GaWx

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):

Keep in mind that this Dec 7th warming has been well modeled for awhile and I assume you realize this is not anything close to a major SSW, which I figure you know requires the mean 60N winds at 10mb to reverse/drop to <0. As one can see on the EPS run below, the 10 mb wind is still way up at ~+30 m/s as of 12/7. So, the current warming is at best considered a “minor” warming. Per this EPS, the first chance for an actual major SSW isn't for another 3 weeks with the best chance not til January. That’s when the real deal may come:

I agree that phases 4-7 have tended to be underestimated for the last few years due largely to the tropical warm WPac per met. Brad Harvey. As I’ve said, he looks at the tropical WPac area N of Australia. That area actually remains cooler than it has been since 2015 and significantly cooler than 2021-3. But what’s happened over the last 7 days? Have the forecasted phases 4-7 strengthened? A. 1) GEFS (bc) run from 11/30: 2) GEFS (bc) run from today: So, today’s GEFS is actually slightly weaker in 4 and significantly weaker in 5-7. ——————————————— B. 1) EPS (bc) run from 11/30: 2) EPS (bc) run from today: So, today’s EPS unlike GEFS is a bit stronger in 4/5 and the first part of 6 vs the 11/30 run. However, it then curls back into the COD beyond where the 11/30 run ended. So, it is a wash over the last week between the changes of the two models. But note that neither of today’s models has it strong at the end with GEFS just outside the COD in 8 and EPS weak inside the COD of 7. Hopefully, the models won’t trend stronger then and that the actual trek into 8/1/2/3 will end up weak. That’s because weak MJO would mean a much better shot at cold late month into Jan vs mod to strong MJO per this diagram of DJF MJO for E US cold shots:

Yeah, per last few extended GEFS and Euro Weeklies, the chance for a major SSW (say when 10 mb winds actually go <0) in late Dec is quite low as of now. The Euro has pulled back substantially on late Dec chances vs earlier runs. But just a few days into Jan, the chances pick up substantially meaning the 2nd week of your two week window has a far greater chance than your 1st week. The EPS is showing right now the best chances for 10 mb winds to first go <0 Jan 2nd-20th. The GEFS suggests best chances Jan 4th or later. Of course, getting one at all is still far from certain. But the signals are there and are probably about as strong as they’re going to be on models still this far (3.5+ weeks) out.

Absolutely awesome and as weak an SPV as on any Euro Weeklies run yet in early Jan! Still, we need to always make sure there’s no can kicking/mirage effect. There’s been some of that in mid to late Dec with not as weak a SPV vs earlier runs. OTOH, for now, I’m not seeing slippage for ~Jan 11th potential, which is where the greatest potential is currently centered. This run appears to have ~~50% of the members with a major SSW between 12/27 and 1/20! The mean EPS gets as low as a mere 12 m/s on Jan 11th vs a climo normal of 33 then! I’ll compare the Jan 11th mean to prior runs to see if there’s can kicking then: today’s run (12/6): 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, no slippage and if anything the opposite with the 12 m/s the weakest yet for Jan 11th. I count 19% that dip to the extreme level of sub -15, which would be near a record low for the entire 12/27-1/20 period. There are 9% that drop to -20, 8% to sub -25, and 5% that go sub -30. Combine that with favorable weak MJO and there would appear to be so much potential for January in the E US, especially mid-Atlantic south:

I was curious and decided to do a Google search to see if I could find any study of the relationship of MJO amplitude and E US temperatures and this is what I found: https://scholarsarchive.library.albany.edu/cgi/viewcontent.cgi?article=1007&context=honorscollege_daes It backs up what I've been saying about weak MJO (including inside COD) as opposed to strong MJO tending to be supportive of cold anomalies in the E US! That's why I'm hopeful for a much colder outcome late Dec onward than 2015-6 and many other winters. Figure 13 (shown just below) in this study suggests that cold anomaly events in the eastern U.S. tend to have weak (amplitude <1) RMM signals. But this includes ALL seasons. All but one of the 17 strong MJO phase 7, 8, 1, and 2 events seen in figure 13 actually occurred OUTSIDE of winter as you'll see in figure 14 shown further down. Figure 14 below is the same except just for DJF. In this, I count a total of 47 cold E US events. A whopping 85% (40) of the cold DJF events had the MJO either just outside, on, or within the COD! A mere one of the 47 (in phase 7) had strong MJO! If you want a cold E US period in winter, your best bet by far is if the MJO is near or inside the COD, which is where model consensus says we're headed. A picture is worth a thousand words: .

Not only Dec, but the entire DJF of 2015-6 was dominated by much stronger MJO than is being suggested this time at least from mid Dec into Jan. Stronger MJO generally translates to a warmer E US. Many of the coldest spells during El Niño have occurred during weak MJO, especially left side. I posted/reposted 15 occurrences with MJO/temps at NYC/ATL in an earlier post to back up my idea. From this point forward, there were only ~10 days of winter near or within COD MJO during 2015-6, with most of that Jan 18-25. The sole big snow of 2015-6 was on Jan 23rd, which was smack dab in the middle of that weak MJO when the MJO was inside the COD phase 2 (red line): In stark contrast to the stronger MJO of 2015-6, the following 2 week progs have a weak phase 8 MJO on Dec 20th with extended model progs suggesting it will remain weak and slowly traverse 8/1/2 going into Jan: 1) GEFS: very slow move in weak MJO 8 at end 2) EPS: slow move in weak MJO 8 at end

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: