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@WxWatcher007 below normal air mass growing and on the advance in the latest 10 day mean.

Me too ! Anthony Masiello @antmasiello Looking forward to the 12/10 00z update. Poleward EP vectors! 10:34 PM · Dec 9, 2020

This look towards the end of December has changed for the better during the past 5 day period. Have not seen today's though.

@psuhoffman Liking the AAM tendencies and what they portend. I feel we can get a rather robust - NAO in the weeks ahead. Might coincide with an improving Pac and a growing cold air source to our NW.

Interesting to see how this evolves in the time period of interest near mid-month. Continued signs of HL blocking persist.

Finally seeing NW Canada turn below average temperature-wise. A good sign moving forward.

Potential in the NAO region and a negative NAM state will present opportunities certainly much better than last year at this time, we're heading in the opposite direction hopefully from where we were during the middle of December 2019.

Pretty sure last December 8 th this was going up, but I am old and can't totally recall.

Regarding the cryosphere, it is looking better with more NH snow cover, while Canada is getting colder. Hopefully, this has a role in January with direct cold air discharge when the pattern becomes more favorable .

Always an issue of timing as HM mentions, and yes coupling is indeed vital. One could speculate this year has a less hostile profile, possibly enabling an increased probability of coupling regarding the SSWE. Talk remains about the effect of last year's tropical fires upon the stratosphere. Seems the 15 th of this month, and the period just after, is key as to what may, or may not transpire.

There is hope. The look you posted puts pressure on the PV. May even improve the NAM state. And, we have all talked already about how the Atlantic may want to play this year in our favor, at least at times. There is growing evidence of a SSWE and even a possible reversal of zonal winds. Yes we want a weaker PV, not a beast, and yes we want HL blocking, but the eventual outcomes as it relates to our area, ( colder, snowier ) is really difficult to forecast. Do we experience a split, where does the PV re-locate to? We talked about this last year and the year before. Many times other areas of the NH benefit leaving us out of the severe cold and snowstorms. Granted, I will take my chances and see what develops in the weeks ahead.

The continuous, almost reliable knowledge, that high precip event are going to arrive shortly regardless of any five day period of dry weather has been going on for almost 24 months. You could make the case that in many of these high impact events, warmth was behind the reason why we achieved such a high precip in the first place. Active use to be a good indicator that eventually as we move deeper into winter the wet becomes white, but in this new base state this is yet another association that has lost value. That goes along with soil moisture as well . You can have a trough in the East and it can still rain in the heart of winter. Very frustrating too regarding recent storm tracks that favor areas North of us. I believe the SST pattern in the North Atlantic may have something to do with this.

As you know the Nina coupling is only getting stronger. Whether this lends further support to the weeklies is uncertain. I have read that the lag effect rules this possibility out. I respect what DT has stated, however, at least several mets and pros that I follow have stated by the time the Nina weakens and works it way into the atmospheric response we will be exiting our snow climo. I know you know all this, but I believe some have hopes set too high for a Nina year. But, looking at the weather acorss the country in 2020 with high precip events, extreme weather, etc. if there was every a winter to present a blizzard within this current base state, it is this winter.

Another positive we are seeing is AAM. As Matt noted below.

Wonder if Isotherm or Benchmark have data on the target locations of the PV in years where there was an actual SSWE in a moderate to strong Nina. Only issue or issues would be the value of the data in this present base state ( West Pac ), not to mention the very warm North Pac waters.

Doesn't that fit the seasonal modeling ? A progressively worse Pac. Shoulder months may still hold the best outcomes but I believe December is a so so month for us based on our location and climo. However in terms on the HL and the NAO domain there are some interesting tidbits. I would not hinge the hopes of winter on any SSWE. Just need to monitor and hope we get a two week period that delivers. It really is all we can hope for in this base state and Nina in general. And there really is something about a turn to warmer near the holidays, this will mark the 4 th year in a row most likely. Say what you want but it is uncanny.

