Isotherm

5 minutes ago, frd said:

Not sure whether the NAO going in our favor has to do with the processes HM described such as wave breaking, or if it has something to do with the wholesale changes in the SST profiles near and around Greenland, actually a portion of the Atlantic.    

I remember for year the theory of the tripole SST profile talked about by certain mets. Maybe we get several factors to work in our favor during Feb to produce a long lasting NAO block that eventually retros to the Davis Straights. 

Boy the look is sweet by Valentine's Day, if the PAC improves further near this date and afterward, could be in for multiple threats.     

Frd, there are a couple [major] reasons why the NAO is becoming increasingly negative. One is the z10 reintegration of the vortex and attendant push downward of the -ve circulation anomalies; aka, the downwelling is finally reaching the critical layers of the troposphere. And, secondly, the tropospheric receptivity to high latitude blocking is increasing by way of vicissitudes in the Pacific tropical forcing regime. Reweighting of centrally based warmth, easterly trades increasing in region 1+2, enhanced LL convergence/UL divergence near the dateline, signalling canonical walker cell emergence.

Posted this on another board. U850 wind proxy is instructive.

It's incontrovertible that the walker-cell orientation and attendant tropical forcing is altering for February, toward a more stable regime which has been largely elusive to date; namely, enhanced low-level convergence and upper level divergence near the more canonical dateline location. The U-wind at z850 is a valuable proxy to ascertain this eastward propagating WLY wind and thus convergence line, serving as a focus for tropical convection. The result of which should be the induction of the canonical Aleutian low / +PNA regime once the contaminating intra-seasonal signal propagates toward late phase 7 / near phase 8 [circa Feb 8th]. 

The Western troughing is courtesy of the slowly propagating MJO phase 6-7 signal, which has already been covered numerous time. We saw the same situation in late December w/ amplified 6-7 and resultant trough deepening in the West. I think we all realize that this winter has not "cooperated with the time scales delineated in many winter forecasts" but I believe the apposite thought in everyone's mind at this point is as follows: one no longer cares how it has been timed, but will winter ever show up? And the answer is that there's a good chance for 4-5 weeks of winter [which quite frankly, if one thinks about, a large percentage of our good winters have came in about a month's period]. The debate of course is the precise z500 structure going forward.

Let me refrain from equivocating: the GEFS is dead wrong with the circling back to phase 6. The ECMWF is closer, but still a bit too much wandering in phase 7. The VPM has been most instructive, and indicates some slowing in phase 7 in early February before phase 8 entrance at the beginning of the second week of February. So the bottom line is that the pattern, a priori, should become progressively improved.

6 minutes ago, ORH_wxman said:

If that vort on the eastern edge of the trough strengthens it could be faster development and you get a really good flash and period of Heavy snow to the coast. That is what you want to root for. 

I've been noting a slow, gradual cave by the ECMWF suite toward the GFS for this one re: worsening angular momentum from the TPV. It's now similar to the GFS in that regard. The ECMWF/EPS prior, had the TPV oriented in a much more elongated favorable manner, such that it acted constructively to the sern vort intensification. Now it depicts the TPV as a "ball of vorticity" with little elongation and thus not much aid to the sern vort; it dampens its intensity. 

It's possible this reverses, but not looking good for the more intense sfc low option right now, unfortunately. Fairly sizable error for medium range ECMWF suite.

16 hours ago, 40/70 Benchmark said:

@Isotherm Tom, are you concerned about your DJF seasonal call for a mean neg NAO?

No, not yet. The call was for weakly negative DJF NAO, and weakly negative AO as well. December was +0.6 NAO, January will probably average around near neutral, and I'm expecting February will be solidly negative (could average -1 or lower), so that should push the trimonthly average negative. We'll see.

