December 2025 Short/Medium Range Forecast Thread

[Carvers Gap]

The 0z Euro, 0z CMC, and 6z GFS all move a trough into the East which looks to possibly have some staying power.  The CMC is much quicker and the GFS is the slowest.  But they all get tend get to a similar point.  Starting to be concerned the Music City Bowl is going to be cold.

[*Flash*]

Happy Winter Solstice, everyone?

[Carvers Gap]

All three deterministic 12z runs bring the trough eastward w/ a mega strong -NAO in place.  Larry Cosgrove mentioned that cold could be coming back east by the New Year, but also noted the forecast is incredible difficult during that time frame.  We have seen this exemplified as models are swinging wildly from one solution to the other.  He notes the NE would take the brunt of this.  

I do think we are seeing December 28-29th as a step off point towards another cold front of the seasonal variety.  That could have a decent amount of amplification with it, so it will need to be watched.

It is what happens immediately after that which I think will determine the first weeks of January.  12z has a good look.  I think the NAO is making its presence felt on modeling now.

I normally defer to ensembles, but maybe not this time.  I think ensembles are way behind the curve on this pattern right now.  It is unusual for that to happen, but it does occur w/ complex setups.  The Euro control and its ensembles(for the Weeklies) were night and day yesterday. 

I think this is one of these patterns which would be easy to over analyze.  For now, I just admire the wild solutions that are out there.  Kind of fun!  

I personally think the end game of this is very cold air getting dumped into the Lower 48.  The mechanism is in place to unload a majorly cold airmass southward.  We may not have a long lead for when this occurs.

Things to watch as we go forward....strength and duration of the NAO.  It is the counterbalance to the Aleutian low.  

[Carvers Gap]

One other thing LC noted last night was that the MJO has no real clear signal - at least that is how I read it.  He has cautioned multiple times about using it recently.  He noted it was almost impossible to decipher the phase it was in.  

He did add that there is room for cold and snow further south after January 20th.  I think he has likely nailed this.  When I read his original forecast back in the fall, I was like, "Wow.  That is really sound reasoning, but it conflicts with so many of the other social media seasonal forecasts."    Heck, it conflicted with mine which came out during June of last summer.  Veteran forecasters are savvy.  And the great thing about the human brain....it doesn't tend to get caught in feedback loops.  

I think we have some circles of thought where opposing ideas are not allowed to be cultivated.  That leads to group think.   Back in the fall, Cosgrove produced a forecast where he cautioned that those waiting on winter would have to be patient.  It is hard not to look at the deterministic runs at noon, and think they are not gonna be in a good place by the second week in January.  

[Carvers Gap]

The normally warmi-sh Euro at 12z rolled this for the Music City Bowl...I truly hope that is wrong, but it looks like a cold front will possible slide in the evening of the 28th.  I am still waiting on my warm-up - I need a short warm-up!  This morning is the first morning I haven't run with gloves in a long time...so that is a start.

[Carvers Gap]

I guess the overall trend I am seeing at 12z is the tendency to amplify a trough over the eastern half of the United States.  Some models are doing this on the 29th(Euro).  Others are doing it with the next system just after New Year's(GFS and CMC).  I can see the path to a warmer pattern, but it sure looks like the cold is going to be pay-me-now or pay-me-later...ie the cold is coming with the NAO block in place and it is a matter of time.

[Kentucky]

I really respect Eric and if he's going to be wrong he'll be backtracking on Twitter soon. 

[*Flash*]

25 minutes ago, Kentucky said:

I really respect Eric and if he's going to be wrong he'll be backtracking on Twitter soon. 

I respect the knowledge base for sure. Just not always the way its conveyed or responded to when counters are presented. Either way, I believe it's wise we maintain a diverse portfolio of follows this time of year. Lot of credible voices out there, not all are doom and gloom on this first day of winter.

[Matthew70]

4 hours ago, *Flash* said:

Happy Winter Solstice, everyone?

Webb is knowledgeable but changes his mind all the time.  He’s more negative than he is positive.  Seems many on other forums cancel winter before it’s even begun. 

[John1122]

Keep in mind, a lot of what Webb talks about is in regards to how things will affect areas East of the Apps. For me, I'm certain that the Aleutian high will break down, they all do. Where we go when it does, I don't know.

[Matthew70]

5 minutes ago, *Flash* said:

I respect the knowledge base for sure. Just not always the way its conveyed or responded to when counters are presented. Either way, I believe it's wise we maintain a diverse portfolio of follows this time of year. Lot of credible voices out there, not all are doom and gloom on this first day of winter.

I’m just not sure why so many are doom & gloom when it’s only December 21st. Many act like December is supposed to be a snowy month. Webb along with others I believe overthink forecasting. It will be interesting how it changes with AI taking over a lot of the forecasting. 

