GaWx

Other than week 2 having 2-3 F AN temps in NW portions, the Euro Weeklies have NN to BN temps in the SE through Jan 29th. And this is with most members having no major SSW. Imagine what could happen in mid and especially late Jan if there is one.

They could since we’re still far enough out in time for that to occur. But by a week from today, the models will know a lot more based on the past. So, say by the 12/21-2 runs, if the runs don’t jump back quite a bit in the weaker direction, I’d then significantly reduce the chances in my mind for an early Jan major SSW. I like to give updates, especially those showing significant changes, whether or not it is what I want to see. I don’t want to come across as one who posts either mainly about what I want to happen nor the opposite. I want to come across as one trying to be as objective as possible for credibility reasons.

I assume you meant to say they shouldn’t. I see no problem with every day for both as they help for following trends. I like to see daily updates. Now if they ran, say, 4 times a day, I’d agree with you.

Neither last night’s extended GEFS (12/14 run) nor today’s Euro Weeklies (12/15 run) was what I wanted to see as they both suggest a sharp decrease vs earlier runs in the chance for a major SSW anytime soon: 1. Extended GEFS: % of members with major SSW 12/11 run: 48 12/12 run: 32 12/13 run: 29 12/14 run: 23 2. Euro Weeklies: After many days showing 45-60%+ of members with a major SSW, today’s suddenly plunged to only ~33%. Yesterday’s was ~50% with a whopping ~17% for 12/28-1/2, alone. Today’s has only 3% for 12/28-1/2! Today’s has 17% for 12/28-1/12 and only 21% through 1/17. The extreme major SSW (sub -15) members stayed ~same with 7% vs 8% yesterday though that was ~17% two runs ago:

But likely only 8th warmest RONI peak and 9th or 10th warmest MEI peak at best (could turn out to be as low as 15th) out of 25 El Niños since 1950 when all is said and done. So, based on RONI and MEI, whereas we’re in a robust El Niño, it isn’t impressive historically. Meanwhile, OISST 3.4 jumped back up to +2.02 from +1.92 on cyclonicwx. It keeps going up and down in this area without any real direction of late.

That’s similar to what I found for the DJ MEI range most correlated to cool to cold E US winters. I don’t want the MEI to be either too strong or too weak. The MEI sweet spot seems to be in the general vicinity of +1.0 for DJ. Thus, I see this adjustment up of ON to +0.8 as good news as far as better prospects for E US BN temps are concerned. Looking at the 25 El Niños since 1951-2, the average change from the ON MEI to DJ MEI was near 0. For 85-90% of these, the absolute value of the change was 0.3 or less. So, that tells me that there’s a high chance that DJ will end up between +0.5 and +1.1. The 10 coldest winters (at least mid-Atlantic south) averaged between +0.9 and +1.0 in ON. The ON for both 1977 and 2002 was the same as 2023’s +0.8. 1963’s ON was very close with it at +0.9. OTOH, sometimes with similar ON MEI, the winter turned out to be mild like 1951-2 (though its DJ fell to only +0.3) and 1994-5. Regardless, for the best shot at cold, the +0.8 of ON is good to see. https://www.webberweather.com/multivariate-enso-index.html

Today’s run has the weakest SPV period starting the earliest in many runs and that period starts only 14 days out, the earliest in any run yet. I count ~17% of members with a major SSW just from 12/28 through 1/2, alone! Moving up like that is a pretty big deal. It earlier looked like @40/70 Benchmarkgetting a major SSW in the first of his two weeks was looking very highly unlikely, but this is telling me the latter half of his first week is now back to being very much in the game:

Dec low SLP records could be challenged in GA, SC, and NC per this:

Whereas the CFS GLAAM forecast is still solidly positive, it has come down a good bit from what was forecasted two days earlier with +1+ instead of +2+ at early Jan peak

Regarding cold periods during DJF in the E US, a large portion of them occurred during weak MJO per this: https://scholarsarchive.library.albany.edu/cgi/viewcontent.cgi?article=1007&context=honorscollege_daes

Note that the coldest and snowiest part of the month was Jan 15-31, when the MJO was weak (near or inside the circle). Jan 1-14 averaged near normal temps whereas Jan 15-31 averaged B to MB. This was similar to the case in the SE US, where Jan 1-14 averaged A with temps before being MB Jan 15-31 along with above average snow.

From Judah Cohen’s blog: “A larger PV disruption is more likely in early January that has the potential to reverse the overall mild pattern for the NH to a much colder one. Hard to provide details just yet and I expect a lot of volatility in the forecasts so buckle up.” “It is of my opinion, much of the winter will likely hinge on the nature of this SSW that is predicted to begin the last week of December.” https://www.aer.com/science-research/climate-weather/arctic-oscillation/ ————————- Interesting update from Judah! Keep in mind that major SSWs are often though not always accompanied by mildness in the E US before, during, and afterward prior to it later getting colder as their influence moves down into the troposphere and often results in a -AO/-NAO to then dominate. It often takes 1-3 weeks (avg ~2 weeks) for them to get deep down into the troposphere. It can of course already be cold when they occur, but that would obviously be due to other factors like a favorable MJO, for example.