21 minutes ago, PivotPoint said:

@Isotherm

Interesting write up Iso and very informative on the pna. I relate it to the likened of baking a cake -- the pna are the ingredients and the nao the oven. Yes, you need the oven at the right temp to get a great cake but if you start with crappy ingredients (upstream pna) then how much does the temp (downstream blocking) really matter in the end. I know my analogy is an over simplification of the concept. Nevertheless, thanks for your insigh

What's your opinion on how the western Atlantic ridge has fit into the overall EC track and if it really is a spoiler or just seems that way due to (at times) less than ideal placement? Thanks

 

@psuhoffman

Good stuff too. In your estimation where exactly do you want the tpv placement to be to allow the war progression into the nao space?

Thanks

@PivotPoint, I think the west Atlantic is a "result" forced by other mechanisms, rather than a cause in and of itself. It's partially a function of the upstream dilemma delineated above re: Nina-esque forcing, which, as this ameliorates over the coming week(s), should begin to decrease the WAR's deleterious effects. The WAR is also a function of the oscillating, positive NAO. A classic -NAO features low-heights from the East Coast across the ATL to Europe.  

3 minutes ago, Bob Chill said:

@psuhoffman

One thing other than the nao that can really help everyone along the coast is the PNA flipping postive. I know you know that backwards and forwards... just posting general (obvious) thoughts. We now have the eps, gefs, and geps building a +pna late in their runs. We can focus on the other parts of the runs that don't look good or we (entire east coast) can focus on a tangible feature that would literally reshuffle the storm track for the better practically on a dime.

Even though ens mean h5 looks like we should be warm for a time d10-15, mean 2m temps don't coincide and are still right at or below normal from the 30th through the ends of the runs. That's more than a subtle hint that buried inside means are more than just a few solutions keeping cold air nearby or overhead. My guess is that a number of members are keeping the tpv in eastern canada while the longwave pattern goes through changes in the Pac. Even if we do go warm for a time, as long as it's part of a reshuffle for the better I personally don't care. A couple 55 degree days would actually be kinda nice...

It's entirely possible that we do get a +pna/-nao combo going faster than we think. At the very least a +pna can fix a good portion of what's killing storm chances up and down the coast. In the meantime we may score some sort of event somewhere around the 30th. 18z gefs very much keeps hope alive as well. Half decent ens run for that period.

Bob, I concur, and would add that one of the primary reasons weak Nino's are felicitous for -NAO is the long-wave structure in and of itself -- which this winter has been devoid of thus far: Aleutian low, Boise, ID ridge axis, downstream trough, which naturally tends to send cyclonic wave breaks northward and force the -NAO.

25 minutes ago, psuhoffman said:

@Isotherm

Thanks for the write up. My comments with frd regarding the sswe hurting was tongue in cheek but we were discussing what’s gone wrong so far from those epic looks for this week from 2-3 weeks ago and I think it’s a combo of the western ridge and NAO. The western epo pna is too far west but if the NAO was negative that could be overcome. We actually want systems to try to cut if we have a -NAO 50/50 pattern like was advertised on the weeklies.  I don’t think the location of the tpv has been a problem (although if it was displaced further southeast it could compensate for the less than ideal epo axis) but I do think the fact it’s been strong has been running interference. It’s amplifying the flow around it and deflecting attempts by the war to pump heights into the NAO domain.  Ideally we want that tpv weak. It’s been centered right where ideally we want ridging. Not so much for you as our perfect pattern is a bit too suppressive for NYC. But a tpv there isn’t awful if it’s weak but if strong the flow around that makes it hard to sustain true stable blocking. Some ridging sure but not a true cut off west based NAO block. And that’s what we would need to compensate for the issues out west. I guess I was looking at it from the perspective of how we could have overcome the pacific deficiencies if we had a perfect Atlantic that was teased on the weeklies back in early January. But yea we could go the other way and overcome the Atlantic if the epo and pna were centered further east so I guess it’s a combo of a less than ideal on both sides. But I would rather see that tpv either weaken or displaced into the 50/50 region when the next attempt to develop a -NAO comes around. 

