GaWx

Regarding the maps: I see WxBell as still being worth subscribing to because they do have lots of great maps. But it’s good to be aware that certain maps shouldn’t be taken as accurate. One of best examples: CFS 2m temperature anomalies. And now we can probably add NAO (WB and WxModels). There are very likely a good number of others, too.

I still love following the CPC based indices due to the invaluable daily history going back to 1950. That’s over 27K days! So, for me, CPC is gold standard, regardless.

There’s a huge difference between the WxBell and CPC 0Z GEFS based NAO forecasts when in theory they should be about the same. So, algo/definition diffs: @donsutherland1 WxBell 0Z Feb 2nd GEFS NAO: -2 on 2/14 CPC 0Z Feb 2nd GEFS NAO: +0.5 on 2/14

Regarding the S-G Dipole that Simon Lee did a study of soon after the 2/12/2018 major SSW due to the perceived connection, the models haven’t at all backed off on it for this week: By the way the S-G Dipole is by definition often associated with a strong +NAO. Note the forecasted strong +NAO (~+1.7) for late week:

Today’s 0Z GEFS based forecast has the AO dropping to -2 Feb 14-16 vs down to only -1 on Feb 14-15 on yesterday’s run. That is not directly related to any potential major SSW as those require a lag period from the SSW to get down into troposphere and it would be occurring at about the same time. Any direct downward effects from it wouldn’t be til late Feb into March. I’m anticipating big changes on some aspects/portions of today’s Euro Weeklies. We’ll see if that’s actually the case.

0Z GEFS mean based AO forecasts are often volatile. For midmonth they’re much lower today vs yesterday (not related to potential major SSW moving down into troposphere because there has to be lag after those to get there and this would be at ~same time): Yesterday: lowest -1 on 2/14-5 Today: lowest -2 on 2/14-6 I’m anticipating big changes on some aspects/portions of today’s Euro Weeklies. We’ll see if that’s actually the case.

0Z Euro: mainly for entertainment since hours 240-264 and very different from prior run: I kind of hope Brick doesn’t see this so as to prevent him from getting overly excited before bedtime; take with grain this very heavy snowstorm some areas; 0.1” snow just N of KATL…would be 3rd within 5 weeks for ATL area SE of I-85! Last winter KATL got 3 measurable events: 2010-11 and 2009-10. @dsaurtell the moles no sleet for them on this run and sleet only in few areas this run (not near you). So not posting it/trying to conserve attachment space lol. Nite nite!

Mainly for entertainment from 0Z GFS as it will almost certainly change a lot on the 6Z since this is so far out and it’s so different from the prior run:

Interestingly, 0Z GFS went toward the 18Z Euro AI to an extent with two consecutive CAD induced sleet and ice events in update SC and much of NC Feb 12-13. But we’re still talking 240+ hours out on the GFS. So, taking with a huge grain right now. It would probably be best to start looking at the ensembles for this period to get a better feel for whether or not this will likely be the next SE winter threat period.

How has the Euro AI done this winter compared to the major globals including the Euro op? I followed it closely for the 1/10-11 winter storm and thought that it was terrible with surface features. I posted about that several times with supporting maps. For example, remember the warming S winds it had going well inland into the SE despite the low being in the Gulf, something that almost never happens and didn’t. It had no wedge and instead it had the S flow ahead of a Clipper and on the backside of a high moving offshore. This is enough to tell me to not put much weight on it when it’s way out on its own especially past 200 hours and with it showing an historic solution on its own. Could this be a little like the old DGEX weenie model that was almost never right with its crazy solutions?

For the SE, alone, going back to 1994, I have 2025 second only to 2014 as the coldest because I have it slightly colder than 2018, 2011, 2010, 2003, and 1994.