I would love that!!!!! BRING IT !

Meanwhile we keep the PV in check throughout December, much better than last year. That raises the possibility of an improved NAM state in January, despite seasonal model calls. Maybe the appearence of the elusive - NAO as mentioned by others here as well. I like the recent trends of the AO . Also, few members of the 35 day GEFS family go Easterly, yes, not many, but more than a few days ago. All in all we stay in the game.

For late December, after the 20 th, looking likely we warm up, not surprisingly. Seems the models mostly correct warmer in this new multi-year base state. Euro doing poorly, similar to last year's forecast of a descending - EPO. What is even more so disturbing is the performance of the EPS and the forecast failure in this ensemble regarding the - EPO and now the complete change up. Once again modeling in this domain in general is not to be trusted. You can see below from Bamwx. The window near mid-month I think is trending more so to areas North of us. Nothing really inspiring any confidence we see any significant snow during the favored period, maybe snow showers, or a snow to rain scenario. However, you can never be certain this far out. Also, keep in mind the consistent theme of inland runner, coastal huggers and cutters. Ned to change that up to score anything meaningful manner in Jan or Feb. I am interested in the next + PNA period. Wondering though if once again our cold air source region will be a concern.Northwest Canada is finally getting a bit colder though.

@psuhoffman certainly an eye opener. This SST distribution interacting with the Nina is something new. Anthony Masiello @antmasiello Recently inspired by @Climatologist49 SST tweet, here's the raw mean ERSSTv5 SST plotted for the North Pacific (off-equator). Nov 2020 is the warmest in the data set. Since 2014, we've been at/above 294.5 K (~70.4°F). Top-3 warmest are 2018, 2019 and 2020. 9:34 PM · Dec 6, 2020

Interesting look later in the month. Eventual outcomes uncertain, however, there is definitely pressure on the vortex and also a disconnect between the spv and the tpv. London & Southeast @TheSnowDreamer Another GFS run which turns up the heat in stratosphere and really stretches out PV not as impressive of 18z from last night, but that was something. Signs of a double pinch wave 2 action this is really what we want to see for a split. One such split we had in February 2018. 3:35 AM · Dec 7, 2020

I had not seen this. I imagine one's perception can alter what is really seen here. For the record I do not endorse the Euro. It has had various issues with its forecasts and various indices. Eric Fisher @ericfisher Some new Euro seasonal data off the presses. No big changes...still a strong La Nina look heading toward January and February 8:42 AM · Dec 6, 2020

Yep.... A window of opportunity, although short. looks to exist as you mention. Possibly even extended a couple of additional days. Afternoon EPS will be telling, looking for some consistency here. Your previous comments about the NAO domain and the Atlantic in general resonate some hope for us, versus a highly positive NAO state. Matt Hugo @MattHugo81 May not last as momentum falls in the coming days but -ve AAM (E'ly) anoms have popped up at 50N as highlighted by the green 'blob' - the troposphere is seriously not in the mood for producing W'lies/a zonal mid-latitude pattern at the moment & the sPV is getting knocked about... 3:31 AM · Dec 5, 2020·Twitter for iPhone

I would imagine changes in the East Coast and locally, versus changes over the entire Conus to a degree, and including a warmer forecast for Canada lends supports for warmer near the 20th. However, I could be wrong. Modeling has been poor. I read maybe some issues might be related to less air travel/reduced data for forecast platforms. Whether that is true, I am not sure.

Thought I read here the CanSIPS latest release was a good one for cold in the East during December ? Remarkable changes once again. I imagine the next weather outcome reverse psychology flip would be a late month change to harsh cold and deep snow. I will be keeping a close watch on the AO for later in the month and the flip back, later in time hopefully, to more West Coast ridging. Not sure what to make of the Ventrice post about ocean and atmospheric increased Nina coupling as we head deeper into December. Many players to watch and the biggest drivers may end up being a combination of a few.