GaWx

When combined with the Dec 25-Jan 1 map that I’ve seen, that means the near two week long period of 12/25-1/6 centers the coldest anomalies over land in the entire NHem in the E US. Keeping in mind that there’s often strong cold air during winter in some mid latitude area at any time, this implies the real possibility of a couple of weeks of that kind of thing in the E US then.

I wish there were an exclamatory reaction emoji! I mean this is by a large margin the biggest weakening on the Euro Weeklies from one day to the next since I started following this on a daily basis. Just two days ago (11/19 run) the ens mean was delayed til 12/25 to go below climo, which was vs ~12/1 on the 11/1 run. I mean major can kicking! Yesterday it moved from 12/25 back to 12/19 a pretty significant weakening on its own. But today takes the cake with it moving from 12/19 to 12/5! The ens mean gets to as low as 21 m/s vs high 20s to 30 the last few runs. The implied chance for an actual major SSW just shot up from under 5% two runs ago to the 15-20% region today.

How would this H5 change once the MJO winds around to 8/1/2, which is being suggested for midmonth on?

Latest TAO (for 11/16-20 averaged): vs prior map warming in 3.4, especially S of equator; warmest SST >31C 170W-180 just S of equator: strongest of WWB now moved E to 150-155W:

WCS daily updates: -Latest Nino 3.4 is still warming steadily and rose from +2.07 to +2.12 -The PDO rose sharply from ~-1.19 to -1.01. That’s the largest daily rise since ~10/17. Cyclonicwx: -1+2: +1.84 -3: +2.30 -3.4 rose from +2.05 to +2.13, another sharp rise! It’s now about same as the +2.12 of WCS. -4: +1.47

There have been only 6 sub -0.25 NAO winters during the last 44 (only 14%)…so this goes back to well before the internet and first online wx BB/before many here were born! So, the frequency of even just moderate -NAO winters has been way down during winter for decades. This is in deep contrast to: -a much higher frequency of -NAO winters than 14% during the late 1950s through 1970s -a big increase in -NAO summers during the last 30 or so years

Regarding the SER: a very knowledgeable and smart met whom I communicate with at times and who I feel is objective without strong political influences and who is neither a winter weenie nor an anti-weenie has been following the avg SSTa for an area of the tropical Pacific N of Australia (120-160E, 15N to 15S) (within the MC) for years that he feels is partially correlated to increased frequency/amp during winter of MC MJO phases, increased forcing from the MC even when the MJO isn’t in the MC, and an increased avg SER strength/La Ninalike pattern. During the prior few years, it had been near record warmth. However, during Aug-Oct of 2023, it was quite a bit cooler than that for recent years. I’ve posted about this in here. We’ll see how it ends up in Nov as it may have warmed a good bit. Regardless, my hope is that the strong El Niño keeps the SER weak this winter no matter how warm this area ends up this winter.

As per what’s in the top image, Phase 8 has on average been the coldest in NDJ in the E US with phases 1 and 7 next coldest. As far as I know (I realize this has been debated), no lag time has to be added as this is what is experienced on average during each phase from what I understand. And to add based on my own analyses, I found that weaker amplitudes of each phase at least during El Niño averaged colder than stronger versions. With phase 6 averaging the warmest, a 6-7-8 isn’t usually all that cold in Dec because of the warm 6 unless the time spent in 6 is short enough. I’d prefer a 7-8-1. That’s why I’d rather not see it too warm in Nino 4 and want to see warmth move well east into central 3.4. Also, when Jan/Feb comes, phase 7 becomes mild and phase 2 cools off and even phase 3 cools off by Feb (see 2nd image). NDJ DJF:

From the hints that I’ve been seeing, I don’t think the E US is going to be affected by a consistent single pattern in December, which I realize isn’t unusual. I’m leaning toward a first half with temps averaging AN and a 2nd half with much of the area averaging BN, especially MidAtlantic south. If this were to verify, we’d be looking at a largely NN Dec as a whole in much of the E US, especially MidAtlantic south, as opposed to a mild Dec.

For the perspective vs the rest of the globe, you can see how cold at 2m is the E and C US as a whole, especially the SE US, on today’s Euro Weekly for 12/25-1/1: pretty much as cold as the coldest anomaly for any large land area as the vast majority outside of the lower 48, Alaska, and Greenland are in pink and only a few small land areas are in blue. So, this map suggests the E US could very well be headed toward another cold holiday period thanks to an El Niño/left side MJO favored +PNA.

Here we go: coldest 500 mb and 2m Euro Weeklies maps for 12/25-1/1 so far with a W Canadian block and E US trough (+PNA)/Aleutian trough: H5: 2m:

I want to make sure I’m looking at this right. Are those 500 mb height anomalies? If not, what are the reds and the blues? Edit: I got the answer. They’re 300 mb ht anomalies.

Indeed, here’s the map that Roundy showed. Assuming I’m interpreting this correctly, it appears to have the strong Canadian block (in red) that he mentioned, which is in W and C Canada and includes the NW US. That is a strong +PNA block along with an Aleutian low to its west (in blue). The accompanying +PNA trough dips down into the E and EC US (blue). This looks like a strong +PNA block for 12/28/23. This would normally be quite a cold pattern for the E US and probably with the strongest cold anomalies in the SE US. This also seems to show a modest -NAO with some red over Iceland/E Greenland and blue to the south. (This cold pattern in late Dec would be consistent with the cold E US pattern being suggested by recent MJO model forecasts for mid Dec due to weak phase 8.)

