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in regards to the NAO From Isotherm courtesy 33andrain This is closer. On the 12z ECMWF, we see an equatorward cyclonic wave-breaking attempt which pumps heights northwestward toward Greenland. We'll see what the EPS depicts, but if the Euro continued past 240 hours, one would want to see this CWB progress farther east, thus detaching the Greenland height/action center from the Azores sub-tropical high. It's almost there. The sensible weather effects with PNA coupling wouldn't be until after the 25th.

Yes, i do remember that psu. 1985 with the intense cold but otherwise a so so winter right. Back in early Jan when you brought that up I researched and pulled up climo records for a station near by by, Wilmington , DE. I looked and scanned across Jan and Feb and sure there was that deep cold interval, but like you stated nothing really great. We sure never got the looks of JB's analogs 09-10, 03, etc. No intense -NAO. no impressive +PNA, no BM snowstorm, just repetitive cutter, surpressed, and the huger, repeat, repeat. Oh so many tihngs to mention that ae to blame but you know what we learn form it and make sure next year we look at the PDO values, the Nino, MEI, SOI, trends, etc. the QBO direction, and hope there is no SSWE . I hate them, the ROI in learning more about them was a disspointment so far. For the lenght of time the wind reversal lasted , nada. Looking the WAR and wondering the impacts we will have in the summer if the waters warm up quikly.

Four days ago when I posted on the reversal of the EPS snow mean, some said the reduced mean was still good, but presently it is matching up to what you are mentioning about week 2. Not looking good. The rest of Feb looks mediocre. A couple inches of snow in prime climo is pathetic. Even the window in early March, based on things presently , seems to be less stellar looking. We can not get blocking , been the story of the winter. Add the effect of the MJO not being productive, as you mention, and what looked great a week ago has resorted back to the typcial of this winter.

I was thinking the same thing. The wave guide over North America sucks for this threat, and the confluence is never lined up for us, even worse for areas to our NE. Amazing too, no storms to the benchmark yet , and it is mid Feb. Disturbances fly in and exit right. Maybe that changes at the very end of Feb, if we get the trough to set up in the East, as alluded to by many here. As for the short term threat, and even longer term ,say what you want about the EPS snowfall trends but it seems it is going to possibly be correct regarding less snow here than others thought , from just three days ago. Needed to have consistency and we lost it about three days ago. Lastly these threat this winter have been either coastal hugger, or surpression or cutter. And the Midwest in the target zone and the SE ridge more Nina like. We need a shake up on a grand scale.

Something to ponder and I guess @psuhoffman ponders this always looking for a lack of effect from the Nino. I know yesterday Isotherm brought severals ideas and reasons up as to why things are not working together. Nino / forcing . etc. The post below is an interestring one, as it looks upon the current - SOI. Courtesy 33andrain Posted 4 hours ago The highest AAM anomalies are actually on my side of the equator. And I think we can bring this down to what is happening with the current MJO wave caused strong WWB in the Pacific. Most of the recent WWB-associated activity has been occurring within the Southern Hemisphere. This explains the very negative SOI anomalies in the Pacific (because Darwin and Tahiti are both in the SH). The interesting thing is CFS notes this WWB continuing for a while, a whole month long. This would have continued impacts on extratropical weather down the pipeline. The activity heading out towards the Baja California, also indicates to me, the signs of a strengthening STJ, from the region up to the Eastern CONUS. It has been interesting not to see this activity, stir up major positive frictional torque activity, but perhaps it is the location, rather than the strength that prompts the +FT. I have some thoughts that are best for another time, but hopefully we see some big responses to quash negative AAM anomalies at 40N. The best way to do this starts with a +FT. Interesting times. - Zac

You are right about the NAO . And I think it is related to a degree to the QBO. But was going say, never do you see it Build SW into the Davis Straights. whatever effect we had were from what HM< called blips and or wave breaking

Amazing how poorly some climo sites North of him are doing. Might be the worse , ( IF things stay the same snowfall wise ie, not stellar ) for a Nino , even though here we know this as a Nino want to be .