The trend of the last 2 days of Euro Weeklies has gone strongly in the direction of a major SSW mid Feb: From just 2 days ago: bottomed out only down to +40 mid-Feb with only 1 major SSW then: Brand new: bottoms out +22 mid-Feb w/7 majors:

2024 https://www.weather.gov/wrh/Climate?wfo=rah

This from 12Z GFS is likely depicting a major SSW on 2/14/25: keep in mind ability of op GFS to lead ensemble means twice (prior 2 Febs almost to the day) as per my La Niña thread post. If this really occurs, look for possibility of it leading to -NAO late Feb (-AO already being hinted even earlier) and potential of cold in E US late Feb through much of Mar but would help if there’s no strong -PNA/SE ridge just before:

This from 12Z GFS is likely depicting a major SSW on 2/14/25: keep in mind ability of op GFS to lead ensemble means twice (prior 2 Febs almost to the day) as per my prior post. If this really occurs, look for possibility of it leading to -NAO late in Feb (-AO already shown on GEFS mid-Feb) and potential of cold in E US late Feb through much of Mar with best chance if no preexisting strong RNA:

Today’s update: 0Z GFS dips to +6 on 2/14 vs +13 on 2/13 for prior 3 runs and +28 on 1/28 run. GEPS dips to +16 vs +32 just yesterday! GEFS dips to +29 vs +39 yesterday. 6 ens members go <0 vs none on 6 prior 0Zs. GFS maintained its impressive 30K warming. GEPS is 10K warmer vs yesterday: For those wondering about ability of GFS op to sniff out a major SSW ahead of ensembles, it did just that twice last 2 winters: 1. It was well ahead in forecasting 2/18/24: 2. It was also well ahead in predicting 2/16/23:

Record high tying 83 at more inland KSAV! Also, that’s only 1 from 84 alltime Jan high and is warmest this season since 83 of Nov 8th! Hunter and city itself were in upper 70s. That month ending record warmth capped off a very memorable month. It was an amazing month with ~6 BN and what very likely was the heaviest sleetfall in modern records (back to 1874) in this area. IMBY I measured 2.9” of a combo of mainly sleet along with some ZR solidifying the sleet and then topped off with a little snow. The sleet was at a min 2” although I suspect it was closer to 2.5”. The 44.9F avg makes it the coldest month since Dec 2010 and coldest Jan since 1981. It was tied with 1966 for the 9th coldest Jan since 1874. It was the 3rd coldest La Niña Jan behind only 1893 and 1918.

The SE may need a major SSW to help turn things around during the last few days of Feb. But in meantime, today’s Euro Weeklies are even warmer for Feb as a whole with some areas a whopping 7 AN, near the normal for Mar!

The last 3 0Z GFS runs have consistently progged a 60N zonal wind min of +13 on Feb 13th, which would be ~one week after the progged S-G Dipole max. We’ll see whether or not these progs actually progress to a major SSW on/near Feb 12th-13th. Regarding the progged 60-90N 10 mb temperature rise, today’s 0Z is the most impressive yet with a whopping 31K rise to +238K on Feb 14-5! Yesterday’s rose only to +231K and Jan 28-29 runs rose only to +227-228K:

Regarding the bolded: the current +QBO is, indeed, the exact opposite of 2/12/2018’s -QBO. However, it is the same as 2/16/2023’s +QBO. Also, Joe D’Aleo found (and I confirmed) a strong correlation between high Solar/+QBO and major SSWs. So, it now being +QBO shouldn’t on its own reduce the SSW chance but if anything should raise the chance. Furthermore, 2/12/2018 was during very low solar. We now have the opposite, which per Joe enhances the chance a whole lot. 2/16/2023 was during pretty active solar as I assume you know. In the meantime let’s first see if there’s even going to be one. It’s fun to see how these evolve!