Today’s 0Z extended GEFS mean, like recent runs, suggests a significant weakening of the SPV and warming of the Arctic in early Jan. But will there actually be a major SSW/reversal of 60N winds? That’s the big question:

Today’s Euro Weeklies are about as weak as any run yet for the last few days of Dec/early Jan. Total major SSWs are ~~50%. The highest concentration of major SSWs occur Jan 2-9 (~25% of members), which is supported by E QBO climo. (The extreme SSWs throughout Jan increased with ~17% total sub -15, ~15% sub -20, 5% sub -25, and 2% sub -30.): 10 mb temp anoms/hts 1/1-8: Also, Jan 8-15 cooled back almost to as cold as the run from 3 days ago. But no football spiking from me!

Yeah, this trend isn’t at all what I wanted to see. This means that the NOAA PDO is quite possibly back down to ~~-2.0. My hope is still for a sharp enough reversal soon to allow for a JF PDO to average >-1 in the NOAA table, a doable but unfortunately very tall task as of now. But regardless of the PDO, the good news from an E US cold lovers standpoint is always having the major SSW wild card possibility to shake things up drastically via -AO/-NAO blocking in Jan and/or Feb as it often means a major atmospheric reset. All major SSWs since 1958 during El Niño have had a 3+ week long period of cold domination after 1-3 weeks following them as I’ve posted about. 60% of El Niño winters have had a major SSW. Also, QBO E have had more than QBO W. The best shot at a major SSW during QBO E per analogs is very late Dec to early Jan as per@40/70 Benchmarkand SSW history. If we can get that combined with weak MJO, I’d be pretty excited about potential for E US cold in a good portion of Jan and/or Feb.

1. That’s about to drop to ~+1.9 based on WCS dropping from +2.0 to +1.89 in today’s update. 2. The WCS PDO has been falling sharply in recent days and is -1.35 in the latest, the lowest in two months (NOAA may be back down to ~~-2):

1. It dropped from 48% to 32%, but 32% is still significant. The EPS is at least that high for very late Dec into early Jan. 2.

Why do you feel it us even a toned down version of 1997/2015? At best as it looks now the MEI may get only to ~1/2 the MEI of those two (say, low +1s). The RONI is looking to top at only low end strong vs the ~+2.35 peaks of 1997/2015. So, based on MEI and RONI, should 2023 even resemble those?

Thanks, very interesting stuff! Regarding what I bolded, is this Nino really all that strong when you consider it is only low end strong on a RONI basis and was still only weak on an MEI basis as per the ON of +0.6? Much of this thread's discussion for a long time has been emphasizing that the current Nino is not that strong and not well coupled with the atmosphere.

+GLAAM wouldn’t favor an Aleutian low instead of a GOA low?

Wow, look at how high the CFS is now forecasting GLAAM to go (consistent with strong El Niño influence)! I don’t recall seeing it this high before. But to be fair I haven’t seen all that many of these charts before as I’m only now first following it regularly:

Now I see why you picked those dates. If I looked at the list linked below, which is more up to date (though it still needs 2/16/23 to be added), it even more emphatically backs up your thinking because it shows Dec 31-Jan 9 to be the most concentrated period throughout winter for a major SSW during QBO E since it also includes 1/9/77 and 1/2/2019. So, for E QBO going by ERA, this source has 1/9/77, 1/1/85, 12/31/01, 1/5/04, 1/6/13, and 1/2/19. So, 6 events in just that 10 day period. If W QBO were also to be included, this source has a whopping 9 events within that 10 day period because 1/7/68, 1/2/70, and 1/5/21 would be added. The only other comparable period for all QBO is the 8 events within the 9 day period 2/21-29. https://en.m.wikipedia.org/wiki/Sudden_stratospheric_warming

The strat stuff discussed by Cohen and others is so fascinating! To me, getting a major SSW resets the whole winter playing field. It is like getting a new QB and perhaps even more like getting a whole new team mid-game. Here’s something I found recently: In this, I noticed these things: -QBO: E beat W by a large margin, 22 to 13 -QBO E: 14 displaced vs 8 split -QBO W: 4 displaced vs 9 split -QBO E El Niño: 6 displaced vs 3 split -QBO W El Niño: 2 displaced vs 4 split -Best bet for one is QBO E La Nina followed closely behind by QBO E El Niño -El Nino had 15 from 12 winters (out of total of 20 winters) and La Niña had 13 from 11 winters (out of total of 18 winters), but neutral had only 7 from 7 winters (out of total of 18 winters) -To get two in one winter, you almost always have to have first one by Dec

Mitch, I didn’t say it that way, but you’ve got the general idea. A study was done showing that the vast majority of cold E US events in DJF were when the MJO was weak (near, on, or within COD) as per this: So, whereas I didn’t go as far as to say that weak MJO results in cold in the E US, I did say that the best chance by a good margin from an MJO perspective for it to be cold is if it is weak. That’s what this chart shows. So, whereas it sometimes is mild even during weak MJO, it is difficult for it to be cold when the MJO is strong. So, as a cold lover, I always prefer weak MJO to dominate so as to maximize the chances for cold. Also, I earlier (independently of the study from which came that diagram because I hadn’t yet been made aware of it) posted 15 periods during El Niño that had weak MJO, mainly left side, that were cold dominated in the E US, especially SE.

1. Today’s Euro Weeklies are still weak with the SPV in late Dec and especially early to mid Jan. The highest concentration of members with a major SSW is during Jan 1-12. Whereas the number of members with one dropped some (~~50% today vs ~~60%+ yest), the number of extreme SSW actually rose (~15% sub -15, 10% sub -20, 5% sub -25): 2. Today’s 1/8-15 warmed up a lot since yesterdays cold E US map.