[Kentucky]

11 minutes ago, *Flash* said:

I respect the knowledge base for sure. Just not always the way its conveyed or responded to when counters are presented. Either way, I believe it's wise we maintain a diverse portfolio of follows this time of year. Lot of credible voices out there, not all are doom and gloom on this first day of winter.

Yeah, I'm not ready to throw in the towel on the first day of winter & Eric has definitely been wrong before. He seems to be a little more unhinged this year. 

[Kentucky]

7 minutes ago, John1122 said:

Keep in mind, a lot of what Webb talks about is in regards to how things will affect areas East of the Apps. For me, I'm certain that the Aleutian high will break down, they all do. Where we go when it does, I don't know.

I did notice Eric says compared to normal. Whatever normal is for us anymore. I suspect he'll be backtracking within days

[Carvers Gap]

The Euro Weeklies control...the majority of that is Jan 10-11.  IF that trough slides east due to the NAO, there is a window for strong amplification which we talked about earlier.  Just a control run...so TIFWIW.  At least two runs in a row of cold temps.  If that cold in Canada can ever make its way to the Gulf....sparks are gonna fly IMHO.

 

[Golf757075]

1 hour ago, Carvers Gap said:

The Euro Weeklies control...the majority of that is Jan 10-11.  IF that trough slides east due to the NAO, there is a window for strong amplification which we talked about earlier.  Just a control run...so TIFWIW.  At least two runs in a row of cold temps.  If that cold in Canada can ever make its way to the Gulf....sparks are gonna fly IMHO.

 

Carver, we should see cold fronts behind systems that cut nw of us. Happens every winter even in the warmest winters. Cools off for a day, depending on how much cold there is to work with. Any sustainable cold won't happen here unless the aleutian ridge moves or shifts for us. Imo of course. I just hope to get close to my average snow

[Carvers Gap]

2 hours ago, Golf757075 said:

Carver, we should see cold fronts behind systems that cut nw of us. Happens every winter even in the warmest winters. Cools off for a day, depending on how much cold there is to work with. Any sustainable cold won't happen here unless the aleutian ridge moves or shifts for us. Imo of course. I just hope to get close to my average snow

Cutters would help.  Where the Aleutian sets up shop as I noted yesterday is what matters.  Lots of noted uncertainty ahead.   That is what make the hobby both challenging and fun.

[Golf757075]

2 minutes ago, Carvers Gap said:

Yeah, first day of astronomical winter.  Not losing a single wink of sleep over any of this.  

There are subtle signs of an aleutian breakdown, depending on progress of mjo

[Carvers Gap]

19 minutes ago, Golf757075 said:

There are subtle signs of an aleutian breakdown, depending on progress of mjo

And honestly, after like 20ish days of BN temps....we were long overdue for some warmer weather.  

I kind of roll with LC.  I don't think the MJO is actually having an impact right now...just a really washed out and conflicting signal.  I think Nina climatology is driving this.  The trough should pull back west for part of the winter due to Nina climatology alone.  Then, as the pattern relaxes at some point in January, it may all rush eastward.  Very, very complicated pattern in the week 2-4 timeframe right now.  

The duration and strength of the NAO is likely key.  The good thing is that we now know that model feedback has caused two pretty significant errors this winter in the week 2-4 range.  As one met noted in another thread yesterday, when models start flipping back and forth....can't really trust that until it settles down.  The potential NAO and HL has upended things.  We are really one good cutter or coastal from having a pretty massive cold air mass slide all the way to New Orleans.

I think we will have a better idea by around Christmas time...

[Golf757075]

50 minutes ago, Carvers Gap said:

And honestly, after like 20ish days of BN temps....we were long overdue for some warmer weather.  

I kind of roll with LC.  I don't think the MJO is actually having an impact right now...just a really washed out and conflicting signal.  I think Nina climatology is driving this.  The trough should pull back west for part of the winter due to Nina climatology alone.  Then, as the pattern relaxes at some point in January, it may all rush eastward.  Very, very complicated pattern in the week 2-4 timeframe right now.  

The duration and strength of the NAO is likely key.  The good thing is that we now know that model feedback has caused two pretty significant errors this winter in the week 2-4 range.  As one met noted in another thread yesterday, when models start flipping back and forth....can't really trust that until it settles down.  The potential NAO and HL has upended things.  We are really one good cutter or coastal from having a pretty massive cold air mass slide all the way to New Orleans.

I think we will have a better idea by around Christmas time...

