December 2025 Short/Medium Range Forecast Thread

[Carvers Gap]

1 hour ago, Jed33 said:

Yeah I saw that earlier. I don’t know about that. Seems a little strange for him to say that. I remember times in the 80’s and 90’s where Alaska hit -70 and lower. I remember one instance where it was even closer to -80! I can remember talk about how airplanes couldn’t function when the temp was lower than -70. So, -60F is not unprecedented at all. I’m not sure where he’s getting the 1000 yr event talk. To me if it was going to be 1000yr event we’d be talking -100 or more. Akin to the lowest temps ever observed on the planet, which happens to be on the other side of the globe in Antarctica. 

Nice post.  Interesting find by Golf.

I keep an off-and-on eye on the coldest modeled mins for North America during the winter.   I do that just to monitor how cold our cold source could be.  The coldest I can find right now is low -60s.  Now, that is pretty cold, but the record is -81 in the Yukon in 1947 according to a quick search.

This is not for you, Jed.  I know you know this.  I am just trying to save a second post.  Models have been having crazy amounts of feedback this winter.  I think they are vastly overdoing certain features(Baja, NW Pac lows on repeat, western Canada cold?) which causes wild feedback all over the Western Hemisphere.  I am not sure why this is happening.  I don't know if there is a data ingest problem or programming has been changed/updated across models.  Maybe they have a bug?  But I have observed some pretty big errors.  It reminds me of the 4' of snow forecast for Charlotte one year...and it never materialized.  It was feedback which sometimes occurs to the SE of the southern tip of the Apps.  Places on the map to watch for feedback...Baja, NW Pac, Aleutians(but not as bad as one would think IMHO), and Greenland.  Now, the fun thing about that area of South Carolina which tends to feedback....sometimes it actually has extreme precip events.  Think Helene.  All of those other places have had extreme events...sometimes I think models go to that extreme due to those data sets.

I would guess that Canada is going to be very, very cold this winter.  That is a pretty easy guess as it already has been there this season.  I think it finds its way south 1-2 times, and that will be plenty for most.  Like you, I don't see even 100 year cold up there right now.  But we'll see.  Not everything is feedback though. I guess maybe the thing that concerns me some is that many of these cold fronts are getting much colder as we get closer to the event - that is kind of unusual.  That might be a signal that the air mass up there is strong.  We have good snowpack for it to move quickly.

I would be more than thrilled to track an all-time great Arctic outbreak w/ lots of snow.  I just don't know that we are gonna get much lead time on that...

That said, I do think the strength of the cold is currently and is going to be in the future...a problem for modeling this winter.  We have had some winters where we get a trough in the East, and there is only Canadian or weak polar air to fill it.  This stuff is legit Arctic air.  

Let's not forget the SSW....we haven't had the cold dive to our side of the planet with that recently.  But Russia and/or China have been hammered when that occurs.  Sometimes, it does come to our side of the planet.  Is this one of our years?  Maybe, and there is some evidence to support that but just to early to know.

edit:  On an interesting note, my daytime highs for the past couple of months have sometimes been well under the point and click forecasts.  I am ready for a few days of warm air.  I keep waiting on some warm mornings!  It was not warm this morning.

[Carvers Gap]

I am gonna tag @John1122in this.  His records are easily the best and most uncorrupted that I know of.  They are rigorous and have good fidelity to boot(they are his family's for those who don't know).  He might be able to shed some light on Maue's thoughts and hopefully chip in some insight.  John, I am not asking you to support or criticize RM...just to add some context to the cold forecast in Alaska and in relation to our area.

[Carvers Gap]

I found this analog in the d6-10 analogs of CPC.  1-7-94.  I could see that being usable.  John always has to remind me of that winter.  I had to go back and look it up.  Sure enough, that winter I had to drive to campus on frozen interstates for about a week.  My apartment started leaking as water backed up under the ice.  It may be a reach on my part, but that analog makes some sense, and it has fit recent winters.  I don't know its ENSO state, but that might be one to think about.

