John1122

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)

There's a stark ratio contrast from N to S across East Tennessee. It's less so the further west you go. I generally hover around 14:1 through the event. 11:1 around I-40 but it gets as low as 5:1 in Northeast Alabama and NWGa.

For looking back purposes.

MRX says no p-type issues anywhere except Georgia border areas.

That was a blockbuster on the RGEM.

MRX has added the wording "moderate snow accumulation possible" to my forecast for next Thursday night already. That's normally their vernacular for 2-4 inches.

My forecast says 1 inch Sunday night, 2-4 Monday, and "Moderate Snow Accumulations Possible" Monday night. That usually means 2-4 inches as well.

I take that back. The NAM was colder over Knox Co and didn't have the p-type issues so instead of 3.5 inches Knox was covered by 7+ inches on the 12k. The 3k still has the p-type issues along and S of 40.

NAM pretty much stayed the same as 00z, 3k looks like it will too. NW edge of guidance for them. Especially the 3k.

It snows forever on there.

SREF snow depth mean change. This is pretty impressive for a mean for snow depth.