John1122

Even though it benefits me the most, I truly hope the NAM isn't right for everyone else's sake.

I can already tell the 18z 3k NAM is going to go for 12-16 inches over Cross Mtn like it did at 12z. It's like a crazy ensemble member that skews the mean in how it skews the NBM.

The ice in some areas is the precip ending as freezing drizzle as moisture falls below the DGZ. It happens fairly often in big snows but I don't recall seeing it in powdery snows. The sounding does say "best guess p-type as freezing drizzle in my area but I think the model is having issues, as two skew-t's within a mile or so of each other in my area are vastly different in the upper levels regarding temps.

I believe this is the HRRR showing downsloping off Cross Mtn that affects things all the way into SW Va. Cross Mtn is 3300-3534ft in the area just left of the arrow start, and it quickly drops to around 1000 feet straight up the heart of Norris Lake there, though the lake is surrounded by 1300-1600ft ridges.

HRRR lee side low popping and keeping East Tennessee under convective snow showers.

I believe it could be due to flake size. The snow will be much wetter in those areas. Those big flakes often cause that too.

Towards the 28-30 hour mark the HRRR is giving what almost looks like convective snow shower cells around the area.

The HRRR gives the entire state around 2+ inches except for the tiny SE corner of Polk Co. Imagine being a snowlover and living there.

The soundings support snow all the way to the border. Very edges of the foothills have sub freezing column from 700 to the surface.

It will, you'll get some virga. West of you it's snowing with air temps lower than that and dps below 0.

The HRRR appears to have heavy snow all the way to the NC border by HR 22. Chattanooga/N.GA are in all snow too.

It's in the NAM family and maybe the same mechanics that are causing the NAM to be NW with the precip shield are what it's seeing. The 15z SREF mean was in about the same arc too.

The dewpoints have crashed into oblivion in the mid-state. I wonder if that is having any effect on some lower QPF outputs for there.

25 this morning and currently 34 degrees. The true Arctic air is over the Mid-State and hasn't made it to here yet.

The Euro initialized way too dry with the system vs real time obs. Eastern Ok. SE Kansas, NW Ark, SW Missouri are getting pounded right now. Grove in SE Kansas is reporting -9 degrees with heavy snow, vis .25 miles. The 12z Euro barely has them getting precip at this hour.

It ingested the NAM 3k for my area. There's some 18 inch areas between the two of us over Cross Mtn/Frozenhead/Brimstone.

As Jax noted, the HRRR is booking it. I've now got 4 digital inches on it by 5am tomorrow morning.

Not sure why but some of the models have been depicting p-types that aren't temp supported. Several have shown rain as the dominant p-type around the s/se side of the precip field but temps never getting out of the 20s while it shows it. I've never seen it before with model outputs.

I look at it more as achieving what's modeled. I honestly take the snowfall maps and shave 30-40 percent off and expect that as actual snow accumulation. Occasionally you get to 100 percent or more, but it's way more common to get in that 60-70 percent range. That's more reasonable and why MRX says 3-6 inches with possible dollops of higher amounts.

There are best and worse case scenarios for your area that are more extreme than most others. But to get the heaviest snow sometimes being right next to the change over to rain is best. Best case for you guys looks like the RGEM. It stays plenty cold and snows all over Hamilton Co even to the border. Worst case is the 3k NAM, but it's more in the way the precip lines up. I will say this in my experience. If you start off as snow in a situation like this, it's normally harder to change over to freezing rain/sleet because the Arctic air is seeping in more and more as the event takes place and the snow helps cool the column.

I prefer the same thread for everything but whatever anyone else wants. (I go back and read these during the off-season and like not having to go through multiple threads to get from predictions to results.)

Sounds solid to me. Rufus it will be from me. For some reason typing RRFS A is way annoying to me fingers.

It looks like it in counties that touch 40 in East Tn and points south. The globals are the best case scenario, giving 12/13:1 over those areas but it lowers into the 10:1 range as the day wears on. The Canadian/GFS look similar. The hi-res models seem to see more warmth but it may be a bias with them. At one point on the NAM your area has 11:1 ratios and McGhee-Tys is closer to 7:1.

Some form of system for that time frame, only the GFS is truly rolling big with it for now. The Euro was an Apps runner but we know the trend is SE this year vs the early runs. This current event was much further NW too when it started showing up.

12z RRFS A (really need a nickname for this)