John1122

I'd be very surprised but it's possible.

Now that's a winter map.

It's downslope area seems to more align with actual terrain than the hi-res models.

You can see in my expertly drawn white circle, why downsloping makes way less sense in this are but makes at least a little more sense further down towards the Central and Southern Plateau.

The RAP is more smooth with accumulations. The HRRR has placed it's downslope/dry slots oddly today. At one point a run had it in Western Campbell where elevation go from roughly 1600 feet in Scott to 3400 feet in Campbell. Not the best location to place your snowhole, with a near 2000 feet elevation rise.

I think the Hi-Res models are trying to downslope a bit too much off the Plateau in the northern areas. It doesn't fall off a cliff here like it does in the Central and Southern areas. Those areas go from 2000ish feet to 800ish feet or even more extreme drops down towards Chattanooga. Up this way like in Claiborne, Union and even Northern Knox it's more 1200-1400 even in valley floor areas and those valley floors are really narrow with a lot of 1500-1800 foot ridges. The area of SE Campbell it shows drying out is almost all 1400-1800 foot ridges with very steep, narrow valleys down into the lake. Same on the other side in NW Union. That hilly country extends down to House Mountain. That's not really favorable downslope country.

NWS Nashville Disco "However, we are starting to pick up on the potential for some additional forcing behind the front when the cold air gets here and we start to transition from rain to snow. This added feature could signal underperforming of the models in regards to snowfall totals, especially for areas north of I-40 and on the Cumberland Plateau. Several spots along the KY/TN state line are pushing 3 inches. On top of this, ground temperatures are pretty warm, so the question is how are we going to get snow to stick? Well, if it comes down hard and fast, we can get those accumulations, no doubt. My first concern lies with the melting snow and rain just before the cold air gets here. Temperatures look to drop below freezing FAST and while the wind will help to dry up some of that liquid, any additional water on area roadways is going to freeze, causing an icing situation. For these reasons, we`ve decided to push out a Winter Storm Warning for areas along and north of I-40 from 6 pm this evening until 6 am tomorrow morning."

Generally the temperature and available moisture are what affect flake size. Warmer and they clump together more, as there's usually more moisture in the air. Cold, usually less moisture and less clumping.

Curious to see which model works out here. Also strange how models evolved with the system. The GFS started it as a clipperish system. Then turned it into a Miller A for a bit. The Euro/UKIE tried to make it a major cutter. Then they all trended back towards a clipper/anafrontal event. If the GFS is even close to correct on snowfall amounts, we will know that the Euro/UKIE have a lot of trouble with this type of event. The UKIE never caught on to Christmas 2020 and the Euro didn't until 24 hours out.

The ratios for the total event are generally coming in at 17:1 to 22:1 across areas NW of here. But many started out much colder. So we won't get there as an average for the event.

This snow will be very tough to measure if we do get much. There will be hardly any surfaces that aren't wind affected.

That's very unusual, it would definitely be something to experience.

Looks like back in Nebraska and Kansas where models besides the GFS showed .5 to 1 inch, they ended up with 1-3 inches. That's if the snowfall maps can be believed, and we know from our own back yard they are very often wrong and virtually always on the low side of wrong.

In my experience with the DGZ that low and temps so cold, you get small ice crystals, even if the sky is blue. I don't recall ever seeing freezing mist at temps below 10.

I believe modeling is a simulated radar and I'm not sure it's equipped to handle snow falling that low in the atmosphere. We see that pretty often here, where the models have cleared things and snow showers linger one as the DGZ drops below radar.

No modeling caught this.

The 15Z HRRR tried to fill in some of the areas in the Valley with snow. It still has a snow hole there but it's much smaller than it was even at 14z.

I usually like the RGEM but it's on something. At hour 27 it has rain over my area with single digit temps. The temp was in the 20s at hour 24, so no way it's a 3 hour average ptype. It has snow to my west, rain over me and snow to my east.

Looks like the Euro coming in with accumulation was enough to get MRX on board to issue a WWA. The added heavy snow wording to my forecast. They also lowered temps. My forecast is -3 tomorrow night with a high of 3 Friday.

HRRR is faster with the cold. At 1am tomorrow it has me in the single digits. The 3k NAM has me in the 20s.

Had a sleet to rain transition there.

That Euro was it's snowiest in days since before it was showing a cutter.

12z GFS forecast for there.

This was today's 12z Euro run for there.

No idea if it means anything for here, but the Euro is badly missing on snowfall in Southern Nebraska and Northern Kansas. At 00z last night it was giving 1 inch in those areas, 1.5 inches at 12z. They are looking at 3-4+ with 3 hours of blizzard conditions. This is the current OBS there. Their NWS said 3 additional inches look possible.