The SE’s best bet to get the pattern to change back to cold by the last few days of Feb and through at least much of March is to have a mid Feb major SSW. As of yesterday, the EPS and GEFS means were still showing no indication of that being much of a possibility with instead showing strong SPV related mean 60N zonal winds at midmonth. However, I was alerted earlier tonight by Dr. Simon Lee tweets that a strong Scandinavian (high)-Greenland (low) SLP Dipole was on the models Feb 6-7. The reason that’s important is that he’s done studies showing that this Dipole is often a precursor to a major SSW by ~~1 week. The last few GFS runs have been hinting at a much weaker SPV in mid Feb. We should know much more by the Sunday runs. In addition, Joe D’Aleo did a study that concluded a high chance for a major SSW during high solar/+QBO winters like 2024-5. Dr. Simon Lee’s study of S-G Dipole: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD030940 0Z 1/31/24 GFS 168: strong S-G Dipole:

Further to the above fwiw, the 0Z 1/29 GFS (latest available) brought the mean wind down to 19 m/s on Feb 13th and 13 m/s on Feb 14th: In comparison, the prior run (0Z 1/28) had it bottoming out way up at 28 m/s on Feb 13th: So, the GFS had a significant drop on 1/29. I’ll be watching the GFS closely because it was ahead of the ensembles in advance of 2 major SSWs since 2023.

You may be onto something that I wasn’t paying attention to til just now when I saw this on the 0Z GFS 168 for Feb 7: check out the strength of this Scandinavian-Greenland Dipole! Is this what you were looking at yesterday? This paper was written by Dr. Simon Lee and others about the 2/12/2018 major SSW that was not forecasted beyond 12 days: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD030940 He talks about a S-G Dipole pattern (strong high over Scand/low over Greenland) often being predictive of major SSWs before models actually do so (they’re still not). This dipole peaked ~2/6/2018, or only one day prior to the forecasted peak of ~2/7/25! Aside: the major SSW of 2/16/23 was also preceded by a similar early Feb S-G Dipole! Dr. Lee’s latest tweets: Despite the models still not showing even a hint of a major SSW, I’ve been wary about it based on Joe D’Aleo’s study showing a heightened chance during high solar/+QBO. I took his idea and looked at the actual #s. I considered high solar for DJF to be 135+. DJ will be ~145. If Feb ends up 115+, it would qualify. Check this out: Solar DJF 135+/west QBO: 57-8: SSW 1/31/58 59-60: SSW 1/17/60 69-70: SSW 1/2/70 78-9: SSW 2/22/79 80-1: SSW 2/6/81 90-1: no SSW 99-00: SSW 3/20/00 01-02: SSW 12/31/01, 2/18/02 So, a whopping 7 of these 8 winters had at least one major SSW! Just food for thought. The progged strong Feb 7th S-G Dipole is consistent with a potential major SSW on or near Feb 13th if it were to actually occur with similar timing to 2018. If so, look for hints on the EPS/GEFS starting this weekend. IF there were to be one ~Feb 13th, look out for the potential of a colder E US pattern starting ~Feb 27th and lasting through at least ~Mar 15th and quite possibly the entire month or further. Anything to keep the bugs quiet would be a winning pattern for me!

We’ll see whether or not they go back to the slightly AN to NN mid to late Feb maps of yesterday. But today was painful to see. Unlike you I like cold regardless of snow, which is very rare here. There’s way too much humid heat May-Sept. I’d much rather the Weeklies show it cold. When they’ve been cold this winter (late Nov/early Dec, much of Jan), they’ve been accurate. They’ve also done well with warmups. That’s why I hate seeing them this warm. Regardless, the 2-3 day cold snap within week 2 of Feb remains on the model consensus.

I never noticed there was a different Euro Weeklies chart for surface! I always look at 2m. For determining frost on ground, I’d think surface would be more important than 2m. On good radiational cooling nights, you may already realize that surface is sometimes couple of degrees colder than 2m due to colder air being heavier. But 2m is official. And thus I’ll continue to use those. On nights after a cold front has just come through and the cold winds are advecting colder air, I’d think sfc would tend to be slightly warmer. When sun is out, the ground should be warmer than 2m, especially in summer.