GaWx

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.

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.

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")Tally:-NAO: 8Neutral 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: +NAOConclusion: 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: https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.cdas.z500.19500101_current.csv RDU data: https://www.weather.gov/wrh/Climate?wfo=rah

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.

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.

I looked at February temperature anomalies of 34 La Niña Febs to see what are the chances based on the last 140+ years for a torch (using respective 30 year averages) in the SE using ATL stats as representative: 1887: +8 1890: +10 1893: +1 1894: 0 (major snow) 1904: -3 1909: +4 1910: -3 1911: +5 1917: -2 1925: +5 1934: -6 (major snow) 1939: +4 1943: +1 1950: +5 1955: +2 1956: +5 1971: -1 1974: +1 1975: +2 1976: +7 1985: -1 1989: +3 1996: -1 1999: +1 2000: +3 2001: +2 2006: -4 2008: 0 2009: -1 2011: +2 2012: +3 2018: +9 2021: 0 2022: +3 If I use +5 as minimum required for torch, I count 8 torches (MA) (24%), which is a lot. There are also 10 A (+2 to +4)(29%). So, a whopping 18 of 34 (53%) are A to MA. Normally, A to MA would comprise no more than ~35-40%. There are 11 near N (+1 to -1)( 32%). I count only 4 B (-2 to -4)(12%) and just 1 MB (-5 or colder)(3%). But that still means 47% (nearly half) were near normal or colder. So, whereas we often read about the assumption (likelihood) of a mild Feb in a La Niña, the reality is that that chance is only a little over 50% and the average of the 34 Niña Febs was only +2 at ATL. That's because the largest # in any category is actually near normal. In fairness though, the chance of cold is much lower than mild. Conclusion: During any La Niña, there is a high chance that Feb won't be cold. However, there actually isn't a high chance but rather more or less only a coin flip type chance that Feb will be mild. --------------- ENSO data: Pre 1950 from Eric Webb: https://www.webberweather.com/ensemble-oceanic-nino-index.html 1950+ from NOAA: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php ATL temperature data: https://www.weather.gov/wrh/climate?wfo=ffc

For those like myself who want the progged mid January chill to be the start of a long period of cold domination, the 0Z EPS and now even more emphatically the 12Z EPS is saying the chances of that are dropping. Whereas the 12Z EPS looks a bit colder than the 0Z toward midmonth with the cold period thanks to a decent +PNA, it is also showing it to be only a ~3 day long chilly period as the +PNA quickly transitions to a zonal/strong Pacific jet/warming pattern to at least near normal with no new cold then in sight. That progged quick end to the chill is still two weeks out and can obviously change drastically. However, today's ensemble consensus changes are clearly moving away from the possibility of the start of an extensive, long duration cold pattern at midmonth. Based on how often model consensus has been doing this kind of thing since late November outside of the big cold of late December, this isn't at all what I wanted to see. Edit: I should reiterate it does look pretty cold on the 12Z EPS for ~3 days near midmonth. That would possibly be a period to look for the chance of snow from an off the coast storm for mainly NC north just taking the run at face value. The run is showing a pretty good number of members with off the coast storms centered at the start of this cold period late 1/13 to early 1/14. If there is a low there then, would enough cold air get entrained before the moisture is gone?

I wonder whether this underestimation of the Pacific jet/overdoing the +PNA by the models in the 11-15 often since late November is partially related to near record high SSTs in Indonesia/Maritime Continent. I was told by a pro met a couple of years ago that the record high SSTs in the MC likely sometimes cause the Pacific to act as if there's a pseudo MC MJO phase (4 and 5) even when the MJO, itself, isn't officially in the MC. It seems as if this has been occurring a lot over the last several years and the MC has been near record highs for several years.

Since yesterday, the EPS (along with the GEFS) has warmed in the SE/much of the E US near midmonth and is now suggesting that the midmonth cooling may not last more than a few days or be as strong with the +PNA then quickly dropping back. Today's 0Z day 14 GEFS PNA forecast took a hit from yesterday's ~+0.5 to today's ~0. That's a drastic change for just one day. The day 14 GEFS NAO rose from yesterday's ~0 to today's ~+0.2. Though the AO still looks solidly negative and the strong Dec -AO favors a sub -1 AO this month, it doesn't look as strongly negative late in today's GEFS run as yesterday's nearing -2. Today's isn't much lower than -1 along with most members then rising. The MJO does still look favorable for cold with a phase 8 though with a little higher amp. (I prefer low amp.) Yesterday I said this: "For those preferring cold domination, the hope is that the EPS won't backtrack like it did for the period near 1/9-10 about five days ago." Unfortunately for cold lovers, today's 0Z EPS backtracked somewhat for midmonth though it is just one run. We'll see whether or not the 12Z EPS agrees. The following link from a knowledgeable NYC forum poster "bluewave" shows very well how much the EPS and GEFS (especially the EPS) have backtracked from a return to cold/solid +PNA for January 10th on the 0Z/6Z 12/26 runs (what I was referring to yesterday) to a warm E US for January 10th on today's 0Z runs due to underestimating the strength of the Pacific jet: I mentioned last week that the Indonesian waters/MC are near record highs (similar to last several years) and that this along with La Niña would likely mean periods favoring the SE ridge. I wonder if this is the main reason for underestimating the Pac jet.

