December 2025 Short/Medium Range Forecast Thread

[Carvers Gap]

I don't have a lot of time this morning.  A trend worth watching...overnight and morning deterministic runs (CMC, Canadian para, 6z AIFS, and 0z Euro) continue to erode the warmup.  That doesn't mean we won't see warm air masses, but go look for yourself.  They have, even the gfs, found the Dec 20th cold front.  This really looks like more of a back-and-forth pattern where warmth surges, cold erodes it quickly due to the cold source, and wash/rinse/repeat.

Ensembles aren't there yet, but at this range...they will wash out any trends.

[Golf757075]

1 hour ago, Carvers Gap said:

I don't have a lot of time this morning.  A trend worth watching...overnight and morning deterministic runs (CMC, Canadian para, 6z AIFS, and 0z Euro) continue to erode the warmup.  That doesn't mean we won't see warm air masses, but go look for yourself.  They have, even the gfs, found the Dec 20th cold front.  This really looks like more of a back-and-forth pattern where warmth surges, cold erodes it quickly due to the cold source, and wash/rinse/repeat.

Ensembles aren't there yet, but at this range...they will wash out any trends.

Carver, we say it all the time. Interesting winter so far. Imo, no winter is the same. Yall have at least seen some snow. We haven't lol.

[*Flash*]

Leaving this as more of an open-ended question. Are decadal warming patterns being over integrated into seasonal outlooks and extended D14-30 forecast windows? The notion pops up every October for me when I review NOAA's winter outlook and note how so much of the country is plastered in orange and red. Not a hypothesis per se, but a suspicion about warm biases in the micro overly influenced by climate progression at large. Probably way more case by case then I'm making it, granted, the way my memory interlocks with recent experiences, it seems more torch previews have needed scale backs than the other way around. 

[Golf757075]

4 minutes ago, *Flash* said:

Leaving this as more of an open-ended question. Are decadal warming patterns being over integrated into seasonal outlooks and extended D14-30 forecast windows? The notion pops up every October for me when I review NOAA's winter outlook and note how so much of the country is plastered in orange and red. Not a hypothesis per se, but a suspicion about warm biases in the micro overly influenced by climate progression at large. Probably way more case by case then I'm making it. Seems this decade there have been more torch previews that have had to be scaled back than the other way around. 

Imo, no doubt climate change related. When you would see a winter forecast from noaa back in the 90s or 2000s, it would show more blue further south and east. Now, not so much lol. Where we are on the map, it will be difficult no matter what due to our geographical location. 

[Carvers Gap]

36 minutes ago, Golf757075 said:

Carver, we say it all the time. Interesting winter so far. Imo, no winter is the same. Yall have at least seen some snow. We haven't lol.

I really think it has been a while since we have had a cold source like this.  Models/people are trying to adjust.

[Golf757075]

15 minutes ago, Carvers Gap said:

I really think it has been a while since we have had a cold source like this.  Models/people are trying to adjust.

I agree to our nw over Alaska and nw Canada it has been cold. Need and want a mechanism to bring it more south and west. 

[Daniel Boone]

3 hours ago, *Flash* said:

Leaving this as more of an open-ended question. Are decadal warming patterns being over integrated into seasonal outlooks and extended D14-30 forecast windows? The notion pops up every October for me when I review NOAA's winter outlook and note how so much of the country is plastered in orange and red. Not a hypothesis per se, but a suspicion about warm biases in the micro overly influenced by climate progression at large. Probably way more case by case then I'm making it, granted, the way my memory interlocks with recent experiences, it seems more torch previews have needed scale backs than the other way around. 

Good,valid point. Post this in the Main Forum and you'll have many going Nuts over there ; particularly the Warmanista and GW brainwashed One's. They'd probably justify the Model's doing that. Fact is, GW is real to a degree but, the Cause and Forecasted Rate is off. Not to say your Post is about GW, just giving an Opinion on why you're right on your Suspicion.

[tnweathernut]

Don’t have a ton of time (ever anymore it seems), but I agree with Jax………. We really need the Rex like block over the Aleutians to be less “rexy”.  Will be like pulling teeth to keep the bulk of cold from going west with that look.

