GaWx

This was released by BAMwx: Thoughts? I’m going to need to research this myself to feel comfy with BAMwx’s idea of the highly counterintuitive idea of a very cold E US on average during La Niña (-AAM) Jan phase 6 periods. They’re saying this probably because GEFS is forecasting phase 6 going into mid-Jan as per my earlier MJO forecast post. I can do the analysis but it will take time. I’m planning to look at actual temp anoms for a city like ATL, Chat., Nashville, or GSP that’s in the heart of the coldest (pink) for all phase 6 days during Jan since 1975. Actually anyone can do it but one needs lots of time to do this. In the meantime, I’ll continue to root for weak to moderate 8-1-2 over 6 or even 7. @donsutherland1@bluewave

I’m calculating that the Dec NAO will come in near -1, easily the most negative Dec since 2010. This is the first moderate to strong Dec -NAO during active Dec sunspots since 2002, when sunspots were 135. I’m estimating Dec of 2025 SSN to be 120.

Looking ahead MJOwise, I hope today’s GEFS forecast doesn’t verify as it has it going into a strengthening 6 as we approach mid Jan: Phase 6 in Jan is one of the warm E US phases along with 4-5. Say it ain’t so, GEFS! Of course, even if it verifies, the warmth is just based on the average and it can still end up cold. The EPS is better but not great as it heads into a weak 7, which is pretty neutral. I’d much prefer to see 8-1-2 for the best shot at a cold E US pattern:

Followup: The full torch period MJO is now in as I had to wait for the reporting lag. It turns out that the MJO during the heart of the torch (12/23-27) wasn’t in a typically cold track after all. Instead of a typically cold in Dec counterclockwise track of 8-1-2 of moderate to weak amp (including near or inside circle left side), it tracked clockwise weak 7-6-4-3, an unusual Dec track that one would not associate with cold as it kind of went in reverse and in typically not cold phases even though they were weak: 2025 12 23 -0.28945175 0.37228486 7 0.47157007 Gottschalk10_method:_OLR_&_ACCESS_wind 2025 12 24 -0.12800699 0.45807526 7 0.47562456 Gottschalk10_method:_OLR_&_ACCESS_wind 2025 12 25 0.16766728 0.36077648 6 0.39783412 Gottschalk10_method:_OLR_&_ACCESS_wind 2025 12 26 0.17544751 -6.13679737E-02 4 0.18587054 Gottschalk10_method:_OLR_&_ACCESS_wind 2025 12 27 4.42237742E-02 -0.35203809 3 0.35480496

One year ago today, this was the coldest Euro Weeklies map (for mid Jan): it’s always going to be hard to match something like this in the SE as a whole in the general sense. This was near the time of the first major snowstorm (that hit ATL among other places). And there was also a second very cold week around the time of the Gulf coast storm. But one doesn’t need historic periods like this to still have a great period of winter at least in more localized areas:

Today’s Euro Weeklies came in colder in mid to late Jan: 1/12-18 a week ago: 1/12-18 today 1/19-25 today:

Today’s Euro Weeklies’ SPV at 10 mb is even weaker based on mean zonal 60N winds: One week ago: Today: note Jan 12th dip to only 22 vs it being way up at 47 a week ago:

The historic January of 2025 looking better isn’t surprising as it had nearly wall to wall intense cold along with major winter storms in the SE and thus is always going to be hard to match in a general sense. The Euro Weeklies were much colder in the SE US for Jan at this point. Edit: But otherwise: 12Z ensemble means update for late week 2: good news overall for E US cold and also snow lovers: 1. GEFS H5 improved somewhat vs 0Z/6Z with a slightly higher PNA though it’s still a -PNA. The best news is that it’s significantly colder with BN temps and it’s snowier in much of the region. 2. EPS is very similar to the 0Z, which makes that good news because it’s chilly along with a nice +PNA. No caving whatsoever to the ugly 0Z/6Z GEFS.

12Z ensemble means update for late week 2: good news overall for E US cold and also snow lovers: 1. GEFS H5 improved somewhat vs 0Z/6Z with a slightly higher PNA though it’s still a -PNA. The best news is that it’s significantly colder with BN temps and it’s snowier in much of the region. 2. EPS is very similar to the 0Z, which makes that good news. No caving whatsoever to the ugly 0Z/6Z GEFS.

Thanks for your reply. I agree it is a risk, unfortunately. But my supported hopes (GEFS 2nd week on avg has been awful and much too warm) are that today’s 0Z EPS’ moderate +PNA, which starts Jan 7th, will prevail: Today’s 12Z ens runs will be extra interesting due to this major disagreement in week 2!

The 0Z EPS (another run with a transition to a +PNA and a chilly E US) and the 0Z/6Z GEFS (staying -PNA and a warm E US) are in different worlds for mid Jan. The CPC GEFS forecasts of yesterday vs today show a bad 24 hour trend if you want it cold in the E US in mid-Jan: Yesterday’s GEFS PNA forecast was heading up/nice trend vs earlier runs: Today’s 0Z GEFS said never mind, I’ll stay -PNA through the end of the run: yuck GEFS 0Z 360 hour 2m temps: mild in E US with the cold way out to the NW….yuck But the good news is that the GEFS has had a persistent -PNA and warm E US bias over the 90 day period for this map: And the EPS, a better performing and recently steadier ensemble, still has a +PNA and a chilly E US:

Carver/Met, I happen to already be knowledgeable about what BAMwx is trying to say. I don’t know why BAMwx is calling it 43 “points” gained for the GEFS. That throws off this tweet and makes it confusing. It’s actually 43 heating degree days gained for the period 12/28-1/3 vs what the run had 7 days ago (12/21 run). This means that the 12/21 run was much warmer for that period than the 12/28 run mainly because it largely was still missing the oncoming E US cold period. OTOH, the 12/21 EPS wasn’t nearly as far off because it was significantly colder than the GEFS in the E US due to already figuring it out much earlier than the GEFS. So, it only needed to gain 12 HDDs to fully see the light. The blues represent colder changes since 12/21 while the red/yellow means warmer changes.

Jax, The OHC has orange for the first time since early July:

CAD doing its magic in NC! I’m jealous of you caddies. Consider that here it is still 70.8 here (with overcast). But even this is better than high 70s with sunny 24 hours ago and better than earlier this afternoon. This contrast between GA and NC was forecasted quite well. Yesterday’s high at KSAV was a sweaty record tying 80.

Well, check this out: Look at how much weaker the SPV forecast is at 10 mb based on the 60N mean zonal wind on the Euro Weeklies! One week ago (12/21 run): quite strong just about all Jan through Feb 4th with no end in sight (mean 40-47 m/s): Today (12/28 run): near normal Jan 10th-Feb 11th (mean only 25-35):