-The cyclonicwx.com OISST updated for the first time in 3 days. Nino 3.4 is up to +2.05, up from the +1.89 of 3 days ago and compared to the latest OISST on WCS of +2.07. So, the two are now very close together. Today’s cyclonicwx OISST for the Nino regions: -1+2: +1.91 -3: +2.27 -3.4: +2.05 (was +1.98 yesterday) -4: +1.49 So, per OISST 3.4 of either source with both still rising, there’s a good shot at +2.0 or +2.1 to be reported for the next weekly (the one based on the avg of this cal. week’s data). Even a +2.2 isn’t out of the question if there continue to be large rises the rest of this week though I think that chance is small. But even a +2.2 would likely still not be high enough for a weekly peak to support a +2.0+ ONI. There’d probably need to be a +2.3 in some future week to get the unrounded ONI to reach +2.0+ (what I’d then classify as super) based on recent El Niños. It is even possible that a +2.4 week would be needed. Regardless, the chances have obviously increased for a super ONI vs where they were 4 days ago.

It isn’t CP. But it isn’t EP either. It is between those. And if we get the super Nino that you’ve been forecasting, that would likely mean Nino 3.4 gets to ~+2.3 on the weeklies. That would likely keep a EP from redeveloping. The most recent weekly 3.4 is the +1.9 issued today (covers last week). So, we still haven’t even had a +2.0 weekly yet though that may change next week depending on the rest of this week.

Today’s NOAA ENSO update has these: Nino 1+2: +2.0 Nino 3: +2.1 Nino 3+4: +1.9 Nino 4: +1.5 That’s just about as flat as it can get, especially for 1+2 vs 3 vs 3.4. Thus, this is no longer a simple EP Nino. And if 3.4 continues to warm faster than the other two, it will trend more and more toward CP: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

The latest extended BoM looks similar to the extended Euro of the same day as regards the favorable MJO being forecasted for after Dec 12th: weak (especially near or inside COD) left side often means cold in the E US during El Niño winters

The latest available Euro Weeklies’ MJO forecast looks very nice for after 12/12 with weak inside COD phase 8 (which just means phase 8 with MJO amp <1), which on average has been cold during winter in the E US during El Niños..keep in mind that weak amp MJO has averaged colder than strong amp MJO:

At only a reliable 780 hours out, the 0Z 11/19 GEFS has an Aleutian trough and +PNA on 12/21 during what I think will be a left side MJO (phase 8/1). The extended models’ MJO progs fwiw really do suggest the MJO will be in those phases after 12/15 and those phases along with El Niño would support an Aleutian trough/+PNA:

Looking at the latest TAO 5 day OHC map vs 10 days earlier (ignore the area west of 180 because that doesn’t “count” so to speak), it clearly is warmer with a lot more volume that is warmer (including some that is as much as 2C warmer) than cooler. What’s easiest to see is the volume that is yellow or orange (3C+) is much larger W of 140W on the 11/14-18 map vs the 11/4-8 map. The volume of +5+ is significantly larger on this same map vs the only small volume of +5+ on the older map. The volume of 0 or lower within 165W to 180 is much smaller. So, TAO subsurface is, indeed, at its warmest so far this event and may still be warming further. I very roughly estimate that the 100W-180 OHC on this, which covers 2S to 2N, is +2.0C. I’m assuming that the OHC for 5S to 5N, had it also been available from TAO, is substantially less than +2.0C since I assume that the warmest OHC is closest to the equator. Regardless, it also just about has to be warming and I’m betting is probably close to its warmest yet this event:

- Here we go again with cyclonicwx OISST. No update in two days. - But WCS is up to date in 3.4 with +2.04, the warmest yet. Keep in mind that WCS has recently been 0.08 warmer fwiw. The implication is that cyclonicwx’s OISST might still be more like +1.96 as a wild guess though that would still be close to 2. - WCS PDO remains down at -1.27 with no sign of an impending rise. NOAA is likely -2 or lower. Not what I want to see obviously.

What source do you go by for the subsurface? Whether or not it is the warmest of the event to date depends on the source and latitude domain from what I’ve seen. I’ve been saying it has been the warmest since early November using TAO per my eyes. But the NOAA OHC time series graph is still not as warm as it was in mid June or even in late August. And then to make it more confusing, the NOAA OHC graph has been cooler than the NOAA monthly table.

There has been solid warming in 3.4 last few days (seemingly from the W portion as per TAO) but very likely not with the rapidity that the cyclonicwx.com CRW (posted below) is showing, which is 0.43C in just three days! That’s more like what the much smaller Nino 1+2 sometimes does, not 3+4. Instead, my educated guess is that CRW was much too cool to begin with in having the cooling to +1.55 for several days even while OISST was ~+1.80. @griteaternoted that the dataset he follows, OSTIA, has acted similarly. So, whereas the near +2.0 in CRW is probably pretty accurate, I think what’s happening is that a good portion of this massive 0.43C rise in just three days on CRW was really a correction for showing cooler than reality the prior days.

And if it goes the way it appears to me it may go, MJO will be back to 8/1 W/C Pacific mid Dec+.

Makes sense since the MJO has been W to C Pac so far this month and is forecasted to go into IO (2-3 11/25-12/2).