December 2020 Medium/Long Term Pattern Discussion.

[Carvers Gap]

SLP sitting over eastern Louisiana at 162.

[Carvers Gap]

Little disorganized by MUCH different solution than 0z.  Looks like a mix of slider and Miller A....out to 180 and that looks like a Miller A/inland runner. Perfect track and cold is lacking.

[Carvers Gap]

At 192, the storm wraps-up.  Looks like a good deal for the Plateau at the very least.

[Carvers Gap]

So maybe the "big" story from the 12z suite is that both the GFS and Euro have Miller As for the second storm.  Cold is marginal.  Need the storm to be strong without pulling westward. Good start.

[Holston_River_Rambler]

EPS looked like it was seeing a signal for anther Gulf storm at the end of its run. Too far out to say much more than that for now. 

[Carvers Gap]

The storm is on the 12z EPS around 180 @ 500....would be later next week.

[Holston_River_Rambler]

Sorry I was talking about a different one, just as an addendum to what you had already said. Should have been clearer in how I phrased it. 

[Carvers Gap]

51 minutes ago, Holston_River_Rambler said:

Sorry I was talking about a different one, just as an addendum to what you had already said. Should have been clearer in how I phrased it. 

Yeah, not a bad looking pattern for sure.  Really hope we keep that block over HB and/or Greenland.  Might be able to use that to bridge to the next trough amplification during January.  I would be tickled to have a back-and-forth pattern vs just getting locked into a crap pattern like last winter.

[Holston_River_Rambler]

For you western TN folks, the 18z 3km NAM looking interesting towards 10 PM and midnight Sunday night into the wee hours of Monday AM:

 

Looks like it is associated with the 500 mb vort, as the N stream races in to try and catch it. 

Meanwhile, for those of us further east, the 18z RGEM still handling the secondary N. stream energy a little more aggressively:

 

 

And it's not all upslope driven. Not quite sure if we get in the left exit region of the jet to the south over GA and the Carolinas, but we're close. 

 

 

 

[Carvers Gap]

Surprised nobody has mentioned the 12z GEM snow map for storm one....The GEM and its ensemble are not terrible in terms of snow or track.  Maybe grasping at straws, but saw the JMA is still holding to a Piedmont track, so I tried to dig around to see if it had support, and found the GEM with still a strong solution for middle TN.  I think the EURO is too far west.  This will be a good test to see if it has a bias towards being too wrapped up.  The 18z GFS still has a few members on the other side of the mountain.  Sure, it is a long shot...but was surprised to see some models still holding out.  With this being a powerful storm and also with a phase...still keeping one eye open.

[Holston_River_Rambler]

18z Euro showing some similar mixing, to the 3km NAM over western TN:

 

 

[John1122]

2 hours ago, Carvers Gap said:

Surprised nobody has mentioned the 12z GEM snow map for storm one....The GEM and its ensemble are not terrible in terms of snow or track.  Maybe grasping at straws, but saw the JMA is still holding to a Piedmont track, so I tried to dig around to see if it had support, and found the GEM with still a strong solution for middle TN.  I think the EURO is too far west.  This will be a good test to see if it has a bias towards being too wrapped up.  The 18z GFS still has a few members on the other side of the mountain.  Sure, it is a long shot...but was surprised to see some models still holding out.  With this being a powerful storm and also with a phase...still keeping one eye open.

 

The Canadian is pretty insistent for this event being decent to great for Middle Tennessee. It's just tough to trust with synoptic details, especially when it's sort of on an island.  

[Carvers Gap]

Oddly, I don't think this is completely set in stone yet.  The Euro is still trying to attempt energy handoff eastward @ 63 either into the eastern valley or western NC.  Probably won't change its solution much, but it is really interesting to follow.  Also, the 18z run was a lot stronger in terms acscums in Indiana and Ohio in comparison to 12z - meaning stronger system.  Probably a bit of a western jog...but seems the slp center bounces around with each run.  Again, if the slp gets clear of the Apps (either east or west), likely going to be much stronger.  Looking very much like a westward track, and that is a good example of what happens when it gets clear of the Smokies.  The operational actually has a piece of the low on the east side of the Apps.  I think pretty much everyone needs to be pulling for this to get stronger.  Even if the eastern valley gets dry slotted, the wrap-around could be pretty intense for NW facing slopes as it pulls northward.

