DDweatherman

Here shows quite well the move the 12k NAM makes wrt to thermal gradient & the snow/sleet line. Pretty sizeable jump SE. 18z top 12z bottom

Yes the 3k is not as good as the 12k depiction. However, take a look at the sounding here in DC which is well into the rain depiction on the frame shown. Column is not far off from being isothermal. Additionally, the low is I'd estimate 50-75 miles east of last run. PSU, keep me honest on that (I'm using TTB)

NAM definitely stopped the bleeding wrt to the west shift in track and thermals closer in even near the fall line. Gets borderline warning criteria to a lot of folks in CMD west of 95. The WAA thump is solid on this run.

Dews look pretty commensurate at this stage. We'll see how the high percolates cold air down through our area overnight.

Well, the only bright side to this is that the WAA slug has looked better today for a thump for a lot of folks in the sub, and the western crew/northern tier can probably get to warning criteria if it performs well.

I am still thinking the true LP positioning is going to end up over the DE bay where the other closed isobar is. Euro does do what the GFS looked to do and wrap the cold air in with a quicker change in wind direction to get rid of the SE winds. Provided we had a decent track, this would be a good run, but re PSU's thoughts earlier, further west is never what we want to see.

I'm mobile, do you have access to the ML depictions on the Euro to see if it has the ML/UL circulations closed off and thats part of its reason on better thermals?

Literally posted at the exact same time on this. That can't hurt us to see regardless of range/res.

On mobile, but about half the GEFS members take the low SE of the opp, less than a handful west. Too close in to take ground truth verbatim, but hopefully the east side of that envelope prevails.

Because it heads due east from Philly, the mid levels would crash and cause us to go back to snow if it happened exactly as depicted on the UK.

Can we see a 0z for comparison? Almost time for the Euro to pull the ole Lucy.

So, what do we look for now for some last minute respite?

Agreed trixie. I think in reality the surface reflection isn't indicative of where the true LP center is. Mesoscale differences aside, a more wound up system that does cause the mid levels to close off/stack for us might also be what is giving the double barrel look where we're seeing a low over the bay instead of over OC/right off the coast.

Although I am definitely rooting for that as part of the outcome, I'd favor a good slug/thump of WAA on the front end to lay a nice base of snow and get some good rates. That could also help keep the column cool if we do get the secondary snow from any wraparound. Keep watching those h7/h85 depictions...those closing off is part of our recipe to do well.

I agree with you on this. It does seem like the meso features help the thermals quite a bit on the GFS wrt evolution, and as I pointed out the ML's closing off. Agreed though that a track up the bay to NAK isn't going to get it done. The double barrel low structure we have seen on a number of models is still a bit puzzling to me, and I've dug into the mid level maps to see if that's warranted. I wonder realistically if that's driven by convection on some models since the UL features don't align with the base of the trough putting a low over the middle of the Chesapeake. I'm still liking a track from VA beach to east of SBY (hopefully on the coast of OC) north to Lewes before going more ENE.

I mean even the ICON improved at 12z which has been one of our worst models to this point on the storm but in reality was more accurate with the low track.

The GEM is the only 12z model that got worse for us so far thankfully. We're gonna need the Euro to hold up.

Agreed, there's not a primary present but if you see what I just said to Joe and he confirmed is we want to see this thing close off in the ML's and have the winds not vector out of the SE pumping in the WAA for the entirely of the low's track to our latitude.

I saw yesterday you are off Lucabaugh right? Good to see we have another member of the Westminster/Carroll crew here in the forum. Looking for my first good snow since moving up here 2 years ago.

Joe, need your thoughts on the GFS. Do you think h7 & h85 closing off has anything to do with the better outcomes on 12z. Tracks are right over us so not ideal, but can't hurt to have it stack a bit?

It has a lot to do with the evolution and where the snow comes from. There isn't much dependency on the backend stuff for us either, it's more WAA driven and enhanced by the low being relatively near before we dry-slot.

Nice GFS run, best look on the snow maps for the myself/mappy/PSU crew but also Moco/Howard folks a la WxUSAF/osfan. You want to see the bomb a bit if you're hoping for improvements at this stage.

It is definitely interesting to see even when the low is going as far W as these models have shown, surface temps barely touch freezing or don't go above for a lot of the northern tier folks. The 3k wasn't a "worse" run per say. I'm thinking a lot of these models are showing mesolow features as the true SLP, whereas the h85 and h5 tracks give us a better idea of where it actually would be.

I think somewhere in between. The GFS is quite a bit warmer at the surface pretty much compared to all other models!

Looking at SV maps, which are posted here above it looks like. Surface temps are also chilly. GFS thermals are like 5-7 degrees warmer.