December 2025 Short/Medium Range Forecast Thread

[John1122]

This is the station closest to me that same date.  

 

[Daniel Boone]

27 minutes ago, John1122 said:

This is the station closest to me that same date.  

 

The Pennington gap Data for the past 15 years has gotten flat out terrible. We've addressed that before. It's really showing it's print on the Model's now too. The Station Siting is terrible and the Observer's are awful. It's Located at the Sewer Plant now. I'll get a Picture one day and you'll see how off the Siting is from Official Guidelines. 

[Matthew70]

This is a brutal air mass.  Will be interesting if January has some that will be worse than this.  I saw reports of lake effect snows in NC.  That’s insane for this time of year. 

[Carvers Gap]

The 6z GFS is back to normal for Dec 19-29th after a warm run at 0z.  Interestingly, the 0z run developed what appeared to be feedback over the PNW.  When that occurs, the rest of the run is warm.  When it doesn't occur...it is back and forth.  For now, it looks like cold air masses will visit(24-48 hour duration) on the 19-20th, possibly the 22nd, possibly the 24th, and then too scrambled to even guess after that.  In between the cool downs, there will be chinooks likely.  I am really interested to see where this pattern settles after this transition timeframe.  But the back and forth pattern might the the actual pattern for a few undetermined amount of weeks.

[Carvers Gap]

The 0z Euro is much different w/ the Dec19-20 cold front potential.  I think it likely wrong.  The 6z AIFS has the cold front.  It would not surprise me to see snow flurries or snow showers behind that front. 

If you watch the 6z GFS at 500, it makes sense.  It pops a ridge in the East.  It gets knocked down.  The next ridge(chinook) pops further west.  It gets knocked down.  Each time the ridge goes up, it gets knocked down, and retrogrades westward.  By the end of the run, it is a EPO ridge.

Jax mentioned the atmospheric river.  It may well be we are still in a base-cold pattern w/ the AR overwhelming the MJO signal which wouldn't be unprecedented (reference earlier discussion).  As it retracts, that trough would slide right back into the East.  I need to actually look at modeling in the Pac to see if that is happening.

Interesingly, western Montana has had severe flooding when they should have had snow.  Troy and Libby have lost several bridges in western Montana.

[Daniel Boone]

3 hours ago, Carvers Gap said:

The 6z GFS is back to normal for Dec 19-29th after a warm run at 0z.  Interestingly, the 0z run developed what appeared to be feedback over the PNW.  When that occurs, the rest of the run is warm.  When it doesn't occur...it is back and forth.  For now, it looks like cold air masses will visit(24-48 hour duration) on the 19-20th, possibly the 22nd, possibly the 24th, and then too scrambled to even guess after that.  In between the cool downs, there will be chinooks likely.  I am really interested to see where this pattern settles after this transition timeframe.  But the back and forth pattern might the the actual pattern for a few undetermined amount of weeks.

That happened in '95-96 as we know. It would Snow and be cold a few Days, warm up rain and even flood some a time or two then cold and snow again. Blocking was the big difference maker that Winter. If we can get strong persistent blocking, I think we'll score some good Snow Events.

[Daniel Boone]

3 hours ago, Carvers Gap said:

The 0z Euro is much different w/ the Dec19-20 cold front potential.  I think it likely wrong.  The 6z AIFS has the cold front.  It would not surprise me to see snow flurries or snow showers behind that front. 

If you watch the 6z GFS at 500, it makes sense.  It pops a ridge in the East.  It gets knocked down.  The next ridge(chinook) pops further west.  It gets knocked down.  Each time the ridge goes up, it gets knocked down, and retrogrades westward.  By the end of the run, it is a EPO ridge.

Jax mentioned the atmospheric river.  It may well be we are still in a base-cold pattern w/ the AR overwhelming the MJO signal which wouldn't be unprecedented (reference earlier discussion).  As it retracts, that trough would slide right back into the East.  I need to actually look at modeling in the Pac to see if that is happening.

Interesingly, western Montana has had severe flooding when they should have had snow.  Troy and Libby have lost several bridges in western Montana.