[Carvers Gap]

The warm-up has been pushed back past the 20th as most models now see a cold front(another strong one) around the then.  Will there be another prior to Christmas and after the 20th?  Maybe.  This pattern will have some anomalous warm days, but will also have some anomalous cold days.  It may average out warmer, but that is not a full on torch on deterministic runs.  It seems like each suite is wiping out more warmth.  If it were the other way around and I was hoping for a flip to cold...I might be questioning whether it could hold on.....

[Daniel Boone]

16 minutes ago, tnweathernut said:

Don’t have a ton of time (ever anymore it seems), but I agree with Jax………. We really need the Rex like block over the Aleutians to be less “rexy”.  Will be like pulling teeth to keep the bulk of cold from going west with that look.

Models have been showing that Block shifting Eastward to being centered over Alaska. I made a post recently that we needed that to happen and get rid of any GOA Low. If that doesn't happen, yeah Trough should drop in the West.

There have been rare times as I'm sure you know, where other Variables altered the typical outcome of Aleutian Ridge equates to western Trough however. 

Carvers can better describe what looks be be transpiring and maybe touch on those Variable's. I'm just too tired and sick to present everything myself. Carvers is much better than I am and a Master at that. 

[Carvers Gap]

The CPC MJO plots, and this is not meant to be contentious, are in phase 8(has never left).  They are parked there.  Something is gonna have to give...either warm modeling or incorrect/correct MJO plots.

Please answer --> Someone remind me...the green is the MJO convection, right?  If so, mid Jan could be freaking cold.  If green is suppressed convection....

[Carvers Gap]

2 minutes ago, Daniel Boone said:

Models have been showing that Block shifting Eastward to being centered over Alaska. I made a post recently that we needed that to happen and get rid of any GOA Low. If that doesn't happen, yeah Trough should drop in the West.

There have been rare times as I'm sure you know, where other Variables altered the typical outcome of Aleutian Ridge equates to western Trough however. 

Carvers can better describe what looks be be transpiring and maybe touch on those Variable's. I'm just too tired and sick to present everything myself. Carvers is much better than I am and a Master at that. 

I think modeling has been suffering from really bad feedback(infinite loops).  The other thing is that our cold source this season is insanely cold.  We have seen years where 500 maps don't match the surface, and this might be one of them again.

[Carvers Gap]

I really hate having to dig through MJO data - yuck.  Anyway, I read the MJO report from the 8th by CPC.  So, I think I know how to read the following map.

The orange is suppressed convection.  Now, it is important to remember there is almost always convection at this time of year over the MC, and I think that is a mistake some(not in this forum!) are making.  You can have convection, but it be suppressed IMHO.  That simply means less than the norm.  I don't "think" phase 8 and phase 5 have a one-size-fits all scale for convection.  I would guess the MC has more convection, ie it could still have convection but less than the norm.  The enhanced(more than normal) convection is blue...and that is phase 8.  It isn't moving.  In fact, you can see some convection firing in east Africa which is 1-2. 

What I want to know on the CHI plot is which color is enhanced and which is suppressed.  I need to get that straightened out so that I can compare the two.  @jaxjagman

[Matthew70]

44 minutes ago, Daniel Boone said:

Models have been showing that Block shifting Eastward to being centered over Alaska. I made a post recently that we needed that to happen and get rid of any GOA Low. If that doesn't happen, yeah Trough should drop in the West.

There have been rare times as I'm sure you know, where other Variables altered the typical outcome of Aleutian Ridge equates to western Trough however. 

Carvers can better describe what looks be be transpiring and maybe touch on those Variable's. I'm just too tired and sick to present everything myself. Carvers is much better than I am and a Master at that. 

Get to feeling better soon.

[Daniel Boone]

12 minutes ago, Matthew70 said:

Get to feeling better soon.

Thanks brother !

[jaxjagman]

57 minutes ago, Carvers Gap said:

I really hate having to dig through MJO data - yuck.  Anyway, I read the MJO report from the 8th by CPC.  So, I think I know how to read the following map.

