John1122

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.

The GEFS actually looks pretty good vs the Op.

The GFS has the odd snow fingers look that run. It tends to do that with the rain to snow scenarios. Basically smooth them out and cover the blank areas between the fingers, cut the amounts by 30 to 40 percent and that's usually closer to what actually happens.

Every run of every model gives me 1.5 to 4 inches ratio'd. So I'll certainly take that.

This Vols vs Arizona game is so horribly officiated its like the refs are on the Wildcat payroll. It's something like 16-2 free throws. At one point we got called for 8 fouls in a row. Both offensive and defensive.

Looks completely saturated all the way to the surface at 141 for instance. The DGZ is at the surface as noted. When that happens you'll see little ice crystals floating down even if the sky is blue.

GFS whopper job for the western 2/3rds of the state. Go Nashville and Memphis area folks!!

No idea if it will mean anything for this event, but the Euro was completely lost on the December 2020 Christmas even snow event as little as 36-48 hours out. The GEFS was rock steady except for maybe one off run in the 36 hours out time frame, the GFS spotted the event first at hour 228 and was steady until it waffled some inside 48 hours. The Euro was all over the place, showed almost every possible outcome. The UKIE kept missing the area completely. The NAM suite was all over the place and the RGEM was steady and eventually very close to correct as well. The RGEM was initially who correctly modeled the snow showers that lasted into Christmas day that added 1-2 inches for many in the area. 24 hours out the Euro finally got close to the actual final solution and the GFS returned from it's 24 hours MIA. I'll also note that in the thread about the December 20202 event I noted the prior year the Euro had also been led by the GFS on a potent cold front/anafrontal snow situation. None of that may apply here but it shows you how much modeling chaos there potentially is remaining in this event at this distance.

Euro is a no go again. Extreme cold front with virtually no moisture behind it, nothing more. Something will give one way or another over the next few days. The GFS is locked in, the Icon moved toward it. The Canadian is locked in and the Euro now is two runs in a row. Eventually it'll all come to a head. The energy for this storm has been over Siberia and is now probably in the northern Pacific.

GEFS basically in line with its OP. Nice snow mean across the area. 1.5 to 4ish at 10:1. Would be slightly higher with a ratio map.

The Canadian was more snowy than its 12z run across the area. But because of it's crazy evolution it shows Lake Effect from every direction on every lake at some point and you get lots of 2-4 foot totals around them all.

The Canadian would be an extremely rare storm. Models show that look of a low retrograding to the WNW on occasion but it almost never happened. I've seen it modeled several times over the years and none of them verified. The Great Appalachian Storm of 1950 did that. And maybe one of the 70s blizzards. They are extremely rare.

Beautiful pass by the GFS. ICON trended towards it as well. Still 72 hours before we can get a better idea what might happen.

I've seen that post showing the 12z gfs snowfall map from that person shared at least 25 times on social media today. It wears me out. The worse part, he claimed all models were showing it then argued with the few people who told him how futile it was to even share that map on social media with people who don't understand its context.

I love looking back on these threads to see what went right or wrong. So I'm glad it's here. I feel like it'll be Tuesday before we have the right idea or something close, on this one. I will say this, I was reading the CPC talking about model biases and model verification. It noted that the GFS scored much better in what they called "extreme events" and I believe this qualifies. It also noted that all models had a North precip shield being to dry bias West of the Appalachians. Something we've discussed on here for years.