@psuhoffman - 

You may have a valid point with respect to non-optimal TPV location, though, intensity wise, the tropospheric vortex has been running weaker than normal this winter. The proxy of which is z150 zonal winds, which indicates upper tropospheric vortex strength:

With respect to the MJO, the apposite maps for El Nino are different than the ones you posted above. Phase 7 Jan/Feb is actually quite good, particularly in the high latitudes:

Further, VPM diagnostics have been superior to other guidance, though the ECMWF is now in concordance on eastward propagation to phase 7. This will likely continue propagating through low-orbit phase 7 and 8.

2 hours ago, frd said:

Yes they are saying the tpv had been a thorn .  I see what your saying about the way it split and such , I think Jason is mentioning that as well. 

I have not seen comments about this outside of you and Amy Butler.  ( thats funny right you are in good company with a Phd )  

I did share what Ventrice wrote and he stated a split like that results is a delayed NAO , it will arriive but not as quickly.   

Isotherm, and a host of strat guys, John Honenuk,etc, I could name 20 of them have not said the SSWE has messed up the NAO.  But, of course maybe I missed that or they have not seen a need to post about it because they share a different view.

Certainly we can get a very negative AO from the SSWE, and they stated just that . 

And normally you get a -NAO with a -AO but not at all times. 

I know HM stated there will be additionaloppurtunities to force it negative later. 

Of course there is the possibilty as well it comes on suddenly and unannouced , who really knows.  The atmosphere may be willing to go more -NAO after the shake up next week. 

The second and third weeks of Feb are a classic time for it to happen . 

If indeed the downwell effects breach the trop on or near Jan 30 to Feb 1 I look for a severe -AO drop and maybe it triggers a -NAO or we get a good pattern even without the full participation of a -NAO.  Ilove to hear @Isotherm take on this NAO messed up by the SSWE.

I do know Tom  has stated the PAC. tropical forcing has rendered it more difficult for the SSWE to deliver snowier outcomes  ( interference, etc )  but I think he is hopeful due to a slew of changes with the MJO, AAM, GWO, jet retraction that things will turn better. 

  

 

   

@frd - the notion that the SSW messed up the -NAO is erroneous in my view, though it did mess up timing significantly this winter. Here's my response to a poster on 33 which included an answer to your inquiry:

Alot of people don't see it that way

 

We have a beautiful cold period coming up and then the clipper cuts. I mean what's happening with this winter ?

 

This is a weak EL Nino and it should have been a good winter.

The answer lies precisely in my explanations which I've been posting ad nauseam in the teleconnection thread: Nina-esque tropical forcing, uncharacteristic for a weak Nino. Maritime Continent forcing will align the Western US ridge axis too far west -- near the West Coast, rather than Boise, Id, which permits cutters.

The NAO domain is not principally why snowfall has been underwhelming. 

If the NAO domain were solely culpable, then how have we had numerous snowy winters over the past - essentially decade - without a stable negative NAO?

The answer is the Pacific ridge axis has been west of ideal. The PNA is simply everything w/ respect to significant snow threats in our area. If the upstream is dismantled, it's very difficult to consolidate energy in the right places downstream.

Now, this may finally be changing, that is, more Nino-esque forcing which will properly place the ridge axis near Boise ID, conducive for us.

Re the SSW messing up the TPV -- while yes, I've always been of the opinion that this winter would have progressed well without a SSW, and yes also, the SSW did aid in messing up timing big time this winter, the SSW is not the reason for a lack of negative NAO. That's a red herring and completely erroneous in my opinion. I can point to numerous examples in which the upper SPV was located adjacent to Greenland, yet we had robust -NAO in the troposphere. 

The key is that tropospheric receptivity has been unfavorable to date to support a negative NAO. This, again, if some of us are correct in our diagnosis of the global regime, will change for the remainder of the winter, and a legitimate negative NAO signal should appear.

EDIT -- Amy Butler states the NAO is not forecasted to trend negative. That's only based upon the GFS. EPS guidance suggests otherwise. This is due to divergence in tropical forcing handling, not the location of the TPV.

