December 2025 Short/Medium Range Forecast Thread

[Matthew70]

16 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

This front loaded to back loaded winter never pans out when people call for them.  Winter has its ups & downs like they always have.  The record books are full of examples.  I remember it used to be the pacific then the Atlantic then no it was another teleconnection.  Throw in SSW & MJO.  Honestly many have made winter way to salty. My opinion is the MJO does influence winter much more than the PNA or AO or NAO. 
 Pull a rabbit out of the hat already? Way too many are canceling winter before it has already begin.  
what makes this forum fun is it’s not constant cancel winter crowd.  
In my opinion December has been great.  It has been cold!!! Plus Canada is plenty cold with snow pack in great shape.  After the next 2 days, I myself will be glad to have some warmer days.  Tomorrow is going to be brutal. 

[Daniel Boone]

Winter as a whole MJO Cold Phases: 8 1 2 .

[jaxjagman]

1 minute ago, Daniel Boone said:

Winter as a whole MJO Cold Phases: 8 1 2 .

Yeah but its still more like NINO than NINA,you generally see the Atmospheric River out west in a NINO  not NINA

[Daniel Boone]

5 minutes ago, jaxjagman said:

Yeah but its still more like NINO than NINA,you generally see the Atmospheric River out west in a NINO  not NINA

I was actually replying to Golf as he questioned what the cold phases were. 

  As far as the lw pattern, yeah, I agree although we do have that Aleutian HP but not the typical Nina Ridging up to there. Odd Pattern. Probably a product of the Waves you mentioned earlier messing with the MJO. Interference.

[Matthew70]

11 minutes ago, Daniel Boone said:

Winter as a whole MJO Cold Phases: 8 1 2 .

Thank you!

[Carvers Gap]

Here is an article about atmospheric river events.  During the 2022-2-2023 La Nina, California experienced nine atmospheric river events.  Mammoth got absolutely buried with snow.  I thought for sure ARs were Nino driven, but new research suggests it actually has less connection than I thought.  An atmospheric river event can actually overwhelm either ENSO signal regardless.  

https://scripps.ucsd.edu/news/atmospheric-rivers-explain-atypical-el-nino-and-la-nina-years

 

[Daniel Boone]

30 minutes ago, Matthew70 said:

Thank you!

My bad, I said Golf Matthew. Sorry man, I'd forgot which one asked. You're welcome !

[Carvers Gap]

RIP to the southern standing wave on the 18z GFS.  We hardly every knew ye.

[Daniel Boone]

1 minute ago, Carvers Gap said:

RIP standing ridge on the 18z GFS.

Surely not, lol 

[Carvers Gap]

And as we see the feedback over the NW resolved....modeling begins to look like an MJO on the left side of the plot.  Those constant spinning vortices are replaced by more reasonable solutions.  That allows multiple cold fronts to march eastward.  I don't think it will be wall-to-wall cold like the first 15 days of December, but we could end with a back and forth pattern which is more amplified.

[Carvers Gap]

4 minutes ago, Daniel Boone said:

Surely not, lol 

We have below zero wind chills in the middle of the warm-up.  If that is the warm-up, I would sure hate to see what a cold snap would look like in January w/ that cold air mass parked in Canada.

[Carvers Gap]

7 minutes ago, Daniel Boone said:

Surely not, lol 

And a nice little inland runner snowstorm where that chinook influenced SER has been forecast to pop.  I may be in the minority, but I really don't see the warm-up as a phase 6 SER.  It is more like a chinook getting pumped by feedback over the NW.  Get those lows moving more progressively, and the chinook dissipates as they pass to the east.

[Carvers Gap]

I mean this is wild.  That is a 5 day map.  PNA ridge.  EPO ridge.  Alaska block.  Low east of Hawaii.  That is a snowstorm setup.  Yes, it is a deterministic run at 300+ AND ensembles have yet to flip....but that is quite the opposite of what has been shown for the past few days.

When I see an ensemble finally flip(and they will take some time if they are going to do it), then we know feedback(infinite loops) were at fault here.  Let's see if the trend(which began a couple of days ago) ends with a decent pattern.  No promises, but fun and interesting to track.

Are models finally starting to feel the MJO?  Maybe.  

