Snowy Hibbo

It would make sense if you are expecting a w2 attack, but I think the SSW will be over by the time that can occur.

Looking at this, it looks unlikely that a w2 event would occur. Where would get the energy to do it? And where would it go? Having a warm Strat blob in the Atlantic, just West of the UK, would be great for you guys, but is it going to happen? Probably not. And as you said, looking similar on other models.

Although I got it wrong (Some you win, some you lose), I did successfully predict that the +MT was going to be as large in amplitude as the -MT phase before it, given rise to the thought of cycles trying to balance each other out, as of course all energy/matter wants to reach rest, so it makes sense, that they try and equalise each other. The weak +FT cycle is worth noting as well, it doesn't have an awful lot of power within the GWO calculation, but it certainly could slow down any rise, should it go negative with a 5 day or so lag. Like I said before, I fully expect the high amplitude GWO cycle like everyone else (the period we are leaving was the only disagreement), as a precursor and a main effector of the SSW we are going to see. We should start seeing the Aleutian Low, setting up in the next 5 days. I have seen people looking at January as a SSW date for this stratospheric cycle. If a SSW is to occur, it will occur from the 26-28 Dec. This gives it a start (around the 18th or so, when the PNA starts to change, so it makes sense that it's momentum flux anomalies would increase by a large proportion by this point ), and about 10 days to weaken to the bottom of this warming cycle. And I still think we will get to a technical SSW.

Yep, the whole idea of the +EAMT driven NP Jet extension is to set up a strong Aleutian Low, which in turn enables a -EPO to build. Once those start occuring, it doesn't really matter if the jet retracts, once it pulls the -EPO/+PNA ridge into place, allowing them to build.

But EPS is on every high like ratio tweet, so it must be correct.... People think that snow posts get the most attention, but my theory is that quite actually warmist and mild posts that are engaged in finding the opposition and the divide of people who want snow, get the most attention. We just don't see it, because people are cognitively disliking the post. And we start getting into these cycles, these echo chambers, of "EPS brings us snowfall when it is time", so they treat the EPS as gospel, particularly when it shows a warmer period. "Move on... nothing to see here..." But the problem is when people who have credentials start blasting this out (and the same goes for when GEFS' biases are hit, and they start blasting out troughs that are never gonna happen, same for GFS LR storms). The whole culture generated by 'LOCKITIN' tweet pages and pro meterorologists posting bias ridden models, and fantasy island plots without disclaimer or noting bias. I get there are only 280 characters, but this is why simply Twitter is a completely flawed system for spreading weather information. People literally treat some meterorologists on Twitter like the gospel, you always have to compare weather info. But then again people are stuck in echo chambers spreading the same biased information, because that is what these mets and other weather bloggers/tweeters, etc, have brought them into, because it boosts whatever they are selling. People need to come to places like this, where they can have proper discussions about the weather. Looking at a single @Isotherm or @earthlight post, would deliver you into knowing roughly what the next few weeks have in store. But on Twitter, a decent portion of tweeters care more about clicks and big storm potential, than actually showing what is going on. I post on other places like Twitter, etc, and I keep hitting brick walls, because people are not open to more than what they can see. They focus on one thing for their forecasting, which is fine to have a focus, but you have to see the bigger picture, or you are going to hit walls in the kinds of timescales you can see out to. Everyone can see 5 days ahead, but do you want to open yourself to the possibilities of exploring beyond that? There is so much development in the field of meteorology, scientists working hard to connect the dots between the stratosphere, troposphere, the GSDM, etc, etc, and people are still just looking at GFS and EC as their only source of forecasting material. And Twitter (and certain other sites) only serves to perpetuate that. I have been given literal videos and presentations on how the MJO ( and by extension, the GSDM) does not equate to US winter weather, going line by line into how there is no connection from tropical weather to extratropical weather, and it's all magically the result of the AO, and the PNA. How does the PNA get there? How does the AO get to a dip of negative? These are questions worth asking, but many just take a teleconnections chart, and write away. Rely on nothing, question everything. It's extreme, but in this world of misinformation in the weather world, we need to think about everything and put it into context of the pattern. It's okay to have different opinions of the pattern (I have had my fair share of different opinions), but not if you are basing it on a GFS LR tweet, or some random tweet about the AO dropping 3 points negative in four days time, based on nothing, but the "vibe". We need to think and analyse every post with questionable motives, content or focal points. Stay safe out there folks Sorry for the rant, but it needs to be said.