Re: concerns pertaining to the lack of robust negative NAO initiation thus far:

1) Recall my last update, I noted that we would be entering a period of destructive interference post the Mid-Atlantic snowstorm, due largely to poor tropical forcing. I expected this to yield a rainstorm for the Northeast coast for the most recent event, which did occur.

2) The development of constructive interference, whereby the troposphere and stratosphere act harmoniously, was said to return after the 25th, in the last week of January.

3) The NAM has been negative; however, the weakly negative NAO ineffectual to date; why is that the case?

4) There's a misconception that the stratosphere entirely governs the progression of the NAO modality, but that is erroneous...

If tropospheric receptivity is such that conditions are unpropitious for -NAO maintenance at the z500 level, it is irrelevant what transpires in the stratosphere

If the stratosphere were entirely governing, we wouldn't have years w/ SSW events such as 2011 in which no tropospheric blocking resulted.

5) So, the stratosphere plays a significant role, but until the rossby wave train is oriented such that a proper block can retrogress into Greenland, it won't occur.

6) The etiology of the destructive interference lies principally in the propensity for upper divergence [convective generation] near the Maritime Continent.

7) This has ripple effects. It disrupts the canonical Nino-esque angular momentum cycle, by creating easterly trades in the central Pacific, lowering momentum, and inducing positive deposits in high-latitude regions which activate the polar jet such that the flow becomes too fast

8] Extratropical momentum pulsing attempts to countervail, but until the Maritime Continent convection [which has also been obviating proper SOI response] diminishes, a strongly negative NAO will not initiate

This is changing.

A weakly negative / transient NAO develops later this week, which could play a salutary role in the resolution of the 27-28th winter storm threat; although, it is largely EPO/PNA driven. Usual caveats apply, but it is certainly a threat to monitor, and the most conducive threat to date.

The Maritime Continent divergence will finally subside by the end of January. This is evinced quite ostensibly on the chi z200 propagation plots, and the easterly negative trades will subside as well, permitting emergence of more classical walker cell forcing.

It's not necessary the MJO itself, but overall divergence has been antithetical to proper +AAM transport through the sub-tropics and consequently negative deposits poleward.

Conclusion: The atmospheric pattern has changed and is much colder. The NAM has reversed, but the spasmodic NAO has permitted rainstorms for the East Coast [expected for the last event]. A real negative NAO will finally emerge as tropospheric receptivity increases dramatically by February 1st.

Notes and asides: Snowfall timing is the most difficult parameter of a long range forecast. However we get there - we get there. A forecaster should not be penalized for snows not being "evenly spread throughout the winter." If the final tally at the winter's end is close, then it's a good forecast. So, while there's been no snow to date, that will simply have to be dealt with. That doesn't intimate non-emergence prospectively. Key indicators and atmospheric changes were foreseen, and now we will watch the final dominos this week. I have read some comments here and there across the boards that forecasters promised a historic winter, etc., or a historic winter period; I simply want to make clear that those words never emerged from my end. My winter snowfall forecast from November for NYC-area was 37-47". This is still attainable.

Tom

28 minutes ago, frd said:

Exactly,  I ran the winter climate numbers for 1985 for my area. A sudden crash of temps and then back up. 

I think JB needs the cold to hit his aggressive minus departure forecast. 

I simply brought it up because I think this Feb might have the cold, ( and more than  a week of it ),  plus storms as well, that were lacking in 1985.

Sort of like the best of both worlds.   I have to do a lot more research as to the whys of that year's lack of snowfall. 

 

54 minutes ago, frd said:

I never post JB but I will once, sorry @psuhoffman

I think severe cold is possible, as we are center stage possibly for the direct impacts of the long duration SSWE. Still ongoing, still to be percieved by the models fully,  but you already see what they are modeling. 