 

[GBOVolz]

Area Forecast DiscussionNational Weather Service Morristown TN154 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 2025A broad upper level trough remains in place over much of the centraland eastern CONUS. Shortwave energy translating through the synopticfeature tonight into Sunday will sharpen the troughing as a surfacefront progresses through the region. Some light ra/sn will occurduring the overnight hours as this energy translates through thecentral and southern Appalachians, however, the greatestprobabilities for light snow accumulation will be limited tohigher terrain of the East Tennessee mountains and southwestVirginia. Overall, moisture in the DGZ is lacking and betternorthwest flow does not initiate until the bulk of the moisture isdeparting the region. Will cover this with an SPS for now, endingit at midnight to allow for the next forecast desk to make anyadditional considerations.The main concerns will be well below normal temperatures advectinginto the region as winds veer NNWly and become gusty behind frontalpassage. Temperatures around 20 degrees below normal are largelyexpected across the region Sunday into Sunday night. A ColdWeather Advisory has been issued for the Cumberland Plateau,southwest Virginia, and our East Tennessee mountain zones startingaround sunrise tomorrow morning. The gusty winds and well belownormal temperatures will result in wind chill values around zero,to as low as 10 below zero in the highest terrain of themountains. By late Sunday afternoon, the remainder of the valleylocations are introduced to the Advisory as cold air continues tofilter into the region. Overnight lows in the low teens to singledigits will be widespread. Many valley locations will see windchills in the single digits to near zero.Cold Weather Advisory products will come to an end shortly afterdaybreak Monday, when a gradual warming trend is expected into themid-week as the anomalous troughing ejects northeast and H5 heightsslowly recover. For Wednesday night through Friday, the main stormtrack will be across the northern third of the nation. The fast butmore zonal flow will quickly move a series of short-waves withassociated frontal boundaries moving across the region. Ensemblecluster analysis shows differences in timing of systems but overallincreasing chances of precipitation are expected towards the latterhalf of the week.

Cold Weather Advisory? Am I the only one that’s never heard of this before?


.

[Daniel Boone]

6 minutes ago, Carvers Gap said:

And a nice little inland runner snowstorm where that chinook influenced SER has been forecast to pop.  I may be in the minority, but I really don't see the warm-up as a phase 6 SER.  It is more like a chinook getting pumped by feedback over the NW.  Get those lows moving more progressively, and the chinook dissipates as they pass to the east.

I agree completely man. NEPAC and western ridge squeeze play of the Pac Jet forcing downsloping imo. Also helping force that ridge to elongate eastward somewhat. Allows for Chinooks. If HLB sets up , even if that Pac Jet atmospheric ruver were to continue, it's going slow and back and buckle the Flow to some degree, whether alot or some depending on Blocking Strength.

[Matthew70]

29 minutes ago, Carvers Gap said:

Here is an article about atmospheric river events.  During the 2022-2-2023 La Nina, California experienced nine atmospheric river events.  Mammoth got absolutely buried with snow.  I thought for sure ARs were Nino driven, but new research suggests it actually has less connection than I thought.  An atmospheric river event can actually overwhelm either ENSO signal regardless.  

https://scripps.ucsd.edu/news/atmospheric-rivers-explain-atypical-el-nino-and-la-nina-years

 

I remember they had snow drifts into July that year.  Truly incredible to think it lasted that long. 

[Matthew70]

You can see the signs showing as Carver has said.  The warm ups are more seasonal as they get closer.  Active pattern seems to be showing its hand around Christmas & after.  That really cold air is staying on this side of the globe.  

[GBOVolz]

I know I seen a lot of 2013 analogs for this winter. Knoxville did really well In January. I remember a 2 week stretch with brutal cold and multiple events.


.

[GBOVolz]

I know I seen a lot of 2013 analogs for this winter. Knoxville did really well In January. I remember a 2 week stretch with brutal cold and multiple events.


.

Forgot the link.

https://www.weather.gov/mrx/Jan_14_17_Snowfall_Cold


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[Matthew70]

40 minutes ago, Carvers Gap said:

We have below zero wind chills in the middle of the warm-up.  If that is the warm-up, I would sure hate to see what a cold snap would look like in January w/ that cold air mass parked in Canada.

THIS!  Tomorrow will be brutal.  The January  fronts like this one will be even more brutal.  

[Matthew70]

37 minutes ago, Carvers Gap said:

I mean this is wild.  That is a 5 day map.  PNA ridge.  EPO ridge.  Alaska block.  Low east of Hawaii.  That is a snowstorm setup.  Yes, it is a deterministic run at 300+ AND ensembles have yet to flip....but that is quite the opposite of what has been shown for the past few days.

