December 2025 Short/Medium Range Forecast Thread

[housemtnTN]

Medium Flurry, dime size flakes in Mascot, TN about 10 mins ago.

[Carvers Gap]

The 18z RGEM has company…the 12z NAM.  Both are at range so the usual caveats apply.  The 18z GFS wasn’t too far off.

[Carvers Gap]

Haha.  If u want to see a wild swing, and it has been going on for a bit…look at 360 on the GFS at 18z and then flip back and look at 12z (temp anomalies).  We are talking 40-60 degree swings!  Good times.

[Carvers Gap]

The 18z GFS shows one of two extremes which have been modeled in the past 36 hours.  That is a crazy cold run.  Real feels have ranged from the 70s to below zero with these swings - for the same hour!!!

[midwoodian]

I created a Winter 25/26 general obs thread in case anyone sees some snow this AM 
[mention=10790]Knoxtron[/mention] and [mention=499]John1122[/mention] I'm staring at y'all with jealousy. 

Heavy flurries in Signal Mountain this afternoon


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[Carvers Gap]

The last four runs of the GFS for Dec 12-17th.  

 

[Carvers Gap]

The 18z AIFS has 2-3 very strong cold fronts w/ the anafront ending the run.

[Carvers Gap]

[Carvers Gap]

The 0z 3kNAM and 0z RGEM show frozen precip over NE TN and SW VA over the weekend.  Just something to keep an eye on....

[John1122]

The UKIE, GGEM, and ICON show a winter event of varying degrees in the area. The Canadian would be a major winter storm with significant ice along the 40 corridor from the mid-state to the mountains. Some snow on top of the ice across areas north of 40. UKIE looks like a long duration sleet event. The ICON is a 1-2 inch snow north of 40.

[John1122]

Euro is just a little too warm for most of Tennessee heading into the weekend, with very light precip.  After, it gets cold, but barely any qpf, looks like warmth and moisture return together mid-month but that may be a head fake too. 

[Holston_River_Rambler]

Overnight ensembles are interested wrt wintry weather in the period around Dec 11-12. As many changes as we've seen with this upcoming system overnight Thursday into Friday AM, will be interesting to see how the 11-12th evolves over the next 5 days or so. 

[Carvers Gap]

The good thing that I see with regards to the mid-month ridge rolling through is that it is temporary on all ensembles this morning.  It is always in the realm of possibility that the ridge is a pattern change, but for now it looks transient at best(3-4 days at the longest).  That ridge, as long as it rolls through, could very well set the stage for the coldest air of the season(so far) to fill that trough behind it.  There are pretty strong mechanisms in place to deliver cold air d10-15.