@Isotherm talked about 1985 a few times in the ever progressing SSWE. When the peak cold reaches us I am still not sure, but there was a delay in 1985. This event after tracking it is different in terms of duration and other elements. Even if we do not challenge long term records I am sure the weather will be exciting. 

I am not hyping cold, nor do I desire cold and no storms, I feel we get both. 

It apperars the atmosphere is finally responding and interference is lessening and impact is increasing. 

  

@frd -- sometimes I see people misusing analogs. A significant commonality on one front does not necessarily intimate that the analog's every attribute should be projected upon the current year. Concordantly, this year will continue to be different from 1985 in terms of sensible weather. The reason I broached 1985 was entirely due to the stratospheric similarities, timing, of the tropospheric response (which has verified well). However, 1985, as a lower AAM year, with low-orbit GWO circuits and Nina-esque background, had a feeble STJ, and thus, moisture was generally lacking. Snowstorms originally almost entirely from the northern stream. This year, we will have a heightened AAM state, w/ nino-esque GWO cycling, and split flow structure w/ much more opportunity for moisture laden storms. 

9 hours ago, qg_omega said:

All these points remain just important today as backn in December.  Pacific remains for at least the next ten days

Your post a few weeks ago stated the following: "Personally, I believe the SSW event and possible split of the PV is a game changer to most winter forecasts and not for the better."

Why didn't you quote your whole forecast? We'll see if your forecast is correct over the coming weeks, but the NAM reversal has already occurred, and it's quite clear to me that a protracted period of blocking is ahead. So, it's far too early to claim victory on your call that the SSW/split event will cause winter forecasts to fail or perform poorly.

Further, there's a major snowstorm ongoing currently in the Mid-west, which will carry to the Mid-Atlantic coast as a significant snowstorm. That wouldn't happen, but for, a favorable GWO/MJO circuit through p7-8, and AAM pulse. It is incorrect to assert we've been in "fast flow" the entirety of January thus far.

The only piece of your post that makes a bit of sense if that the Pacific has been problematic this winter to date w/ regards to a stable PNA structure, and I noted that in a lengthier post the other day. However, that will be altering later this month as AAM/MJO and the SSW after effects constructively interfere. But, again, I don't recall seeing your winter forecast in November, so it's much easier to see these issues after they've already revealed themselves (i.e., the past few weeks).

3 hours ago, CoastalWx said:

Isotherm is right, and a few of us have been saying that. The Pacific, mostly due to the MJO, has acted a bit more nina  like.  We have had forcing near 135E, 850 MB easterlies, all which really go against Nino.  Maybe I’m wrong, but I feel and have heard that it should change later this month into February. 

2 hours ago, 40/70 Benchmark said:

I think he is acknowledging that the threats haven't panned out and is explaining why. I don't think he is hedging RE the future.

Yes - agreed - and, right, Ray [not altering the overall outlook, just explicating why we've been "fighting" to get snow in the Northeast corridor a bit more than anticipated so far].

6 minutes ago, psuhoffman said:

@frd The way he worded it sounded more negative than it really was.  In essence he was only (in a much more technical way) reiterating the progression we have been discussing for a while.  After this weekend there will be a pullback in the pattern to an average looking one with some good and bad features as the transition period takes place.  We discussed the coming rise in the SOI before another crash which is related to and coincides with a possible weak/fast traverse of the warm mjo phases.   The January 20th period is variable based on the pacific.   There is a risk that becomes a rainstorm if it times up poorly with the transition in the trough/ridge alignment out west.  There is the risk the trough digs into the central US initially.  But we all see how the pattern evolves after January 22.  So it is very possible we don't score something by then...but the core of this has always looked to be after that.  These threats before then are kind of a bonus during the transition period.  I think our best chance for a significant snowstorm or several of them... will be the very end of January and February.  That seems to be what he is saying...in a nutshell.  