Here is that entire post from Isotherm , silly just to provide a few sentences on second thought. Great post, thanks Tom ! Posted 5 minutes ago Science is all about advancement, usually due to anomalies that emerge spontaneously in any given dataset. Most scientific advancement occurs not as a function of status quo, but because something atypical, aberrant has arisen in any given field, and the scientists who are independently minded (and financed) enough to pursue those anomalies, are generally the ones who pioneer and "break ground." Before I get into this, just as a disclaimer: it is still entirely possible that there's a "late-game comeback" with respect to this winter, but, it is apparent enough to me at this point, that the winter deserves/warrants a re-analysis post of sorts, regardless of how we finish over the next month, which may or may not ameliorate the widespread busts of this winter. Over the past few weeks, I've used some time to investigate, and believe I have a cogent hypothesis regarding the failings of this winter. In retrospect, I am rather disappointed in myself, being one who tries to be as meticulous as possible in research, that I missed this; however, it's easier to say such in hindsight, and I may not have detected this, but for the miscalculations of this winter. We had quite a bit of +AAM in the atmosphere this winter, but I think to some extent, in not exactly the "right" places, to induce the necessary countervailing easterlies in the high latitudes. The lack of FT cooperation courtesy of the meager Nino forcing was a major factor, which would have produced more sub-tropical westerlies / +AAM, initiate the STJ, form sub-tropical TROUGHS, and thereby weaken the polar jet. We have had a lot of sub-tropical RIDGES this winter, more La Nina like. I do strongly believe the issues with respect to this winter's failures goes even deeper. Retrospectively, the tropical forcing pattern during much of autumn 2018 more closely resembled a La Nina, w/ subsidence large-scale over the Pacific, and more uplift over the Indian Ocean. This did attempt to flip somewhat in November, which is partially what led me down the putative rabbit's hole, prior to reversing back toward a Nina-esque tropical forcing regime in December. This was an aberration year in which November's regime certainly did not augur the mean winter pattern. Additionally, the positive 30mb QBO hurt us and destructively interfered more than anyone thought in my opinion. We were expecting that the -50mb QBO, which has high correlation to SSW events (that truly helped!) would countervail. Unfortunately, yes, the negative 50mb QBO produced a SSW, but it also tends to intensify the MJO/intraseasonal signal. Along that vein, I actually think this winter was too UNSTABLE in a number of ways. The MJO simply did not cease: constant propagation from amplified phase to phase, obviating any stable PNA or cold pattern from becoming locked in, compared to winters in which we stabilize in the colder MJO Nino phases. The negative 50mb QBO and thereafter the massive SSW only aided further to augment the incessant MJO signal. Then, the 30mb QBO, which I now think is really more important than the 50mb QBO, aided in stabilizing the tropospheric polar vortex, and decreasing the very necessary tropospheric receptivity to blocking. The unpropitious 30mb QBO, the negative 50mb QBO induced intraseasonal amplification, unstable MJO, and Nina-esque forcing, precluding FT cooperation, sub-tropical +AAM, sub-tropical troughs, and polar easterlies -- were all the factors in my opinion. Furthermore, the negative 50mb QBO, coupled with the cooling tropical stratosphere as a function of the major SSW event (I have noted this before), and the abnormally warm off-equator SST's in the West Pacific, aided in expanded hadley cells, poleward / retraction of the northern stream, yielding a less amplified, more disconnected, Nina-esque type of paradigm. Further, the very cold tropical stratosphere led to a convective disarray, much like a low-cap T-storm day, wherein destructive interference from rossby waves, and MJO amplification in the warm phases was frequent. The NAO has been trying to go negative this season, evincing pretty positive geopotential heights over Greenland, but the Azores/sub-tropical high never departed, which has kept the NAO calculation technically slightly positive thus far. I think that's Nina-forcing and QBO induced largely. Notice in the below composite, and you'll see even on model data going forward, we try to achieve the higher heights in Greenland, but it doesn't DISCONNECT and DETACH from the Azores sub-tropical high, thus, Europe remains mild, rather than the classic undercutting jet -NAO signal. Regarding the AAM point; this is a highly unpropitious / unfavorable diagram right now, if you're looking for high latitude blocking of significance. +AAM in the wrong places. The belt of easterly/-AAM deposits in the sub-tropics tends to induce more nina-esque sub-tropical ridges, and indirectly, intensify the polar jet, tending to countermand sustained blocking. http://gsdmsolutions.com/~gsdm/clim/daily_total/glaam.sig.90day.gif That needs to alter for any major blocking to occur. Finally, this particular QBO permutation (similar to this year) has only occurred two times since the late 1970s, namely, a +QBO descending at 30mb while the easterly -QBO at 50mb maintained. Those two years were nina like, with amplified intra-seasonal signals. One of those winters was one of the worst winters on record snowfall wise in our local area. Now, with all that being said, these are hypotheses, and correlations, with arguably debatable causation chains, but evidence of causality in meteorology is quite difficult as it's nearly impossibly to control for confounders and isolate the pertinent variables. Nevertheless, I am satisfied with re-analyzing this winter, and I will certainly not make this particular mistake again. As far as the remainder of this winter: the WWB looks good, as does the MJO propagation, but will the atmosphere respond? Or will the Nina-esque tendencies w/ atypical AAM distribution, and dichotomous QBO keep the blocking muted? That seems to be what models are currently indicating. Like I said, there is a chance for a late-game "save," and then, hopefully, all of the above will simply be good, abstract discussion regarding my take-aways going forward. On the other hand, if there isn't a late game save, the above is effectively a post-mortem on the issues underpinning this winter's miscalculations by virtually everyone if not everyone in the meteorological community this winter. Thanks for reading. Tom Posted 2 minutes ago Added this paragraph into the above: A short summary of the problems: The Pacific was the largest problem; stronger blocking would have countervailed, but that wasn't the principal issue. The AO will average slightly negative for the winter, and the NAO probably near neutral to slightly positive. It was the pacific - due to reasons expounded above, and secondarily, the lack of more effective blocking, intraseasonal amplification / hadley cell expansion, due to the SSW and QBO as well as SSTA profile.

