GaWx

Coldest Euro weekly for 1/6-12 once again! Much of the area in the 4th shade of blue in the E US is 11-15F BN. The 5th shade is 18 BN! Also, the 2 weeks after this are easily the coldest for those weeks yet suggesting that some areas could see a 7 to 8 BN Jan!

Imho not yet can kicking for Jan 9-12, which has been showing with the best Gulf Miller A potential for several days

12Z EPS snow mean: yes, less snow most well inland areas (don’t shoot the messenger; besides there’s still a good amount there and this is still way out in changeable land) but actually more Gulf coast/FL Panhandle and further east. Looking back at what I’ve saved, this has the most snow along the Gulf coast to some of the deep SE of any run yet with these amounts amounting to 2-3 years worth of normal: @beanskip @Awesomesauce81

I bet it will be 5-6+ days before the details for the period around 1/10-12 are getting semi-stable on the operational models. Five days from now would still be near a week out.

12Z Euro fwiw since it will keep changing (being an operational this far out) is consistent with a good number of ensemble members showing a weak Miller A Gulf low ~1/10-11: this produces light ZR along/near the Gulf coast @beanskip

Despite it being not quite as cold around days 9-10 vs some recent runs, the 12Z GEFS remains notably cold overall with BN in the SE every day Jan 2+. It still is very cold much of SE Jan 9-13. It also continues to show a good number of members (~9/30%) with a Miller A Gulf low somewhere within Jan 9-12.

12Z GEFS at 246 vs 6Z: 2m temps not as strong a push of Arctic with not as strong a mean high at surface (5 mb lower) as just posted: But it is still quite cold:

Though not to the extreme of the warmer 12Z GFS days 9-10, the 12Z GEFS is coming in less cold than recent runs then due to significantly lower mean sfc high pressure coming down the Plains: 12Z GEFS SLP mean: max in Plains only ~1027 mb (still cold but not as strong cold coming down then) 6Z GEFS mean SLP: max was a much higher 1032 mb in Plains supporting colder air

As usually occurs, the warmer change on the GEFS mean is much more subtle than that on the highly unreliable GFS operational out at day 9: GEFS 2m anomalies: only slightly less cold than recent runs and still quite cold overall in SE: GFS: much less cold than runs the last couple of days in SE (very unreliable that far out):

The 12Z GFS op is near worthless crapola imo. Let’s see what the 12Z GEFS has.

12Z GFS not even that cold 0Z Jan 9th in SE! I’m throwing it out as a warm outlier at this point, especially since it is the GFS out at 228:

The 12Z GFS at 192 (fwiw since it is 8 days out on the GFS op) is setting up for not as strong a push of cold air southward soon afterward compared to most of the recent runs. Those who don’t want it too cold in the SE should like this run…again fwiw.

The prospects during the 1st half of Jan for a weak to moderate left side of diagram MJO, along with mainly a +PNA, -AO/-NAO (both the strongest yet on GEFS), and -EPO remains intact on the models. That combo can’t be beat for cold E US potential. The GEFS mean now gets the AO/NAO down to ~-4/-1.5 ~Jan 7-8. The other Jans since 1950 with a lowest AO/NAO of sub -4/-1.5 have been these: 2010, 1979, 1970, 1966, 1963, 1959, and 1958. 5 of the 7 were during El Niño. None have occurred during La Niña. So, 2025 could be the first Niña Jan on record with this. Temperature anomalies for these 7 Jans: cold most favored Midwest, Plains, and South but overall quite a cold map for a 7 Jan composite:

-This CFS is still going into phase 8 but with it under 1 in amplitude, which is what inside the circle means (~0.85-0.9 in this case). -Whether it is just outside the circle, near or inside, it is a weak to borderline moderate left side of diagram path, which is the most favorable for a cold E US and has been on the models for many days. A cold E US obviously means higher chances for snow in general. -Model consensus is favoring weak to possibly moderate phases 8, 1, 2, and probably 3 thereafter. These are the 4 coldest phases in Jan on average and have been colder in the means when not strong. -Natural gas prices are up over a whopping 20% since just Friday bringing prices to their highest in nearly 2 years due to a potentially very cold Jan! GEFS (bc): EPS (bc):

0Z ensemble means: 1) Check out FL/deep SE. Miller A lows are being progged by a good # of members to be well south in the Gulf between Jan 9 and 12. This kind of track COULD give the deep SE a rare wintry event ~Jan 9-12 if there ends up being a track over S or C FL while moving ENE or NE. Just something to watch and nothing to get excited about now as it is still quite a bit too far out and these often disappear when getting closer. The last time there was just this level of ensemble noise for wintry precip in the deep SE was way back with the rare coastal winter storm 7 years ago. 2) There’s still plenty of action further north. 3) This is the best pattern in years for many in the SE for wintry precip potential as it continues to look like there will be multiple chances for the SE as a whole thanks to a long duration cold dominated period along with an active feed of southern shortwaves. The new Euro ens mean for RDU maintains the -13 F BN Jan 6-12, meaning it’s forecasting the 3rd coldest week there since the winter of 2011-2. 10 of the 11 coldest weeks since then had measurable wintry precip averaging nearly 3” of snow/sleet along with ZR during a good % with four of the 11 having 3.7+” of snow/sleet. Euro: GFS: CMC:

Regarding the CMC, it gives snow to N GA, upstate SC, and nearly all of NC. Plus there’s a followup system waiting in the wings over the W Gulf. Of course it is just the day 9-10 CMC, which has little value and will almost definitely keep changing quite a bit during this period.

