Holston_River_Rambler

That disco sounds pretty optimistic wrt the dynamics involved.

WPC has a disco about the potential as well I just noticed: Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 152 PM EST Fri Feb 10 2023 Valid 00Z Sat Feb 11 2023 - 00Z Tue Feb 14 2023 ...Southern Appalachians... Days 2-3... Difficult forecast Sunday into Monday as an intense closed and vertically stacked mid-level low ejects slowly across the Southeast before lifting off the North Carolina coast Monday morning /D3/. As this trough advects to the east, a trailing subtropical jet streak will strengthen along the Gulf Coast providing favorable LFQ diffluence over the Southeast, resulting in impressive synoptic layer ascent across much of the area. As this evolution occurs, moisture advection will intensify out of the Gulf of Mexico and the Atlantic noted by 300K isentropic upglide surging into the Carolinas with 6g/kg mixing ratios, lifting into within the WCB into an impressive TROWAL by Sunday morning, with PW anomalies rising to +1 to +2 standard deviations above the climo mean. This should result in heavy precipitation amounts, with rates becoming impressive especially within what should be a strong pivoting deformation axis overlapping negative theta-e lapse rates NW of the mid-level low. Additionally, upslope flow into the terrain will likely drive additionally enhanced UVVs. The concern for this event will be how much cold air can be dynamically produced by the system itself, as the antecedent airmass is modest for early February. This could result in a situation where snowfall accumulates during periods of more intense ascent (within the deformation, in the terrain due to upslope) but changes back to rain when rates lighten. The guidance is fairly well clustered overall, but there are clear camp differences noted in DESI clusters with the ECENS a slow/strong solution, the GEFS a faster weaker model, and the CMCE somewhere in between. With such an impressive closed low, the slower solution seems more reasonable, and while this would limit the snowfall potential towards the Mid-Atlantic, it could enhance the snowfall potential in the Appalachians from northern GA through WV, with additional bursts of snow possible anywhere from MS through central VA during periods of more intense lift. The other challenge with this event will be the snow-liquid ratio (SLR). Even during periods when precipitation changes to all snow, the soundings suggest the near-surface layer will be right around freezing with a similar near-0C isothermal layer above. The median February SLR for this area is only 9:1 according to the Baxter climatology, and this is maybe a ceiling for the SLR forecast for this event. With rain and snow mixing at times, SLR will be highly variable and probably quite low, which is also reflected by PWSSI for moderate impacts being driven primarily by snow load. A lot of variability results in a lower than usual confidence forecast, and CIPS analogs suggest accumulations will be confined to the higher terrain, which in this case would be above around 3000 ft according to NBM snow levels. However, as noted above, dynamic cooling under intense ascent could result in light accumulations almost anywhere in the vicinity of the upper low. Still, the greatest risk for any significant accumulations will be in the terrain, and WPC probabilities for 4 or more inches of snow reach 50-80% across the NC mountains and into southwest VA where locally 8-10 inches of snow is possible. Probabilities for more than 2 inches extend northward almost to the MD Panhandle.

I think its just "see where everything sets up" time.

WPC still has an inverted trough, but just at a different orientation.

If you can get up to Black mountain in Crab Orchard, it has nice views and is pretty high up.

Where's the facebook meteorologist who types in all CAPS @Greyhound I trust that person's forecasts the most.

I think the AI just copy and pastes info in a more sophisticated way than the average college student lol:

You've inspired me Carver!

For us plateau folks I don't know that its looking much worse. RGEM soundings don't have as pronounced a warm nose even though the boundary layer temps are less than ideal, lol. GFS soundings do have the warm nose to an extent though. Here is another example like those from last night: Since I started looking at these soundings for this system, it seemed that this warm nose was the problem more so than the boundary layer. It was enough to melt the snow at 5000 - 7000' and since the boundary layer was too warm, it just stayed a cold rain. My question is, why in the world are we getting an elevated warm layer on the NW side of an upper low. NAM shows warm advection at 700mb coming off the Atlantic: Even with that WAA we still get a pretty good sounding over a place like SE Cumberland county at hour 45: Good forcing and moisture into the DGZ and nearly isothermal later from 700 mb down. Some of the soundings above even say snow in their "best guess precip type" box, even though the precip depiction is rain. IDK though it still looks very marginal, but I guess that's nothing new. It seems like its been so long since we've even had a shot with a system like this I don't remember any personal experience to help out lol. Probably time for ye old weather rock.

Actually just read back and saw where Jeff answered this, sorry.

Here's one more from the RGEM this time from around Fall Branch, TN at 5am Sunday morning. That is a stout warm nose. Interestingly, it seems like the NAM is usually the one to sniff out warm noses and although it has one, it is not as notable as the RGEM's. IDK. Is forecasting some downsloping?

Here's another over Hamblin county at 8 AM Sunday: says rain, but that is some good forcing into the DGZ. Rates will overcome?

18z NAM soundings show that it is darn near run thing for my area: Says thats rain and this is snow:

Sorry for taking a million years in model watching time to get back to this. Was out quite a bit today. I think it provides an extra focus for lift and may have something to do the upper low lagging behind the surface reflection over the warm coastal waters. The flow is still S or SW at the mid levels so that as the developing cyclone throws moisture back the upper low can lift that moisture. I could also be really wrong about that write up lol. https://glossary.ametsoc.org/wiki/Inverted_trough#:~:text=An atmospheric trough with pressure,side of the subtropical high.

6z Euro:

Further afield the MJO has lit a fire wrt cyclones in the Maritime Continent and western Pac: That does look like it is really trying to work its way into the Pacific though. WRT the Strat, there's been some slight can kicking forward in time, but I suspect it will be pretty shredded by the final week of February. That's about the same time we had one in Feb 2018.

WPC projects an inverted trough back over Roan Mt. As it has slowed down it has kept moving further into long range for the Hi Res models, so hopefully still time for a few more adjustments for those of us on the plateau, lol.

18z Euro: Looks like heights are starting to crash at hour 90 when the run ends.

I guess we need to start watching how far south this first system pushes the boundary to try and see where the surface low will get going. I would prefer it to start up just south of Panama City and take a Valdosta -> Columbia, SC -> Raleigh type track.

6z RGEM digging it the cut off all the way to the Gulf coast and looks like it is about to spread precip back over all of east TN There might be problems with cold air in this scenario below 3000'

Red moon rising to the SE here in Morgan County: What is the old wives' tale? Red moon in evening, sting jet be screamin' ?

Will the SE ridge help with this one and help it strengthen and wind up quicker?

18z Euro dug more than it did at 12z IMO, consolidated everything a bit better at least in respect to vorticity: Looks like that would try to go negative at or just east of East TN

I bet in next few days we get a wild NAMing of locations above 3000'.

How long has it been since we've had a system so strong its dynamics drove a change from rain to snow? I'm not talking about one of the "wave rides an arctic front" scenarios we've done pretty well with lately. I mean a big old bowling ball upper low rippin' fatties. 10 or 20 years? I'd love to chase some rate driven snow this weekend across the upper plateau.