John1122

It's at the very end of it's range but the RAP has most of it's moisture behind the front with the storm diving SE.

We are still maybe 24 hours from the NAMRGEM wheelhouse on these type of events. I expect the GFS to either throw in the flag or get others onboard in 36 hours or so.

Looking at the vort maps, the 500mb vort takes a similar path on the Euro/CMC/GFS it's just much more consolidated on the GFS and dips slightly further south.

It definitely looks like it on the GFS. Looks like it moves SE then back north across the Ohio Valley. You rarely see them attached to this potent a cold front. This is basically as Siberian express. Probably not as severe as the 1982 version though.

I've been including it here since the thread covers the winter threats from Dec 23rd to 30th. The Euro was closer to the CMC but very suppressed at 0z I believe.

The current OBS/Radar are a perfect example of how massively models struggle with the size of a precip shield. It's listed on the known biases of the GFS for areas just west of the Appalachians.

You're unlikely to ever see a low take that track that it does on the Canadian and have such a small precipitation shield. That's a big winter storm track for the Eastern half of the state especially.

Well the GFS drops SE than goes almost straight north as it strengthens. Still keeps the idea of being a nearly all anafrontal event.

The GFS looks like it's going full on clipper here with the LP moving SE.

06z GFS has pockets of very heavy snow being depicted behind the front now with almost all of the precip with it being anafrontal. Very little rain out ahead of it. Very similar to Christmas 2020.

The cold is insane on the RGEM. It has me at 1 degree at 1pm Friday.

06 NAM has heavy snow working across the state, laying down 1-3 inches but it just dies out as it reaches the western Plateau. The 0z RGEM did as well, but the 06z RGEM pushed snow into East Tennessee. We are still about 24 hours from really beginning to get into the wheelhouse of those two. The Euro is still completely Grinchy regarding backside snow, but as I've mentioned, it took until around 24-30 hours out before the Euro caught on that it was going to snow on the back side in 2020. Same for the UKIE. The GFS was steady until about 60 hours out and then it lost the 2020 storm for about a days worth of runs and came back around 30 hours out. The RGEM handled things the best. Hopefully it leads the way here. Euro is also grinchy on the second system the GFS and GGEM see.

I'd definitely take the 7 inches the Canadian gave me that run. You'll often see storms attack as the cold air leaves.

It may go down in flames but the GFS isn't backing down.

RGEM is better than the NAM. Still at the very edge of their range but I still believe there's a good shot snow showers will sweep to Western NC.

The NAM is coming in with a fast hard thump on the back end for a few areas. I think it would be more consolidated. Should have a much better handle in the next 48 hours.

Every model just struggles any time they show snow here. At one point the Euro had us with blizzard conditions but the ICON of all things started showing the cutter first. However, suppressed, dry or rain storms. A+ on all model verification.

The RGEM looks good out West at the end. We will see if 0z has that snow spreading East. GFS was in finger mode still with good spots and bad but its insistent on moisture being behind the front and that's what matters.

The Euro also appears to show a period of sleet as the change over happens.

The UKIE and Euro were slightly better, the UKIE had been showing 0 in Tennessee at 0z and almost 0 in Kentucky. Now it shows .5 to 1 inch over the western 2/3rds of the area. The Euro went from maybe .25 inches across more western areas to some .5 to 1+ inch amounts. The GFS and Canadian are basically in the 1-3 inch range for a lot of the area. We should get more into the short range wheelhouse in the next 24-36 hours. The RGEM is usually pretty good with these type events. Better than the NAM as a rule.

Its going to be a midnight high on all models. We will struggle to escape the single digits to low 10s Friday during daylight hours.

Very small step on the Euro as well. Wasn't a lot but it was a slight increase from 00z last night. It just cuts everything off really fast. That's actually not super common with powerhouse arctic fronts, they usually squeeze out every last drop of moisture. It just wraps in an incredible amount of dry air. The GFS has 80 percent RH at 700mb over me at 102, the Euro 12 percent RH. The Canadian has 60 percent.

A baby step, but the UKIE went from absolutely no snow in Tennessee to .5 to 1 inch across most of the Western 2/3rds and far Eastern Mtns. I believe it really struggles with post frontal snow and I am not sure it ever caught on to Christmas 2020.

The GFS remains enthusiastic about the anafrontal prospects. We will see if if keeps it up. It hands down beat the Euro for the last several. The Euro didn't really get on board with the Christmas 2020 event until 36 hours out.

Ratio'd would be about 25-30 percent above these totals.