Carver I believe it will be hard pressed to get the cold further west due to the east based nao. If it morphs into west based, all bets are off. We deal with the hand delt and hope for the best

[Matthew70]

This forum is the best of any of them.  Everyone gives sound reasoning & terrific discussion as to why.  Everyone is welcoming & helps others learn. There is no negativity & winter cancel thankfully.  Yeah the pattern has not been the best for snow in TN but when has there ever been a snowy December in TN? Yet many places have had a lot of snow already.  As Carver said it’s been a well below average December.  Many days have been like a January day.  December has been a win in my book.  It’s felt like Christmas! I do hope everyone is having a great Christmas season & wish everyone a Merry Christmas! 

[John1122]

The Canadian is into the vodka for cold to close the month. Dry as a bone unfortunately.

[Carvers Gap]

If the cold air mass for Dec 28-Jan 1 verifies, ensembles across the board missed that cold air mass outside of day 7.  To me it looks like another one is right after that(roughly Jan 6-7).   As John noted, the late December cold snap looks like a dry frontal passage.  I would guess higher elevations probably see some upslope if the CMC is correct.  It would make sense that the atmosphere would wring out some moisture.  

One thing in weather, we are rarely going to get perfect placement of every feature on the map.  What we want is the feature(which is in our favor) to be the driver.  Outside of climatology Jan10-Feb10, it really doesn't want to snow at lower elevations in the Upper South.  The base pattern is rain.  So, we generally need a little bit of help outside of that window.

As is, the pattern in the weeks 2-4 is likely going to have some cold shots, and some warmups.  Timing and intensity of any longterm cold snap when/if it returns is TBD.  That is why we are tracking what happens after the cold shot to end this year and begin the new one.  

My guess...models are handling the NAO poorly (duration, intensity, placement).  That has occurred more times than I can count.  As LC noted, it makes it difficult for models and forecasters to get a handle on things.  That is creating wild swings in modeling.  It does make sense that at some point, things line-up just enough to send a lot of cold air into the east at some point during January.  But really, that is a pretty easy call - it is our coldest month!  LOL.  

[Holston_River_Rambler]

I know it’s all fantasy but I think the 6z GFS was about to give us a new years present if it had run about an extra 36 hours. 

 

 

[Holston_River_Rambler]

1 minute ago, Carvers Gap said:

My guess...models are handling the NAO poorly (duration, intensity, placement).

Yeah, wild swings based on the placement and evolution. 

[*Flash*]

12 hours ago, Matthew70 said:

This forum is the best of any of them.  Everyone gives sound reasoning & terrific discussion as to why.  Everyone is welcoming & helps others learn. There is no negativity & winter cancel thankfully.  Yeah, the pattern has not been the best for snow in TN but when has there ever been a snowy December in TN? Yet many places have had a lot of snow already.  As Carver said it’s been a well below average December.  Many days have been like a January day.  December has been a win in my book.  It’s felt like Christmas! I do hope everyone is having a great Christmas season & wish everyone a Merry Christmas! 

Merry Christmas to you! I agree 100% with this post; hence, why AmericanWx has become my 1a forum over the years. Understandably, for snow weenies at our latitude, we must contend with FOMO angst. Unless you're a FL/TX/CA transplant, warm holidays are hardly enjoyable, like a warm beer on a hot day. This riding 6 weeks of cold/dry and near misses to our north. 0.2" of snow IMBY since November 10. Drive 3 hours north and you get 50x. Say what you want about climo, but that's tough sleddin', pun intended.

Like New Years resolutions, there's hope with a side of dopamine in anticipating a reset/workable pattern within 14-21 days. As long as we can get a quality two-week window during peak snow climo, I won't complain. Middle TN, in particular, has seen this work for several winters this century where DJF skews mild, but we somehow sneak to average snowfall or higher. 

Having just been discharged from the hospital with our last little Bag Fry, I've had time to reflect back to exactly 10 years ago when we were gearing down for our first. Unlike this month, December 2015 was pure torch with the pattern almost entirely ENSO dominant, but like this month, we were begging for a sign. The morale of the story has been alluded to in recent days with all the Grinch posters going to town. Even with the atmosphere, what goes up must come down. The question isn't 'if', but 'when'. Ask yourself, starting December 1...would you rather go cold/warm/cold or warm/cold/warm? We'll see how this all shakes out. 

[Carvers Gap]

1 hour ago, *Flash* said:

Merry Christmas to you! I agree 100% with this post; hence, why AmericanWx has become my 1a forum over the years. Understandably, for snow weenies at our latitude, we must contend with FOMO angst. Unless you're a FL/TX/CA transplant, warm holidays are hardly enjoyable, like a warm beer on a hot day. This riding 6 weeks of cold/dry and near misses to our north. 0.2" of snow IMBY since November 10. Drive 3 hours north and you get 500x. Say what you want about climo, but that's tough sleddin', pun intended.

