GaWx

Yes, to be fair, those historic Euro AI snow maps were for when this week’s activity was 8-9 days out. Now we’re within 6 days. So, perhaps those too cold misses (including way too cold 850s) aren’t as relevant now. Also, I now realize that the S portion of StormVista snow maps have to be added to the non trusted snowfall map list. So, a portion (not all and probably not even most) of the overdoing of snow on the insane SV Euro AI maps may have been due to SV algos. But regardless, the 0C 850/snow line verified way too far S.

1) As just mentioned it had very heavy (historic in some cases) snow on several runs in a row very far to the south (as far S as NE GA, upstate SC) for earlier this week, for example. However, to be fair, those runs were further out than 5 days. 2) For the Jan 10-11 storm, it had warming S winds ahead of the N Gulf low on the backside of the high moving offshore and ahead of a Clipper. That hardly ever happens. It ended up dead wrong at the surface. 3) I’m not disputing what you’re saying, but I don’t know exactly what you’re referring to and what exactly the verification measures. It could have been an H5 verification for all I know. The main problems may lie underneath 500 mb. Do you have a link or can you post the graphics? 4) I’m not saying it couldn’t end up right with the very suppressed track. With the preceding -5 AO, it could occur despite La Niña. What I’m saying is I’m taking it with a huge grain while it is on its own. 5) Are you favoring this very suppressed track?

The Euro AI has not been good overall this winter imo as I just posted. It especially blew the most recent storm’s snowfall, way overdoing it with 850 0C line way too far south and thus having historic snow amounts way far south of the actual snow line (though Stormvista snow maps likely overdid the amounts somewhat). So, I’m taking this very SE suppressed 12Z Euro AI with a gigantic grain at this point:

This Stormvista 12Z EPS snow map is way overdone in some of the southern portion. Here’s the comparable WB 10:1 map:

And unlike some other snow maps, these WB 12Z Euro Kuchera maps look legit based on the 850 mb 0C line. There’s a short period of non-snow just N of the NC/VA border in your vicinity when 850s go >0C (centered on 6Z of Feb 20th), but otherwise it is snow.

12Z Euro ZR looks bad for many in NC, especially Triangle vicinity and S/SE of there: Low track 12Z Euro: Sleet:

12Z Euro Kuchera:

Looking at this more closely, this 12Z Pivotal UK map has 2.5” of snowfall at RDU. Based on 850s, RDU gets no snow, ~0.2” of qpf as sleet, and ~0.5” qpf as ZR. Based on that, that’s ~0.6” of sleet (and no snow) vs this Pivotal map’s 2.5”. The SE/S portions of Pivotal UK snow maps are often not a reliable indicator of what the UK is actually generating. Algorithm issue at Pivotal for the UK snowfall maps is the problem.

The SE portion of UK snowfall maps on Pivotal, just like the Icon snow maps on Tropical Tidbits, are beyond awful because they’re often way overdone. This map is likely counting much of the ZR as 10:1 snow.

I disagree. The Euro AI has been awful. For example, check out these insane snowfall amounts (and the model really had it as snow with 850s <0C):

0Z Euro: major snow far N GA/W NC/NC NC/VA and ice, ice, baby many of SE VA/NC big cities into N SC:

That would likely be the biggest winter storm in that area in La Niña in Feb since 1989.

Tony stuff: ZR:

0Z CMC: ice, ice, baby and Tony sleetstorm NC:

0Z CMC setting up to come in more suppressed/colder than 0Z GFS. Let’s see.

0Z GFS: Based on maps through hour 93, my guess is that this will unfortunately look more like the 12Z than the 18Z. We’ll see. I hope my guess is wrong. Edit: Indeed, I don’t think the 0Z GFS will be liked.

Way better run than yesterday’s 0Z, which had virtually no snow in NC/SC/GA but not nearly as good as 12Z especially in NW SC, N GA, and SW NC. So, an in betweener.

