December 2020 Medium/Long Term Pattern Discussion.

[Carvers Gap]

That 12z run of the Euro...just want it to nudge just a bit more east of the Apps where it can consolidate (if you live in the E TN valley....stay where it is if in middle TN).  The Apps disrupted the system quite a bit with that shift.  There are times it shifts roughly 200 miles east.  Problem is the slp gets disorganized so sometimes a shift is just a result of about three different low locations.

[Carvers Gap]

12z EPS shows the shift eastward.  There is a cluster of lows over central(east side of central) NC that wasn't on any of the three previous runs.  The 12z EPS is south and east of previous runs.  So, looks like the trend is just that(south and east) for the 12z suite.  Does that continue?  Maybe.  I think at some point things shift back NW after the eastward jog stops.  Will be interesting to see if the Euro does indeed end-up being too far to the west during the past few days.  

[Carvers Gap]

Second storm on the 12z GFS just a monster with 957mb off Bar Harbor.  (saw the mention in the MA thread and thought...no way....well, way)

[Holston_River_Rambler]

18z NAM is west again, but shows some change over in Middle TN toward Monday early AM

 

[Blue Moon]

2 hours ago, Olhausen said:

The latest nam12k run seems to suggest up here on the highland rim we could see some accumulating snow. Although some of the heaviest bands seem to be when temps are still above freezing. I always wonder if it’s still possible to get a surprise snow like the 2003 storm that dropped 7 inches on Nashville? I know the models are much better now so maybe not. I was not living here until 2006 but have never had a huge over achiever like the 2003 storm. It seems like overachievers are more likely in the elevated areas of eastern Tennessee.

Were you not in Nashville in 2016? Jonas was an overachiever for your area IIRC

[Carvers Gap]

23 minutes ago, Holston_River_Rambler said:

18z NAM is west again, but shows some change over in Middle TN toward Monday early AM

 

So is the NAM the furtherest West solution now?   Going to be a good upslope event.  MRX has updated their afternoon disco and has a prelim snow map.  Elevation driven event for their forecast.

[Holston_River_Rambler]

1 minute ago, Carvers Gap said:

So is the NAM the furtherest West solution now?

Looks like it, lol. 

18z RGEM is coming in further SE. 

[Holston_River_Rambler]

18z RGEM plows the surface low right up the TN/ NC border. 

 

 

[Carvers Gap]

1 minute ago, Holston_River_Rambler said:

18z RGEM plows the surface low right up the TN/ NC border. 

 

 

Definitely jog SE over the past couple of days and with this past run...but can it get east of the mountains?  Just seems to me like a track between Asheville and Charlotte makes the most sense with maybe a some energy running up the eastern valley(aka the warm nose).  Pretty crazy to see that type of move this late in the game.  Think it is a testament to how tough this phase is to model.

NAM is definitely northwest of its previous run as you all have noted.  The storm right after this also has my attention.  Looks like it will be further east with enough separation and maybe storm 1 providing a bit of a block to slow it down so it can phase.  Really like the energy coming across the TN Valley feeding into that coastal.  Chance for a really big storm for eastern sections IF it were to phase earlier.

[Holston_River_Rambler]

 

Just now, Carvers Gap said:

Just seems to me like a track between Asheville and Charlotte makes the most sense with maybe a some energy running up the eastern valley(aka the warm nose).

The WRF NMM showed a similar solution at 12z:

That would be as much of a  run for my location as I can probably hope for. 

 

 

[Carvers Gap]

3 minutes ago, Holston_River_Rambler said:

 

The WRF NMM showed a similar solution at 12z:

That would be as much of a  run for my location as I can probably hope for. 

 

 

There is no shame in hoping for a solution that hammers your local...same goes for everyone else.  LOL.  If we had that run in January, all of the northwest quadrant would be snow.

[BhamParker]

I’m hugging the RGEM. MRX saying 1-2 for elevations between 2000-3000 feet and that seems a little conservative to me after seeing the RGEM, Euro, and GFS. Even the 18z NAM seemed to have some nice totals even around gatlinburg. 

[Holston_River_Rambler]

Yeah, their 1 -2 for Roan Mountain seemed a little low to me, but maybe they mean the town of Roan Mountain and not the 5500 - 6000 peak. 

Did I read earlier that you were getting a cabin near Gatlinburg @BhamParker? 

[Holston_River_Rambler]

18z GFS looks like it almost wanted to run the SLP from Macon, GA to Charlotte, NC, but randomly jumps at hour 36 back to the TN/ NC border:

 

I guess we're just at "see what happens time" now. One thing I did notice today was that there was a stronger wedge (from obs at southerwx) and a little bit of a leeside low near Asheville:

 

That's now transitioned to a more of a diffuse area of lower pressure and the WPC even has a couple of what I think are inverted surface troughs and a Low hanging out in the piedmont. This may play a role in how the surface low behaves too, but honestly I'm not sure:

 

[Carvers Gap]

9 minutes ago, Holston_River_Rambler said:

18z GFS looks like it almost wanted to run the SLP from Macon, GA to Charlotte, NC, but randomly jumps at hour 36 back to the TN/ NC border:

 

I guess we're just at "see what happens time" now. One thing I did notice today was that there was a stronger wedge (from obs at southerwx) and a little bit of a leeside low near Asheville:

 

That's now transitioned to a more of a diffuse area of lower pressure and the WPC even has a couple of what I think are inverted surface troughs and a Low hanging out in the piedmont. This may play a role in how the surface low behaves too, but honestly I'm not sure:

 

Good stuff.  Yeah, 18zGFS is west a hair though the slp is a bit strung out between two pieces of energy.  I am just now resigned to following the dry slot to see if the system is moving east or west.  The precip shield is a hair west in west TN.  Definitely worth trying to see the 0z runs.  Just let me see some snow in early Dec, and I am ready to roll.  LR ensembles still look good through mid December.  Am watching to see what happens on the GFS after 120 on this run...