The orange is suppressed convection.  Now, it is important to remember there is almost always convection at this time of year over the MC, and I think that is a mistake some(not in this forum!) are making.  You can have convection, but it be suppressed IMHO.  That simply means less than the norm.  I don't "think" phase 8 and phase 5 have a one-size-fits all scale for convection.  I would guess the MC has more convection, ie it could still have convection but less than the norm.  The enhanced(more than normal) convection is blue...and that is phase 8.  It isn't moving.  In fact, you can see some convection firing in east Africa which is 1-2. 

What I want to know on the CHI plot is which color is enhanced and which is suppressed.  I need to get that straightened out so that I can compare the two.  @jaxjagman

The MJO is at the bullseye of the COD today,but whats been happpening the last couple  is semmingly whats going on into the WP and MC from Rossby/Kelvin Waves,just really getting destructive interference,RRMS which show it climbing back out into the NH,but its already there

[Carvers Gap]

2 minutes ago, jaxjagman said:

The MJO is at the bullseye of the COD today,but whats been happpening the last couple  is semmingly whats going on into the WP and MCRossby/Kelvin Waves,just really getting destructive interference,RRMS which show it climbing back out into the NH,but its already there

The CFS forecast has been a lot different than any other MJO forecast.  Is it an outlier, but also correct?

[jaxjagman]

6 minutes ago, Carvers Gap said:

The CFS forecast has been a lot different than any other MJO forecast.  Is it an outlier, but also correct?

More than likely but its correcting itself recently on the RMMS,if you noticed a couple days ago its RMMS showed moving into the MC back into the NH in about 10 days doing basically the cycle,kinda fast dont ya think

[jaxjagman]

35 minutes ago, Carvers Gap said:

The CFS forecast has been a lot different than any other MJO forecast.  Is it an outlier, but also correct?

Why i prefer to use the JMA when looking at the RMMS,screw that 14 day crap,you can even see Kelvin is going to disrpupt the signal once again around the mid month into the NH

[John1122]

The official BOM observed for the last 3 days available (8th, 9th, 10th) has been COD/6, COD/5, and back to COD/6, but headed towards 8 (hopefully). It's 3 days behind so it could be in 8 now.

[Daniel Boone]

Just now, John1122 said:

The official BOM observed for the last 3 days has been COD/6, COD/5, and back to COD/6, but headed towards 8 (hopefully). It's 3 days behind so it could be in 8 now.

Yeah, there's apparently some mixed up data as there's different locations from different Modeling. I think the Kelvin and Rossbys are alot of our problems as Jax pointed out. Makes sense. 

[Golf757075]

9 minutes ago, Daniel Boone said:

Yeah, there's apparently some mixed up data as there's different locations from different Modeling. I think the Kelvin and Rossbys are alot of our problems as Jax pointed out. Makes sense. 

I hope it gets resolved soon. Apparently things aren't in sync where we want them to be with kelvin waves/ rosby waves etc. Larry Cosgrove is good, but he sometimes hypes things too much. He has much experience doing weather for a long time. He called for a warm December and cold mid January through March. I hope he is correct. 

[Daniel Boone]

12 minutes ago, Golf757075 said:

I hope it gets resolved soon. Apparently things aren't in sync where we want them to be with kelvin waves/ rosby waves etc. Larry Cosgrove is good, but he sometimes hypes things too much. He has much experience doing weather for a long time. He called for a warm December and cold mid January through March. I hope he is correct. 

Yeah. Would be nice to have a full blown MJO Ph8 Pattern. 

[Carvers Gap]

Area Forecast Discussion
National Weather Service Morristown TN
154 PM EST Sat Dec 13 2025

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 1236 PM EST Sat Dec 13 2025

- Light snow accumulations expected across the high terrain of
  East Tennessee and southwest Virginia overnight into Sunday
  morning.

- Bitter cold will surge into the area for Sunday through Monday
  morning. Please see the Cold Weather Advisories for additional
  details.

- Warming trend begins Tuesday with above normal temperatures by
  mid to late week. Conditions will be dry during this time.