Thanks, Chuck. Why is there a discrepancy between your map and the CPC? The graph below shows all days within 1/15-2/11 to be either +PNA (1/15-17 and 2/6-11) or neutral (1/18-2/5). So, 9 days +PNA and 19 days neutral meaning a mean of weak +PNA.

Regardless of Mar, in the meantime some of the best climo of the winter is in the last half of Feb. We still have another 2 weeks before March. Granted, it isn’t normally as good when it is La Niña. El Niño has the best Feb climo as we know. However, the pattern is anything but Ninaish with the -5 AO about to hit along with a rising +PNA to a strong one (combo typically has lingering effects). Will there be a NW trend like is common and occurred for the 1/10-11 storm? Or will there not be one like was the case for the 1/21-2 storm? We’ll see! So far there’s no indication of an impending NW trend, which may be partially related to the rare very strong -AO.

Barney says hey to E NC: holy snowcover but very likely way overdone: single digits at 1PM? No, Barney, you’re being silly! GFS has a strong cold bias over fresh snowcover. Nothing new.

18Z GFS: Barney doing his cold thing at 2m and 850 mb. Preliminary maps showing the low over MX in combo with the cold may mean more suppressed than 12Z.

That doesn’t mean dry. It means drier than climo avg. for 2/17-23. For Marietta, it still is giving 0.70” (not dry at all but drier than climo avg of 1.1”).

Asheville is +9 for Feb 1-12. The forecast per the 12Z EPS mean (which is between the less cold GEFS and the typically colder GEPS) is for -7 the rest of the month. If the EPS mean verifies well, Asheville will end Feb very near average. I admit that the 12Z EPS mean may be overdoing the length of the BN to some extent. But fwiw, it literally has Asheville BN on Feb 14 and then the 12 day period Feb 17-28 implying high chances for a significantly longer than 4-5 day period BN. Here is the new Euro Weeklies (based on 0Z EPS) for Feb 17-23, coldest yet by a good margin: that’s ~11BN for Asheville. The entire SE other than FL is BN even for mid-Jan: Feb 17-23 qpf: keep in mind that NN or even slightly BN is still pretty wet in mid to late Feb: 0.85-1.5” NW to SE in much of GA/Carolinas (ATL/Charlotte 0.85”; Triad/Triangle 1”, Augusta/CAE/ILM 1.2”; CHS/SAV 1.5”)

The models remain unanimous with a low of sub -5 AO on/near Feb 15th. Below is the latest GEFS. Today (2/13) it was at -3.7, which is actually lower than the -3.25 this chart shows. That gives me extra confidence that it will go sub -5 in 2 days: Sub -5 AOs are pretty rare and have always been accompanied and/or immediately followed by intense cold and/or wintry in parts and often much of the SE. Here are the ones during DJF since 1950: 1. 2/10-11/2021: major ZR GSO 2/12-13 2. 12/18/2010: significant to big snow one week later much of inland SE and light on coast 3. 2/6-7/2010, 2/14/2010: two winter storms (2/5, 2/12-13) affecting most of SE between them including some on coast 2/12-13 4. 1/2-6/2010: light snow N GA/very cold SE 5. 12/20-25/2009: winter storm mainly NC 12/18-19 6. 1/18-20/1985: 1-2 mainly light snows much of inland SE 1/17-20 followed by historic cold 7. 2/5-6/1978: several mainly light snows SE 2/2-9 including some on coast 2/8-9; very cold 8. 1/11-17/1977: snow events almost all of SE during and soon after including Miami and parts of Bahamas 1/19; very cold 9. 12/28-29/1976: several wintry events then into first few days of Jan inland SE; cold 10. 2/13-16/1969: major winter storm 2/15-17 Charlotte to GSP/Asheville; wintry precip most other areas within 2/14-17 including light on coast 11. 1/28/1966: several wintry events 1/25-30 including on coast 1/27 and 1-2 majors much of NC; extreme cold 1/29-31 12. 1/21/1963: extreme cold the week following; several light wintry events inland