GaWx

Today’s Euro Weekly for 1/20-6 came in the coldest yet for it for the E US overall….fwiw since 2+ weeks out and the upcoming week while very cold/MB normal (Euro Weeklies did very well to hint at this starting 3 weeks ago way back with the Dec 14th run) is looking to verify a bit less cold in many areas vs the coldest runs. I’d like to see the next few days of runs to get a better feel for 1/20-6. Plus, there’s been an overall cold bias of models in general the last 8 years. But if this were to verify it would solidify even further a cold month, overall, in the E US as it would mean 3 cold weeks in a row:

2.2” for Asheville

This illustrates well that the 12Z GFS is somewhat of a NW outlier vs the 12Z GEFS regarding the low track, which the op has inland from Destin to just NW of Savannah to Charleston. This image suggests a 3:1 ratio of the members SE of the operational vs near to it and the mean low SLP ~150 miles to the SE:

The Dec 2024 PNA came in at +1.70, setting a new record high PNA for a non-El Nino (going back to 1950) beating the +1.58 of 2020. The only Dec PNAs higher than 2024 were during El Niño: 2006 +1.86 1969 +1.84 1963 +1.77 https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

Indeed, the 12Z GEFS snow dropped for more northern areas but increased notably for an area to the south stretching from S of Augusta/Columbia to E NC:

12Z UKMET: Due to little qpf (under 0.10”), RDU doesn’t get much (0.6” snow).

12Z Euro Snow (24 hour):

12Z Euro: precip types: ignore N of NC/VA border to get the 1/10-11 storm by itself 24 hour qpf:

12Z UKMET: ATL major snow (3.5-4”) and AHN 3”; 850s below 0C with 0.4” qpf; clown map algos causing too much snowfall to show up on southern end (like around Macon) and so I won’t post it but for ATL it looks legit @Cheeznado

If so, that would probably increase sleet and freezing rain since colder at lower levels.

12Z CMC ZR: Sleet:

12Z GFS ZR:

12Z Icon: low from FL panhandle to Savannah What’s not shown here is that Atlanta and other areas appear to get significant amount of sleet. ATL temps near freezing entire event. @dsaurthis appears to be giving you 0.4” of qpf in form of sleet. Snow: notable increase some areas 0Z had this:

Models generally have had a cold bias for a good number of years, unfortunately. All levels are affected including surface and 500 mb. That’s why there’s often (though not always of course) a NW trend in the track of storms as you get closer. They often start off in the modeling as southern sliders and become inland runners as you get closer. These cases were destined to be inland runners from the start but the models weren’t smart enough to know far in advance. Hopefully we’re now close enough so that there won’t be more NW trending for this one. In Atlanta, the coldest days’ lows were projected to be well down into the teens awhile back. Now they’ve warmed there ~10 degrees. Still a solidly cold period with lows well down into the 20s (MB normal) and cold enough for wintry but not nearly as cold as earlier projected meaning less room to play with.

6Z GEFS mean had an increase: Atlanta area 1-2.5” Members: ~1/2 give ATL 1”+ (that would be biggest snow there in years); avg annual is ~2”; median annual is lower

0Z EPS snow: large increase/most yet by far Members:

0Z Euro snow: highest yet for Euro Sleet: highest yet for Euro ZR: highest yet for Euro Total liquid equivalent: by far highest yet overall

0Z GEFS: excludes IP/ZR Members: @dsaurTony there are also several with sleet at your abode!

UKMET has ~0.50” qpf of mainly sleet and ZR for ATL. Would be their biggest of that type since 2/12-13/14.

The 0Z GFS has major snow in Atlanta. Should this verify (4.5” airport), would easily be biggest snowfall there since Jan 9-10th of 2011.

Wake Forest 0.43” qpf Wake Forest 850 temp -2: snow Wake Forest temperatures 31 (snow sticking) So, I’m guessing this is giving you a real nice snowfall of 4”.

The Dec QBO came in at +12.70, down from +13.78, the first monthly drop since March. https://psl.noaa.gov/data/correlation/qbo.data

Good eye! Consistent with the further south operational Euro, the 18Z Euro ensemble mean’s axis of heaviest snow to the west at 144 came in ~50 miles south of the 12Z’s 150: It’s going to be tough to get the mean low track back southeast enough for a place like Atlanta to get at least several inches of snow but we’re still just far enough out that it’s still very doable even if not likely.

E US cold bias of most models strikes again. Hoping they won’t warm even further the next few days.

18Z GEFS: significant increase many areas, especially N GA (keep in mind this excludes ZR and any sleet Tony and others might get):