@psuhoffman, thanks for the summary - you are correct. The polar field has already rapidly improved c/o of the SSW, and we have a nice Pacific favorability window this weekend c/o of the MJO/GWO 7-8 circuit which will benefit you all in the Mid-Atlantic w/ a nice snowstorm. As the AAM starts rising again this week, and MJO re-circulates, before we arrive at the period in which all factors are "working together perfectly", the PNA may be a bit unstable. This makes the 20th threat a bit risky, with unstable PNA and non-retrogressed -NAO, but that will rapidly improve thereafter, which is why I think 22/23rd--> could bring the lower-risk / higher ceiling opportunities. Everything is progressing as expected atmospherically, but as PSU said, that post was more directed toward the NY forum (applicable to BOS too) which has rolled snake eyes in every favorable window thus far.

@frd

7 hours ago, frd said:

 

Fascinating here. I believe the reversal a while back was not forecasted this low.

This is a new interim record for the date for 10 hPa60N 

We are also ahead of 1985 @Isotherm  Tom mentioned 1985 in a few posts a couple days back. Lined up with his mention of this timeframe. 

It also appears more warming is on the way. 

PV-Forecast‏ @Forecas55175638 6h6 hours ago

More

The strat. vortex is currently weaker than all other years in the ERA interim record!!! The zonal mean zonal wind at 10 hPa 60N is today (GFS analysis): -9.2 m/s Weakest zonal wind at 10 hPa 60N in ERA interim record for todays date is: -7.0 m/s 1985

 

  

Yes, @frd -- NAM diminution 1 week from SPV-split on track, as well as nascent -NAO, and more felicitous EPO/PNA domain as a function of propagating tropical forcing; ERW contamination finally decreases w/ MJO coherency uptick into phase 8 over the next several days. Good to see model data reaching concordance on the reality of tropospheric alterations today, and I think it's ostensible that the GEFS had the upper hand w/ respect to the detection phase [this was expected due to MJO disparities].

All in all, the winter outlook is still on the table.

And yes, I'm not sure if I posted this here, but below is the NYC data for December 1984 and January 1985. The SPV-split [EQBO] occurred January 2nd, 1985. The temperature reversal really intensified January 8th+. Will be similar this year.

1 minute ago, CoastalWx said:

The EC VP200 plots have handled it well....probably better than the gfs. Those wheeler diagrams can get noisy so they aren’t always accurate, but better than nothing. They do weaken it and send it to SAMR and points east as a stronger wave. But I still take it as a weakening pac jet and more favorable state. The problem is that all guidance has been too fast in doing this. I agree that a compromise could come to fruition between the GEFS and EPS. 

Right, I agree, chi 200 definitely detects the ewd propagation better. We will probably see a compromise but weighted more toward the GEFS propagation, in my view.

1 minute ago, frd said:

Old news the same as the new news. 

I guess manybe today, or in the next several,  the EPS may sense the correct MJO phase/progression.  

Speculate in a wonderful world the weeklies tonight suck, and the weeklies on Thursday show a KU potential down the road. 

However that may indeed be wishful thinking. Will be cool to see though. 

 

I posted this just now on the New England thread. The RMM plots are currently apocryphal/erroneous: 

"Yes - this is what I was posting a few days ago re: the stratospheric amplification of the MJO signal, hence the propensity for increased warmth/cutters over the Dec 20-Jan 5 period. The MJO is actually in phase 6 right now. RMM plots suffering from rw/kw interference. The ECMWF has been attemping to send the wave into the null phase since p 3, and has been correcting since. The stratospheric driving augments the MJO signal, and there's no physical reason for the ewd propagation to cease. 

The potential threat period around the 8th-9th will feature a phase 8 MJO by that point."

25 minutes ago, OSUmetstud said:

 

in reference to the MJO stuff. Eric Webb says the GFS can outdual the ECMWF re: MJO when there is a high amplitude wave that originates in the maritime continent. It doesnt make sense that such a high ampltiude wave would suddenly die like the ECWMF shows, anyway. 