When I see an ensemble finally flip(and they will take some time if they are going to do it), then we know feedback(infinite loops) were at fault here.  Let's see if the trend(which began a couple of days ago) ends with a decent pattern.  No promises, but fun and interesting to track.

Are models finally starting to feel the MJO?  Maybe.  

 

MJO for the win please!

[Golf757075]

2 hours ago, Matthew70 said:

This front loaded to back loaded winter never pans out when people call for them.  Winter has its ups & downs like they always have.  The record books are full of examples.  I remember it used to be the pacific then the Atlantic then no it was another teleconnection.  Throw in SSW & MJO.  Honestly many have made winter way to salty. My opinion is the MJO does influence winter much more than the PNA or AO or NAO. 
 Pull a rabbit out of the hat already? Way too many are canceling winter before it has already begin.  
what makes this forum fun is it’s not constant cancel winter crowd.  
In my opinion December has been great.  It has been cold!!! Plus Canada is plenty cold with snow pack in great shape.  After the next 2 days, I myself will be glad to have some warmer days.  Tomorrow is going to be brutal. 

Its an interesting pattern with a few conflicting signals imo. I wouldn't mind a pattern that produces clippers, which my area hasn't seen in a long time. A few inches is better than no inches lol

[Jed33]

1 hour ago, GBOVolz said:

Cold Weather Advisory? Am I the only one that’s never heard of this before?


.

Last year, the NWS replaced the wind chill advisory with cold weather advisory and wind chill warning was changed to extreme cold warning or something like that. 
 

Also, MRX discontinued frost and freeze advisories unless they occur well outside of when they would ordinarily occur. So, basically before October or after May 1. Like it or not, they will likely never issue many, if any frost or freeze advisories or warnings again. Not every state is doing this, but I think OHX and MEG are as well. So you won’t hardly see any of those warnings in TN again.
 

[Daniel Boone]

1 hour ago, GBOVolz said:

I know I seen a lot of 2013 analogs for this winter. Knoxville did really well In January. I remember a 2 week stretch with brutal cold and multiple events.


.

Yeah, 2013-14 was a cold, snowy January and into February. 

[Daniel Boone]

1 hour ago, Jed33 said:

Last year, the NWS replaced the wind chill advisory with cold weather advisory and wind chill warning was changed to extreme cold warning or something like that. 
 

Also, MRX discontinued frost and freeze advisories unless they occur well outside of when they would ordinarily occur. So, basically before October or after May 1. Like it or not, they will likely never issue many, if any frost or freeze advisories or warnings again. Not every state is doing this, but I think OHX and MEG are as well. So you won’t hardly see any of those warnings in TN again.
 

Yeah I disagree with some of their changes. JKL still issues frost/freeze advisories for first widespread of Season.

[Daniel Boone]

1 hour ago, Golf757075 said:

Its an interesting pattern with a few conflicting signals imo. I wouldn't mind a pattern that produces clippers, which my area hasn't seen in a long time. A few inches is better than no inches lol

My Sister used to live near you in Humboldt. I recall Ice Storms seemed more prevalent there than here back then (80's).

[Matthew70]

2 hours ago, Golf757075 said:

Its an interesting pattern with a few conflicting signals imo. I wouldn't mind a pattern that produces clippers, which my area hasn't seen in a long time. A few inches is better than no inches lol

The old northern clippers.  It would be really nice to see those again I do agree! 

[jaxjagman]

4 hours ago, Carvers Gap said:

Here is an article about atmospheric river events.  During the 2022-2-2023 La Nina, California experienced nine atmospheric river events.  Mammoth got absolutely buried with snow.  I thought for sure ARs were Nino driven, but new research suggests it actually has less connection than I thought.  An atmospheric river event can actually overwhelm either ENSO signal regardless.  

https://scripps.ucsd.edu/news/atmospheric-rivers-explain-atypical-el-nino-and-la-nina-years

 

Excellent,i did some research of the DMI earlier today and gave up because of the ENSO,but these years into 2010 and 2022 like you mentioned in the modern day era more or less had like the same pattern to some extent with whats going on in the WP,even tho you had a more strong Nina in 2010 and even less  so in 2022 and even more less so this year,the ENSO still plays a part into the IO