GaWx

Per the avg of the last 12 runs of the 4 member CFS ens, much of the SE is forecasted to be near 10 F BN for the two week period Jan 8-21! The SE is forecasted to be the coldest area anomalywise on the entire globe through that period!

12Z Euro ensemble mean snow: pretty similar to GEFS Here was 12Z GEFS:

This is kind of an odd setup and would actually be an extremely close call on/near the coast on the 12Z Euro if it were to somehow play out closely to this: 850 mb temps several degrees <0C during start of precip and even the coast never gets close to the 0C line: 1000-500 mb thicknesses at start of precip well below the common 546 dm needed to support snow in SE as these are in the mid to high 530s and they actually drop from this point: Surface dewpoints well below 32 just in advance: But surface flow is then a warm SW flow that warms low levels up rapidly just in time: Clipper surface low coming down allows SW flow ahead of it on backside of Arctic high moving offshore, a pretty unusual setup with a low also in the Gulf: The qpf ends up too light (<0.15”) to allow the easily cold enough levels between 850 and 500 to have sunk enough to counteract the warming surface SW flow:

6Z GEFS mean:

0Z Euro ens mean: most areas have more than on 12Z with largest increase C GA/SC to 1.1-1.5” range with all of that falling starting 8 days from now; that’s a lot of snow showing up that far out for that area: @jburns@buckeyefan1please pin this thread

It looks like Dec NAO will probably come in moderately positive in the table…..~+0.6 to +0.8. Then we’ll have the very strong first half of Jan -NAO. It may be as low as -2 tabular equivalent. But then it should rise quite a bit per model consensus. However, Jan as a whole should still come out decently negative, possibly sub -1. If it were to end up lower than -1.11, it would be the lowest since the mid 80s! If so, Dec-Jan would average a weak -NAO with only Feb left. So, there’d then be a shot at a sub -0.25 NAO near a solar max though I wouldn’t bet on it as of yet.

18Z Euro ens mean:

Based on thicknesses (546 is usually snow line in SE), 850 mb temp anoms, and qpf (2m are too warm), that’s actually likely a major (3-7”) snowstorm on the 12Z Euro AI with the NW extent of the 3” Columbus to Macon to Augusta to Fayetteville to Greenville, NC, with ~5-7” from NC coast down to ~Charleston.

As I expected, today’s Euro weekly for 1/6-12 isn’t quite as cold as the last two runs although it’s still very cold: The subsequent week (1/13-19) is about as cold as yesterday’s (solid cold but not as cold as 1/6-12).

I saw only one Euro ens member out of 50 (2%) (#44) holding a surface low back for 72 hours in the W Gulf like the op. and only a couple of others remotely resembling that scenario. So, the 12Z Euro op was clearly a major outlier and will likely change a lot in some way at 0Z.

12Z Euro mean snow: not as much as recent runs for most areas but still enough to end ATL 0.5”+ snow drought of prior 6 winters:

12Z Euro: The 2nd storm, while the upper level energy is held back and there’s a surface low well down in the W Gulf, gives ZR (as much as ~1” far S LA) 1/10-11 to part of the Gulf coast:

12Z GEFS has less for most areas vs recent runs though still notable amounts N GA and much of Carolinas:

12Z GFS is still another model suggesting a wintry threat to the Gulf coast/deep SE after the initial storm. This is actually from an even later 3rd wave (Jan 11-12) as the 2nd wave dampens out with nothing wintry in the SE. To put this into perspective (the details fwiw since this is way out on days 11-12), these amounts from FL Panhandle to Charleston would be mainly 2-5 times these areas’ normal annual amounts, which are only 0.1-0.5” due to no measurable wintry in most years:

For the first storm in addition to the snow that was already posted: Significant ZR: IP: mainly light but significant upstate SC (up to 2”):

The prospects during the 1st half of Jan for a weak to moderate left side of diagram MJO, along with a moderate to strong +PNA, strong -AO/-NAO (-AO strongest yet) and weakly negative to neutral EPO remain intact on the models. That combo can’t be beat for cold E US potential. The GEFS mean about like yesterday gets the AO/NAO down to ~-4/-1.5 within Jan 6-9. The other Jans since 1950 with a lowest AO/NAO of sub -4/-1.5 have been these: 2010, 1979, 1970, 1966, 1963, 1959, and 1958. 5 of the 7 were during El Niño. None have occurred during La Niña. So, 2025 could be the first Niña Jan on record with this. Temperature anomalies for these 7 Jans: cold most favored Midwest, Plains, and South, but overall quite a cold map for a 7 Jan composite. This is quite similar to yesterday’s 1/6-12 Euro Weekly map that you just posted:

1. Although very cold, 7-8F BN in the SE/MidAtlantic/Midwest wouldn’t be nearly as cold as 77 or 40, which were 9-15 BN in much of the same area. 2. Although still very cold, today’s Euro Weeklies may not be quite as cold.

After 4 straight Euro Weeklies runs that were the coldest yet for Jan 6-12, it looks like the next run will finally be less cold than the prior despite still being very cold. ,

0Z GEFS speaks for itself:

2nd storm Gulf coast to NC coast 48 hour snow accum (10:1):

2nd storm:

2nd storm: wintry mix Gulf coast moving into SW GA

0Z GFS has a nice split flow with the incoming system:

Indeed 2009-10’s -NAO was amazing and one of my favorite winters! Honorable mentions go to 1963-4, 1962-3, and 1968-9.

I like your hopes and would love to see that amazing combo. But these hopes are very unrealistic due to the extreme rarity of a +2 PNA in met. winter. Since 1950, there have been only 3 winter days with a +2 PNA: 2/28-29/1968 and 2/28/1983! That’s it! The NAO on those 3 days was +0.2, +0.4, and -0.5. There have been many more -2 NAO winter days (45) but the last one was 12/1/2010! Sub -2 NAO days almost all occurred in 2009-10 as well as the 1970s/1960s. The PNA for these -2 NAO days was +1 or lower on all but two days with a large majority neutral or -PNA. The two days that came very close to the NAO -2/PNA +2 combo were 12/2-3/1963. The NAO on 12/2/1963 was -2.1 while the PNA was +1.7. They were -2.0 and +1.8 on 12/3/1963. So, these were very close calls. But again that’s the best that’s occurred. My point is that despite the two day close call, we’ve not had the -2/+2 combo even once in 74 winters. Thus, I’d be very satisfied with the predicted ~-1.75/+1. That along with a progged sub -3 AO, a moderate -EPO, and a favorable (weak left side) MJO would itself be at most a once per decade(s) occurrence in January! I don’t think many folks realize the rarity of what’s about to occur. Even I didn’t realize it til I did the research by looking at the historical data that’s out there.