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

[John1122]

2 hours ago, Carvers Gap said:

The clown map is gonna be fun.  LOL.

It only gave me 17-18 inches. Toss. 

[Carvers Gap]

12z Euro has a western forum area snow threat next Sunday.  The CMC is slightly more progressive.  Blend might move snow chances further eastward - if indeed real.  Storm could be a strong one wherever it ends up.......

[Carvers Gap]

12z ensembles are also starting to get the potential pattern change in their sights as the post Dec 20th transition window slides into view.  Ridge is getting dislodged on both the GEPS and GEFS.

[Carvers Gap]

MRX afternoon disco.  All right, foothills/plateau/mountain residents, here is the evening disco from MRX:

.LONG TERM...
(Monday night through next Sunday)
Issued at 318 PM EST Sun Dec 3 2023

Key Messages:

1. Another shortwave trough brings colder air and a NW flow pattern,
with accumulating snowfall expected in higher elevations on
Wednesday.

2. Potential for a strong system to affect the region next weekend.

Discussion:

Not much has changed over the last 24 hours as we progress the long
term period out another day. Outside of lingering precipitation
overnight Monday night, we quickly move to the next shortwave that
will come swinging into the area Tuesday night. As has been the
discussion, the cold air the shortwave is bringing with it along
with decent low level moisture and upslope flow will combine to
produce a light snowfall accumulation in the mountains. Some snow
showers into the lower elevations of NE TN and SW VA is also
possible, but accumulations beyond a quick dusting will be hard with
marginal surface temperatures. With all the clouds and rain/snow
showers around, Wednesday will be the coldest day of the week, with
forecast already below NBM and might go even cooler for daytime
temperatures given the ongoing weather at that time. NAM has a high
of 36 at Bristol, adjusted the temperatures to move slightly in that
direction.

The good news is once the upper trough exits sometime Wednesday
evening heights will build back in as a ridge moves into our area,
bringing a warming trend on through the for the remainder of the
week. Ensembles and the deterministic guidance still show a deep
upper trough this upcoming weekend which will be the next system
after Wednesday to watch. Guidance is keyed in on a potent overall
setup, just details to hash out when we get closer. Though the
solutions are different, both GFS and Euro bring strong return flow
and potent dynamics. At the very least this should boost us back to
pleasant temperatures, though this reprieve will be short lived with
the presumably strong cold front.

 

[Carvers Gap]

All global ensembles to varying degrees have the pattern change at around d15-16.  Still a ways to go, but good to see that ridge getting the boot.  

[Carvers Gap]

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.

 

[Holston_River_Rambler]

NAM = Liberty? 

[Itryatgolf70]

42 minutes 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.

 

Carver, I'm assuming when there is a legitimate pattern change, it will show in the ensembles about 10 days out and the op runs will hint at it as well? I personally can't believe anything 15-16 days away and typically if it's legit, it usually gets moved up in time. I read something at another forum that there is a typhoon throwing things out of whack currently with the pattern. 

[Carvers Gap]

54 minutes ago, Itryatgolf70 said:

Carver, I'm assuming when there is a legitimate pattern change, it will show in the ensembles about 10 days out and the op runs will hint at it as well? I personally can't believe anything 15-16 days away and typically if it's legit, it usually gets moved up in time. I read something at another forum that there is a typhoon throwing things out of whack currently with the pattern. 

Of course everything is subjective past 5-7 days.  However, it looks like modeling has been quite consistent in switching the pattern up around the 20th at 500mb.  Now, that might take a few days past that for cold air to enter the pattern.  I think Nino is driving the boat now.  We are seeing increased precip, cloudy days, and the signature 50/60s temps and lows in the 40s.  My seasonal ideas have the pattern changing to cold by mid January.  Models are much faster than that w/ the Dec 20th change...if they are right.   The WAR showing up on modeling does hint at an SSW incoming.  I used to get frustrated when I would see the SER hook-into the NAO.  Not anymore.  That is usually a fairly big precursor to big pattern changes down the road.  The 12z GEPS has the change now at d14-15 now.  Honestly, it is pretty impressive that the Euro Weeklies could possibly have nailed this switch from 4-6 weeks - pretty amazing when one thinks about it.

[Carvers Gap]

1 hour ago, Itryatgolf70 said:

Carver, I'm assuming when there is a legitimate pattern change, it will show in the ensembles about 10 days out and the op runs will hint at it as well? I personally can't believe anything 15-16 days away and typically if it's legit, it usually gets moved up in time. I read something at another forum that there is a typhoon throwing things out of whack currently with the pattern. 

Cosgrove feels like the storm this weekend sets the stage for the trough to drop-in about 10 days later.  He thinks that is the catalyst.  

