Holston_River_Rambler

Weatherbell is down for me, so probably not much from me until either that comes back up or SREFs finish around 230 pm.

Nice fantasy storm on the 12 GFS around hr 300. It's even got the '24-'25 winter Baja lowTM trying to interact with the N. stream. surely nothing will change in 300 hours?

@PowellVolz yeah wrt speed, some of the models have it out of my area by 10 am or so. I would definitely take an earlier onset tonight.

Pretty good precip field, virga or otherwise, already:

Looks like MRX went with the NBM for that map:

Virga introduced, in case any of us had hope of earlier onset Some dry low level air will keep any precip light at onset, until forcing increases toward sunrise and precip rates increase. The timing of this will greatly affect snow accumulation amounts. A later arrival time will decrease the chance of accumulating snow, because rising temperatures during the day will become a stronger limiting factor. Once the sun comes up, snow accumulation during the daytime is difficult in the later parts of winter with the higher sun angle.

Sorry that only has East TN but it’s from a station based out of Columbia, SC

Here is the latest GRAF animation and yeah @PowellVolz I think this is the one

WBIR in house model showing snow starting at my location around 11pm tomorrow night. Wish I knew which model that was.

Key parts of their rationale for accums: If this precipitation moves in earlier in the morning we`ll likely see more accumulating snow before sunrise, but if it holds off even just a couple of hours and doesn`t start to precipitate in the southern Appalachians until after sunrise, then chances for accumulating snow really decreases. Once the sun comes up and starts to impact the cloud layer history indicates that snow occurring during the daytime, in the later parts of winter with the higher sun angle, and when temperatures are around or just above freezing... It can lead to much slower snow accumulations. In addition there could possibly be some downsloping flow which warms up the atmosphere and eats into the QPF totals. With temperatures expected to slowly climb through the day to above freezing for most of the Valley locations any precipitation that lasts into the afternoon hours will have a decent chance of flipping over to cold rain, which would also help wash away some of the snow that might have accumulated earlier in the day. At this time the most likely scenario is to see advisory level snowfall for much of the Valley locations, with the lowest amounts in the south and along the foothills of the Appalachians. We could see 4+ inches in the higher elevations of the northern Cumberland Plateau and over into far southwest Virginia on Wednesday as they`ll have the snow begin the earliest and the coldest temperatures throughout the day.

Euro upped .qpf a tick again at 12z. Looked RGEMish.

But it is the NAM, so let's see how the rest of the runs go this PM.

Oh yeah, if we got a line of storms pumping moisture N/NE through the deep south rather than parallel to the coast that should help.

I liked that NAM run. It got the heavier precip further north from the Gulf: 12z. vs 6z

I think the hi resolution of the Euro is seeing (rightly or wrongly) more convection in the Gulf. The above is a gif of lightning flash density according to the 6z Euro. It's maxed out just south of Louisiana and the convection is parallel to the coast. The whole complex just pushes SE further into the Gulf. Like Carvers said I think this is kind of a watch and see radar deal now. I wish the RGEM had a similar parameter on weatherbell for comparison. Also, I think the convection is a nail in the coffin for anything more than a widespread 1-3" or 2-4", not necessarily a nail in the coffin for the whole event.

RGEM really likes the upper low/ TPV swinging in. It even has some FGEN over east TN: I wonder if that might turn into something like an arctic front with 20:1 ratios?

I think maybe if we just pretend this is and old fashioned I-40, 2-4" clipper, just forget the precip. to our south, we might not be too far off.

The more I looked at the 500-700mb relative humidity depicted on the Euro, I actually got a little bit more optimistic.

MRX notes the main mechanism for lift is being in the right entrance region of a jet and that looks pretty well set: The lagging jet initially over Montana and Wyoming in the gif above tries to help buckle it But there has to be some precipitable water/ relative humidity to lift. Most of our deeper, mid level moisture is west Pac moisture Some gulf moisture gets involved late, and I think there is some room for the Euro to improve here, but not much.

6z Euro looked a little less dry, but not by much. 4 run qpf trend

12z NAM goes full on Miller B with bit of lp running up through the foothills of the Apps.

AAAnnnddd it's snowing a little bit here now.

I think western areas probably are looking better than eastern ones.

Can't believe I'm saying this, but Im actually rooting for the NBM of the models I posted above.