December 2025 Short/Medium Range Forecast Thread

[Carvers Gap]

The 12z Euro bring subzero temps into the Ohio River Valley(western sections) 2x.  Once is around Dec 2nd and the other is Dec 6h.  There is probably some snow field enhancement there, but still...it is very cold here.  Single digit real feels by Dec 6th.  Maybe a couple of days w/ sub freezing highs for areas north of I40 on two separate occasions.

[Carvers Gap]

IMHO, there is a decent storm signal showing up IF the cold settles into the Ohio River Valley.  There are multiple CAD signatures for W NC.  I would also think there is potential for winter storm across the upper tier of the Upper South with the way that storm track sits.  We will see if this trend continues going forward.  This started late yesterday with both the AIFS and GFS trending colder.  The 12z suite is cold across the board.  It could just be a batch of data or it could be a continuing trend.

[John1122]

Thanks for all the posts Carvers. I had to take care of some stuff early today to clear up my Tennessee game time. Checking in during commercial breaks. 

[Carvers Gap]

4 minutes ago, John1122 said:

Thanks for all the posts Carvers. I had to take care of some stuff early today to clear up my Tennessee game time. Checking in during commercial breaks. 

Ah, yeah.  Thanks for the reminder.  I about forgot about the mid-day game!!!

[Daniel Boone]

30 minutes ago, Carvers Gap said:

The 12z Euro looks remarkably similar to the 12z CMC.  I am kind of surprised by that.  Winter storm potential exists on it as well.

Yeah, the Trough orientation screams gulf wave or LP Production and even hints of Anafrontal.

[Carvers Gap]

8 minutes ago, Daniel Boone said:

Yeah, the Trough orientation screams gulf wave or LP Production and even hints of Anafrontal.

I don't think that is look is a slam dunk, but nice to see 12z deterministic runs(across the board) show a great pattern.  Ensembles are understandably slow to respond.  I think a lot of the mean temps are skewed on the ensembles.  There are 4-5 big ridges out of 20 members.  The temps under those 4-5 members are skewing the mean.  If those were tossed as outliers, the mean would be much colder.  Hopefully, those warmer ensemble members begin to exit as we get closer...that could mean deterministic models may be closer to being right.

[Daniel Boone]

17 minutes ago, Carvers Gap said:

I don't think that is look is a slam dunk, but nice to see 12z deterministic runs(across the board) show a great pattern.  Ensembles are understandably slow to respond.  I think a lot of the mean temps are skewed on the ensembles.  There are 4-5 big ridges out of 20 members.  The temps under those 4-5 members are skewing the mean.  If those were tossed as outliers, the mean would be much colder.  Hopefully, those warmer ensemble members begin to exit as we get closer...that could mean deterministic models may be closer to being right.

I agree. I see the usual warmanistas on the Main Forum are using Ensembles to preach their warm Outlook still but, now calling it a possibility. Also, not wanting to admit they were sold the first Week of the Month would be warm. I like those guys personally and they're smart meteorologically speaking but, as with many have their biases and let that sway them.

Update: Upon further investigation, I see where they're coming from and partially why the , mainly GEFS, is spitting out what it is irr late December. It has a Scandinavian Block setting up. That generally forces a +AO. However, that's being brought on by models interpretation of a reflective SWE and the rebound. Sometimes the Scandinavian blocks reteograde over into the AO Domain and flip it negative.

[Carvers Gap]

18 minutes ago, Daniel Boone said:

I agree. I see the usual warmanistas on the Main Forum are using Ensembles to preach their warm Outlook still but, now calling it a possibility. Also, not wanting to admit they were sold the first Week of the Month would be warm. I like those guys personally and they're smart meteorologically speaking but, as with many have their biases and let that sway them.

I have repeatedly watched the deterministic GFS lead the way over other deterministic and ensembles at this time of the year(during past winters).  It maybe doesn't do that as we get later into winter, but it seems to do a little better(than other models) during late shoulder season and early winter.  I do admit ensembles carry more weight, but a lot of those ensemble members are cold.  At the very least, some very cold weather is not out of the realm of possibility.  And if the trend continues during future runs, those ensembles will flip.  Fun 12z suite for sure.  Pretty big cold signal for Dec 3 and/or Dec 6.  

 

[Carvers Gap]

Glad @John1122reminded us of the basketball game.  Wow.  Insanely good on offense today.

You all know that I like the Euro controls.  I went back to the last 7-8 runs.  They are alternating almost perfectly from warm to cold...every other day.  Well, here is today's, and this has support across the 12z suite(even though this was a 0z run).

This is a 30 day map for the month of December.  Lot of big troughs swinging through w/ the SER flexing as the cold retreats.  To me at least, that seams like a reasonable pattern compromise.