[Carvers Gap]

That is a massive vort coming out of the Plains at 132...going to have to be reckoned with.

[BhamParker]

38 minutes ago, Holston_River_Rambler said:

Yeah, their 1 -2 for Roan Mountain seemed a little low to me, but maybe they mean the town of Roan Mountain and not the 5500 - 6000 peak. 

Did I read earlier that you were getting a cabin near Gatlinburg @BhamParker? 

Yes we are. We are staying in a cabin that is about 2800 feet up in elevation outside of gatlinburg. It’s off of ski mountain road. We are so close to that 3000 feet threshold that I hope it really helps us out. 
 

We came up for a storm back in early February of 2018 that produced an inch or two but it was a quick hit. The models to me see to paint a pretty prolonged period of snowfall for our area, at least I’m hoping so.

[John1122]

4 minutes ago, BhamParker said:

Yes we are. We are staying in a cabin that is about 2800 feet up in elevation outside of gatlinburg. It’s off of ski mountain road. We are so close to that 3000 feet threshold that I hope it really helps us out. 
 

We came up for a storm back in early February of 2018 that produced an inch or two but it was a quick hit. The models to me see to paint a pretty prolonged period of snowfall for our area, at least I’m hoping so.

Elevation makes massive differences across the area. 2800 should see accumulation for sure. Even 2 or 3 hundred feet is night and day at times though.  3000 is a magic number there it seems because MRX uses it frequently.   I know that above 3000 in my area sees a significant amount more than 2500. There are also places that are much better for upslope than others and those even vary based on the angle of the wind. Hopefully your cabin is located in a favorable spot.

[Daniel Boone]

2 hours ago, BhamParker said:

I’m hugging the RGEM. MRX saying 1-2 for elevations between 2000-3000 feet and that seems a little conservative to me after seeing the RGEM, Euro, and GFS. Even the 18z NAM seemed to have some nice totals even around gatlinburg. 

They're pretty much always conservative.  I'll say this, IF there's strong nw flow off the lakes and enuff steep lapse rates, I guarantee much more than they're showing. NW flow alone would yield more than 2 inches in places like Wise, Va for example..

[Carvers Gap]

18z GEFS low locations.  Still quite a bit of spread even at this range.  Again, I think this goes up east of the Apps with some energy going up west as it usually does during events from the GOM(aka the warm nose).  

Great conversation by John above about elevation.  I am at 1,300'.  However, about a mile behind my house there is a ridge which reaches 2,400'.  You can actually see the snow line for most elevation dependent storms.  

 

 

[Carvers Gap]

Will try to save this.  This is the 90hr GFS 500 map.  When we look back on this thread, this is the set-up.  Looks like the crazy type of block(which has been forecast and not come to fruition during past winters), might actually verify.

[Carvers Gap]

@Holston_River_Rambler, I am dropping my SREF plume in the main thread.  LOL.  1" mean for reference after I have to delete this image later for space.

[Holston_River_Rambler]

They've been pretty consistent for both our areas with a one inch mean and no members showing 0. 

[Holston_River_Rambler]

18z Euro mighty close to making the jump across the Apps:

 

[Daniel Boone]

1 hour ago, Carvers Gap said:

Will try to save this.  This is the 90hr GFS 500 map.  When we look back on this thread, this is the set-up.  Looks like the crazy type of block(which has been forecast and not come to fruition during past winters), might actually verify.

What a boobyful Map !

[Carvers Gap]

32k 0z NAM is further south than 18z through 11 hours.  Will update in this post....just hit refresh in a minute.

Through 18 slp over the panhandle of Florida.  

Through 27, south and east of 18z.

Switched back to 3k NAM as it is populating more quickly:

Through 38, very similar but a hair quicker and maybe a bit more robust to the NW in Indiana.

@44 down to 990mb...quite a bit stronger than 18z.  Wrap around moving in.

 

[Holston_River_Rambler]

'Twere pretty @Daniel Boone 

but surely no match for SREF plumes:

 

[Olhausen]

5 hours ago, Blue Moon said:

Were you not in Nashville in 2016? Jonas was an overachiever for your area IIRC

Yes I was in White House. Got 12 inches from that storm but the night before they were calling for 6 plus with localized areas of 8 or more. In other words it was very clear there was good possibility for a big snow. I believe the 2003 storm was calling for an inch maybe two in Nashville. Anyways I don’t want to clutter the thread up with this but hopefully someone in Tennessee gets a surprise out of this one coming up.

[John1122]

00z hi-res, the 3K NAM and RGEM looked better for more of us than the 12K NAM. The 3k is down right aggressive in some areas even outside of elevation. I assume it's trying to guess as mesoscale bands that drop heavier stuff. 

[Blue Moon]

Yeah, was just coming here to post about the NAM. It has a changeover from rain to snow that is quite heavy in some parts of northern Middle TN and southern KY. 

Hopefully this event can overperform. If the low doesn't move as fast as anticipated, and if temps are lower than expected, it might. Hard to score both of those variables though.

This shouldn't be one of those situations where dry air screws everything up, right?