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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.

Nearing the 20th, right on cue to warmer.

Loving the trends on the - AO moving forward

NH Cold growing more expansive as we get to December 10th

Thanks, with wave breaking and some comments from Paul Rodney I believe about an eventual block forming in the NAO domain certainly something to keep an eye on.

Does the block increase opportunities for clippers and East Coast cyclogenesis at lower latitudes versus 2015 ? Thanks

Current Canadian 10- Day Mean forecast. Imagine this will be changing soon.

As we move closer to mid December a little clarity on developments regarding the Aleutian High.

Wonder if this time period between the 16 th and the 20th delivers a Northern stream disturbance. Some indications of upstream blocking which may work in favor regarding our latitude. Speculation only of course, some signs of Greanland blocking, maybe spur East coast cyclogenesis, or Clipper potential. Keep in mind also Griteaters post. There appears to be some roll forward/analog support.

Besides the holiday period warm up of recent years the multi-year lack of BM storms and the propensity of inland runners and cutters look as a risk to possibly continue this month. Hopefully we get a opportunity to score during mid month. One nasty cold outbreak being forecast mid-month as you mentioned. Maybe a Manitoba Mauler would be nice .

Cross-polar flow in the long range ! Awesome look ! Natural gas futures in play.

Pretty remarkable to see this forecast, of course have to see it become reality for weather outcomes, however, the trends grow stronger for a weakening vortex and a eventual improving NAM state. Increasing odds of blocking as well.

- EPO / perturb the PV / NEW EPS = Yeah baby !

Interesting

Wonder the implications further down the road, if and when, the pv weakens ? I would speculate good for cold and snow if we weaken the PV as this would improve the odds of favorable NAM state. Really liked the long range zonal wind forecast from the Euro yesterday. I believe Isotherm has Jan. in mind for a better cold and snow outcome. The evolution from mid December on will indeed be very interesting. As we read the period around mid December is key to observing effects from wave 1 event and maybe a further weakening of the PV. You can't help but feel a bit better about the odds of snow and cold here eventually .

Wave 1 configuration coming up Anthony Masiello @antmasiello Replying to @antmasiello Guidance in the extended range is rapidly intensifying the Aleutian High in stratosphere/wave 1 configuration. 2:43 PM · Nov 30, 2020

Yes, based on MJO movement and other signals. You can be skeptical, however, it would seem the evolution of the pattern to warmer near the 20th is logical. This is a long-range discussion and the period near the 20 th is weirdly associated with a turn to milder in the East.

This is so true i....t was mentioned early in the season the importance of the cryosphere The latest 10-day mean temperature from the Canadian ensemble shows most of Canada is above normal. Granted it's cold for Canada but not cold nearly cold enough for us as you mentioned. Hopefully at some point during the winter Canada can be loaded with extreme cold which coincides with a - EPO discharge. Also hoping any future - NAO occurs as well after a Eastern Canada cold period.

As mentioned above, the change to warmer at Christmas and beyond is rather clear. Just like clockwork again. It is remarkable the change to warmer in the East near the winter solstice.

" Transient pattern " , the new 2020 weather buzz word. Not to be confused with the visual 1 inch mean snowfall maps always posted last winter. cough cough .... Paul Rodney I believe may have latched onto this pattern and the subsequent change later in the month of December to warmer. I always mention the 20th of December, as that has been golden in terms of the change to warmer the last 3 years, and maybe longer. But, maybe we do a continued progression back to a Nino-ish pattern in January. Again, we are in a new age of weather drivers, and as some here have mentioned, the West Pac / MJO and standing wave will all have a lot to say about the outcomes in Jan and Feb. Nice to at least see some influence here on the PV. Maybe a harbinger for January, or not. At least it is not 70 degrees after today for a while.

Lots of waves...... as HM posted, on would occur as wave lengths changed.

Can you kindly post the Euro ensemble AO, PNA and NAO please. I am asking because the AO really seems to go deeper to -SD than a couple days ago from the CPC site.

Update is in on the extended Euro. It does show a weakened strat vortex from mid December onward.