December 2025 Short/Medium Range Forecast Thread

[Knoxtron]

You guys weren't kidding on the winds, weather station recorded a 30 mph gust (only counts a 5 second avg for gust speed) and temp dropped 12 degrees in 5 mins from 1010 to 1015 last night 

 

Interesting that the winds were from the north all day and flipped 180 degrees to from the south in that time period. 

 

Whipping fog at 60 degrees in heavy wind is awesome weather haha

[Carvers Gap]

Line moved through here this morning.  Wind and rain.  Both the 0z CMC and Euro move plenty of cold air eastward beginning around the 29th.  They could be too fast in breaking down the warm-up, but both have a cutter where the GFS does not.  My guess would be the GFS is slightly too progressive, and misses it.  If that cutter is legit, cold would roar down the Plains.  Not sure how excited about cold on the 30th I am - Music City Bowl would be miserable!

[Carvers Gap]

The para 0z GDPS is very cold on the 28th-29th before the run ends.  I have a feeling (if the NAO strengthens and models aren't hurrying it up too much), that cutter may bring down more cold than models are depicting.  If the NAO starts a bit slow, then the GFS will score that timeframe.

[Carvers Gap]

The first thing we are gonna have to know(and it is increasing in likelihood) is whether the NAO is a legit player.  On modeling where it is missing or weak....it is warm here.  When it is present, cold fronts drop through the Plains(instead of sliding through Canada).  

[Carvers Gap]

With opposing teleconnections (high in the Aleutians and high over Greenland), modeling "could" have its hand full.  The base pattern would be an eastwardly displaced PNA ridge w/ cold attempting to stretch from Alaska into the NE.  Cold would roll over the top of that ridge and any storm(Miller B or A) would bring down very intense cold behind it into the SE.  I wouldn't say it is a great pattern for snow unless we can score an inland runner.  But...it could get crazy cold IF the NAO is as strong as projected on both the Euro and CMC(especially the GDPS).  

FWIW, ensembles aren't seeing cold fronts at all - just completely washed out until the last minute.  That is why I am using them less.

It is entirely possible the NAO does not develop, but it is infamously difficult to predict.  I am a bit wary of any model where it is absent late in the run.

The wind is absolutely howling here....that must be what you all were describing.

[Holston_River_Rambler]

Yeah, it's wild some of the flip flopping OPs are doing right now. 

Huge NAO -> No NAO-> some sort of N Atlantic blocking

Meandering cutoff over the Southern CONUS -> Now just a cutter 

I am also glad some of the runs are starting to move that Aleutian ridge around. 

 

Hopefully once they ingest the thunder we had last night for their 12z runs, things will start to move around even more 

[*Flash*]

1 hour ago, Holston_River_Rambler said:

Yeah, it's wild some of the flip flopping OPs are doing right now. 

Huge NAO -> No NAO-> some sort of N Atlantic blocking

Meandering cutoff over the Southern CONUS -> Now just a cutter 

I am also glad some of the runs are starting to move that Aleutian ridge around. 

 

Hopefully once they ingest the thunder we had last night for their 12z runs, things will start to move around even more 

Yep! If we can move that darn pig, chances are things will get better. #suey 

[Carvers Gap]

Ideally we want the cutter.  I think it shakes up the 500 pattern.

As for wind, hole mackerel it is howling out there.  On my run this morning, I saw a roof blown off shed, and poly from another roof.  Constant roar out there right now.

[Carvers Gap]

If the CFSv2 seasonal is right this morning, LC is could be set to score a pretty coveted seasonal win....and I mean an outright thumping. He dared to go the exact opposite of many seasonal ideas.  

[Carvers Gap]

 

[Golf757075]

1 hour ago, Carvers Gap said:

 

I have a friend who teaches meterology for a college. Very smart guy. He is supposed to call me in a few hours. I have alot of questions for him lol. I will let you know what he tells me. 

[Golf757075]

I just spoke to my friend. He had to cut me short because rain was flooding his driveway in Albany lol. He indicated that mid January at the earliest for a colder pattern here. He said the convection is going strong in phase 6 and he thinks it should shift east over time,  but no guarantee and we get colder and he said January is pretty cold in phase 8 on average. We shall see

[*Flash*]

3 hours ago, Golf757075 said:

I just spoke to my friend. He had to cut me short because rain was flooding his driveway in Albany lol. He indicated that mid January at the earliest for a colder pattern here. He said the convection is going strong in phase 6 and he thinks it should shift east over time and we get colder and he said January is pretty cold in phase 8. We shall see

Glass half full people be like…just in time for peak snow climo at our latitude. Nice…

[Carvers Gap]

I suspect the 12z GFS is just a bit quick, but that is a potent winter weather pattern just after 300 that run.  By the end of the run, the blues and reds are in the right places w/ split flow.  That is a plausible(though certainly not certain) solution.  Great trend if it sticks.

[Carvers Gap]

12z CMC is on board and about 2-3 days quicker as it has been for a bit.  The mechanics for cold an snow are in place around the new year if these trends hold

[Carvers Gap]

Between 180 and 240, the CMC completely erases any remnant of the chinook, and fills NA w/ BN temps again.  Impressive if it is real.