Seems when you look at the QBO for this winter we have a rare occurence. First time I heard of this combination taking place. @Isotherm was talking about things this morning. He states there are several things at play in regards to why we have not seen the typical responses including the blocking. I brought over this section from his detailed update over , since we had touched on the QBO earlier. His entire post covers a lot more, and is over at 33andrain. He states : <<< Finally, this particular QBO permutation (similar to this year) has only occurred two times since the late 1970s, namely, a +QBO descending at 30mb while the easterly -QBO at 50mb maintained. Those two years were nina like, with amplified intra-seasonal signals. One of those winters was one of the worst winters on record snowfall wise in our local area. >>>>

Just for curiosity, I wonder if the way the CFS gets the block going is from a rather deep North Atlantic Ocean storm , sort of a wave breaking event and a NAO response then it goes form there.

The NAO issue might have something to do with the QBO and how it is moving since late November . I also mentioned in that other post I did where the met stated the QBO might have halted the proper reponse from the SSWE to downwell in a typical manner. and he mentioned again, ( backtracking ) the unusual nature of the SSWE , how it was driven ( wave 2 versus wave 1 ) and the way the main vortex split into 3 may have as he stated diluted the response . All very interestiing maybe just maybe a short bit more sudden wind reversal and then a recovery would have been better in my mind, but I am really reaching. also think base state leading into to this winter, December was horrible in terms of the SOI , so again what did that effect have.

might be the gradient SST we spoke about , or maybe the extreme warm waters East of Aussie. I know we mentioned that as well. Bob spoke of the Waters East of Japan, to me the PDO looks Ok, not bad enough to cause a huge impact. But, not sure.