[iluvsnow]

Here is a link to current coldest temperatures on the planet. I tried to copy and paste the top 15, but it didn't work....so go to the link and peruse for yourselves. Canada does have some of the top 15 low temps on earth for the date. We should also remember that its only December 22nd. The really bottom level stuff in the Northern Hemisphere doesn't occur until late January and February up top. This is pretty rare for Canada to have lows this cold, this early......the link:  https://eldoradoweather.com/climate/world-extremes2/world-temp-rainfall-extremes.php

[Carvers Gap]

Just now, iluvsnow said:

Here is a link to current coldest temperatures on the planet. I tried to copy and paste the top 15, but it didn't work....so go to the link and peruse for yourselves. Canada does have some of the top 15 low temps on earth for the date. We should also remember that its only December 22nd. The really bottom levels stuff in the Northern Hemisphere doesn't occur until late January and February up top. This is pretty rare for Canada to have lows this cold, this early......the link:  https://eldoradoweather.com/climate/world-extremes2/world-temp-rainfall-extremes.php

I will re-respond.  Mercy!

Cold source. Check.

[Matthew70]

And as I have been saying.  Top snows for TN is in February.  With the cold air source in Canada.  If we were to get one of the ole blue northern clippers.  The ratios of that snow with them would be plentiful. 

[Jed33]

I’ve been following the weather for many years. Most years during my childhood (80’s) the weather was oftentimes very cold during the winter and I took note of it. I didn’t write down the dates when the brutally cold air would build in Alaska and Canada,  but my dad and I watched it and we knew it would usually eventually be unleashed into the lower 48. I looked it up on google just now and found about 24 cases where the temps were between -70 to the record of -80. These were scattered from Jan 19-20 1952 to Jan 29 1999. The coldest being Jan 27 1989 at -76 and Jan 5 1997 at -77. The ultimate coldest Jan 23 1971 at -80. I don’t see any temps that cold though in the 2000’s. So, there is definitely precedent for it to be lower than -60 with 24 cases at or below-70 in Alaska.

[Daniel Boone]

5 minutes ago, Jed33 said:

I’ve been following the weather for many years. Most years during my childhood (80’s) the weather was oftentimes very cold during the winter and I took note of it. I didn’t write down the dates when the brutally cold air would build in Alaska and Canada,  but my dad and I watched it and we knew it would usually eventually be unleashed into the lower 48. I looked it up on google just now and found about 24 cases where the temps were between -70 to the record of -80. These were scattered from Jan 19-20 1952 to Jan 29 1999. The coldest being Jan 27 1989 at -76 and Jan 5 1997 at -77. The ultimate coldest Jan 23 1971 at -80. I don’t see any temps that cold though in the 2000’s. So, there is definitely precedent for it to be lower than -60 with 24 cases at or below-70 in Alaska.

-80 in Prospect Creek  Alaska Jan. 23 1971. It was coldest US Record. Coldest lower 48 is -70 Rogers Pass Montana in 1954. -83 NA Record in Snag. Yukon.

[Jed33]

This is the link I where I found the information on Alaska.
 

https://www.currentresults.com/Weather-Extremes/US/lowest-temperatures-alaska.php

[Daniel Boone]

My reply from earlier just posted. My phone really fouled up tonight. It's sticking and closing out on me. Tan cleaner and took some things off but still not up to par.

[Golf757075]

The ensembles are starting to somewhat extend the pacific jet in the extended. I believe that will be a game changer if it comes to fruition 

[John1122]

The Canadian is just full blown winter, snow, ice box cold before New Years and after. +PNA looks beginning to appear and downstream we win. Old fashioned clipper/Siberian express on there.

 

 

[John1122]

I think we'd all take this, with single digit cold pressing in behind the second clipper.

 

[Carvers Gap]

Some bitterly cold runs overnight for the end of the year and beginning of the New Year.  We are gonna get June and January within about 48 hours of each other.

LR ext (weeklies) modeling has started to pick up on an EPO ridge towards the end of January.  The CFSv2, Euro Weeklies, and CFSv2 seasonals have it.  My guess could be sometime around the last week of January.  

The current pattern appears to be classic "C-FYAO" pattern, otherwise knows as a chinook - then freeze your tail off.

[Carvers Gap]

Two, back-2-back cold fronts appear possible between Dec 28 and Jan4.  

If recent model history trends hold...that second front might be colder than what is modeled(well, except for the GDPS which brought it).  The Canadian is likely too cold, but it looks like it might be about to score the coup for the Dec 28th run - most models have trended colder and if memory serves me correctly...it caught that first cold front before any other model(maybe the Euro Weeklies as well).

Will models back off the intensity of the cold like they did in early December?  I keep asking myself that, and then I remember this is a late December and early January air mass which is BN over western Canada.  It is possible that the fronts are under modeled outside of seven days.

