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Mid to Long Range Discussion ~ 2023


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3 hours ago, Upstate Tiger said:

I know its not much and cold air is marginal at best but watching next week.





 Per the new 12Z EPS for the SE US, the 8th-9th has some precip  but only very limited cold air and thus practically no wintry precip. Then the 11th has much more significant precip along with a low that then tracks offshore the SE for many members. Whereas that's often favorable for SE wintry precip in mid January, it is still not cold enough in most areas except the NC mountains and possibly parts of N NC into VA. As of now, this looks like a minor deal at most but should be watched especially since there's an outside chance that it trends colder and the more N areas might have a decent shot at something.
 But then we come to 1/13-15, which is a totally different story. This period is the highest threat level for SE wintry of the run by a good margin. Like the 11th, the run has many members with a low that either tracks offshore from the NE GOM or inland or forms offshore the SE US and there is a strong signal for significant precip over the SE. Unlike the 11th, this period has ample cold air to potentially work with depending on the low's track. Thus, several members bring snow to the SE, especially NE GA, SC (heaviest upstate and E), and NC (heaviest E) along with VA. This run has by a good margin the highest threat yet for 1/13-15 for the SE overall.

 There's nothing boring about this run for the SE.


Edit fwiw since this is the very unreliable GFS this far out and cold air is still limited: 18Z GFS has the Jan 11th low move NE from the E GOM and then wind up offshore strongly and pretty far south giving much of the E Carolinas several inches of snow 1/11-12.

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 Regarding the potential 1/13-15 SE wintry threat, the consensus has the MJO then at a moderate level mainly in phase 8 but possibly still in 7 during part of it. The GEFS has a weak +PNA (though the EPS' PNA may be up to moderate), a moderate -AO (~-1.5), and a moderate +NAO (~+0.6).

 So, moderate phase 7 to mainly phase 8 MJO, weak to moderate +PNA, moderate -AO, and moderate +NAO. For those fretting about the +NAO, a good number of major SE snowstorms have occurred with a +NAO per my research. I may post these later if I were to get the chance and if this threat were to grow.

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 I've got more to say about a -NAO not even being close to being required for major SE snow chances. I brought this up due to the moderate +NAO (~+0.6) forecasted during 1/13-15, which could become a threat period for a SE winter storm per the EPS. Here is the NAO for the 23 Raleigh 6"+ SN/IP storms that I found since 1950. (I'm calling neutral NAO to be from +0.25 to -0.25):

-1/19/1955: -NAO

- 12/11/1958: neutral NAO

- 3/2-3/1960: neutral NAO

- 3/9/1960: neutral NAO

- 2/26/1963: neutral NAO

- 1/25-7/1966: -NAO

- 2/9/1967: +NAO (+0.5)(9.1")

- 3/1/1969: -NAO

- 1/7-8/1973: -NAO

- 2/18-9/1979: neutral NAO

- 3/1-2/1980: +NAO (+0.4)(11.1")

- 1/13-14/1982: neutral NAO

- 3/24/1983: neutral NAO

- 2/6/1984: +NAO (+1.1)(6.9")

- 1/7-8/1988: +NAO (+0.5)(7.3")

- 2/17-8/1989: +NAO (+1.7 )(6.2")

- 1/24-5/2000: -NAO

- 1/2-3/2002: -NAO

- 2/26-7/2004: -NAO

- 12/25-6/2010: -NAO

- 2/24-6/2015: +NAO (+1.0)(6.5")

- 1/17-8/2018: +NAO (+1.2)(6.1")

- 12/9-10/2018: +NAO (+0.9)(8.9")


-NAO: 8

Neutral NAO: 7

+NAO: 8

 Note that RDU had 5 big snows with an NAO much more positive than the +0.6 that is being predicted for 1/13-15!

Honorable mention since Raleigh didn't get heavy snow from it but many others did: 3/12-3/1993 Storm of the Century: +NAO

Conclusion: results like this on a pretty nice sized sample tell me that any correlation of -NAO with heavy SE US SN/IP is likely low, if any.


NAO daily data:


RDU data:


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Both the 0Z Euro and CMC have wintry precip in portions of the W Carolinas and NE GA late on 1/13 as a result of the system highlighted on the 12Z EPS. This system, no matter how it ends up evolving, has the makings of quite an energetic one in the upper levels.

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16 minutes ago, Coach McGuirk said:

The coastal low ten days out on the 12z GFS run today is the best hope for SE snow I've seen in a few weeks.  All the traditional ingredients are in place.  Obviously, the problem is it's ten days out and likely to change.

 Agreed. This was also on the 0Z CMC and 0Z Euro as well as recent EPS runs as noted earlier. In addition, the 12Z CMC has wintry precip in the SE 1/13-14.

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 The 12Z EPS, consistently with the 12Z Euro, has the strongest signal yet for a SE winter storm on 1/13-14. The 12Z Euro has a closed upper low that is associated with this over MO early on 1/13 that strengthens and moves SE/ESE to the SE and hits max strength just offshore the SE US early on 1/14. At that time, the center is a whopping 25 dm below normal at 500 mb. So, plentiful cold air from above gets into this. In addition, strong CAD from a large SE Canadian high gets involved and imparts low level cold air.

 On the 12Z EPS, the winter storm signal is mainly for VA, NC, NE GA, and the N half of SC. It is important to point out that though this is the strongest signal from the EPS for 1/13-14, it isn't the first run with a significant signal for then as this is the 3rd in a row and 5th of the last 6 runs going back to the 0Z 1/2 run.

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54 minutes ago, LakeNormanStormin said:

I'm biting. Signal is their for wintry precipitation.

1/13 is usually when the Piedmont gets it's chance.

Will keep the weenies warm on the flat top 


I’m not biting yet but keep one warm for me. As I will bite it it’s still there over next two runs. I can come get a weenie after I cliff dive at last moment 

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42 minutes ago, olafminesaw said:

Average historical daily odds of measurable snow within the following date ranges in Greensboro:

Jan 1-7 4.3%

Jan 8-14 5.3%

Jan 15-21 6.1%

Jan 22-28 5.9%

J 29 - F4 4.9%

Put another way, the odds of going completely snowless in the second half of January is about 40%.

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