December 2023 Mid/Long Term Pattern Discussion: Let it Snow!

[jaxjagman]

33 minutes ago, Carvers Gap said:

That map by Jax has the mid NA ridge which sets the stage for a WAR to go up briefly.  Behind that WAR is the pattern change.  That is the last or second to last ridge to roll through.  

Hey, does anyone have a link to the Google AI maps?  JB mentioned that ECMWF had them for free.  I haven't looked.  

Great discussion everyone.  

That's what i have

https://www.ecmwf.int/en/forecasts

[Itryatgolf70]

 

[Itryatgolf70]

Just now, Itryatgolf70 said:

 

Saw this posted. Amazing stuff really!! Out west in mountains

[Carvers Gap]

The 18z GFS just slams the door on fall.  That is winter.  I doubt that verifies, but that is winter.

[Carvers Gap]

Or maybe I should have just said...

The 18z GFS heard the thundahhhh!

[*Flash*]

8 hours ago, Carvers Gap said:

If weather models were college football playoff teams:

Michigan = Euro.  We know they are good, but that model steals our signs and Heismans(I mean snow).  And some of us really just don't like that model, because it is only blue(at 500) in Michigan.

Texas = GFS.  It is all American, and is only good during the fall.

Washington = CMC.  They seem like they should belong, but nobody is quite sure until they actually win against a good team.

Alabama = AI model.  AI should be better.  Why? It is AI, and it gets in because Google made it.  But really, we aren't sure if it is better, or just has a good day every once in a while.

FSU = CFSv2.  We know it is good, but we just don't think it can stand up against other models.  But A LOT of us don't like the AI model, and would prefer the CFSv2 as a personal preference. (no offense meant towards our AI friends in the Big Bend area of the TN river).

Georgia = UKMET.  It leads the way right before the Euro comes out every day.  But in the end, it just isn't the Euro, and AI made it look bad.

Tennessee = Euro Weeklies.  They always look good from a distance.  But when reality hits, it is just a passing cold front.  But we love them, because they alway show orange(on 500 maps) over Greenland.  Plus, the Weeklies are said to be able to throw it 80 yards.  But last year the Weeklies were better than the AI model, and we are gonna live on that for the next five years.

 

If this was last year, I'd say TCU is like the NAM. Solid in the short passing game and the resolution is ideal, albeit within a small sample size. Verification is a mixed bag. Got crushed by the UKMET though somehow defeated the Euro...but now the Euro is back on top where it belongs. 

[Carvers Gap]

Winter Weather Advisories posted for the spine of the southern Apps along most of the TN/NC border.  Snow showers are in my forecast for late tonight and early tomorrow AM.  MRX:

A trough over the northern Plains this morning will be pushing SW
and amplifying through the day. A channeled vort max around the base
of the trough will be pushing into our area this afternoon,
generating some weak lift and steepening lapse rates. Initially,
moisture will be confined below 850 mb, as we are seeing with the
low clouds this morning. By 00Z, the midlevels begin to saturate as
the trough brings colder temps aloft, and precip should increase
quickly around that time in northern sections. Initial temperatures
at precip onset will be in the mid/upper 30s to lower 40s, but a
shift of 850 mb winds around midnight will enhance cold advection
and steepen lapse rates, changing rain showers to snow showers in SW
VA, NE TN, northern Plateau, and the TN mountains. In lower
elevations, surface temps will likely be too warm for much snow
accumulation (mid 30s), but for locations above 2500 ft, temps
should be cold enough for snow to accumulate. A NW flow of around 25
kts will enhance precip rates in the higher elevations through
Wednesday morning. With low level trajectories off the Great Lakes
and the 850 mb flow persisting around 25 kts, the TN mountains and
higher elevations of SW VA will continue to see some accumulating
light snow into Wednesday afternoon.

With this duration of snowfall, at least 1 inch accumulation is
likely for locations above 2500 ft, so a Winter Weather Advisory
will be issued. Above 4000 ft in the Smokies, amounts will likely
exceed 3 inches, but will have an Advisory for that area given the
snow amounts will be highly dependent on local terrain, and most
populated areas will be under 3 inches.

 

[Carvers Gap]

Euro seasonals say, "Bring it."

[Itryatgolf70]

8 minutes ago, Carvers Gap said:

Euro seasonals say, "Bring it."

Hey Carver, if you can post them, I would appreciate it

[Carvers Gap]

 

 

 

 

[Carvers Gap]

Temps are above normal for December(first 2/3 of the month AN temps are not going to be overcome I don't think) and slightly BN for Jan/Feb depending on your location in the forum area.  Precip is BN from the Plateau westward, and seasonal for the Apps.  Get out a paddle, though, come springtime.  No idea if the those maps verify, but that is about as opposite from last year as we can get.  Could the seasonals be falling into a trap by relying on outdated analogs?  Maybe.  This will be a good test.  OTH, we are seeing the pattern change now on global ensembles and even operationals. If the Euro gets this right, it nailed the longwave pattern from way out there.

[*Flash*]

All I know is at this point: I'll take my AN temps pre-calendar winter and roll the dice of a pattern flip during climo winter. We saw this two years ago granted the teleconnection deck was entirely different. A torchy December was a small price to pay for what would transpire in the months to follow. Ideally, that pattern would have flipped two weeks earlier to allow some seasonal temps in time for the holidays. If December could blend the last two years together with less blowtorch warmth on the front end and less intense of an arctic blast by EOM, that would be awesome. 

