GaWx

Look at this OISST plunge of Nino 1+2! Did anyone foresee this?

1. The Nov +PNA means that for only the second time since 1950, there was a +PNA in all of June-Nov. The only other time was 2021. But 2009 was a very close call. I consider +0.25+ a +PNA month. 2. The Nov -NAO means that for only the 3rd time since 1950, there was a -NAO in all of June-Nov. The only other years were 2012 and 2010. I consider -0.25- a -NAO month.

Nov: The NOAA PDO of -1.79 compares to the WCS PDO of ~-1.00. Oct: The NOAA PDO of -2.26 compares to the WCS PDO of ~-1.10. So, the NOAA continue to be more negative though the gap narrowed a decent amount in Nov.

Today’s Euro Weekly for Jan 1-8 has about the strongest E US cold signal of any run yet (runs for Jan 1-8 go back nearly two weeks):

Not much. The heaviest concentration is early to mid Jan for a possible major SSW.

I absolutely have been saving a bunch of the Euro Weeklies SPV progs. I was the one repeatedly mentioning the can kicking that went on between the Nov 1 and 19th runs. Remember? After that, they suddenly got much more bullish about a weak SPV. In recent days, I’ve noticed not as weak of an SPV in early to mid Dec as in runs from a few days ago and in late Nov. We have to make sure this won’t turn out to be a mirage just like with all model progs for anything. Today’s isn’t as weak as the three prior runs of 45+% of members with major SSWs. Today it is ~38%. Also, the # of members with a sub -10 is only ~18%. That was way up at ~30% a couple of days ago.

I’ve posted many examples of weak left side MJO during El Niño showing that this combo during winter is often cold in the E US, especially SE US-Mid Atlantic. And that’s not necessarily even requiring a weak SPV. Throw a weak SPV on top of this and then cold is even more favored.

I wouldn’t bet on a combo of El Niño, WEAK (including inside the COD) 8/1/2/3 MJO, and a weak SPV being mild in the E US in winter.

Dec 4th Euro Weeklies look similarly impressive with numerous EPS members (~45%, which is similar to prior two days) with major SSWs 12/28-1/18. A year ago (~12/31/22) the SPV was in stark contrast near a record high strength! Strongest SSWs: ~27% <-10 vs 25% prior run 8% <-20 vs 5% prior run 7% <-25 vs 3% prior run 5% <-30 vs 0% prior run

SON ONI (ERSST based) came in at +1.78. So, ONI-RONI gap dropped in SON but only slightly to 0.44 from 0.49 in ASO. Nov ERSST input to ONI was +2.02. Nov OISST was +1.90 due to different base climo because absolute SSTs came out the same (28.72).

Thus, El Niño is about as flat/basin wide as can be. Neither EP nor CP but a blend instead.

From EPS at 10 mb for 1/1-1/8:

OISST Nino 3.4 was down sharply in both of today’s updates: -WCS from +2.09 to +1.97 -cyclonicwx from +2.09 to +1.95 The other three cyclonicwx regions also dropped and keeps 3.4 the warmest just ahead of 3.

No clearcut answer as the timing varies a lot and they sometimes don’t work their way well down into the troposphere or don’t always focus on the E US. Sometimes it is already cold in the E US because of an +PNA or cold MJO phase. And then sometimes like for last winter there’s a strong -PNA in place that mutes the cooling or delays it more. But keeping these caveats in mind, the rough average lag to see the start of the major effects is ~2 weeks afterward. So, that would mean a wild guess of a start between ~Jan 8th and Jan 29th, way earlier than the mainly mid March cooling from the 2/16/23 major SSW.

