GaWx

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.

The MEI warmed from +0.3 in SO to +0.6 in NO. That warming is good news as the 10 coldest El Niño winters in the SE US since 1950 had a DJ MEI of +0.5 to +1.5. So, we needed the MEI to warm up and now we’ll need the next two MEIs to maintain this warmup and preferably warm a little more as we reach DJ. The 10 coldest El Niño winters back to 1951-2 were 1957-8, 1963-4, 1965-6, 1968-9, 1969-70, 1976-7, 1977-8, 2002-3, 2009-10, and 2014-5. Per Webb’s table these were the rounded DJ MEIs: +1.5, +0.9, +1.3, +1.2, +0.8, +0.8, +0.7, +1.0, +1.1, and +0.5. So, a range of +0.5 to +1.5 for the DJ MEI with a mean of +0.95 and a median of +0.95. So, sweet spot near +1.0 for the 10 coldest in the SE. The 6 coldest were 1957-8, 1963-4, 1969-70, 1976-7, 1977-8, and 2009-10. MEIs for these 6: +1.5, +0.9, +0.8, +0.8, +0.7, and +1.1. So, range of +0.7 to +1.5 with mean of +1.0 and median of +0.85. El Niño Winters with DJ MEI within +0.5 to +1.5 that weren’t cold: -1958-9: +0.7 cool -1979-80: +0.7 NN -1986-7: +1.1 NN -1987-8: +0.9 cool -1991-2: +1.5 mild -1994-5: +0.9 NN -2006-7: +0.8 NN So, when DJ MEI was within +0.5 to +1.5 during El Niño, the SE had a cold winter 10 times, cool twice, NN 4 times, and mild once. When the DJ MEI was outside that range during El Niño (7 times with 4 higher and 3 lower), the SE had no cold winters. For the SE if we could get a DJ MEI to within the +0.6 to +1.2 range, a <-0.50 DJF AO, and a <+0.25 NAO, I’d bet heavily on a 2F or more BN DJF. —————- MEI: https://psl.noaa.gov/enso/mei/

Bullseye! The MEI warmed from +0.3 in SO to +0.6 in NO. That warming is good news as the 10 coldest El Niño winters (in the SE US, TN, and at least nearby areas to the north) had a DJ MEI of +0.5 to +1.5. So, we needed the MEI to warm up and now we’ll need the next two MEIs to maintain this warmup and preferably warm a little more. The 10 coldest El Niño winters back to 1951-2 centered on the SE and nearby were 1957-8, 1963-4, 1965-6, 1968-9, 1969-70, 1976-7, 1977-8, 2002-3, 2009-10, and 2014-5. Per Webb’s table these were the rounded DJ MEIs: +1.5, +0.9, +1.3, +1.2, +0.8, +0.8, +0.7, +1.0, +1.1, and +0.5. So, range of +0.5 to +1.5 for the DJ MEI with a mean of +0.95 and a median of +0.95. So, sweet spot near +1.0 for the 10 coldest in the SE and nearby. The NE’s list is probably not too dissimilar. El Niño SE winters with DJ MEI within +0.5 to +1.5 that weren’t cold: -1958-9: +0.7 cool -1979-80: +0.7 NN -1986-7: +1.1 NN -1987-8: +0.9 cool -1991-2: +1.5 mild -1994-5: +0.9 NN -2006-7: +0.8 NN So, when DJ MEI was within +0.5 to +1.5 during El Niño, the SE had a cold winter 10 times, cool twice, NN 4 times, and mild once. When the DJ MEI was outside that range during El Niño (7 times with 4 higher and 3 lower) the SE had no cold winters. All of this likely largely applies to the NE, too. Actually, 1958-9 was downright cold there vs just cool in the SE. —————- MEI: https://psl.noaa.gov/enso/mei/