Hopefully the Ridge doesn't do like the guy in thaht Song, I get knocked down, but I get up again, ain't nothin gonna slow me down ". Lol. I just had to man !

[Golf757075]

2 hours ago, Daniel Boone said:

Hopefully the Ridge doesn't do like the guy in thaht Song, I get knocked down, but I get up again, ain't nothin gonna slow me down ". Lol. I just had to man !

Each winter is different than other winters in some ways. That's the reality of it. The trough has been too far east for my area to see anything other than glancing blows of cold air. We definitely need a pattern reshuffle I believe. 

[nrgjeff]

Mele Kalikimauka it's gonna be a warm Christmas! Wake me up for the first tornado watch.

[Daniel Boone]

32 minutes ago, Golf757075 said:

Each winter is different than other winters in some ways. That's the reality of it. The trough has been too far east for my area to see anything other than glancing blows of cold air. We definitely need a pattern reshuffle I believe. 

Just carrying on there man. Yeah, that's been the fault during the entire cold period overall. Southern Virginia from about Lebanon Eastward to Va Beach have had a great Stretch with plenty of Snow.

[Daniel Boone]

18 minutes ago, nrgjeff said:

Mele Kalikimauka it's gonna be a warm Christmas! Wake me up for the first tornado watch.

Yeah, we need those Features Opposite of where they are. Hopefully guidance is off with that Depiction but, looks pretty likely until Blocking sets up late Month or those features shift.

[Carvers Gap]

12z suite highlights.  The 12z Euro(surprise!) now carries the banner for cold.  The Dec20-30th timeframe for NE TN is normal-ish.  It has the least feedback over the PNW.  The Dec 19-20 cold front is now a "go" with it being legit Canadian cold.  Can we score another front on the 22nd per the Euro - the GFS lost it, but I bet it's real.  The really interesting one is the backdoor cold front on the 27th.  Yes, it looks like Christmas should be warm with the cycle of warm fronts and cold fronts seeming to have it locked in between cold fronts - but who knows really.  At nine days out, anything can happen.

Maybe the really big news is the NAO looks on steroids on both the GFS and Euro 12z runs.  It is east based, but retrograding to the West.  It doesn't take much imagination to see a full latitude trough developing over NA between the Aleutian and NA ridges.  A true block w precedent.

[Daniel Boone]

1 hour ago, Carvers Gap said:

12z suite highlights.  The 12z Euro(surprise!) now carries the banner for cold.  The Dec20-30th timeframe for NE TN is normal-ish.  It has the least feedback over the PNW.  The Dec 19-20 cold front is now a "go" with it being legit Canadian cold.  Can we score another front on the 22nd per the Euro - the GFS lost it, but I bet it's real.  The really interesting one is the backdoor cold front on the 27th.  Yes, it looks like Christmas should be warm with the cycle of warm fronts and cold fronts seeming to have it locked in between cold fronts - but who knows really.  At nine days out, anything can happen.

Maybe the really big news is the NAO looks on steroids on both the GFS and Euro 12z runs.  It is east based, but retrograding to the West.  It doesn't take much imagination to see a full latitude trough developing over NA between the Aleutian and NA ridges.  A true block w precedent.

Yeah, eastern areas(east of the TN Valley )may very well not see much of the warm-ups at all. I think, as you alluded to earlier as well, we get in on some of them until Blocking asserts. I'm betting we see a couple very warm Days (60's) with maybe 70's western area's.

     I made a comment over in the MA Sub how we could get around the NPAC GOA Low problems as they're down on that being there as many are. Blocking is the key .Secondly, MJO in cold Phases .

Also, gave you a Shout-out about your Pac NW Feedback Idea and how it could very well be the Case. If Jeffs still viewing, what's your take on what Carver's Ideas are irt the Feedback possibility of the Model's in the Pac NW ? 

[Carvers Gap]

I think the trough shifting back NW makes sense given climatology.  I also know that LR models like to end winter with that....only to have the entire trough come crashing SE w/ one good cutter.  I suspect we have a really big cold snap coming...timing TBD, but I would guess LC has this nailed to the wall.