[Daniel Boone]

thunder in the mountains ftw ! Thunderstorms crossing area currently. Large claps of thunder here.

[Carvers Gap]

The 12z EPS is showing a switch to the long discussed switch to Nino climatology - meaning SE trough.  The switch/transition is now at d14.

[Carvers Gap]

5 minutes ago, Daniel Boone said:

thunder in the mountains ftw ! Thunderstorms crossing area currently. Large claps of thunder here.

Truly amazing how accurate that rule is.......

[jaxjagman]

Think i'd toss this afternoons Euro run

[Carvers Gap]

13 minutes ago, jaxjagman said:

Think i'd toss this afternoons Euro run

Just a slight disconnect!

[Carvers Gap]

Man, the Euro Weeklies drop the hammer at about d14 at 500...takes the temps about 3-4 days later to come down, but 09-10esque.  The weather today just feels like the intro to a transition.  Thunder, lightning, wind, rain...everything that fall wasn't.

[Carvers Gap]

Snow map is posted so that you can see the storm track.  Notice the deep snow cover over Quebec and eastern Canada - that is like a recharging battery for cold over the East.  On the 500 map(30d map from Dec20 -Jan19, notice where the BN heights are.  This has present for weeks if not months on LR modeling.  HL latitude blocking signatures are present as is a +PNA w/ split flow.  Bout time to mount up.  Lots to like about those maps.  Even better, the 12z EPS supports the 0z Weeklies 500 maps.  On about a 14-16 day countdown at this point.  This is the exact opposite of last winter where we could see the end of the cold at this point.

 

[Holston_River_Rambler]

6 minutes ago, Carvers Gap said:

The weather today just feels like the intro to a transition.  Thunder, lightning, wind, rain...everything that fall wasn't.

It was definitely a weird feeling morning down this way. Mommatus clouds rolling in, in the AM, then rain, then clearing, and nice convective clouds in the PM:

[jaxjagman]

10 minutes ago, Carvers Gap said:

Just a slight disconnect!

Maybe its, right,just looks odd,we arent use to seeing that strong of HP this early

[BNAwx]

11 minutes ago, Carvers Gap said:

Just a slight disconnect!

1043 highs aren’t what they used to be….

[Carvers Gap]

1 minute ago, jaxjagman said:

Maybe its, right,just looks odd,we arent use to seeing that string of HP this early

I mean it is possible that a cold high could slide into those short wavelengths and get trapped with a high over the top.  That is ice city if real - which it probably isn't.  To my untrained eye, that would be a fairly shallow surface high with big pressure building over the top.

[jaxjagman]

1 minute ago, BNAwx said:

1043 highs aren’t what they used to be….

yeah that screams ice

[jaxjagman]

1 minute ago, Carvers Gap said:

I mean it is possible that a cold high could slide into those short wavelengths and get trapped with a high over the top.  That is ice city if real - which it probably isn't.  To my untrained eye, that would be a fairly shallow surface high with big pressure building over the top.

that would definite be ice

[Carvers Gap]

1 minute ago, BNAwx said:

1043 highs aren’t what they used to be….

It is really cold under that high though.  There are -15F readings in Quebec.  I think it is the combination of tight wavelengths, and early season hp.  Those early season highs aren't super strong, and it is originating from a less than stellar cold air mass.  Very Nino looking though w/ marginal air masses down this way.

[Carvers Gap]

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.  

[Carvers Gap]

5 minutes ago, BNAwx said:

1043 highs aren’t what they used to be….

Hey, man, and good to have you in thread.  When BNA shows up, it is time for business.

[tnweathernut]

If the squall today is any indication of the energy to come through northeast TN and the mountains Tuesday overnight into Wednesday morning, could be a surprise or two........  I didn't expect to have thunder, lightning, and 40-50 dBZ's.

[Holston_River_Rambler]

If y’all have a minute and are near a computer check out the Beech Mt resort cam. You can see the storm rolling in from the valley. I’m definitely going to try to watch it since temps are still in the upper 30s up there. 

[tnweathernut]

6 minutes ago, Holston_River_Rambler said:

If y’all have a minute and are near a computer check out the Beech Mt resort cam. You can see the storm rolling in from the valley. I’m definitely going to try to watch it since temps are still in the upper 30s up there. 

Snow boarders about to go from this is fun to not so fun if this comes in as a wind driven rain................  

 

[Daniel Boone]

Saw on SE sub that it was snowing at 4500 ft this morning. I'd venture to say Thundersnow occurred above 4000 feet with the cells this Afternoon. Temp fell from 52 to 43 during storm here.