Today’s released weekly SST anomalies (which cover last week) show a dramatic cooling in 1+2 to only +1.3 from +2.1 the prior week! Nino 3 remained at +2.0 while Nino 3+4 dropped slightly from +2.0 to +1.9. Nino 4 dropped notably from +1.7 to +1.4. So, the bookends dropped while the middle two regions stayed about the same and have the warmest anomalies. This makes it currently a cross between EP and CP. With Nino 1+2 so much cooler now and Nino 4 still unusually warm for it, it is arguably a little more CP than EP. Regarding the current RONI, it is likely hanging only near low end strong (~+1.5 to +1.6). So, we currently based on RONI appear to have the equivalent of a low end strong CP/EP El Niño and nothing close to a super strength EP.

Plentiful rain on and off mid afternoon through now with thunderstorms included during the afternoon. Very gusty winds in the 40s this evening with the cold front totally unexpectedly knocked out my power ~11:30PM. So, these winds weren’t associated with thunderstorms, which occurred hours before. Now a light chilly rain with ~50 as I await with candlelight for my power to return. I hear generator(s) running. Update: Power back on 12:20AM, yay! (just under an hour out…not bad).

All of the sudden, today’s Euro Weekly for 1/8-15 came in much colder than yesterday and is the coldest for that week since it started being covered on Nov 30th: Also, today’s 12/25-1/1 isn’t quite as warm as yesterday’s.

Today’s Euro Weeklies SPV is significantly weaker in late Dec and early Jan than for any recent run. There are far more members with a major SSW in early Jan and there are even 6% Dec 27-31 after there being only one on the prior 3 runs, combined. Just for 12/27-1/7, alone, I count ~30%! Then for 1/9-16, I count a whole lot more. This is the first run with a clear majority of members with one (60%+). (For the stat nerds like me, I see ~23 sub -10, 8 sub -15, 4 sub -20, 2 sub -25, and 1 sub -30.)

The prelude to any potential upcoming major SSW is starting to get in range on the non-extended GEFS. The Siberian warming on this 12z GEFS 384 is stronger than what’s been on earlier runs fwiw. These runs will be watched over the upcoming week to see whether or not an actual major SSW appears to be coming. For a major, it isn’t just the warming, itself. It is the reversal of mean 60N winds at 10 mb that defines it:

The way things have been trending on recent Euro Weeklies, we may need a major SSW for multi-week cold potential. Hopefully for cold lovers they’ll reverse back colder. But yesterday’s Euro Weekly 2m temp map for 12/25-1/1 was the warmest run yet for that week for the E US (and yesterday’s 1/1-1/8 was also its warmest though not nearly this warm with the only E US BN suggested in the far SE US):

How have SE US temps been 1-3+ weeks following major SSWs (per ERA) in winter during El Niño? (Excluded 2/29/80 and 2/24/07 because too late to affect met winter) 1/31/58: very cold Feb 12/16/65: very cold mid Jan to early Feb 11/28/68: cold Dec & 1st half Jan 1/2/70: very cold Jan, cold Feb 1/31/73: cold mid to late Feb 1/9/77: very cold mid Jan-mid Feb 1/23/87: very cold mid to late Feb 12/8/87: cold took 3 weeks to start (very late Dec) and continued through Feb 1/18/03: cool late Jan-early Mar 2/9/10: very cold mid Feb-early Mar 1/2/19: cold mid to late Jan -So, ~half of Ninos since 1958 had a major SSW per ERA by mid Feb. vs 40% of others. -So, for the 11 that had one, all (100%) had BN temps in the SE dominating for a 3-8 week period starting 1-3 weeks after the major SSW date. Conclusion: Due to unanimous agreement of the 11 Nino cases: if a major SSW actually occurs in early Jan, I’ll be expecting a 3-8 week period of SE US BN domination starting mid or late Jan and ending anywhere from early Feb through early Mar. If instead one occurs in mid Jan, push these dates out 1-2 weeks. So, most likely period of cold due to major SSW in early to mid Jan would be late Jan-early Feb. It is possible that it will already be cold during or before any major SSW. I’m talking about aftereffects from the SSW, itself. https://en.m.wikipedia.org/wiki/Sudden_stratospheric_warming

