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HM is onboard

Things looking good moving into Jan. PV still under pressure even though it may temporarily get a little stronger. Scandi High and good support for a + PNA. Also looks active. Exciting possibilities next week and later in the month. EPS had some really deep members at this range for the 23 rd. Could be a rather intense cyclone along with very high winds.

The outcome for the system on the 23 rd might be similiar to what is going to happen tomorrow into Friday. Dr No probably has the right idea as @CAPE reviewed the differences between GEFS and the EPS regarding the system on the 23 rd. Difficult to think we fail moving forward with a - 4.0 AO and block north of Alaska There is generally a lag from 5 to 10 days after these indices peak negative, but I am not seeing a significant snowfall mean acrosss our area at this time.

Still very much like the period from 12/20 to 1/10.

Tomer Burg feels the period near December 23 rd will have downstream cyclogensis, but feels currently the data favors inland locations. He did stress though this is based on the "current" data.

Snow should be nearby. The real window for significant snowfall in our region might be right after this time period. Of course, I gladly take a SECS prior to Christmas. To have that airmass over snow covered ground would be epic ! The depiction of snowfall from the GEFS is interesting, thought there be more of a Tenn. Valley component.

GEFS trends continue to get colder and the extreme departures are moving East.

Another reinforcing drop in the - AO towards day 7 through 9.

@bluewave since we are getting deeper into December would that association, with the - 4 AO and the block North of Alaska, work for areas near Baltimore and Wilmington, DE. regarding snowfall ? Thanks

Oh my, unreal and eerie

Siberian Express and snow too

Well, this is a great thread by Allan where he provides composites of the 500 mb anomalies and surface tempertures based on the CPC super ensembles then rolled them forward 5 days from Dec 22 nd to Dec 27 th and then another 5 days centered on 1/1/23. Wow !!! HM chimes in at the end.

Agreed, that was my point. Certainly appears we are entering a long duration negative AO regime. This will also be the first December in many years where the robust snow cover extent in North America didn't go poof after December 20th. A healthy cryosphere, a good sign.

Compared to yesterday's AO forecast it shows less likelyhood of nearing - 1.0, also less spread. Here is yesterday's forecast. Here is today's.

Improvements out West really showing up on the modeling. The looks might continue to improve in the days ahead. Real winter weather in the East is fast approaching.

The AO is trending more negative further out in time. Looks really nice up top.

Nice animation and discussion by @griteater

Very active pattern weather pattern coming up between December 20 th and Jan 15 th. Massive arctic airmass pooling in Western Canada by day 8 to 10 and disturbances focused near our area, mostly undercutting the block, hybrid coastals and eventual clippers are possible. The Pac improves as we move deeper in December. Snowcover continues to expand South and East over time increasing the odds of min. temps falling to near 10 degrees at some point after the arctic passage(s) later in the month. Blocking wants to recycle in the EPO and NAO domains. We already achieved a statisical significant - 4.0 AO SD to add to this continuaton of HL blocking. You can see that here: https://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_nh_anim.shtml

National temps on December 26 th using a blend of the GEPS, GEFS and EPS. Brrr.....

Everything considered, including comments from several media outlets regarding frigid conditions in the East near Christmas, its not really that cold. We had colder already, teens as low temps were recorded at many locations. That was when we had the record - EPO a while back.

Can you imagine if we get snow cover prior to this arctic beast. What an opposite December from the last 10 years. It does look like a 1960's type winter pattern for a period of time, leading up to and most likely going past the first of the year.

Interesting CPC D+ 11 Analog Composite. Notice the years from the 1960's, 1970's. I believe @Bob Chill mentioned he was looking at 1960's type winter comparisons for this winter.

Well we did it ! Achieved a - 4.0 SD on the AO. Good times should follow. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.daily.ao.nao.pna.aao.gdas.120days.csv The AO looks to remain negative.

Expect some crazy outcomes late week as the jet reverses.