Welcome to the Tele thread @Thomas Roundy. I host some AAM Composites here. https://snowyhibbo.home.blog/aam-composites/ Those composites can be compiled using this tool from NOAA: https://www.esrl.noaa.gov/psd/cgi-bin/data/composites/printpage.pl Nicholas Schiraldi keeps GWO composites also on his page: http://www.atmos.albany.edu/student/nschiral/comp.html I hope this helps.

Yeah okay that's fair. Normally the jet would be a bit further south and undercut the -EPO ridge into California, but with the poleward shift in the NP jet, would mean not a full extension (which is good for negative heights in the Eastern US as you state), and the potential for a split jet. But by and large looking at the whole Pacific, it still looks like an extension through Xmas IMO which in turn helps to build the ridge anyway, with the Aleutian Low on board.

Interesting because the GFS Phase diagram shows it entering the Jet extension phase around the 18th or 19th, which matches the forecast of many experts like @Isotherm, and others. So I am not sure about it extending on the 17th onwards, and then suddenly retracting just as it starts to get up. It doesn't match the pattern to get the PNA positive on the back of the poleward shift, as the pattern progression suggests.

With all due respect, I still think you are underestimating the Phase 1 > 4 GWO progression. It's not going straight over to Phase 5, the -MT anomalies were significant. And this sets up the temporary strength in the SPV (after weeks of smaller scale SPV attacks), that you are discussing later on in your post. It just needs that proper -AAM kick to get it to work effectively, which I still think will occur in the next week. I do highly agree (as you have seen in my current posting habits) with the strong +AAM that you suggest in the final days of December, throughout January, and the GWO Phase 6 & 7 "hover" period. In order to get there, it needs a contrast in negative anomalies, not just tendencies in my opinion.

Nice @Isotherm Just to add to that, because of all of that, there is a good chance that the first two weeks of January will see a colder pattern, given the continued push of the STJ (via +AAM forcing, via recent climatology and the feedback loop caused by the SSW), and the tropospheric impacts of the SSW (high latitude blocking).

Latest EPS 46 is now out as @PB GFI has put the weekly maps out. Focus is on the cold January, turns cold in the last days of 2018. There is probably an over-focus on the SE US based ridge, and I'd suspect it would push more to Greenland via a more northern route just before Christmas. It also seems to be wrong with the timing, there will be definitely enough westerly momentum to get rid of that ridge out of the CONUS domain by Xmas. The Aleutian remains expansive beyond the short term, being a precursor to a SSW. In the first days of January, it pushes south (more Nino like) and strengthens. This with the disintegration of the B-K Sea Ridge shows the end of momentum flux to the strat around New Year. This will be plenty, and would keep the stratosphere from being ripe for another SSW well into January and February. We end with a -AO, and a rough -NAO. Doesn't look bad for Europe either, in terms of troughing.

@MattHugo The above post from the winter thread may be of interest. The B circle showing the easterly momentum around the Arctic, is probably more a result of the -AO in the latter half of November.

Day 6 - Barents - Kara Blocking Day 7+ Aleutian Low with influence on SPV. That's a lot of room to grow for a SSW or Strat weakening of some kind (and also a great +EAMT setup in terms of synoptic pushing). I bet that we will see that blocking over Quebec, move over towards Greenland and over the Arctic, to eventually link with the B-K sea blocking. A nice w2 attack in 10 days on EC 50hPa. A split is an interesting subject. It's also interesting because everybody else on the block is against the idea. GEFS, GFS Op, Navy ensemble, GEPS and NASA's GMAO model are all downgrading w2 amplitudes, and pushing up w1 amplitudes at the 50hPa level. So it will be interesting to see where ECMWF Op will see itself in the next couple of days in terms of stratospheric forecasting. Obviously a split would be more effective in terms of reversing the zonal winds, and causing a full blown SSW. Probably a greater tropospheric effect too, according to the strength and location of the displaced halves of the vortex.