Thanks for posting. The potential of a major SSW is every winter lover’s baby! 1. I roughly estimate that a whopping ~48-50% of these 101 EPS members have a major SSW (vs ~45-48% yesterday and ~38% two days ago) meaning the highest % yet! They occur 12/25-1/16 or ~3-6 weeks from now. I’d venture to guess that ever getting much more than 50% of members that far out is rare meaning I believe that this is just about as strong a signal for a major SSW as you’re going to get 3-6 weeks out. On Jan 13th, the EPS mean is a mere 15 m/s, vs climo of 35 m/s (similar to yesterday). 2. Although the # of major SSW members increased slightly, the # of extreme dropped some though still the #s are still significant: -sub -10: ~25 vs ~30 yesterday -sub -20: 5 vs 12 yesterday -sub -25: 3 vs 8 yesterday -sub -30: 0 vs 2 yesterday

Wow! The chance for a major, and possibly even an extreme SSW in early Jan is even higher! On Jan 9th, the EPS mean of 101 members shows a mere 14 m/s vs climo way up at 35! There are so many members with a major SSW that it will be tough to count! This appears to be at a whopping 45%+ for a major, easily the highest yet beating yesterdays ~38%. Dates are from 12/25 through 1/16. This has ~~30% of the 101 members down to sub -10 m/s (vs 20 in prior run), 12 sub -20 (vs 10 in prior), 8 sub -25 (vs 4 in prior), and 2 sub -30 (vs none in prior):

More on the above. 2022, 2009, and 1985 were the only sub -2 AO 12/1-16, where 2023 is possibly headed. The most -AO winters in order were 2009-10, 1976-7, 1968-9, 1962-3, 1969-70, and 1985-6. So, 2 of the 3 most -AO 12/1-16 ended up within top 6 most -AO winters of 73 winters! Only 2022-3 didn’t. Of those 6, only 1962-3 and 1985-6 weren’t Nino but they were neutral. 2022-3 was a solid Niña. Not being La Niña and being El Niño changes things tremendously. Despite difficulty in getting -NAO winters since 1979, -AO winters haven’t been overly tough and this along with progs for weak SPV for at least first half of winter tell me that a -AO winter is now looking likely. Don’t know if that would drag the rare winter -NAO along with it, but that sure would increase its chances.

But big diffs -we're in El Nino (favor PNA) vs 2022's La Nina, which favors -PNA -there was record strong SPV late Dec 2022 vs progs for weak SPV late Dec 2023 -mid to late Dec was in warm MJO; then much of Jan-Feb was in strong often right sided MJO vs progs for weak left sided MJO late Dec into Jan

Per this GEFS prog mean, the 12/1-16 AO may end up the 2nd lowest to 2022 back to 1950. The only others that were sub -2 were 2009 and 1985. So, only 3 sub -2 back to 1950 with 2023 progged by GEFS to become only the 4th:

OTOH, these MJO progs for late Dec suggesting weak left side MJO for then and extending well into Jan and when also considering El Niño and the weak SPV progs, tell me that the possibility of a cold E US overall and even moreso in the SE US in particular is there based on many analogs that I’ve posted showing MJO/E US temps: these end Dec moving slowly in weak 8 and likely would then go slowly into weak 1 followed by weak 2, a recipe during El Niño based on analogs for a multi week dominated cold E US

Although not quite as weak in late Dec as some of the runs, this latest run has the weakest in the 1st half of Jan with a total of ~38% of members with a major SSW 12/23-1/16! ~20 go sub -10, ~16 go sub -15 and ~10 go to sub -20 (extremely weak). There are even 4 that go sub -25, among the weakest on record. These #s are all the highest yet. To compare, the major SSW of 2/17/23 went down to -13, which itself was quite notable.

The cyclonicwx 3.4 rose similarly from +2.01 to +2.12. Latest cyclonicwx: 1+2: +2.10 (down from +2.3) 3: +2.07 (up from +2.05) 3.4: +2.12 (up from +2.01) 4: +1.91 (up from+1.75) Thus this is about as flat/basin-wide as you can get.

The new WCS (for 11/29) had a big daily jump to +2.10 from +1.99 the prior day. So, most likely cyclonicwx will have a gain today.

The model consensus progs have strengthened the MJO in both the MC and WP since yesterday: Though not at all a reliable model, the CFS is fairly similar to where the GEFS and EPS are on Dec 14th, the end of their runs. Note where the CFS then goes, into weak 8/1/2 in late Dec (including inside COD), which tends to favor a cool to cold E US, especially SE US: