SnowDawg

Seems the clear point of divergence between the GFS/NAM and the Euro/CMC is the track of the upper level vort. The GFS camp takes a more gradual ENE climb off the gulf coast staying well SE of us putting us in the sweet spot. Whereas the Euro and Canadian have become pretty consistent in a more drastic NE turn bringing the core of the ULL almost into the southern mountain counties, benefiting eastern Tennessee and Kentucky. I can't spot the reason for this difference, the only thing that sticks out to me is there is still a significant timing difference between the two camps with the ULL's approach to the gulf, with the GFS camp several hours faster. I know the Euro and CMC have known tendencies to hold energy back too long. Thing is I don't know if this is causing the difference in eventual track or if it's insignificant. On the brightside, even a solution in between the two camps is probably a nice event for most of the area. Hopefully as we get more into the wheelhouse of short range models accuracy windows things will become more clear.

One thing I'm interested in seeing in the morning is what the spread on the EPS low locations looks like, cause on the GEFS there is maybe a few members that are as far west as the Canadian and none are anywhere close to the Ukie. The vast majority of the Canadians ensemble members are east of its own operational as well for what its worth.

GEFS Mean: 18z: Current:

Verbatim it has me riding the edge, but that was a huge step in the right direction from previous runs.

This actually looks way better for us than the 18z run. Knew that moisture transport back to the west, or lack thereof, looked fishy at 18z. Its not that far off the NAM, especially at H5 just takes a little longer for the surface low to get going thus a little later with the 850's crashing.

It seems to be on the far west side of the guidance envelope today. It has the surface low over 300 miles west of the NAM at 84. So it seems for now at least through the runs seen since this morning we have the GFS furthest east, RDPS furthest west, and everyone else at various points in between.

Definitely didn't hate it, can't imagine what folks west of Atlanta are thinking with that run. Wish there was just a few more hours on that run to see final totals. Needless to say its the NAM at range, so whoop-de-do, but I gotta say it feels good just to get NAM'd considering how bad this winter has been.

Euro control looks like a decent estimation of what that run would look like rolled forward. Not terrible for the mountain counties, but far from ideal. That eastern cutoff moves further west, and East-Central Tennessee ends up the big winner as far as the south is concerned. Hopefully we're just seeing some of the windshield wiper effect and it'll start ticking back eastward over the next couple days.

Westward and stronger trend continues on the EPS. Even though there was much ado about the GFS being east, I'm far more concerned about this west trend that's been going since last night. Euro control jackpots west of knoxville for the SE.

Yeah, the OP was paltry with precip on the NW side so it tracks that the GEFS would be as well given what we know about it. I think the GFS is probably around the eastern edge of the envelope since all other guidance is west of it. I'd bet on the final track being west of the current GFS, how far west is the million dollar question. Per usual, the safe bet at this point is somewhere between.

Beware GEFS under-dispersal problem. It tends to waffle around with its OP run most of the time.

Gotta remember the GEFS under-dispersal problem as well. The GEFS will always somewhat resemble the OP to some extent because of this. The key is to try and see through the noise and if there's a large number of members are fighting against the OP's idea, which its clear there is. GFS led the way in sniffing out this threat, but its now been left on an island in terms of timing and placement of the heaviest precip.

If this could go just a few frames more I still think it would look really good in the mountains, the 850's are just starting to crash. It is even slower than the Euro, notice the surface low still in SW GA while most other guidance is around Hilton Head at the same time.

Something definitely off with that run. At H5 and with the surface low it continued to tick towards the other guidance with the slower/west trend. But the precip map is just bonkers. 1004 mbar low over Savannah to a 1002 over Charleston and somehow almost no precip in the mountains. The physics don't even add up.

Haven't looked at the members yet but just looking at that I suspect it's split between two camps with where the jackpot zone is.

That makes perfect sense, thanks. Even when I know better given the setup it's hard to ignore paths to a better boundary layer lol

Looks like the GFS may be becoming a bit of an outlier on timing. Looks like it's about 6-12+ hours ahead of most other guidance. Not sure if there's any significance to that or not, just something I noticed. Curious whether the slower timing could allow time for some weak CAD to build in from that 1025-1030 high?

Man that is a painful run for North GA. Snow south of Augusta but none up here in the mountains.

Boundary temps are largely insignificant in a ULL setup. Pretty much the entire SE is at play. ULL track and intensity determines where snow falls.

18z looks more like the 0z from last night. (Edit: oops, meant 06z from this morning) ULL takes more of a north easterly track than the 12z, focusing the heavier snow in the mtns and foothills from NGA/upstate SC up through the mid-Atlantic. Was actually a hair weaker with the surface low than 12z. Still a great signal and too small a change to be focused on at this range on a global model. Just shows how important the track of that ULL will be for individual backyards if we manage to reel this threat in. ULL's can produce big winners and big losers with very little margin between.

Just crazy trend at H5 on the EPS from 12z yesterday to 12z today.

First time all winter we've seen positive trends at this timeframe. This has pretty much been the range when long range threats have went sour so far.

Quit focusing so much on surface depictions right now. ULL snow is a top down process. Anybody who has experienced it knows how fast the surface temps can drop as long as it's cranking. This event will be entirely predicated on the track/tilt/strength of the ULL. That has improved on basically all guidance since yesterday. The question is will it trend far enough to matter.

The Canadians ensemble also made big movements as well. Much like the GEFS it's sort of split right now, but the trend is clear.

So the GEFS still largely favors more of a positive tilt solution meaning very little snow outside the mtns with NW flow. This is apparent when you look at the individual members snowfall. The mean is being generated by a handful that do go neutral/negative and produce heavy snow. It's not all bad though, despite that being the consensus at the moment the trend towards more amplified solutions is clear. If we can keep it going for a few more runs I'd expect the snow mean to start jumping big time. It's all a wait and see game right now. But at least it's a plausible look.