How have E US temps been 1-3+ weeks following major SSWs (per ERA) in winter during El Niño? (Excluded 2/29/80 and 2/24/07 because too late to affect met winter) 1/31/58: very cold Feb 12/16/65: cold Jan mid-Atlantic south 11/28/68: cold Dec & 1st half Jan 1/2/70: very cold Jan, cold Feb 1/31/73: cold mid to late Feb 1/9/77: very cold mid Jan-early Feb 1/23/87: cool Feb 12/8/87: cold took 3 weeks to start (very late Dec) and continued through Jan 1/18/03: Feb very cold mid-ATL north/cool SE 2/9/10 (10 mb winds prior to this dropped to +2 m/s 1/29/10): very cold SE mid Feb-early Mar; cold Mid-Atl mid to late Feb 1/2/19: cold mid-Atl south mid to late Jan -So, ~half of Ninos since 1958 had a major SSW per ERA by mid Feb. vs 40% of others. -So, for the 11 that had one, all (100%) had BN temps Mid-Atl south dominating for a 3-7 week period starting 1-3 weeks after the major SSW date. In the NE US, 8 of 11 (73%) had BN and others were NN. Conclusion: Due to unanimous agreement of the 11 Nino cases: if a major SSW actually occurs in early Jan, I’ll be expecting a 3-7 week period of E US BN domination, with highest confidence mid-Atl south, starting mid or late Jan and ending anywhere from early Feb through early Mar. If instead one occurs in mid Jan, push these dates out 1-2 weeks. So, most likely period of cold due to major SSW in early to mid Jan would be late Jan-early Feb. It is possible that it will already be cold during or before any major SSW. I’m talking about aftereffects from the SSW, itself. https://en.m.wikipedia.org/wiki/Sudden_stratospheric_warming

OHC looked to have topped at least for now:

Today’s ext GEFS has this at 10 mb as of Jan 2, which looks like the kind of Siberian map you often see preceding a major SSW: the warmest of that is -18C, which is well above normal. That warmth then rotates N around the SPV toward the Arctic over the subsequent few days. The EPS has a good number of members with a major SSW in early Jan that appear to be associated with this same warming. So, these two ensembles are suggesting to look toward early Jan for the first good opportunity for a major SSW. This GEFS run also has a cold E US/+PNA and developing high latitude blocking the first week of Jan. By then, the MJO appears to be headed toward weak 1-2-3, which would be cold supportive. So, regardless of how mild parts of mid to late Dec end up in portions of the E US, Jan would appear to be a whole other ballgame:

Today’s Euro Weeklies SPV runs are similar to yesterday in that they don’t have any new can kicking though they maintain the Dec can kicking of the prior week of runs with only a moderately weak SPV then. A week ago the Dec SPV was significantly weaker. We need to see whether the can kicking looks like it will spread into Jan. But in Jan, today’s maintains a very weak SPV with a similar ~45-50% of members having a major SSW 1/3-22. I count ~16% (vs ~18% yest) that are sub -15, which would be a new record low for early to mid Jan. (The ~10% sub -20 and 2% sub -25 are same as yesterday.) It looks like the first clump is during 1/5-9 (from warming that really gets going in Siberia ~12/28) with a 2nd more spread out grouping 1/12-20. So, once the non-extended models reach the last few days of Dec, it will be quite telling about this first clump. Thus, we’ll start to know much more about the likelihood of that early clump being a real deal mid next week and learn more late next week. Jan 11th EPS mean: still very weak 12/8 run: 15 m/s 12/7 run: 14 m/s 12/6 run: 12 m/s 12/5 run: 17 m/s 12/4 run: 14 m/s 12/3 run: 15 m/s 12/2 run: 15 m/s 12/1 run: 18 m/s 11/30 run: 23 m/s 11/29 run: 23 m/s Check out this 10 mb temp anom and geopotential ht map for 1/8-15. Note the quite displaced mean SPV well S of the N pole at 70N and the high over S AK:

This GEFS PNA forecast tells me that Dec is likely to end up with a +PNA. Should that be the case, that would mean that every month Jun-Dec will have had a +PNA. Since 1950, the only other year with a PNA>0 for all of those months was 2009: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

The latest AAM forecast (CFS ens) is dominated for the next month by a pretty robust +GLAAM, which is typically associated with El Niño:

The latest EPS extended (bc) MJO forecast is quite encouraging if you want the best chance for BN cold to dominate the E US, especially mid-Atlantic south, late month into Jan from an MJO perspective because it shows weak MJO: Keeping this EPS weak MJO forecast in mind, look at the amplitude of the MJO when there were E US cold events during DJF: almost entirely weak

How do you explain the following from the link below? This leads us to the third aspect of the convection– SST relationship, namely the reduction in convective activity above SSTs of around 30C. As documented by Waliser (1996), these warmest SSTs often occur within the Pacific warm pool region or the Indian Ocean, with timescales of weeks to a few months, and are termed SST ‘‘hot spots’’ or ‘‘warm anomalies.’’ These regions of warmest SST are often free from convection. The crucial point that we have attempted to add to the debate is that current theories on their own do not explain the reduc- tion in convective activity with SSTs greater than 30C. https://journals.ametsoc.org/downloadpdf/journals/clim/14/5/1520-0442_2001_014_0633_otrbtc_2.0.co_2.pdf

Today’s EPS is once again not as weak in late Dec as the prior run. This is the first run without a major SSW member in Dec. But it still has ~45-50 members with a Jan major, similar to yesterday. There are ~18% of members that go sub -15, which would be a new record low for the entire late Dec through mid Jan period. Yesterday, there were 19% that were sub -15. There are 10% sub -20 and 2% sub -25. Jan 11th EPS mean: 12/7 run: 14 m/s 12/6 run: 12 m/s 12/5 run: 17 m/s 12/4 run: 14 m/s 12/3 run: 15 m/s 12/2 run: 15 m/s 12/1 run: 18 m/s 11/30 run: 23 m/s 11/29 run: 23 m/s So, despite mid to late Dec can-kicking over the last week or so, no can kicking yet for around Jan 11th. I’ll be watching to see if early to mid Jan holds in future runs or if the can kicking spreads into Jan: Compare this to the 11/28 run to see how much weaker was Dec on the old run though Jan 5th-12th is weaker on the new run:

Why is +30C a sort of magical SST? From a wx physics standpoint, why is that SST so important? Why not a different SST?

Does +30C still have the same convective significance that it had when the globe was cooler? Let’s say way on down the road that due to AGW that the entire area of, say, 30N to 30S goes +30C+. Would 30C still have as much significance? Wouldn’t the key convection producing SST be higher then? Again, I’m thinking RONI style.

1. I’m not sure what Brad’s thinking is, but I’m suspecting he prefers to keep his area limited to the tropics in deference to the ENSO regions being limited to equatorial. Actually, he goes much wider than the 5N to 5S of ENSO and uses 15N to 15S for his N of Australia area. I recall your area going much further north (to ~30N). Are you sure you should be going so far N of the tropics? Isn’t the tropical area the most important? For that matter, isn’t the equatorial the most important? 2. I realize the record Nov SST warmth that you refer to. But the globe, overall, has been at its warmest much of this year by a significant margin with many other areas at record highs during much of the year. So, on a relative basis (a la the Roni way of thinking), is it really that big a deal that the area you referred to has record warmth? Why wouldn’t other record warm regions balance this out?

The WCS PDO has risen ~0.25 the last 3 days to -0.76 (NOAA PDO probably in/near the -1.3 to -1.6 range):