’m expecting this winter to be), you are looking at AN temps simply due to the magnitude of the warmth when the pattern is unfavorable exceeding the magnitude of the cold when things get favorable. So despite me being more optimistic than most about this winter, I still am going with AN temps. Especially with how warm the ocean temps are (which could amplify SE ridging), 1 month of MJO camping in phases 4-6 can undo 2 months of BN anomalies.

It would not be good for winter (often what happens in November is a sign of things to come) but I would take what the models are saying about November with a grain of salt. Too far away

I’m skeptical of a cold Feb too but I’m more optimistic about December and January. I agree about December being a sign of things to come, usually in La Niña winters winter shows its hand early.

Makes sense, -PDO, strengthening GOA cold pool and recent uptick in tropical activity is consistent with a strengthening La Niña background state. It’s strange, with these observations you would expect a much stronger ONI response. Makes me wonder if there is a risk that the ONI plummets way more than expected, like a solidly moderate ONI peak or even close to strong. I’m not expecting that given where the ONI is currently at (sticking to my -0.8 to -1 call), but it is something that crossed my mind as a potential wild card factor for this winter.

It’s interesting how disgusted the mid Atlantic posters are about the thought of a 2007-2008 winter redux. I say bring it on, often when they rain we snow. That’s exactly how it went down that year.

Now this is a great example of why a pattern being “good” or “bad” means a completely different thing depending who who’s posting it. 07-08 in particular had an extremely sharp snowfall gradient. We all live in different areas, so we have different perspectives on what constitutes a good vs bad winter. For me, I live in SNE and I ski so I prefer areas farther north to do well too. Good winter for me, record breaking good for ski areas. So I have zero issues with 07-08 and if I could sign a lifetime contract that guaranteed an 07-08 redux every year, I would do it instantly.

I would prefer 07-08 to 20-21. 07-08 was honestly straight up better than 20-21 for my area, it was snowier and a bit colder. 20-21 the best snows were south and west of SNE. My range for best and worst case scenarios is wider. Best case for my area I would say 2010-2011 redux, worst case 2022-2023 redux. I don’t think either of these scenarios is particularly likely, it would be foolish to forecast such an extreme outcome at this point. But that’s the range of outcomes. I’m thinking average to slightly above average snow for my area at this point, nothing too crazy in either direction.

07-08 was a great winter in New England especially for ski areas. It was decent for SNE too, then sharp cut off south. I would consider that to be a successful winter.

Agree. I’m not putting any stock into what the polar vortex is doing one way or another until December.

Looks like we are going to end up at roughly 140 before the next lull. The average ACE increase from now until the end of hurricane season is roughly 20, so that would put us at around 160 ACE by the end of the hurricane season. We probably will fall short, but I’m starting to think there is a very real shot at going over 180. Likely? No, but stranger things have happened.

Agreed the pattern was not too late at all, it just wasn’t a favorable enough pattern. The epic March 2018 pattern set in just as late but that didn’t matter, it still worked out.

That makes sense. It’s not about the ACE index in itself, it’s about how you get there and the pattern in place that facilitated those high ACE totals. This is where my approach falls short, relying heavily on statistics to try to make sense of things is helpful, but just knowing a correlation exists and how strong it isn’t everything. The WHY is just as if not more important. That’s why I’m glad we have this board, there is so much useful information here that helps amateurs like myself fill those gaps. That has me thinking, although there is nothing out of the ordinary about the raw ACE numbers this year, how we got there is somewhat unusual. The hurricane season peak this year has been quite a bit later than usual, it may or may not mean anything, not too sure but it’s definitely an interesting observation.

I have seen some evidence for a weak to moderate positive correlation between solar and the NAO (both on this board and outside). However, I haven’t seen anything indicating the r^2 value for the correlation between sunspots and NAO is greater than 0.7, though I am open to being proven wrong on that. Regardless, you are correct that sunspots and solar activity aren’t the only +NAO indicators this year. I wasn’t aware of how strong the correlation between geomag and NAO was so I dug into it some. Apparently the correlation between high geomag and +NAO is 0.76 between 1962-1994, which is strong. Thats a good 32 years of data too. That is a great point you brought up about the strong correlation between high geomag activity and +NAO.

Just my opinion but I wouldn’t be worried where you live. Long Island in particular does better in miller bs (common in Nina’s) than even NYC, and you do significantly better than say Philly, DC, etc. Hell, even the whole solar = +NAO thing isn’t a given. I read the papers, all the meteorology shit goes over my head but the one thing I did get out of it is the correlation coefficient is highest in Feb, and even then the correlation is moderate at best. I would lean +NAO, but I just don’t think the correlation is strong enough to justify ignoring certain analogs due to solar. Also, the NAO itself has a weak correlation to temps above a certain latitude (I believe it was an r^2 value of .2 for me and .3 for you, I’ll have to go back and check though). The thing I care about the most is the fall pattern leading up to winter. It is a lot different than the past 2 years as we do not have a parade of storms crashing into the Pacific Northwest. That’s part of the reason I was so bearish last winter (forecasted 20-30 inches of snow in the Boston area, and this turned out to be way too optimistic). We aren’t seeing that this year, and frankly that’s the big concern with strong -PDO Nina patterns. I get the pessimism, I really do. I agree with the pessimism south of say NYC because the farther south you go, the more hostile +NAO patterns are (although far from a guarantee, a positive NAO should be favored over a negative one). Also, snow wise areas farther south are more likely to get screwed in bigger storms during La Nina’s. Those areas do better in a strong STJ El Niño pattern. There are plenty of reasons to be optimistic that have absolutely nothing to do with ACE.

Bluewave is in fact correct about ACE not having much of a relationship to the winter pattern. I dug through some of Raindances old posts, and the correlation coefficient is only around .1 in Boston for ACE and snow in La Nina’s. It is slightly higher for NYC and Philly (roughly .23 in NYC and .21 in Philly), but that is still considered weak.

seasonal ACE is now up to 130 thanks to hurricane Milton going nuclear and deepening significantly more than expected by the models. Milton has already produced nearly 20 ACE, and we may be looking at an ACE of 135-140 once Milton falls apart. On average we see around 20 ACE after today, which means we are looking at potentially a 150+ ACE season despite just a couple weeks ago the hurricane season looking like a complete bust. Things can change fast in weather, something worth keeping in mind during the winter as well if things start slowly.

Damn looks like 120-130 is going to be too conservative. Hurricane Milton deepening significantly more than expected made a big difference, the ACE is already up to 120 now.

I don’t even think the most aggressive hurricane models had the low in the 920s by now

I don’t get it. There is nothing weak about this storm. I am very skeptical of the models that have it landfalling in the 960s given how much they underestimated the strength of the low so far and the initialization errors.