Phil

Flat ridge.

Lol, no reason to take it that far. One great event can make an entire winter worthwhile, IMO.

Well the monthlies just came out a few hours ago, so whatever he was praising it certainly wasn't this.

Obviously just a model, and even verbatim it doesn't preclude a few decent periods. Overall, it's a disappointing run.

Yeah, very familiar looking (last winter comes to mind). Combine the 500mb anomalies of 1974/75, 1974/76, and 1999/00, and that's basically what the monthlies are showing.

New ECMWF monthlies are ugly..complete about-face from the October run. Every month from December - March features a +EPO/GOA vortex, neutral PNA/flat ridge south of the Aleutians. Looks sort of like 1974/75 or 1975/76. January and February are particularly horrid looking, with a giant vortex from the Aleutians all the way through Alaska, into the western Arctic. Strong west/southwest flow dominates both months. End result is a wetter and warmer than average winter.

Strong NPAC blocking is favored under Niña/+QBO. However, that requires a coherent Niña state in the tropics (ideally with forcing centered around 150E), and so far that Niña background has been very inconsistent. I don't want forcing at 120E either, as it has been through most of this autumn.

Made it to 31.4 degrees here at 640AM. Second latest freeze I've recorded.

Might at least pull off our first freeze tonight. Currently 33.9 as of 245AM. I think we make it.

Really, what a snoozefest. #makeweathergreatagain

Not taking that verbatim, obviously. Just pointing out that the climatological loading pattern for a GOA vortex is indeed a flat aleutian ridge. Can be an incredibly self-sustaining dynamic.

:( http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/57788D99-5A4D-4DD1-AA53-5D6FCF34B267_zpsjletxumu.gif

Haha, yeah pretty much. I wouldn't be as worried if the Niña convective state were stronger (hence better synchronization w/ fluxes under QBO). Can't rely on that if intraseasonal forcing is dominating.

Watch what happens if that flat Aleutian ridge decides to stick around for awhile. For the sake of this forum, I hope it doesn't.

Well, the EA measures one of the dominant modes of atmospheric circulation within the NATL domain, like an Atlantic counterpart to the PNA in some respects. You'd expect some coherence w/ global temperatures given the Hadley Cell expansions are a conduit for significant extratropical warming regardless of the reason(s) for the expansion, and these circulatory changes are responsible for some of the "issues" we've been discussing here as of late.

Saw this discussed on Twitter earlier and think it's pertinent to this discussion. Another artifact of the modern day climatological boundary state is the increasingly positive East Atlantic Pattern. We're currently observing record breaking positive values, and have been for the last several years. Note how it abruptly switched modes in the late 1970s, in tandem with the great Hadley Cell shift and Pacific climate shift that occurred at the same time: http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/8F585BD5-3D8D-4BF7-9E65-E525E6AA8934_zps2id2dbtd.jpg

Poor wording. Meaning, an amplified aleutian ridge without a notably strong EPO component or deep anticyclonic wavebreak in the vicinity. That was almost solely a -PNA driven winter, something that probably cannot happen today, IMO.

Another conduit is actually achieved via the Aleutian low induced WAFz/PV perturbations (think DEC 2009, NOV 2014, etc). This is arguably easier to achieve in the modern Hadley Cell era, however this sort of event is often quick and/or can slide east of the Rockies more easily. Events like 1955/56 w/ the modest Aleutian ridge amplification are nearly impossible under today's Hadley/Walker state(s).

Huge misconception here, IMO. Flat Aleutian ridging destructively interferes with the processes that lead to the necessary amplification. It's a huge negative. The amplification occurs when that boundary state is perturbed externally, often via changes in the E-HEM circulation which induce east-Asian mountain/gravity wave drag torques. This then leads to the changes in the NPAC.

That's probably true, haha. I've just seen so many beautiful hemisphere-scale wavetrain progressions ruined by them. It doesn't affect my winter climo or anything, but I'd much rather have an anomalous hemispheric wavetrain and perturbed PV than a mundane, flat process like we've seen over the last few winters.

Definitely a better look than what we have currently. I'm just terrified of flat NPAC ridging in general. It's the primary +EPO loading pattern, and it inhibits poleward propagating vertical wave activity fluxes, which are required to keep the PV/NAM in check. Amplified, poleward biased NPAC ridging is another story.

You looking at the same ensemble run I am? The Aleutian ridge has trended flatter in four consecutive runs. That's all that's going to matter in the long run, assuming it verifies.

It's definitely Arctic, just nothing extraordinarily cold given the PV column is on the other side of the pole, and the fact that we'll still be recovering from the (ongoing) Pacific hose job. I also don't like how flat the EPS mean gets with the Aleutian ridge in the long range. That's the perfect loading pattern for another GOA vortex. Really, there's nothing more dangerous that a flat Aleutian ridge, IMO. Can be a very self-reinforcing pattern, as we've seen over the last 7+ weeks.

The overall setup is great, in my opinion. Just need to build up some cold air on our side of the pole.

Where's Rob?? He's usually all over GFS runs like this.