Holston_River_Rambler

Noticeably more confluence over NE I would say at hour 45. It isn't much, but enough to make a difference.

I think there is a hair more confluence on the NAM at hr 39. Like 4 pixels worth, lol.

https://www.spc.noaa.gov/exper/sref/ There are lots of parameters to toggle at the top.

now here's a real weenie post, looks like the SREF members like em some gulf lows, lol: I count 16 gulf lows or gulf coastal lows and 8 inland ones.

I think part of the problem we are seeing with the lp locations, has to do with the fact that this big ball of energy is just dropping in from the NNW. Normally with a bowling ball system like this it rolls in from the 4 corners and so pops an initial low in TX or the Gulf, but this system already has a surface low dropping in and so as the energy makes the turn, that low gets confused ( I know its not alive, but hear me out) wrt which boundary to jump to. Does it jump up into the eastern TN valley? Does it jump down to the toasty Gulf coastal waters? Does it stay near its energy? And while all this is going on, the system is moving, so pretty soon the Gulf stream becomes an option too. I think we want this energy to drop in so far south that there is never a doubt about where the low pops: the Gulf. I wish I knew more about the physics and meteorology of surface low formation so I could convince myself that the warm Gulf waters would override these other options.

If the TN Valley had a motto for winter storms, that would be it, lol. Ligans aculas

As I was trying to find a picture to help Dsty's question (I was looking for an ideal situation for the eastern valley), I found this reanalysis image from Feb 2014: This energy is much stouter, but we have a similar HP to deal with: Here is the radar of what that produced Again the energy that is creating this storm is stronger, so there is more worry of WAA and downsloping, but notice in 2014 we also had a kicker dropping in. Sure I would like to see a 2014 repeat, but I don't think that is exactly where we are headed. I will say though that that storm was one of the top analogues the MA folks kept throwing around a day or two ago.

Nary a clue. I will say that I think the 6z Euro was pretty close to having a deform band move across the state, but I don't know exactly how to recognize those this far out. But if that happened we could get higher than 10:1 ratios.

And I understand that the 10:1 isn't realistic, but at this point I just don't care, lol. That were a run for many parts of TN

Pivotal's snowfall, 10:1 for the prettiest colors:

Here's what Pivotal did with the precip. type maps:

Just looking at the energy you would think it would spawn a low near Mobile that ran up the coastal plain.

Yeah I was about to say the center of the upper level energy on the 6z Euro was ~100 miles south of 0z at hour 81.

Maybe the UKIE will win this one. It's had the weirdest outcomes when compared to every other model and maybe that's the approach this system needs, lol.

@AMZ8990 is the 6z RGEM winner: 6z GFS seemed to take a really nice energy pass: and we get a 999 low just south of Atlanta, but the 850 low still makes a run at the eastern valley. However, the 850 low has been trending SE the past 4 runs: if we could get that 850 low to round the Apps, that would be nice. But as it stands this AM, on the GFS at least, that is ne Bueno for areas that would get downsloping from the Apps and be impacted by a piece of the low trying to slide up the eastern valley. 6z GEFS looks like it tries to have a few members be straight up Miller As, but the majority are still these Miller B messes: but like Tellico said last night, those members don't quite get the precip back over the Apps. 6z NAM looks like it is a little further south than the GFS, but still sends some energy up the valley.

I think the Sillin post is regarding the energy in blue, and that piece is important and the one that was sampled earlier today. But pay attention to the one I've circled in pink as the NAM runs. That is the primary vort in this set up, IMO:

IMO NAM will be interesting, it is slower in the primary shortwave as the above post suggests, but has some stronger vorticity at hour 24

Thanks @Stovepipe your posts were one of the reason I joined this community, so you are much appreciated!

The NAM, it do be running. Shall we extrapolate?

I think that 540 line is just more of a guideline, than a hard and fast rule. That being said, climatologically it will be hard to deal with the downsloping for the eastern valley and even me on the plateau off of frozen head with a ENE and NE wind. MRX had good points in their PM disco: "In [my] experience many times Miller B type events, and the resultant snowfall totals are not handled by the long range models especially well due to low topography resolution. One of the biggest things they seem to incorrectly forecast is the strong downsloping that occurs with these systems. The downsloping then results in higher surface/low level temperatures and really eats away at snowfall totals with a slightly warmer atmosphere. Combine this with many of the deterministic models predicting the heaviest snowfall to occur during the daytime hours... and the only slightly below freezing temperatures overnight... and temperatures possibly reaching into the 40`s in the Valley during the day on Saturday/Sunday... It all leads to heavy skepticism in some of the high snowfall totals that some of the deterministic and ensemble amounts being depicted." In the main thread, Jeff also noted that even NWS offices in West Virginia were worried about a warm nose. For my part, I hate anything that even resembles a Miller B. That low is trying to find a thermal gradient to use as a transfer pathway and the lower elevations of East TN create a warm pocket for some part of that low to go. In my limited experience, Miller Bs have been STJ systems. I know that isn't always part of the KU definition, but for us in the east TN valley, ANYTHING that sends a piece of low pressure up the valley as the energy transfers to the coast, might as well be the same. I can understand people further north using the A/B hybrid distinction, but it really doesn't matter if you live from Chattanooga to Morristown, IMO. This is not a STJ system though. The angle of attack for the energy is unusual for us and there have been soooo many shifts, some dramatic, in NWP, over the past few days. That normally suggests ensembles are more useful in unusual situations like this, but we also have to consider that ensembles are compounded iterative differences of initialization conditions, while we're lookin for frinkin' reality. Ensembles suggest, but don't precisely foretell. To me, the OPs have led ensembles for this system, and that also suggests that this is an unusual set up. We've seen a few model cycles where the OP ripped the ensembles out of their happy median and said basically "Nope, we going this way." The smoothed mean can't account for realtime conditions and any small bird fart perturbation chaotically shifts the NWP outcome. I guess all I can say is La Nina. Fast flow in a chaotic medium = chaotic results. One thing I found of interest on the 18z Euro were the Dewpoints: That's some cold dry air trying to filter over the mts and making some headway at TRI. PSU in the MA forum was commenting on some analogues and says that this antecedent airmass is the coldest among those analogues. Now, they are closer to the HP in the mid Atlantic, so that may not apply here, but it is something to think about. I think this storm has one or two more tricks up its sleeve before it's finished, but I am also prepared for my heaping helping of a warm nose, served piping hot, if that happens.

Here's Pivotal's precip output:

TBH the 850s look pretty doggone similar to me.

12z run Sunday AM: 18z run Sunday AM: Looks a little stronger, so it could wash out the slightly south tick

Just a touch further SE with the center of the energy at hour 78.

Looks like a smidge more confluence over NE on the 18z Euro an I mean a smidge. It is out to 66 hours so far.