Yes - this is what I was posting a few days ago re: the stratospheric amplification of the MJO signal, hence the propensity for increased warmth/cutters over the Dec 20-Jan 5 period. The MJO is actually in phase 6 right now. RMM plots suffering from rw/kw interference. The ECMWF has been attemping to send the wave into the null phase since p 3, and has been correcting since. The stratospheric driving augments the MJO signal, and there's no physical reason for the ewd propagation to cease. 

The potential threat period around the 8th-9th will feature a phase 8 MJO by that point.

18 minutes ago, CoastalWx said:

Ignoring the wheeler diagrams and looking at VP200, it’s slowly moving east. My guess is the pac jet relaxes over the next week and we’ll finally see changes. I know I said it may start to look better after 1/7....but that’s probably too early. Seems like later in the 11-15 day at the earliest. 

I suppose it depends upon one's definition of "better." KU pattern - certainly no by the 7th. However, I do believe the troposphere will be rapidly improving beyond the first week of Jan. The inchoate NAO response occurring this week, with NAM/AO diminution initiating post the first week. The new EPS coincides more closely with the GEFS now re: the NAM decline in the second week of Jan. We'll see.

The reason for the significant bifurcation b/t the GFS and ECMWF based guidance in the D7+ period is almost entirely MJO/tropical forcing related. The ECMWF has been insistent upon killing the wave, while the GEFS propagates this wave eastward. The ECMWF has been correcting more / more coherent each day with respect to the MJO; further the stratospheric amplification suggests this will carry eastward. I cannot envisage a physical reason for a rapid COD entrance. Clearly, both sets of data are intransigently insisting upon their respective solutions, and the inflection point w/ the MJO is right now. We'll know by January 1st what the picture looks like. Note: EPS much less unfavorable than the operational beyond D7.

6 hours ago, LibertyBell said:

Tom, it's hard to argue that it's been a canonical El Nino pattern when everyone seems to agree that the atmosphere has been behaving much more like a La Nina with the SOI values rather than an El Nino.

Yes, that was my point - that December was not a canonical-Nino pattern. It was more Nina-esque. CONUS temperature departures were running cooler than normal until the MJO began to amplify, "out of control" in the warm phases, due in part to stratospheric elicited feedback / convective growth, in my view.

1 hour ago, CoastalWx said:

Isotherm that does make some sense. I’m sure some other things are involved too. It’s been a standing wave more or less with easterlies too prior to more recent westerlies. We are still getting a strong PAC jet. We’ll need that wave to finally move east. I’m sure it will over the next two weeks.

I agree, Scott. Not saying it's the only variable, though I do think it's a significant one. There's quite a bit of contamination currently re: the RMM plots due to rossby / kelvin wave interference. 

The correct initialization of the MJO as of today is phase 6, in my view, and will be propagating through 7 and 8 by the 4th +/- a couple days.

52 minutes ago, Typhoon Tip said:

Not to pin anyone's ears back in this discussion... is that published.  I'm just curious, how/what is/are that physically connective tissues - if you will.  Obviously, ...goes without notice that the arctic domain is opposite the equitorial band.  That tends to stretch the direct model's credibility some but ... who am I to say. Perhaps there's some larger integral that concurrently favors both ... so they are not causally linked, per se, but are given 'boosts' at the same time.  ...heh, I like that... 

I mean, on the surface. ...certainly seems plausible do to the eerily coincident timing of this sudden onset warm intrusion in the usual SSW-candidate sigma levels over the arctic domain and the modeled acceleration of the MJO... Okay... But... SSW years (looking back over the 40 year's worth) tend to fire off beginning now anyway - do they all have concomitant MJOs' going nuts?  I'm not sure it wasn't just a coincidence.  It'd be cool if it was more directly instructive though...