&&

.DISCUSSION...
Issued at 1236 PM EST Sat Dec 13 2025

A broad upper level trough remains in place over much of the central
and eastern CONUS. Shortwave energy translating through the synoptic
feature tonight into Sunday will sharpen the troughing as a surface
front progresses through the region. Some light ra/sn will occur
during the overnight hours as this energy translates through the
central and southern Appalachians, however, the greatest
probabilities for light snow accumulation will be limited to
higher terrain of the East Tennessee mountains and southwest
Virginia. Overall, moisture in the DGZ is lacking and better
northwest flow does not initiate until the bulk of the moisture is
departing the region. Will cover this with an SPS for now, ending
it at midnight to allow for the next forecast desk to make any
additional considerations.

The main concerns will be well below normal temperatures advecting
into the region as winds veer NNWly and become gusty behind frontal
passage. Temperatures around 20 degrees below normal are largely
expected across the region Sunday into Sunday night. A Cold
Weather Advisory has been issued for the Cumberland Plateau,
southwest Virginia, and our East Tennessee mountain zones starting
around sunrise tomorrow morning. The gusty winds and well below
normal temperatures will result in wind chill values around zero,
to as low as 10 below zero in the highest terrain of the
mountains. By late Sunday afternoon, the remainder of the valley
locations are introduced to the Advisory as cold air continues to
filter into the region. Overnight lows in the low teens to single
digits will be widespread. Many valley locations will see wind
chills in the single digits to near zero.

Cold Weather Advisory products will come to an end shortly after
daybreak Monday, when a gradual warming trend is expected into the
mid-week as the anomalous troughing ejects northeast and H5 heights
slowly recover. For Wednesday night through Friday, the main storm
track will be across the northern third of the nation. The fast but
more zonal flow will quickly move a series of short-waves with
associated frontal boundaries moving across the region. Ensemble
cluster analysis shows differences in timing of systems but overall
increasing chances of precipitation are expected towards the latter
half of the week.

[Golf757075]

10 minutes ago, Daniel Boone said:

Yeah. Would be nice to have a full blown MJO Ph8 Pattern. 

Just a pattern that sets up a better overlap of cold and precipitation. Thankfully it's still mid December 

[Carvers Gap]

Definitely good trends here.  If the Pac is gonna be taking its time getting its act together, we can try the Atlantic.  With the QBO negative and the SSW, a strong NAO is possible and even likely.  Keep in mind that -NAOs are often not forecast well in advance.  They can upend LR modeling in a New York minute.

 

 

[Golf757075]

2 minutes ago, Carvers Gap said:

Definitely good trends here.  If the Pac is gonna be taking its time getting its act together, we can try the Atlantic.  With the QBO negative and the SSW, a strong NAO is possible and even likely.  Keep in mind that -NAOs are often not forecast well in advance.  They can upend LR modeling in a New York minute.

 

 

Looks good Carver. I personally would rather have the Pacific on our side instead of the Atlantic. We have gotten shots of cold air, but no precipitation in my area. Each winter is different though. If it's front loaded, then we need to pull a rabbit out of the hat pretty soon lol

[jaxjagman]

Maybe we are starting to see a pattern change as the Pac Jet get retracted into East Asia after Chistmas,dunno,ill beieve it when i see it

[Matthew70]

1 hour ago, John1122 said:

The official BOM observed for the last 3 days available (8th, 9th, 10th) has been COD/6, COD/5, and back to COD/6, but headed towards 8 (hopefully). It's 3 days behind so it could be in 8 now.

What is the good phases again for a trough in the East.

[Carvers Gap]

24 minutes ago, Golf757075 said:

Looks good Carver. I personally would rather have the Pacific on our side instead of the Atlantic. We have gotten shots of cold air, but no precipitation in my area. Each winter is different though. If it's front loaded, then we need to pull a rabbit out of the hat pretty soon lol

Middle and Western forum areas definitely do better with a good PAC.  The Atlantic helps us with inland runners.   We can also do well with a good PAC in NE TN…but many good winters IMBY have good NAO setups, even if briefly.   In some ways, TRI scores when DC does.