The Music City Bowl is trending colder....oof.

[Kentucky]

Eric has indeed backtracked today, Merry Christmas to all. 

https://x.com/i/status/2003487195450286581

[Carvers Gap]

The 12z suite looks reasonably consistent w/ the exception of the 12z GFS which for whatever reason sometimes completely loses the NAO on random runs.  The 12z AIGFS looks about right.  So, we are just gonna sub out the 12z GFS and grab the sixth guy off the bench.

[Carvers Gap]

The 12z GFS and GEPS ensembles have finally broken towards the deterministic camp...bout time.

[Carvers Gap]

Just looking at the cold in the Canadian front range and prairies across modeling at 12z...it sure looks like "when" not "if" that comes roaring into the Lower US.  Modeling appears be working out which front is going to carry it.  I would think some snow along the incoming front(whichever turns out to be strongest) seems like an increasing possibility.

I think the GFS had -75F at some point late in the run (Yukon).  Likely that is feedback, but if it isn't...we may challenge the NA record at some point during January.

[Matthew70]

18 minutes ago, Carvers Gap said:

Just looking at the cold in the Canadian front range and prairies across modeling at 12z...it sure looks like "when" not "if" that comes roaring into the Lower US.  Modeling appears be workout out which front is going to carry it.  I would think some snow along the incoming front(whichever turns out to be strongest) seems like an increasing possibility.

I think the GFS had -75F at some point late in the run.  Likely that is feedback, but if it isn't...we may challenge the NA record at some point during January.

Let’s keep the mojo going!!!

[beavis1729]

1 hour ago, Carvers Gap said:

Just looking at the cold in the Canadian front range and prairies across modeling at 12z...it sure looks like "when" not "if" that comes roaring into the Lower US.  Modeling appears be working out which front is going to carry it.  I would think some snow along the incoming front(whichever turns out to be strongest) seems like an increasing possibility.

I think the GFS had -75F at some point late in the run (Yukon).  Likely that is feedback, but if it isn't...we may challenge the NA record at some point during January.

Yeah...hovering over the pixels in the Yukon on the map below, there's a modeled -71F at hour 312. I keep an eye on modeled temps up there in the winter, and seeing anything colder than -65F on the GFS (since it's a global model and therefore doesn't capture the local terrain/cold spots very well) is extremely rare. While I agree it could be driven by model feedback, it's still very impressive to see.

As for ground truth...I believe the coldest temp in Alaska since 2000 is -64F in early Feb. 2024. So, if these modeled temps come close to verifying, I'd argue it would be the coldest temps in 25+ years in that part of the world. Great article on Alaska's 2024 cold outbreak here:

https://alaskaclimate.substack.com/p/alaskas-2024-cold-snap

Also, for anyone interested in Alaska weather & climate, this is a great blog:

https://ak-wx.blogspot.com/

 

[GaWx]

 I don’t think that it’s an exaggeration to say that today’s Euro Weeklies colder changes in the aggregate for the E US are at least near the largest I can recall this entire season with 4 of the 5 weeks notably colder and only the other (Jan 5th-11th) staying about the same (pretty mild). 
 

 I’ll leave it to @Carvers Gapto post more about them as he normally is thorough communicating about them here. But if you want to look specifically at the big changes in the ecmwf in-house maps, themselves, vs yesterday, you can go here to the main ENSO thread:

 

[Carvers Gap]

45 minutes ago, GaWx said:

 I don’t think that it’s an exaggeration to say that today’s Euro Weeklies colder changes in the aggregate for the E US are at least near the largest I can recall this entire season with 4 of the 5 weeks notably colder and only the other (Jan 5th-11th) staying about the same (pretty mild). 
 

 I’ll leave it to @Carvers Gapto post more about them as he normally is thorough communicating about them here. But if you want to look specifically at the big changes in the ecmwf in-house maps, themselves, vs yesterday, you can go here to the main ENSO thread:

 

Thanks, man. I am finishing up some Christmas shopping so feel free!  I am looking at them right now…Large scale changes.   

[Carvers Gap]

1 hour ago, beavis1729 said:

Yeah...hovering over the pixels in the Yukon on the map below, there's a modeled -71F at hour 312. I keep an eye on modeled temps up there in the winter, and seeing anything colder than -65F on the GFS (since it's a global model and therefore doesn't capture the local terrain/cold spots very well) is extremely rare. While I agree it could be driven by model feedback, it's still very impressive to see.

