TellicoWx

I've noticed a few people are getting the surface low and the 850 vort comfused, they are 2 separate things. The surface has been roughly locked in going along the coast in more of a Miller A style. The totals across the TN/KY line include the front-end snow, which the central and southern valley will miss. The angle and exact pivot point of the 850 is what makes or breaks the valley. Just glancing at the FV3, it is pivoting or transferring sooner and maxing out the uvv's over the valley as well in the coma head leading to the crazy output.

TYS Snowfall range:

GEFS: 1"-8"

EPS: 0.5"-24"

6 minutes ago, PowellVolz said:

 

So you’re saying the EPS has fewer members turning the system through Tennessee?


.

 

Everything is still on the board, GEFS/EPS members are all over the place...its almost as if they are saying it's either go big or go home scenario 

1 minute ago, Save the itchy algae! said:

I'd expect so, but if there were indeed only a few slps moving towards TN then you think the ensemble would be more favorable.

The problem is their is no consensus across any modeling really right now on how to handle it, even individual ensemble members. EPS has members that go from nothing for everyone nearly to members that make the epic 12z run the other day look like a walk in the park.

10 minutes ago, Save the itchy algae! said:

Is there precedent for an 850 low splitting into two clear lows that move in different directions like what is depicted on the Euro? It seems to me that one or the other would take over.  

None off the top of my head, but we have seen the Euro go from taking it completely south of us, to shooting it to Indiana, now to south of us then split in two for a sec. The wild ride is far from over I believe.

Until the transfer is worked out, it seems there is some wild swings on the individual members of the EPS...absolute crush jobs board wide.

Here's the closer one

12z EPS

After looking over everything, I believe the Euro is having some problems on how to handle the transfer to the coastal. When it begins it's transfer over N AL, it splits the low into two distinct pieces #1 due North to the middle TN/KY border, #2 ESE into GA heading for the coast. The transfer should have been more smoothly. Due to this odd scenario, it shoots the 850s way up over East TN responding to the #1 piece. A smoother transfer and this would have been an even more major storm for the board. Sorry for the long post.

Very weird couple frames...it wants to jump the 850 vort (that is traveling due east) in northern MS/AL, into the KY/TN line due north at a 90 def turn.

3 minutes ago, Math/Met said:

I'm focusing on that too. The position of the low at 850mb makes a huge difference for parts of East TN. We want the flow over our region to have more of an easterly component and less of a southerly component. For multiple reasons (less WAA, less downslope potential…).

I'm kinda at a loss on that run, looked great but for some reason it shoots the 850s up the valley at 90/96...trying to find the driver for it and at a loss. If not for that it would have been a great run.

120 it starts it's transfer to the coastal

Vast improvement on 850 vort compared to 00z in Indiana

102 the 850 vort is south of 00z

18 minutes ago, John1122 said:

The WPC model disco. They will update post Euro but for now gave the most weight to the 00z Euro.

 

 

Hopefully the 850 comes back south, the 00z roasted NE TN and spelled ice storm instead of snow.

2 minutes ago, Coach B said:

So while the trailing 850 low is actually extending snow/precip chances back this way its also screwing up the thermals? In other words, the thermals are not as clear cut like a consolidated low pressure system would be?

Yes it's messing up the thermals in a big way. Here is an example from the epic 12z Euro and the current 00z...the 850 went from tracking south of TN thru MS/AL, to now being up in KY. The 850 has to track completely south of us or phase to the coastal sooner.

17 minutes ago, Coach B said:

Look at the warm nose into middle TN/S KY! Dang, I hate to waste a chance at a system taking what would ordinarily be a perfect track. I really cant figure a warm nose like that with the LP over Jacksonville?? Why the heck are the 850s not dropping when it goes by to the south?

It's not a "true" Miller A, more of a hybrid Miller B. The warm nose in central TN is in response to the uv riding up into that region before pivoting into the coastal. 6z had that more sw flow up the valley compared to the 12z. My guess is it's pivoting just a little quicker which helps the eastern valley.

Next frame you can see the 925s response with plenty of moisture still on going. Just one model run, but a step in right direction for GFS.

52 minutes ago, Wurbus said:

@TellicoWx What site do you use to get those charts?

WxBell site

Big improvement in the 850s as the comma comes overhead in East TN. Also, increased the precip rates which may translate to the surface better.

6z GFS vs 12z GFS

2 hours ago, Carvers Gap said:

I think part of what is going on...we are trying to match models with what will eventually become reality.  If reality is a true Noreaster that goes from Louisiana to SE GA, up the coast, and impacts the I-95 corridor...that changes things quite a bit.  I mentioned that yesterday, and still am looking over my shoulder for that.  Looks like the overall track though is a good one.  Temps are the issue, and that might not be resolved for several runs.  Put me in the northwest quadrant of a storm, and I will take my chances.  It won't work out every time, but that is where big snows happen.  I would rather be there more times than not.  On to the 12z suite...By 0z tonight we should be getting an idea of where this his heading.  The trends from last night to tonight on the operational will begin to outweigh the ensembles...but the ensembles still matter with so many varying tracks out there.  Time to watch trends...and those admittedly were not the best at 0z.   At 6z, the trends are not all that bad.  That tells me that models are still wobbling from run-to-run, and understandably not dialed-in yet.

Good point on the wobbling and not dialed in, here is a good example of this on the 6z GEFS...basically almost a coinflip at TYS.

00z EPS is close to same, exception is south of 40 and the valley the totals came down. Looks similar to the OP, so finally starting to get a consensus.

15 minutes ago, Carvers Gap said:

LR NAM IMO tends to amp things up just a bit too much late in its run, say after hour 60.  That causes crazy snow totals, systems out of place, but not sure about its bias of high pressure.  That usually causes all kinds of mischief because of that.  But it can give us a clue to how the GFS might look early in its run.  Just my two cents...

Yeah the NAMs HiRes helps it when dealing with microclimates in short range. When dealing with microclimates even a 5 mi shift can have a dramatic effect so with so much variability when extended out it results in some wild swings.