Know what it almost reminds me of... well, does, otherwise I wouldn't of thunk it.  But, if you take a conditionally chilled medium of water ...say at 37 F (2.5 C) and suspend it in ice for a few moments...then, just slightly ting the side of the glass beaker, the suspended liquid medium flashes to ice. It's really pretty cool looking.  Going the other direction ... different physics mind you, but, take a boiling cup of water... run out into field five miles outside Tower Minnesota (...but ya gotta be naked for this to work) while it's -40 F ... and throw said boiling contents into the air... Half instantly freezes and half falls shimmering to the ground while the other looks like the anvil on a thunderhead kiting away as a semi-translucent airborne snowball.  

The impetus there is neither... It's to draw examples pertaining to capped conditional saturation forces being suddenly set into restorative balancing, in general ... Here's a hypothesis:  Ozone residence in the polar stratospheric vortex may be unable to absorb heat due to being at a delicate equilibrium with a PV=NRT ...But some kind of gravity wave... perhaps produced by the MJO its self ... very subtle propagates through the medium is that "ting" that allows the cascade uptake of thermal energy ... the PV flashes warm.  I dunno...just spit ballin'  

There are plenty of papers on strat-trop coupling and feedbacks, and additionally, on the propensity for enhanced intraseasonal signals in easterly z50 QBO winters.

From a physical forcing standpoint, the brewer dobson circulation strengthens significantly prior to SSW events, which cools the tropical stratosphere. As I posted on the prior page, z70 temperatures 25N-25S are approaching record lows, which increases lapse rates, inducing enhancement in tropical divergence and convective potential - i.e., invigoration of the MJO signal.

And while, no, strong MJO does not proceed every single SSW event, it is a fairly common occurrence. As said, easterly QBO winters tend to feature the MJO/strat dual pathway more significantly than westerly QBO, and there's no secret the former is a more perturbed background state.

1 minute ago, 40/70 Benchmark said:

Thank you. Your work is very educational and has helped me tremendously over the past several years.

I will remember that...verification is great, but precise causation is needed in order for true mastery of material...as much as possible within this context, anyway.

Thank you, Ray, and again, I didn't intend to imply that your call for this month was a lucky one. You've had a great handle on the pattern thus far. Hopefully, this winter will continue in accordance to what we've both forecasted.  

2 minutes ago, 40/70 Benchmark said:

I wonder if the paradoxical impact of the incipient SSW warmer pattern emerges from an analog perspective immediately preceding major SSW? It would be easy enough to find out, and thus specify as causation for a warmer interlude on a seasonal scale?

I'll bet that we can utilize this experience moving forward to more precisely forecast the evolution of the winter season....IOW, next time I will know to mention that impact of the nascent SSW when elucidating the rationale for a warmer interlude.

Fascinating-

Ray -- I don't think it's a coincidence that sensible weather tends to be warmer than normal preceding and during sudden stratospheric warming events in the Eastern US. Historically, this is a fairly strong common denominator. As I said, last year had a similar temporal association w/ the MJO amplification. Certainly, correlation is not tantamount to causation, but in light of the available literature which seems to underscore this dual pathway, and the empirical evidence of MJO amplification concurrent with precursor stratospheric warming events, I think it's tenable to assert that 1) if you're expecting a SSW event, 2) forecast a warm period for the 10-15 days preceding / during the time wherein you expect it to occur.

The upside to all of this, is it could potentially render the core of the climatological period more productive this year.

Just now, 40/70 Benchmark said:

I def. thought that we would have availed of it with some snow early, though....tough break.

I agree with your rationale of how the SSW paradoxically promoted the short term relaxation.....and also agree that that specifically could not have been forecast at a seasonal level, but the more general trends were is my contention.

 

Ok, we agree completely then. I'm mostly talking about the specific reasoning for this late December decline in sensible wx prospects.

And agree, most would have a different "flavor" of this month if the early December event ended up farther north.

5 minutes ago, CoastalWx said:

I guess my question is, does the warming causes a deeper and colder upper troposphere for tropical Convection? Is that what you implied?

Correct, IMO that is a large part of the pathway. If we note z30, z70, etc., temperatures right now 25S-25N as a proxy, they're down near record lows, which enhances the convection signal. Do you agree with this line of reasoning?