The above two posts make it sound like AN temps will dominate the SE through the somewhat foreseeable future (say 15 days). If I read them and didn't look at any data, I'd be inclined to think that. Also, if I saw it that way, I wouldn't be afraid to suggest similarly as my style is to post with objectivity as a prime goal. But I don't see it that way. In a nutshell, the current torch will end abruptly all areas by 1/5 followed by a couple of chilly days. There will likely be a return to AN a few days later that is expected to last no more than 5 days. After that, the prospects for significantly colder starting ~1/13-4 are coming into better focus. Below is a link to the entire run of 12Z EPS 850 mb temperatures, which illustrate all of this quite well. The chance of a return to a solid +PNA by midmonth looks as high on this run as any in the last 5 days. For those preferring cold domination, the hope is that the EPS won't backtrack like it did for the period near 1/9-10 about five days ago. Based on midmonth GEFS progs of the combo of strong -AO (nearing -2), which is supported by the 3rd strongest Dec -AO on record since a strong Dec -AO tends to have a memory; a drop in NAO toward zero; and a favorable MJO for +PNA/cold SE, I feel that the EPS is probably on the right track this time as opposed to my saying this just based on my desire:

This shows 850 mb temperature anomalies for the entire 12Z EPS. It shows at 850 mb (5K foot elevation) in the SE US a torch 1/1-4, a cooldown to BN 1/5-6, a warmup to AN 1/8-12, and then a cooldown to BN 1/14-5 in most of the US due mainly to a combo of the strengthening +PNA/-AO. Keep in mind these are 850s rather than ground temperatures. Ground temperature changes often lag 850 changes. Also, low level features like CAD are often not reflected well up at 850 mb:

This is mainly a rehash of old news for the SE with it showing a torch for 1/1-5 followed by downs and ups into the first half of week 2 with a lean toward AN. But it then shows a gradual transition to BN by the end of week 2 and the start of week 3. This is fully in line with recent days' expectations/model consensus. By the way, my take on RonH is that he's pretty objective in his Twitter posts with him mainly sticking to objective wx model output, whether warm, cold, or whatever from day to day.

The 12Z EPS is a bit warmer through early week 2 than prior runs and has a mild SE through 1/13 overall in the means. However, it then quickly evolves to much colder with actual BN mean by 1/14-5 thanks to the strongest +PNA late in any EPS run since the runs from 12/27. IF this were to end up real this time (keep in mind we're talking way out in the unreliable late week 2 and that the BN/solid +PNA late in the 12/27 runs (for 12/9-11) has since changed to AN) and when considering my post above with progged favorable AO/MJO along with NAO finally dropping back to 0, mid January and potentially beyond would very likely be much colder than the first 12 days of the month. Keep in mind that the very strong December-AO has a memory of sorts per analogs and that mid to late Jan being dominated by a strong -AO is a distinct possibility.

Today's update vs yesterday on the 5 indicators I've been following with first 3 being 0Z GEFS 2 week based: 1. PNA: less + with it now dropping to neutral ~1/7 before slowly rising to ~+0.3 at end of week 2 (vs +0.6 yesterday) 2. AO: slightly + on/near 1/7 vs previously having been - through entire run a few days ago but then still goes back to solidly - (sub -1) by the end of week 2; strongly -AO Dec analogs do favor sub -1 Jan AO overall (more on that in another post) 3. NAO: strong + week 1 but now drops to ~0 by end of week 2 vs +0.5 yesterday 4. MJO: still progged to be in a supportive position to allow for cold to dominate once into mid January with very slow moving low amp in/near phase 8 5. EPS: 0Z little changed with weak to borderline moderate +PNA after day 10 ---------------------- Summary vs yesterday from SE cold preferring standpoint (I know some prefer warm): Worse: PNA overall; AO for week 1 Same: AO late week 2, MJO, EPS Better: NAO Conclusion: probably no return to cold domination through next 10 days but significant drop in NAO to neutral by day 14 (first time in many days showing this) along with solid -AO, beautiful looking MJO, and back up to a weak +PNA by then tells me that the potential remains for mid to late January to be when cold domination returns. Remember that mid January is still a virtual eternity away in terms of model forecasting abilities.