[Carvers Gap]

I was talking to a friend(I missed the 18z GFS run, and he pointed it out)  and one thing that came from that discourse is that many cold, winter patterns begin with a very powerful storm.  The Euro Weeklies tonight have moved up the 500mb pattern to Dec 17th.  The 18z GFS has the flip on December 18th and it begins with a monster storm in the East.  I have been watching 2-3 piece of energy between say Dec 11th and 18th.  They have been close to phasing on several runs.  

[Itryatgolf70]

52 minutes ago, Carvers Gap said:

I was talking to a friend(I missed the 18z GFS run, and he pointed it out)  and one thing that came from that discourse is that many cold, winter patterns begin with a very powerful storm.  The Euro Weeklies tonight have moved up the 500mb pattern to Dec 17th.  The 18z GFS has the flip on December 18th and it begins with a monster storm in the East.  I have been watching 2-3 piece of energy between say Dec 11th and 18th.  They have been close to phasing on several runs.  

I really believe imo that once the mjo signal gets in west pacific, the ensembles and op runs will adjust accordingly. Not until then. Consistency is the key

[Carvers Gap]

Some decent hints at coastal development between Dec 14-18.  There are two pieces of energy.  The one around the 14th is quite strong, but OTS.  The trailer is interesting as energy from the Midwest slides over the top.  Right now, there is nothing major on modeling, but it is close....

[Carvers Gap]

To clarify, that is mainly on the GFS(past several runs).  It might just be a GFS bias, or the GFS is spotting potential at range.  It has energy between the 13th and 17th which other modeling seems to be holding back or is missing altogether.

[fountainguy97]

There is a single EPS member that dumps 20+ inches over Erwin with the storm mid-next week. Anyone have access to snow maps for it?

 

[Holston_River_Rambler]

56 minutes ago, fountainguy97 said:

There is a single EPS member that dumps 20+ inches over Erwin with the storm mid-next week. Anyone have access to snow maps for it?

 

Yeah I actually meant to the evolution of it in banter. 

[Holston_River_Rambler]

Some chance for our every popular wave riding a front solution with this weekend's system from the plateau east: 

 

[Carvers Gap]

The 12z Euro was pretty close to something good for eastern areas.

[fountainguy97]

13 minutes ago, Carvers Gap said:

The 12z Euro was pretty close to something good for eastern ares.

Yeah this weekend feels so close but so far. Need that low reformation to happen a bit further south. Some of the gefs members show some action. Touchy system. I don't think we see much in the end because the 500mb energy is pretty far north.

[Daniel Boone]

1 hour ago, fountainguy97 said:

Yeah this weekend feels so close but so far. Need that low reformation to happen a bit further south. Some of the gefs members show some action. Touchy system. I don't think we see much in the end because the 500mb energy is pretty far north.

Yeah, more than likely too North. May be some tailend wraparound and some upslope. If we can get that Front riding wave we'd do well. 

[PowellVolz]

Anyone else surprised at the trend has been south for the weekend system? I know we are still way off on getting to the winter side of this but we are much closer than I ever imagined also. If we could get the low to form 200 miles SW, it would at least give us a little backside opportunity.


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[PowellVolz]

Yeah this weekend feels so close but so far. Need that low reformation to happen a bit further south. Some of the gefs members show some action. Touchy system. I don't think we see much in the end because the 500mb energy is pretty far north.

I didn’t see this post but I was thinking basically the same thing. The low forming SW of the valley would be ideal but I won’t complain if it’s just south of us. One other tend has been for the trough to stay positive longer. If that trend would continue, it would open up the back door for the wrap around NW flow machine even if the the low stays north of us a little.


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[PowellVolz]

One other note on this… I believe when this system showed up 2 weeks ago it was in a much better location but we are trending towards that the last two days.


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[Met1985]

1 hour ago, PowellVolz said:

One other note on this… I believe when this system showed up 2 weeks ago it was in a much better location but we are trending towards that the last two days.


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Originally this system was buried in the SW on the GFS and the Euro and we warmed way up. Now it's going to barrel through here as a pretty stout front and set up a different type pattern.

[fountainguy97]

Hmm... this humpback look is how we score with this.

[Daniel Boone]

43 minutes ago, fountainguy97 said:

Hmm... this humpback look is how we score with this.

Yeah, neutral tilt . Be nice if goes negative after reaching our longitude. Either way, Neutral should still have decent backside. Archumbault may be at play here. 

[Holston_River_Rambler]

Kind of a compromise on the EPS overnight for this weekend. A few less members showing snow, but a few more members showing a higher end potential. 

Here is Elizabethton, TN but most locations from the N Plateau in TN and KY to the east look similar. 

Someplace like Richlands, VA might have the best upside potential:

 

I would say overall on the operational runs things are looking a little better, but not enough to get too excited yet. 

RGEM:

Euro:

Too little too late with the N stream s/w boost, but my bar is moodflakes. 

I feel like this set up looks really similar to one from last year, but don't really want to go back and dig through gifs at this time. 

 

Pretty wild look at the end of the OP 6z GFS too (300 hours +)

 

[PowellVolz]

Kind of a compromise on the EPS overnight for this weekend. A few less members showing snow, but a few more members showing a higher end potential. 
Here is Elizabethton, TN but most locations from the N Plateau in TN and KY to the east look similar. 

Someplace like Richlands, VA might have the best upside potential:

 
I would say overall on the operational runs things are looking a little better, but not enough to get too excited yet. 
RGEM:

Euro:

Too little too late with the N stream s/w boost, but my bar is moodflakes. 
I feel like this set up looks really similar to one from last year, but don't really want to go back and dig through gifs at this time. 
 
Pretty wild look at the end of the OP 6z GFS too (300 hours +)
 

Maybe I don’t pay attention enough but I can’t remember a trough just completely collapsing on the backside like this. I can anyone explain why this happened?


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