GaWx

GFS runs with significant SE coastal wintry precip within 1/21-2: Jan 11 6Z and 12Z Jan 12 6Z and 18Z Jan 13 0Z, 6Z, 12Z, 18Z Jan 14 0Z So, 9 of last 12 and 6 in a row! Normally when the models tease this area the NW trend takes the wintry precip away as it gets closer. That has yet to happen at all in this case. The coastal wintry GFS runs for 1/21-2 started at just over 10 days out. We’re now down to 7.5 days out and there’s no NW trend yet. The prior threat trended NW enough to end the coastal threat by 6 days out. If this doesn’t trend NW by during the Wednesday runs, this would be looking like a totally different situation. It already looks suspiciously different and I wonder if it is due to the Siberian high/extreme cold making this a different situation. 12/1989 and 1/2018 also had extreme cold to the north feeding those coastal storms. Edit: 2 of the last 6 Euro 0Z/12Z runs have had it then, both on 1/12: 0Z and the insane 12Z. The two on 1/13 were dry. The 0Z 1/14, just out, is also dry. No CMC runs through 0Z 1/14 have had it yet. So, since 1/13, GFS has been on an island. @Awesomesauce81 @gtg947h

I’m not really familiar with WxModels to be able to compare them.

0Z GFS has 12/1989 or 1/2018: chances of this actually occurring with these amounts on or near the coast…history says small; but note that these types of runs haven’t yet gone away

0Z GFS

0Z GFS

If so I have no access to them.

0Z Icon is significantly colder run vs runs from 12/24 hours ago. Coldest of season by far 1/20-1 and bone dry/no nearby surface low. Has lows on 1/21 of 10/9 at ATL/RDU! The plumbers would be busy! Minn/SPaul highs below 0F 1/19-20! Chicago barely gets above 0F on 1/20! Most of TN highs on 1/20 only in teens! Unlike those stupid cold Euro runs for last week, this frigid run actually seems possible due to Siberian high.

Here are the op model surface low positions as of 1/1-3 runs for 1/9-10 that I saved. They all verified poorly since the actual track was much further NW than the models showed: 12Z 1/1 Euro 0Z 1/2 GFS 12Z 1/2 GFS 12Z 1/2 Icon 12Z 1/2 CMC 12Z 1/3 Icon 18Z 1/3 Euro-AI Some models shifted NW on 1/3. Then on 1/4 (6 days before the storm), just about all modeled well down into the Gulf tracks that gave SE coast significant wintry precip were abandoned as the NW trend continued, including in the ensemble means. So, that means the NW trend was strongest 6-7 days prior to the 1/10 storm. So, looking ahead to 1/21 and projecting similar timing, I’ll be looking to see if the far SE tracks giving significant coastal wintry are largely abandoned 6-7 days prior to 1/21 or on 1/14-5. So, by Wednesday we’ll see what happens. Could this time be different? Of course it could. What is different with this one? - More runs develop the low not til offshore the SE coast as opposed to mainly developing in the Gulf for the 1/10 storm. - A much colder Siberian high. For example, Chicago’s coldest preceding and during the 1/10 storm was only down to 14F. Progs for 1/20 are for 15-20F colder - Related to this, the surface high coming down is progged to maintain much stronger intensity just before and on 1/21. Most model runs at this forecast point had at best a rapidly weakening 1020s high to the N or NE of the 1/10 storm, which verified pretty closely. The Euro had even weaker with an Alberta clipper low to the north on many AI runs. Remember that? In stark contrast, the progged high to the north of the upcoming threat is mainly 1038-1045 or 15-20 mb stronger! - So, we’ll have to see how this evolves.

Here are some comparisons between 1/10-1 as of 1/2 and possible 1/21-2 (11 days later) as of today (1/13): 1. 12Z EPS: 1/2 run for 1/10-11 1/13 run for 1/21-2: eerily similar in GA/SC and a bit more in NC 2. 12Z GEFS: 1/2 run for 1/10-11: 1/13 run for 1/21-2: significantly more N GA, N SC, and NC with ~same S GA and S SC

1/21-22 seems to have the strongest potential, similar to 1/10-11 for last week’s storm.

The 18Z GFS tells us that this remains at least a potential close call for ~1/21!

It is far from certain whether or not there actually will be super cold in the SE. Just go back to last week, when super cold was showing on a number of runs at about this point in advance, especially the Euro. The SE ended up with much below normal cold along with a widespread winter storm but no super cold.

This is pretty consistent with prior expectations. Regardless, a BN temp winter is almost assured now.

Another cold week coming next week (1/20-6) per the last two Euro Weeklies runs. Then the cold is done per many runs in a row. Will it be drier than normal for most? Latest ensemble means have gotten drier. Current 2m: H5:

I assume you mean Jan of 2014, which I acknowledged would still be colder. I didn’t consider Feb 2015 because I was looking only at Jans.

The EPS mean precip during 1/21-3 has dropped a lot since 24 hours ago:

12Z EPS snow mean:

12Z Euro very cold and dry 1/20-22. Cold likely overdone of course, which in this case would be a good thing.

This GEFS run’s mean was colder than most of the recent ones for 1/20-22 at H5 and 2m.

More plausible than that insane run but still highly improbable of course with it being 9 days out and showing an extremely rare solution per long historical records. If this were say only 5 days out and runs were pretty consistent, it would be a much different story though even then still far from being set in stone, of course. Keep in mind that there are only 3 pretty similar analogs with this degree of snowfall deep to the SE coast to the 12Z GFS over the last 50+ years: 2/1973 12/1989 1/2018 So, only about once every 20 years or so.

Just remember that the 12Z GFS solution showing major wintry precip in the SE is merely an improbable option because it is but one of many possibilities still 9 days out. Just think of it as an active ensemble member. And don’t forget about a handicap when you realize there’s a cold bias.

In contrast to that clownish video circulating on Facebook yesterday that sounded like “The Day After Tomorrow”, this one done yesterday by pro met. Jason Simpson in Birmingham is excellent. He shows yesterday’s 12Z Euro snow, but puts it into proper perspective: https://m.facebook.com/reel/633732655893596/?referral_source=external_deeplink

A general model cold bias that includes the SE US is always a factor that should be considered because it often (though not always) leads to less cold air verifying vs what is shown, say, 8-10 days out (like what happened last week…keep in mind those extreme runs with widespread single digits to middle teens) and consistent with that storm tracks correcting to reality further NW (like also just happened as instead of offshore the SE coast it was mainly well inland). But every case is different. So, we’ll see. For one important thing, how strong will the strongest 1/19-23 Arctic high actually be? If it ends up there’s a 1050ish coming down that maintains itself well into the 1040s for quite awhile and keeping in mind Siberian cold would be involved, that would favor deeper into the SE wintry precip possibilities and thus affect more people though it could also end up dry. I’d rather have the big high and see how it plays out.

0Z EPS: has some big ones

I’ve got someone still texting me at 1AM because of yesterday’s ridiculous 12Z Euro! What will the next 12Z show? Stay tuned!