Like New Years resolutions, there's hope with a side of dopamine in anticipating a reset/workable pattern within 14-21 days. As long as we can get a quality two-week window during peak snow climo, I won't complain. Middle TN, in particular, has seen this work for several winters this century where DJF skews mild, but we somehow sneak to average snowfall or higher. 

Having just been discharged from the hospital with our last little Bag Fry, I've had time to reflect back to exactly 10 years ago when we were gearing down for our first. Unlike this month, December 2015 was pure torch with the pattern almost entirely ENSO dominant, but like this month, we were begging for a sign. The morale of the story has been alluded to in recent days with all the Grinch posters going to town. Even with the atmosphere, what goes up must come down. The question isn't 'if', but 'when'. Ask yourself, starting December 1...would you rather go cold/warm/cold or warm/cold/warm? We'll see how this all shakes out. 

Well, the Tenn sub-forum wins the internet today.  You all did good, Flash!  Cute as a button.

So, if flash is up watching the 0z runs…we know Flash is on the midnight baby shift!!!!

[Carvers Gap]

1 hour ago, Holston_River_Rambler said:

I know it’s all fantasy but I think the 6z GFS was about to give us a new years present if it had run about an extra 36 hours. 

 

 

Amplified patterns with an NAO and cold…definitely worth watching.  

[GaWx]

28 minutes ago, Carvers Gap said:

Amplified patterns with an NAO and cold…definitely worth watching.  

Look at how much the EPS has cooled for the lows of Dec 30th in just 6 runs thanks to the pushback from the strengthening -NAO despite the Aleutian ridge not budging!
It has cooled this much from the Friday 12Z run, an amazing amount for an ensemble mean over such a short period:

- Roxboro, NC 12F from 38 to 26
- Charlotte 14F from 40 to 26
- CAE 14F from 43 to 29
- SAV 15F from 48 to 33
- ATL 18F from 45 to 27
- Chattanooga 19F from 41 to 22
- Nashville 19F from 42 to 23
- Birmingham 20F from 47 to 27
- Tupelo 19F from 48 to 29
- Chicago 13F from 30 to 17
- Tulsa 11F from 43 to 32

12Z 12/19 EPS:

0Z 12/22 EPS:

[Matthew70]

2 hours ago, *Flash* said:

Merry Christmas to you! I agree 100% with this post; hence, why AmericanWx has become my 1a forum over the years. Understandably, for snow weenies at our latitude, we must contend with FOMO angst. Unless you're a FL/TX/CA transplant, warm holidays are hardly enjoyable, like a warm beer on a hot day. This riding 6 weeks of cold/dry and near misses to our north. 0.2" of snow IMBY since November 10. Drive 3 hours north and you get 50x. Say what you want about climo, but that's tough sleddin', pun intended.

Like New Years resolutions, there's hope with a side of dopamine in anticipating a reset/workable pattern within 14-21 days. As long as we can get a quality two-week window during peak snow climo, I won't complain. Middle TN, in particular, has seen this work for several winters this century where DJF skews mild, but we somehow sneak to average snowfall or higher. 

Having just been discharged from the hospital with our last little Bag Fry, I've had time to reflect back to exactly 10 years ago when we were gearing down for our first. Unlike this month, December 2015 was pure torch with the pattern almost entirely ENSO dominant, but like this month, we were begging for a sign. The morale of the story has been alluded to in recent days with all the Grinch posters going to town. Even with the atmosphere, what goes up must come down. The question isn't 'if', but 'when'. Ask yourself, starting December 1...would you rather go cold/warm/cold or warm/cold/warm? We'll see how this all shakes out. 

Congratulations!  Enjoy because they grow fast.  My two kiddos are  now 22 (boy)19 (girl).  

[Matthew70]

48 minutes ago, GaWx said:

Look at how much the EPS has cooled for the lows of Dec 30th in just 6 runs thanks to the pushback from the strengthening -NAO despite the Aleutian ridge not budging!
It has cooled this much from the Friday 12Z run, an amazing amount for an ensemble mean over such a short period:

- Roxboro, NC 12F from 38 to 26
- Charlotte 14F from 40 to 26
- CAE 14F from 43 to 29
- SAV 15F from 48 to 33
- ATL 18F from 45 to 27
- Chattanooga 19F from 41 to 22
- Nashville 19F from 42 to 23
- Birmingham 20F from 47 to 27
- Tupelo 19F from 48 to 29
- Chicago 13F from 30 to 17
- Tulsa 11F from 43 to 32

12Z 12/19 EPS:

0Z 12/22 EPS:

Good stuff GaWx. Always backing your positivity with facts!  Love it!