[Carvers Gap]

Even the Euro AIFS at 12z(which has been reluctant of late to budge) completely erases the chinook pattern.  I think some version of a full latitude trough w/ some ridges/troughs sliding across the base...sure makes a lot of sense.  

[Golf757075]

13 minutes ago, Carvers Gap said:

I suspect the 18z GFS is just a bit quick, but that is a potent winter weather pattern just after 300 that run.  By the end of the run, the blues and reds are in the right places w/ split flow.  That is a plausible(though certainly not certain) solution.  Great trend if it sticks.

You mean 12zgfs lol. 

[Carvers Gap]

I mean...really these are some WILD solutions.  The 12z Euro is cooking one up as I type - doubtful it verifies.   Good trends, but wild.

[Carvers Gap]

1 minute ago, Golf757075 said:

You mean 12zgfs lol. 

Haha.  I am a time traveller.

[Golf757075]

Just now, Carvers Gap said:

Haha.  I am a time traveller.

Model madness at its best

[Golf757075]

16 minutes ago, Carvers Gap said:

I suspect the 12z GFS is just a bit quick, but that is a potent winter weather pattern just after 300 that run.  By the end of the run, the blues and reds are in the right places w/ split flow.  That is a plausible(though certainly not certain) solution.  Great trend if it sticks.

We go through these highs and lows with the models every winter. Makes it interesting to an extent 

[Carvers Gap]

12z is definitely a choose your own adventure.  Definitely NOT an easy pattern to model, but LIKELY to produce some interesting solutions on deterministic runs.  Normally, I would say check the ensembles, but I think they are at least 24-36 hours behind the curve.  

[Golf757075]

3 minutes ago, Carvers Gap said:

12z is definitely a choose your own adventure.  Definitely NOT an easy pattern to model, but LIKELY to produce some interesting solutions on deterministic runs.  Normally, I would say check the ensembles, but I think they are at least 24-36 hours behind the curve.  

Interesting look for sure

[Carvers Gap]

2 minutes ago, Golf757075 said:

We go through these highs and lows with the models every winter. Makes it interesting to an extent 

Models have "likely" made two big errors this year.  One was the Baja low situation for early December.  The next one(appears as of now) was the repetitive lows sliding out of British Columbia to off the Coast of California.  The Rex block might produce one or two storms on the West Coast...but not the sequence which was causing the endless chinooks.  Even though modeling is still working things out....the exiting of feedback helps.  Some chinook makes sense...but it was way overdone it appears.

Now, is the NAO feedback?  IDK.  I have definitely witnessed years when models over-did how strong it was and missed the duration (sometimes too little duration...sometimes too much).  The same could be said for the Aleutians high - but it has actual precedence for being there and at that intensity.  I think we end up w/ a full latitude trough w/ cold dropping into Montana, modifying just a bit, and then heading eastward.  I think the difference this year(compared to recent Nina winters), the source is much colder and this cold finds its way all the way to the Atlantic coast.

I do suspect models could be too quick with the move back to cold, but again, sometimes they aren't quick enough if the NAO is going to be a player.  The storm track could be more favorable as we enter January.  As your friend notes, mid-Jan makes a bit more sense or even just the second week of January.  

[Carvers Gap]

6 minutes ago, Golf757075 said:

Interesting look for sure

The real fun with that is the NAO and Aleutian's highs bridge across the top.  They trap a lobe of the TPV in NA.  I think the biggest take away from 12z is that HL blocking is showing up across modeling, and the signal is stronger at 12z than yesterday at this time.  Good trends.

[Golf757075]

Just now, Carvers Gap said:

The real fun with that is the NAO and Aleutian's highs bridge across the top.  They trap a lobe of the TPV in NA.  I think the biggest take away from 12z is that HL blocking is showing up across modeling, and the signal is stronger at 12z than yesterday at this time.  Good trends.

Good trends so far. I personally would feel better if the epo went negative, but that's just my opinion lol

[jaxjagman]

4 hours ago, *Flash* said:

Yep! If we can move that darn pig, chances are things will get better. #suey 

That's what i'm gonna call it now "The Pig"...lol

[Daniel Boone]

47 minutes ago, Carvers Gap said:

The real fun with that is the NAO and Aleutian's highs bridge across the top.  They trap a lobe of the TPV in NA.  I think the biggest take away from 12z is that HL blocking is showing up across modeling, and the signal is stronger at 12z than yesterday at this time.  Good trends.

That's what we talked about and what it's going to take to spoil the warm pattern early.  Still not sold it'll happen though. If it doesn't, that massive nina HP and freaking GOA low are Staples for awhile. 

[*Flash*]

33 minutes ago, Daniel Boone said:

That's what we talked about and what it's going to take to spoil the warm pattern early.  Still not sold it'll happen though. If it doesn't, that massive nina HP and freaking GOA low are Staples for awhile. 

Hearing you say that gives me bad 2016-17 vibes. Awful winter but there were some breaks if you include March.