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.

[Maggie Valley Steve]

8 hours 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.

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.

Like you, I see the typical biases in that thread as well. I have engaged them way back in the Eastern Weather days and unfortunately I believe there are some agendas at play. You guys always have great discussions in your Sub Forum and I follow y'all closely!

[Matthew70]

Discussions in this forum are awesome.  There is no doom & gloom (winter cancel).  Everyone is respectful & considerate.  I have learned a lot in this forum.  As for many other forums having their typical bias, this forum has none of that.  The whole picture of what could & could not happen is always spoken in here.  Thank you to all for sharing. 
I do hope everyone has a wonderful Thanksgiving! 
 

Bring on that Arctic air!!!

[Carvers Gap]

The 0z CMC has ice for the western half of the state and typical CAD locations of W NC.  The 0z Euro is close to a storm.  The 6z GFS is just cold which differed greatly from its 0z run - even just after 100h!  The 0z Euro was one cold front after another.  I do think the SER will flex between fronts.  Could be some wild swings.  Definitely plenty to look at from overnight.

[Holston_River_Rambler]

Decent overnight runs with a front swinging through and a weak low forming around Dec 1-2. Room for a NW trend at this range. 

[Holston_River_Rambler]

3 minutes ago, Holston_River_Rambler said:

Decent overnight runs with a front swinging through and a weak low forming around Dec 1-2. Room for a NW trend at this range. 

I haven't started my WxBell or other subscriptions yet, but would be interested to see some of the individual members  on GEFS and EPS for Dec 1 -3. 

Edit: 

[Carvers Gap]

1 hour ago, Holston_River_Rambler said:

I haven't started my WxBell or other subscriptions yet, but would be interested to see some of the individual members  on GEFS and EPS for Dec 1 -3. 

Edit: 

Sitting at the dentist for a checkup, or I would post the maps.  Quick glance…there are some with light amounts west of for Apps.  The GFS deterministic run has some support for sure.  

[Carvers Gap]

The irony of looking at a monster SER for a few days on modeling…only to need a NW trend this morning.  That is what makes this hobby so great and maddening at the same time.  The CMC cuts west of the Apps.  We prob need the GFS to stay SE of us.   If that SER flexes at all, that system is going to St Louis.  But the cold pressing eastward on modeling and ensembles is strong.   I would suspect a system is brewing, but with model mayhem, I have not idea where it is going.  I would think someone in our forum area might do ok with it.

[John1122]

Little NW trend on the 12z GFS.

[Save the itchy algae!]

Little NW trend on the 12z GFS.

Don’t let it jog too much more!


.

[John1122]

13 minutes ago, Save the itchy algae! said:

Don’t let it jog too much more!


.

We know how that story goes. It'll be all over the place over the next week, I'm sure.

[Carvers Gap]

Amazingly, the 12z Euro has a very similar solution to the 12z GFS.  And the 12z Euro absolutely hammers the area with cold throughout its 360 hour run.  

I think it is safe to say that modeling is "seeing" the MJO rotation now through cold phases.  I am just going to have to file this one away for safe keeping.  I bet if I go back through the threads, I can find a similar scenario where the MJO wasn't recognized until the "last moment."  Usually, modeling(as noted the other day) will try to sustain cold while in the warm phases of the MJO.  Then, at the last minute, models flip warm.  I think we have seen this one, except in reverse.  

Now, I do think we see some warm-ups.  These are deep troughs and steep ridges.  That is going to move a lot of cold air and warm air into places which don't see things like that often.  There is a mechanism to transport subtropical air to the Arctic Circle and a mechanism to transport Arctic air into the subtropics.  During La Nina, especially early in the season before long range patterns flatten into more stable waves for winter, these wild patterns are possible.

I would suspect that we see this wild pattern persist through much of December.  I would definitely think an anafront is on the table.  We have seen several of those recently, and the cold that is present on modeling would certainly allow for one.