GaWx

Interesting! That’s a bold call for Atlanta. Your map has mainly plain rain (light green) all the way up to Sandy Springs (N of Perimeter) with no snow and just a little ice. This is bold because all 12Z models but UK have further south downtown ATL at 30-32 (UK starts 34 but it has thermal issues and still then drops to 32 with heavy snow) GFS: 5.5”; little IP/ZR; qpf 0.95” UK 5”; little IP/ZR and some rain lol; qpf 0.85” Icon 3.5”; qpf 0.95” Euro 2”; moderate IP/ZR; qpf 0.58” CMC 0.2”; mainly ZR and IP; qpf 0.70”

Today’s Euro weeklies are still full steam ahead fwiw for -PNA/SE ridge in the first half of Feb.

That depends much more on colder 850s than it does on surface dewpoints.

Not me. I’m over 100 miles away from the good stuff! I can relax because there’s nothing to worry about since there’s virtually no chance of anything significant nearby.

12Z models’ snow/other wintry/qpf for downtown Atlanta: huge range: GFS: 5.5”; little IP/ZR; qpf 0.95” UK 5”; little IP/ZR and some rain lol; qpf 0.85” Icon 3.5”; qpf 0.95” Euro 2”; moderate IP/ZR; qpf 0.58” CMC 0.2”; mainly ZR and IP; qpf 0.70” AVG: 3.2”; qpf 0.81” So, anywhere from heavy snow, generous qpf, and little IP and ZR of GFS/UK to CMC’s almost all ZR/IP and more moderate qpf. I wouldn't want to be an Atlanta forecaster right now! Anyone have a good feel for ATL yet?

12Z Euro: ZR: IP: qpf:

I’m questioning more the snow line on the 12Z GFS. Snow in some places with thicknesses as high as 555 mb, a low tracking near Cordele, GA, and 5-6” of snow in Atlanta don’t usually all go together. I’d say that on the GFS either the thicknesses are too high (and will end up being lower like that of UK/Icon), the low track is too far north, and/or the heavy snow line is too far south.

This UKMET map, like CMC, makes much more sense in relation to 1000/500 mb thickness guidelines with it having all the snow with thicknesses lower than 548 dm. But then it has rain in NC up to 540 line, which doesn’t jibe. Aside: Note that UK has 547 line much further south than GFS/CMC. Thus it makes sense that ATL has heavy snow on the UK.

I hate to see this but mainly ZR instead of mainly snow actually makes more sense for much of this area based on 1000/500 mb thicknesses guidelines. Also, I’m considering the track of the low.

Here’s the 12Z CMC for the same time, which much better concurs with the guideline of a 546-7 thickness snow line: this is like night and day vs the GFS! Again for comparison, here’s GFS with snow with thicknesses almost to 558!

Is anyone else bothered by this thickness/precip type 12Z GFS map? Typically in the SE the snow line is near 546-7. But this shows snow with thicknesses well over 552! How can this be? This is so odd! Can anyone explain this? I’d be highly suspicious of precip types on this.

12Z Icon 10:1 clown has 1.4” of snow at Statesboro, GA, from 0.21” of qpf. That can’t be right with 850s of +2C and surface temps of 34+. It could be sleet but 0.21” of liquid equivalent of sleet won’t accumulate to more than half that and that’s with no melting (temps of 32 or lower). And then it has accumulation up to 0.2” in my area and 0.1 into far N FL. CHS is 37+ and 850s are +2 and it shows 0.4”. Impossible! All of the southern end of this map looks way overdone based on its own parameters. Looks like an algo issue:

12Z Icon qpf

The Arctic sfc high ahead of the low on the 12Z NAM is 3+ mb weaker than that on the 6Z and much weaker than what’s on the 0Z. Any opinion about this?

12Z NAM: ZR IP Qpf

0Z EPS snow by member:

0Z EPS woke up with a significant increase in snow!

He’s transformed into Rain Cold.

0Z GEFS snow:

0Z Euro ZR: IP: @dsaur Qpf:

The 18Z GFS would easily give the Atlanta area as a whole its most impactful storm since 2/12-13/2014.

But even if so, that coldest may not include much of the S US, at least in the means as we’re going to be quite cold these next 2 weeks it appears.

Today’s Euro Weekly for 1/20-6 once again has cold dominating much of the US (especially N Rockies to MidAtlantic) though this continues to be the final week of the cold week streak (that includes the 2 weeks prior) before the long advertised change to much warmer:

About an hour ago it was 40F warmer here with low 70s and winds gusting to 40 mph. It has now dropped to mid 60s.

Tony, Based on looking at decades worth of old maps of 850s at the time of SE winter storms, I’ve found that the sweet spot for significant sleet is +1 to +2C at 850 mb combined with good wedging. The models that aren’t delaying the precip have in or near that sweet spot for your area for most of the storm fwiw (yes it will change but you’ve got a decent shot). Colder than that is snow and warmer than that is often ZR, especially +3C+.