[Carvers Gap]

The phase at 18z is just earlier as more energy is in the northwest quadrant of a disorganized low pulling out of Louisiana.  It doesn't take much to get an earlier phase, and it doesn't take much to get a later phase(meaning spine of the Apps track).  Going to depend on the exact location of the greatest amount of energy is that comes northward out of the GOM.  I still think the Euro is a little over-amped, but man, it is not budging a bit.  

[Carvers Gap]

12 minutes ago, John1122 said:

 

The Canadian is pretty insistent for this event being decent to great for Middle Tennessee. It's just tough to trust with synoptic details, especially when it's sort of on an island.  

The shape of the storm(if one didn't see the pressure) is not all that different.  The 12z GEM doesn't really do an energy handoff like the Euro.  It goes into western NC and dry slots the Smokies.  That puts the comma head and earlier change over for middle and parts of west TN.  I would guess the Euro is probably right as it fits right with the RGEM.  The GEM, the NAVGEM and the JMA are still consolidated east...and probably not a model group I would share a foxhole with, but just interesting to note.  

[Carvers Gap]

Again, going to be an interesting test for the Euro as it is has steadfastly been on the western edge of modeling.  And models like the GFS and CMC operational models have moved to it.  

[Carvers Gap]

0z 32k NAM is rolling.  Bit south of 18z and maybe a bit slower.

[Carvers Gap]

Unless it bounces north during the next couple of slides...the 3k NAM looks like it took a jog southward.  Tough to tell if it is just slower or south or both.

[BhamParker]

Enjoy reading your analysis, Carvers Gap. I am looking forward to seeing how this storm pans out for the smokies. My wife and I will be coming up from Alabama on Sunday and staying in a cabin in gatlinburg off of ski mountain road that is about 2,800 feet in elevation. I am definitely hoping for a strong NW flow once the system starts to lift. I feel like we will be in a good spot so far from what I’m seeing on the models. 
 

We stayed in this same place February 2, 2018 and scored a couple inches, but it was a quick mover and didn’t snow long. Hope to send y’all a good report on Monday afternoon and Tuesday morning before we head back home. 

[Carvers Gap]

Bham, yeah might be good, especially Monday night.

The 0z 3K NAM is a mb or two deeper.  Can see some mixing in west TN at about 56.

[Carvers Gap]

3k NAM tracke directly over the Apps - nearly perfectly along the spine.  The NAM is just coming into range.  My guess would be that it jogs a tad more eastward as it also has a tendency to be overly amped - but it should be leaving that bias quite soon as we get closer to the event.

[Carvers Gap]

WRF-ARW is also just coming into range.  It is way down there.

[Carvers Gap]

0z RGEM is similar to 18z but maybe a hair north of the run six hours ago.  Entry might be a bit sharper as well.  Will wait until the globals begin to run before commenting further.  If not, the nightshift can have at it...always enjoy reading their info in the morning.

[Carvers Gap]

Fun deal that the 12z RGEM does(also think I noticed it on the NAM), is that there is a fairly powerful secondary low that pops around Delmarva and feeds back into the system which prolongs the snow over the Ohio Valley.  Starting to see the "stalled" solutions come back vs the recent solutions which seemed quicker to get out of the way.

[Carvers Gap]

0z GFS is most eastward of the last four runs with a slight eastward jog of the slp center since 0z last night.  The 0z. GFS now sends a portion of the energy east of the Apps.  The 0z run from last night too the center through middle TN.  This run is splits the app with the designated low along the spine or just a hair west of it.

[fountainguy97]

Hey all.  Interesting storm. Tons of small variables can really enhance or suppress our backside moisture.  Hoping to squeeze out an inch or two here! 
 

Waiting to see what high res models show over the next day. Very fascinating storm evolution.

 

3km has a legit line of broken cells and then snow a few hrs later.. going to be a wild few days.

[John1122]

If you're in a favorable upslope area you're probably going to score regardless. Above 4000 will be rocking, I'd say LeConte will rack up 10+ inches. They are the upslope capital of the south. 

[John1122]

Snow amounts did tick up in the 00z suite so far.  If I were guessing I'd say an inch or two may fall in some non elevated areas of Middle Tennessee especially, but it'll be hard to have more than a heavy dusting to 1/2 inch on the grass the further west you are due to time of day and warm ground temps. 

 

Right now I'm just hoping to see something and hopefully it's not the best event of winter. 

[Carvers Gap]

0z GEFS now has a just more than half the SLPs east of the Apps with a low now coming through between Mars Hill and Asheville.  That is a decent shift in the location of the slp.

[John1122]

The Euro is about 90 miles south through 48 hours. Some frozen starting to pop in SW Missouri.