December 2025 OBS and Discussion

[jm1220]

4 hours ago, eduggs said:

There's very little support on any of the major ensembles for much snow through 10 days... or even 12 days (corrected, the GEFS shows the Dec 4/5 potential wintry event). It looks relatively active with cold air not too far away, but the multi-guidance consensus suggests the progression and evolution of the longwave pattern is not locally favorable. Even the individual members are stingy with wintry outcomes for the moment. Early December is still highly trackable... and we know that ensemble members group too close to the parent model, so favorable changes are still possible especially out past 7 days.

The worst for me is the cold/dry. If it won’t snow I’d rather it be mild. Last winter was the worst for that reason-so much wasted cold. 

[MJO812]

Here comes the gfs lol 

[eduggs]

Pretty sick GFS run! Wow. The CMC is going to be a little warmer, but close-ish. The key difference is the high pressure nosing down reflecting the slightly more suppressive mid-upper level flow over New England. Here's to hoping the models home in from here instead of wild swings.

[MJO812]

43 minutes ago, eduggs said:

Pretty sick GFS run! Wow. The CMC is going to be a little warmer, but close-ish. The key difference is the high pressure nosing down reflecting the slightly more suppressive mid-upper level flow over New England. Here's to hoping the models home in from here instead of wild swings.

Gefs is trending colder in the mid range. PV is ticking further south.

[bncho]

Just now, MJO812 said:

Gefs is trending colder in the mid range. PV is ticking further south.

GEFS has good signal for Dec 2-6

[MJO812]

1 minute ago, bncho said:

GEFS has good signal for Dec 2-6

Cmc also has a storm but its warm. Aifs is further south. 

[SI Mailman]

A foot and a half of snow the week after Thanksgiving?  Lock it in.  

[IrishRob17]

7 hours ago, MJO812 said:

Here comes the gfs lol 

And there goes the GFS 06z

[North and West]

I like to come back and engage right before Thanksgiving for great maps like this.




.

[MJO812]

24 minutes ago, IrishRob17 said:

And there goes the GFS 06z

And its gone on the models

[wdrag]

Lots of variability in solutions but snow acc possibilities exist next week,  esp I84 corridor. 

[MJO812]

[eduggs]

Check out this discontinuity between 0z and 06z on the GFS. That's day 5.

[eduggs]

All guidance appears to be "struggling" with the amplitude of shortwaves coming down the ridge from AK to CA. This is an area where minor perturbations grow into mature trofs or deep upper lows. It may or may not also be a data sparse region. This is leading to huge intra-and inter-model variability with respect to west coast trofs, their amplitude, and which is dominant.

[MJO812]

[NEG NAO]

10 minutes ago, MJO812 said:

its not impossible - we are heading into a more favorable pattern for cold/snow events - it has snowed during this time period many times before - worth tracking for sure..........

[Snowlover11]

if I dont get 17” like the gfs showed last night im rioting 

[MJO812]

22 minutes ago, NEG NAO said:

its not impossible - we are heading into a more favorable pattern for cold/snow events - it has snowed during this time period many times before - worth tracking for sure..........

Agreed but we have to watch the SE ridge since the PNA is going to be negative.

[forkyfork]

1 hour ago, MJO812 said:

Agreed but we have to watch the SE ridge since the PNA is going to be negative.

you will get rain. no need to track anything

[MJO812]

4 minutes ago, forkyfork said:

you will get rain. no need to track anything

Typical

[MJO812]

Euro is frigid going forward.  What a change.

[eduggs]

So I guess we have our first definitive threat period Dec. 2-3. All mid-range modeling indicating at least the threat of a wintry storm. Still highly variable setup so I'll try to keep my enthusiasm in check. Of note, the GEFS have backed off the past few runs but that brings us closer to a model consensus.

[jm1220]

2 minutes ago, eduggs said:

So I guess we have our first definitive threat period Dec. 2-3. All mid-range modeling indicating at least the threat of a wintry storm. Still highly variable setup so I'll try to keep my enthusiasm in check. Of note, the GEFS have backed off the past few runs but that brings us closer to a model consensus.

If we’re dealing with an overrunning SWFE parade I’ll gladly pass. 95% of those are quick sleet to rain, just rain or slop to rain here while we watch I-90 get 6”+. Gradient patterns here are way more often than not lame crap. If we can get storms to slide SE of here or redevelop south of our latitude I’ll be more interested. 

[MJO812]

[Krs4Lfe]

It's good to see those in the Upper Midwest and Great Lakes getting in on some snowstorm action. Always good to see the buildup for snow and winter weather to our west. Hopefully if we build that pack, that cold air can bleed east and try to dampen down the SER that will be rearing its ugly head by mid-December.