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 !