[Carvers Gap]

The 18z GFS joins(?) the 12z Euro in muting the chinooks with multiple cold fronts.   I did notice ensembles beginning to cool off at 12z (look at the run 2 run for reference).   I hesitate to say the GFS joins the Euro since the GFS was the first to the party and then went and smoked a cigarette on the back porch at lunch.  

[Golf757075]

6 minutes ago, Carvers Gap said:

The 18z GFS joins(?) the 12z Euro in muting the chinooks with multiple cold front.   I did notice ensembles beginning to cool off at 12z (look at the run 2 run for reference).   I hesitate to say the GFS joins the Euro since the GFS was the first to the party and then went and smoked a cigarette on the back porch at lunch.  

Pattern where you have to be patient and hope we get what we need to get to shake things up a little down the line

[Matthew70]

The winter canceled chatter is quite prevalent in some forums.  I for one will not complain for some warm days.  This cold snap was brutal.  The electric bill could use some rest.  lol.

[Holston_River_Rambler]

That -WPO has got to be one of the most persistent features I've seen on models. Don't take this as an addition to the warm vs cold debate, I'm just struck by how well that Aleutian ridge is holding on. It's not just that there is a ridge there either, but how stout it has been. 

 

 

 

[Matthew70]

Just now, Holston_River_Rambler said:

That -WPO has got to be one of the most persistent features I've seen on models. Don't take this as an addition to the warm vs cold debate, I'm just struck by how well that Aleutian ridge is holding on. It's not just that there is a ridge there either, but how stout it has been. 

 

 

 

What is the average time frame for one to remain negative? 
Wonder what effects it will have going into spring.  
Also with a -NAO wonder what effects it will have.

[Holston_River_Rambler]

1 minute ago, Matthew70 said:

What is the average time frame for one to remain negative? 

1 minute ago, Matthew70 said:

Wonder what effects it will have going into spring.

Heck if I know a good answer for either of the above. Sorry. 

 

2 minutes ago, Matthew70 said:

Also with a -NAO wonder what effects it will have.

That could be interesting. There has been some on again, off again talk about a potential -NAO across the boards, depending on your source based on either wave breaks in the N. Atlantic or strat. stuff from around a month ago. Could be a little bit of both. If an Greenland block kisses an Aleutian block we might get some fun as suggested in fantasy land on the 18z GFS:

500mb:

 

The surface has fine looking Canadian high dripping down into the CONUS:

 

One thing about this pattern is that it's blocky is some spots in the N. Hemisphere, not just the Aleutians. 

 

I have some family in Europe right now, so I have been watching there a little more than usual and they have some intersting patterns progged by the Euro and GFS:

 

Could you imagine if we had a pattern like that in the US? Highs over top and a series of meandering lows to the south. 

[Golf757075]

31 minutes ago, Matthew70 said:

What is the average time frame for one to remain negative? 
Wonder what effects it will have going into spring.  
Also with a -NAO wonder what effects it will have.

A -nao with a -ao would be ideal for us. I don't mind a pattern reset, as long as we can get back to cold thereafter. 

[Matthew70]

5 minutes ago, Golf757075 said:

A -nao with a -ao would be ideal for us. I don't mind a pattern reset, as long as we can get back to cold thereafter. 

True.  -AO are known to make this area cold.  Just curious how the -WPO affects us.  Add with that a MJO in phase 8.  
Good gracious all these teleconnections.  Was nice years ago when it never was even discussed.  Seems today’s times are so confusing.  Simple days of forecasting are long past. 

[Matthew70]

31 minutes ago, Holston_River_Rambler said:

Heck if I know a good answer for either of the above. Sorry. 

 

That could be interesting. There has been some on again, off again talk about a potential -NAO across the boards, depending on your source based on either wave breaks in the N. Atlantic or strat. stuff from around a month ago. Could be a little bit of both. If an Greenland block kisses an Aleutian block we might get some fun as suggested in fantasy land on the 18z GFS:

500mb:

 

The surface has fine looking Canadian high dripping down into the CONUS:

 

One thing about this pattern is that it's blocky is some spots in the N. Hemisphere, not just the Aleutians. 