I see nothing exciting on the entire 12Z EPS as well as other ensembles through the end of the runs suggesting a return to a cold pattern. If accurate, that would mean that a new cold pattern would not be until midmonth at the earliest. Let's see what happens.

Sharp contrast in airmass here (and in the SE overall) vs 48 hours ago, when it was 59/27. Now it is a somewhat sticky 73/60. I'd enjoy 73/45 much more.

The ensemble model consensus continues to suggests no return to a cold dominated pattern in the SE US and the E US in general through the next 7-10 days. After that it is a tougher call as is typically the case when going out past 10 days. But admittedly nothing exciting on the cold side is yet showing on the ensembles in the 11-15 despite the MJO still progged to be in a supportive position to allow for cold to dominate once into mid January. The 0Z EPS was pretty close to yesterday's EPS with only a weak to borderline moderate +PNA after day 10. The GEFS still has a moderate +PNA (~+0.6 vs +0.5 yesterday) while the AO forecast is still solidly negative after day 10 (still sub -1). But the NAO is a little higher today (near +0.5 vs +0.3 yesterday), which is not supportive of cold. Expect model volatility in the 11-15 due to the conflicting signals of cold supportive MJO/AO and slight cold support from the modest +PNA vs the support for mild from the +NAO. I'd think a cool off down at least to near normal averaged out would be quite doable.

Followup vs 24 hours ago regarding January indicators I've been following: (0Z GEFS based for first three) -AO not only held serve but actually looks a bit stronger. The mean now drops it to ~-2 ~Jan 9th. Keep in mind that per strong -AO Dec analogs, a sub -1 AO for the subsequent January is favored. - +PNA held serve at ~+0.5 (borderline weak/moderate late in the run) but didn't come back to the ~+1 of three days ago - +NAO still at the end but weaker with +0.3 vs +0.5 yesterday although still above the near 0 from the run of three days ago. - MJO is back closer to the favorable look for cold of three days ago headed to slow moving low amplitude phase 8/1 instead of stalling for a long time in phase 7 per yesterday - 12Z EPS is even weaker with the Aleutian trough/+PNA vs the already weaker run of yesterday In summary in regard to SE cold prospects Jan 8-31 overall vs yesterday, AO and MJO look better/as favorable as any recent run, the NAO looks very slightly better, and the EPS looks worse. We've got an eternity before this gets here and thus it is very much up in the air. The biggest keys for me would be whether or not the PNA goes back to a stronger + and the NAO goes back to neutral in future runs.

This weenie post is only worthy of banter because it is about the super vodka cold 12Z CFS run. It has the warmth end on Jan 6th followed by cool to frigid every day in the SE but two days through the rest of the run, which ends on Jan 28th with a glacier thanks to three major SE winter storms during the final 7 days of the run. The 0Z was similarly cool to cold dominated also starting ~1/7 and has a SE winter storm 1/12, but with less extreme cold and somewhat longer warm periods between the cold. Of course, these are mainly for entertainment as they have very low credibility that far out and aren't ensemble runs. In addition, they get too cold over snowcover. For example, the run from just 24 hours ago was a torch for most of the run!

Update two days later: - AO per GEFS still looks to most likely go back to negative in early January and a sub -1 for January as a whole is favored per analogs already shown. Keep in mind though that the spread is very wide (+1 to -4 for day 14). - PNA still looking to remain positive although not as high as shown two days ago, when a return to ~+1 was favored. Now it's aiming toward only ~+0.5. Analogs I was showing had minimum of +0.5. Going forward, the PNA progs will continue to be crucial in looking ahead to potential colder prospects for January after the first week. - NAO still looking to fall back from the current strong positive, but not as much as how it looked two days ago, when it was aiming for neutral. Now it is aiming for ~+0.5. - MJO still aiming for upper left side low amp, but now looks to loop back/stall in phase 7 instead of slowly heading toward 8. - The 0Z EPS still has a +PNA late but it and the Aleutian low are weaker than shown two days ago. Summary: Although the solid -AO prospects for January overall have remained steady and the analogs back that, the other four things (PNA, NAO, MJO, EPS) don't look as favorable for cold as they looked two days ago. I also just learned that record warmth remains in the Maritime Continent/Indonesian waters. That in itself has been a factor helping to favor the southeast ridge pattern in recent years. That in combination with the current La Niña means everpresent higher than normal chance for SE ridge to dominate at times. So, all of this tells me that the chance for a cold January 8-31 overall isn't as high as it looked two days ago. Good/bad trends for warm/cold lovers vs how it looked two days ago. I'll keep following these five factors going forward as there's lots of uncertainty that far out in the future.