@psuhoffman courtesy 33andrain . I bolded some parts that I felt were interesting Posted 3 hours ago @MattHugo, There was evidence in favour of the E to W transitional QBO stage supporting SSWs occurring, but not necessarily propagating all the way downward. I believe for that we needed a predominantly wave-2 driven vortex split event, instead of the mainly wave-1 driven displacement-then-split event that we saw. Reason being that the former drives a much faster response that would likely have outpaced the descending W QBO and established major easterly flow anomalies in the troposphere. The much slower 'drip-down' nature of the event we've seen instead has allowed the W QBO to become a blockade that's kept most of the negative zonal wind anomalies in the stratosphere. I have a feeling that the manifestation for a time of a very unusual three-way vortex split right after the reversal initiation may further have impeded the downwelling by distributing the negative zonal anomalies more widely, essentially making them more diffuse. At the time of the SSW, part of the response was a cooling of the upper troposphere above the tropics, enhancing convection even where the base state doesn't support it. Alongside the negative zonal anomalies, the SSW-driven positive temperature anomalies have also been held in the lower stratosphere, keeping the upper tropical troposphere cooler than usual and allowing the convection to continue to behave in ways that don't tie in with the Nino base state (interference with the patterns the Nino base state otherwise drive being the scrambling of the tropical-extratropical processes that Tamara refers to). Climate change may have taken this even further than it would otherwise have gone via increased overall oceanic heat content, but that's a matter of debate - to me the stratospheric mishaps seem more important for this particular winter's turnout. I think we can see a good example of the interference this coming week; the neutral ENSO MJO composites (top row) fit the ECM 00z much more than the Nino ones, despite AAM and GWO observations indicating that it would usually fit more to the positive ENSO composites; GFS fits mostly the neutral P6 composite before seemingly jumping straight to something akin to the P8 neutral composite (see below, left) with little P7 response - probably due to how it stalls the MJO in P7 for a while; continued eastward propagation is needed to bring about the typical response to activity within a given phase of the RMM plots. The negative NAO-related UK cold potential for late this month and into March depends on how well we can break free of the Nina-like interference and so bring about an MJO P8 response more typical of the Nino base state. So more toward the right-hand composite than the left-hand one. Note how I'm saying 'more toward' here; the composites should never be taken too literally (ideally we'd have different ones for each possible combination of MJO phase, GWO phase and AAM tendency, but there simply aren't enough historical years of obs data to do this meaningfully!). As you can see - the temperature regime across the UK will be extremely sensitive to how much the interference gives way.

I am going to bring over to this thread some good insights about the PAC and the evolution of the SSWE, It seems to touch on some things you were talking about. Does not answer everything but touches on some good theories. I am going to look around today about the SE ridge you brought up a little while ago.

Your posts are well balanced psu. I think you have to present the good and the bad. Just because I mention a negative does not mean I am cancelling winter threats out there in the long range. But, discounting bad runs, or trends and sugar coating things is not cool, then you are biased. I think the purpose of this thread is the long range and the good and bad. It is also a platform to ask questions about the long range, learn from one another and seek answers to things that are relevant regarding the weather patterns and drivers that guide the long range forecats for our forum.

Your mower might sink

I think this stuff is what spooked Don S. Moving back to seven from eight. I admit it has been a bizzare winter. I mean the hell with how much snow falls, from a modeling and association point of view, this has to be the worse winter ever for results that go against what you would normally expect. I think certain long range forecasters have stopped posting out of the boy who cried wolf saying. For all I know a blizzard could strike in March but damn these models are having the hardest time.

The positve trend the EPS had for snow for the past four days has reversed. I don't really think this is exciting , given it is a active 15 day period. But, maybe the best potential is after Feb 27. Certainly the EPS is not as enthusiastic as the GEFS. I am only using this tool as a guide and not gospel. Must be a mixture of events. As for screwing the mean, I did not look at indivdual members in regards to that. I know Bob spoke about a mix in the various members, versus all snow in his updates a little while ago. Certainly this can, and will change.

Must be over 21 to view this :

I wager we get a -NAO and A MECS late in Feb or early March . If we get the -NAO maybe early March is a better bet.

The flow in the NW Atlantic, the boundary and the indices at that time dictate that might be a big one.

Good tip

Wonder if that NAO comes along in the lag period ala Feb 26 th to March 7... . HM can you follow up? please

way to go Kevin........ LOL

The Pac forcing looks great this morning, and now you see the indicies starting to line up with a typical MJO phase 8 and then a phase 1 composite. Out in the Pac now is the perfect storm lining up to produce snow for our region.