As for ground truth...I believe the coldest temp in Alaska since 2000 is -64F in early Feb. 2024. So, if these modeled temps come close to verifying, I'd argue it would be the coldest temps in 25+ years in that part of the world. Great article on Alaska's 2024 cold outbreak here:

https://alaskaclimate.substack.com/p/alaskas-2024-cold-snap

Also, for anyone interested in Alaska weather & climate, this is a great blog:

https://ak-wx.blogspot.com/

 

Here are the WxBell maps at 342 from 12z.  -75.4 is the coldest I could find.  I have the 2m map, and for kicks and giggles, the real feel.  I know there has been some discussion of the WxBell algorithm being colder than other models.  

 

[Carvers Gap]

Nice run of the 18z GFS.....

[Carvers Gap]

Shiver me timbers.  Trough drops into the East and holds.  Slider present.  NW flow present.

[Carvers Gap]

Fun with maps...the 18z GFS.  We should see these types of runs given the potential for HL blocking.  There are gonna be WILD swings as exemplified by the r-2-r map below.  

 

[beavis1729]

4 hours ago, Carvers Gap said:

Here are the WxBell maps at 342 from 12z.  -75.4 is the coldest I could find.  I have the 2m map, and for kicks and giggles, the real feel.  I know there has been some discussion of the WxBell algorithm being colder than other models.  

 

Yikes, and good stuff…just a bit chilly. It’s strange to me that an algorithm could affect temperature outputs from a model. You’d think the model output is what it is, and then is simply displayed in map form. Maybe there is some interpolation that WxBell and other companies do, to “fill in” the data gaps? A discussion for another time, I suppose.

Anyway - as an example of the ongoing cold in eastern AK and the Yukon, Juneau AK dropped to -10 yesterday. It hasn’t been colder than -10 in Juneau since 1974.

[John1122]

Looks like January 1982 is showing up as an analog at 500mb according to Webb. 

January 1982 was the year it snowed basically every day for a week.

The biggest was 3 inches, but it would snow 1/2 to 1 inch almost every day. We had accumulating snowfall on 9 of 10 days. Even Knoxville recorded 1.5 inches 3 days in a row. 

 

It was capped off by an epic ice storm on January 18th, that the NWS records for some reason, ignore for Knoxville.

It says Knoxville got .21 qpf of ice in the "official" record. 

This is from a KNS article about January 18th/19th 1982. 

 

"That Jan. 18th date was all about ice. The mother of all freezing rains turned the entire area into a skating rink with ice an inch or more thick in most places.

Law enforcement reported more than 150 wrecks. Power failures showed up across the grid. Schools and businesses were shut down. Downtown hotels filled up with ice-locked workers unable to get home. The less fortunate spent the night in their cars unable to do anything but spin their wheels.

The National Weather Service personnel called it the worst ice storm they'd seen in decades.

Stories abounded of people latching up their ice skates for a trip to the store or literally crawling from their cars to get back into their homes and offices."

 

Temperatures in the -10s here just before that ice storm. 

[Golf757075]

2 minutes ago, John1122 said:

Looks like January 1982 is showing up as an analog at 500mb according to Webb. 

January 1982 was the year it snowed basically every day for a week.

The biggest was 3 inches, but it would snow 1/2 to 1 inch almost every day. We had accumulating snowfall on 9 of 10 days. Even Knoxville recorded 1.5 inches 3 days in a row. 

 

It was capped off by an epic ice storm on January 18th, that the NWS records for some reason, ignore for Knoxville.

It says Knoxville got .21 qpf of ice in the "official" record. 

This is from a KNS article about January 18th/19th 1982. 

 

"That Jan. 18th date was all about ice. The mother of all freezing rains turned the entire area into a skating rink with ice an inch or more thick in most places.

Law enforcement reported more than 150 wrecks. Power failures showed up across the grid. Schools and businesses were shut down. Downtown hotels filled up with ice-locked workers unable to get home. The less fortunate spent the night in their cars unable to do anything but spin their wheels.

The National Weather Service personnel called it the worst ice storm they'd seen in decades.

Stories abounded of people latching up their ice skates for a trip to the store or literally crawling from their cars to get back into their homes and offices."

 

Temperatures in the -10s here just before that ice storm. 

He really has changed his tune i guess lol. It makes sense if the pacific jet extends to get things shifting in the pacific. Not putting the carriage in front of the horse lol