KATL ended up with 0.1" of snow/sleet KSAV last four mornings had very hard freezes with these lows: 19, 21, 22, and 25. Another freeze is expected tonight with upper 20s. This long stretch of hard freezes isn't something seen often way down here. The last time was five years ago. I (and my Sago Palms) am actually looking forward to some warming, especially feeling that it will likely not be a long lived torch but rather just an interlude of mild. I enjoy the volatility of winter overall as long as a good amount of cold/very low dewpoints is included. It is so much more interesting than the dog days of summer. What an up and down month with first half torch and last half brrrrr. It will go down in the books as near normal, but that's deceptive as there wasn't much normal about it when you break it into halves. As of today, the month has averaged almost dead on normal!

Starting just before 10 PM, snow suddenly started coming down quite nicely from the eastern burbs of ATL eastward under those impressive radar returns! Expect road problems almost immediately! Edit: light snow reported at all immediate Atlanta stations as of midnight!

The radar looks pretty impressive between Atlanta and Athens. But how much is reaching the ground? So far in Atlanta, itself, and just north, very little or nothing has reached the ground with dewpoint depressions still 25-30 in most cases.

Thanks and YW, Mr. Wedge! The GEFS retains the favorable solid +PNA/-AO forecast of yesterday as the 2nd week in January arrives. In addition, the MJO model consensus progs still have a very slow moving low amp upper left side path that actually starts near Jan 1 and persists, which in combo with the progged +PNA/-AO based on history/analogs back to the mid 1970s would scream a decent shot at an extensive period of cold SE potential from sometime within the 2nd week of January onward. The main fly in the ointment (there usually is one) indexwise for cold potential is that the NAO is projected to approach neutral rather than be negative. But it is falling steadily from a stout +NAO preceding it. Perhaps it would head to a -NAO by midmonth as that's beyond the two week forecast. All 8 of the SE cold January solid +PNA/-AO analogs have a moderate to strong -NAO except for 1961 (weak +NAO). So, that says it would still be possible to have quite a cold January without a -NAO. However, the chances would obviously be significantly better with it. Looking at the four non-cold January +PNA/-AO analogs, three of them had either a neutral or weakly +NAO. Then again, 2 of those 3 were super-El Niño's. The 12Z EPS, similar to recent runs, confirms the transition to a west coast ridge/solid +PNA popping from strongly negative Aleutian heights late in the run. This could easily turn out to be a fun month overall for cold lovers. For warm lovers, please don't shoot the messenger plus you'll have your week in early January, regardless.

If I were in the Atlanta to Athens corridor and even well south to below the southern ATL burbs, I'd be pretty excited about the chance to see snow fall tonight, possibly even with light accumulations in some areas. This is a very tough call due to the very dry air there now, but check out Tunica in far NW Mississippi posted at the bottom. They received one inch within an hour! Memphis and other nearby areas also got snow. Most models, including mesoscale, didn't have that much there. In GA though, dews are only in the single digits to just below 0! In the Memphis area, dews were a bit higher in the mid teens before the snow fell. So, there's a good bit drier air over N GA to overcome at the surface. Nevertheless, though it isn't mesoscale and thus fwiw, the 12Z UKMET has an area of accumulating snow from N AL to NW GA. But it also has a heavier area from the W ATL burbs through ATL with a likely overdone max of 1.5" at Carrollton and tapering down to ~0.3" in Atlanta. The 12Z Euro has nothing of the sort and instead has a max of ~0.5" between Gainesville and Athens. Neither model had the 1" at Tunica. On the mesoscale models, both the latest NAM and WRF have nothing accumulating over N GA other than a very thin strip of a tenth or two on the WRF from E of Lake Lanier to the SC border. But both have a very narrow band quite a ways to the south over north central GA but not til ~midnight with a max on the NAM of nearly 1" near LaGrange! Going to be fun to follow: AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN UPDATE ISSUED AT 1125 AM CST MON DEC 26 2022 QUICK UPDATE. TEMPERATURES ARE QUITE UNEVEN ACROSS THE FORECAST AREA AT THIS HOUR. MOST SUBFREEZING TEMPERATURES CAN BE FOUND ACROSS NORTH MISSISSIPPI, WHERE HEAVY WET SNOW HAS CREATED ICY ROADWAYS, BRIDGES, AND OVERPASSES. TUNICA, MISSISSIPPI PICKED UP AN INCH IN ABOUT AN HOUR AND REPORTED VERY DENSE FOG LAST HOUR. TEMPERATURES LOOK TO REMAIN SUBFREEZING ALONG THE TENNESSEE AND MISSISSIPPI BORDERS FOR THE NEXT COUPLE OF HOURS, WHERE ACCUMULATING SNOWFALL IS EXPECTED TO CONTINUE. ANOTHER HALF INCH UP TO AN INCH OF SNOW IS POSSIBLE IN THESE AREAS. Edit: Check out this from Tunica at 10AM CST! TUNICA HVY SNOW 31 29 92 S8 30.27R VSB<1/4 WCI 23