Indeed it was very cold. Detroit was 14BN 1/14-20/24. But I don’t recall the Euro Weeklies being anywhere near that cold over such a large area over a week out like today’s map is.

So, these 11 very cold RDU weeks since 2011-2 averaged an impressive 2.7” of snow and/or sleet. But the median is much lower, 0.9”. Thus, if I were living there, I’d certainly consider 2” during Jan 6-12 a solid win and 4” a big win. And having 3 of 11 with 6-9” (at or above avg season total) tells me that getting a full season’s worth then due to the degree of cold is not at all out of the realm of reasonable possibilities, especially if the bulk of the wintry falls as snow. Possibly a 25% chance? Of course any is a win in my book. Also, these stats show that getting a significant portion of the wintry as ZR is quite possible (maybe 25-33% chance). So, it is mean/median SN/P 2.7”/0.9” plus possibly some amount of ZR.

More regarding the frigid Jan 6-12 on the Weeklies. As has been said, it isn’t projected to be dry like very cold weeks can be. As has been shown for several days, the signal is mainly neutral to slightly wet. Today’s is slightly wetter than yesterday’s/others and this continues to show good chances for Gulf Miller A potential as many members and operationals have shown. Most are 0.8-1.1” qpf. RDU is at 0.8” qpf for Jan 6-12 along with 13 BN: RDU coldest 7 day periods (-10 BN or colder) since the winter of 2011-2 show this would be the coldest week since Jan 1-7 of 2018. In terms of absolutes as opposed to anomalies, 1/6-12/25 is being forecasted by today’s Euro Weeklies to be the 3rd coldest 7 day period at RDU since the winter of 2011-12 with only Jan 1-7, 2018, and Feb 15-21, 2015, colder. RDU 7 day period temp. anom: rainfall/wintry 12/20-26/22 -11: 1.22” rainfall/T wintry 12/6-12/18 -11: 2.48” rainfall/8.9” SN 1/14-20/18 -11: 0.49” rainfall/6.1” SN 1/1-7/18 -21: 0.06” rainfall/0.9” SN 2/9-15/16 -15: 0.33” rainfall/0.2” wintry 1/17-23/16 -12: 1.19” rainfall/1.2” mix +icestorm 2/15-21/15 -22: 0.67” rainfall/1.4” mix 2/23-3/1/15 -15: 1.87” rainfall/6.5” mix 2/11-17/14 -10: 1.30” rainfall/3.7” mix 1/20-6/14 -10: 0.50” rainfall/0.1” wintry 1/22-28/13 -10: 0.33” rainfall/0.2” mix So, all 11 of these periods had wintry precip with all but one having measurable. The heaviest snowfalls tended to be with over 1” of rainfall though the 3rd heaviest snow (1/24-20/18) had only 0.49” of liquid equiv. So, I’d say that 0.8” of liquid equivalent would be pretty favorable for significant wintry precip.

Ditto to the above with today’s Euro Weeklies ens mean once again coldest by a decent margin for the SE US so far for Jan 6-12 and coldest for the SE US a week+ out I can recall for any week since I’ve been following this product (several years). The bulk of the SE US active posters are ~11-13 BN. The coldest days are 1/10-11 when many are nearly 20F BN, a very strong signal from a large ensemble still 12-13 days out! Don’t be surprised if we end up with 1-2 days that are nearly 25F BN! Note that the area covered by the 4th shade (-11F or colder) is even larger today. We could easily not have another week like this in the SE US for many years to come. Credit to the Euro Weeklies starting to see a cold signal for Jan 6-12 two weeks ago! It still looks solidly cold for Jan 13-18 though not at least yet close to this degree.

Ditto to the above with today’s Euro Weeklies ens mean once again coldest by a decent margin for the E US so far for Jan 6-12 and coldest for the E US a week+ out I can recall for any week since I’ve been following this product (several years). The bulk of the E 1/3 of the US is 9-13F BN. The coldest is near Nashville with 15F BN! Note that the area covered by the 4th shade (-11F or colder) is even larger. We could easily not have another week like this in the E US for many years to come: Credit to the Euro Weeklies starting to see a cold signal for Jan 6-12 two weeks ago!

The last 2 EPS runs have each had 15 (30%) of its members with at least a T of wintry precip here, something we haven’t had in 7 years (longest drought at least since 1880s). The 0Z EPS mean has us way up at 0.6” from those 15 members! That means that run’s mean is at 3 times our average annual snow in just the next 2 weeks. I haven’t seen model predictions like this since the big 1/3/18 coastal winter storm. The next run probably won’t have as much. So enjoy it while it is there. @gtg947h @Awesomesauce81

Per the model consensus, especially today’s GEFS, there’s a good chance for the following to verify when averaged out over Jan 1-11: PNA > +0.5 AO < -2 NAO < -0.5 -EPO Since 1950 the only Jan 1-11 with this combo were 2010 and 1985 (the only La Niña). So, this would be a rare occurrence if it occurs. On top of that the MJO is forecasted to be favorable for a cold E US.

Per the model consensus, especially today’s GEFS, there’s a good chance for the following to verify when averaged out over Jan 1-11: PNA > +0.5 AO < -2 NAO < -0.5 -EPO Since 1950 the only Jan 1-11 with this combo were 2010 and 1985 (the only La Niña). So, this would be a rare occurrence if it occurs. On top of that the MJO is forecasted to be favorable for a cold E US.

12Z EPS: a whopping 30 of 50 (60%) have at least a T of wintry precip somewhere in FL (largest % I can recall seeing over the years on EPS this far (a week+) out) with 13 of those giving TLH a T+! 18Z GEFS: 14 of 30 FL!