 

I have some family in Europe right now, so I have been watching there a little more than usual and they have some intersting patterns progged by the Euro and GFS:

 

Could you imagine if we had a pattern like that in the US? Highs over top and a series of meandering lows to the south. 

No reason to apologize, sir.  You are a wealth of information and fun to learn.

[Holston_River_Rambler]

I've been thinking about weighing in on the MJO stuff, but I'm not really sure what I make of it. This sort of mess is new to me:

For what seems like most years lately, its been doing this loop d loop mess between 5 and 6. When I look at the Maritime Continent region, it basically looks how it has looked to me for most of the times I've looked at it over the past few years:

 

 

Sahara satellite just because it is so fun:

 

So what are we looking for wrt tropical convection and why? I can look at the RMMs as well as anyone and see where it is, but I'd like to start to dig deeper.

 

I'm going to poke around in this article for a while and see if I can come up with a useful summary:

https://journals.ametsoc.org/view/journals/wefo/29/1/waf-d-13-00102_1.xml

 

 

[Holston_River_Rambler]

3 minutes ago, Matthew70 said:

No reason to apologize, sir.  You are a wealth of information and fun to learn.

No worries at all. I've been trying to think of some way to contribute, but I'm kind of burned out on looking at tropical convection, lol. 

[Golf757075]

4 minutes ago, Holston_River_Rambler said:

No worries at all. I've been trying to think of some way to contribute, but I'm kind of burned out on looking at tropical convection, lol. 

When the RMM charts show between phase 8 and cod, does that make sense to you based on convection or is there something else going on? 

[Holston_River_Rambler]

5 minutes ago, Golf757075 said:

When the RMM charts show between phase 8 and cod, does that make sense to you based on convection or is there something else going on? 

Good question. That's something I'd like to figure out: how to read via satellite to see where impactful tropical convection is (for the pattern over N.America in general and the TN Valley in particular) and how it that convection is evolving (moving, increasing, and decreasing) to potentially modulate weather in extra tropical regions. 

[Matthew70]

All these teleconnections can cause headaches & burn out.  It’s like playing old maid over & over getting the maid. Lol.

[beavis1729]

2 hours ago, Carvers Gap said:

The 18z GFS joins(?) the 12z Euro in muting the chinooks with multiple cold front.   I did notice ensembles beginning to cool off at 12z (look at the run 2 run for reference).   I hesitate to say the GFS joins the Euro since the GFS was the first to the party and then went and smoked a cigarette on the back porch at lunch.  

I like your optimism, but unfortunately I don’t see anything redeeming at all on the 18z GFS. There’s essentially no snowfall south of 46N through the entire 16-day run. I know it’s only one model run, but my takeaway is that the chinook pattern is continuing, even if any “torches” are generally muted in our areas. The area east of the Rockies to the Mississippi River continues to be dry as a bone, run after run.

And for me, any temps warmer than 40F this time of year is considered a torch. The 18z GFS is just way too mild over the next 2 weeks in NE IL for my liking, and another concern is that Canada and the northern tier of the US are losing the deep cold.

We need to see more of a look where the ridge retrogrades and forms a -EPO. Maybe the pieces are being put into place for that to occur in January, but I would hate to lose the most festive two weeks of the year (holidays, short days, etc.) to mild and boring weather. 

I would love for someone to correct me, and encourage me to be more optimistic. But it’s maddening to see temps in SD, CO, and NE in the 40s and 50s day after day after day. That never seems to work out well here. 

Here is an example panel. Of course it’s only a snapshot from one model at one exact point in time that’s pretty far out, but those temps are way too mild for the coldest part of the day (12z). That would be a decent map for late November, but not late December.

[Carvers Gap]

Have to look at the surface.  500 maps are missing cold shots.  I think we are going to see a fairly normal pattern for December at this latitude.  What I am looking for is not non stop chinooks.   I am resigned to some chinooks mayhem.   We were close to a winter storm that run.