GaWx

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

What an impressive cold spell that went all of the way to the coast at its peak on 12/24 thanks to very strong W to WNW winds that prevented modification from the ocean. The little bit of modification was mainly from the marshes west of there. The inland areas had lows of 19 on 12/24, but Ft. Pulaski right on the coast had 22! The highs there and inland were only 33. On 12/25, Ft. Pulaski had a low/high of 27/44. This morning they were down to ~31. What's even more impressive are the offshore buoys 41004/41008: - On 12/24, 41004 (Gray's Reef 50 miles SE of Savannah) got down to a low of 28.2 at 9:50 AM, which was over an SST of 60! It was below 32 for 9 straight hours and below 40 for 40 straight hours! - On 12/24, 41008 (Edisto 45 miles SE of Charleston) got down to a low of 28.4 at 11:40 AM, which was over an SST of 69! It was under 32 for 10 straight hours and under 40 for 41 straight hours!

Current (as of 12/25 GEFS) AO prog for Dec 2022: -2.60, which trails only 2009's -3.41 and (barely) 2010's -2.63! What does a strongly -AO in Dec suggest for the Jan AO? A very good shot at a sub -1 Jan AO: Strongest 10 Dec -AO/following Jan AO 2009: -3.4/-2.6 6th strongest 2010: -2.6/-1.7 2000: -2.4/-1.0 1995: -2.1/-1.2 2005: -2.1/-0.2 1976: -2.1/-3.8 strongest 1985: -1.9/-0.6 1950: -1.9/-0.1 1969: -1.9/-2.4 9th strongest 1952: -1.8/-1.0 AVG Jan AO after top 10 Dec -AO: -1.5 So, when also incorporating today's GEFS prog, Jan will likely have a sub -1 AO. In addition, the model consensus is suggesting a +PNA for early Jan that intensifies the 2nd week (just confirmed by the 12Z EPS). The MJO is then progged to be on the left side, which tends to favor a +PNA then. That all suggests a decent shot at a moderate or stronger PNA (+0.50+) in Jan. At KATL, how were temperature anomalies in January when BOTH the AO was sub -1 and the PNA was +0.5+? (12 of them since 1950) 1953, mild +4 1958, cold -4 1961, cold -5 1963, very cold -6 1970, very cold -7 1977, record cold -14 1985, very cold -7 1987, normal -1 1998, mild +3 2010, cold -5 2011, cold -3 2016, normal -1 AVG: -4/cold with 8 of 12 cold and only 2 mild So, this suggests a 2/3 chance for a cold SE US Jan vs the normal 1/3 chance. Thus, despite the progged mild 1st week of January, the above suggests there's a good shot at actually getting a cold month overall. If so, Jan 8th-31st is liable to be very cold in the SE US to make up for the mild first week. Edit fwiw: two of the four non-cold Jan's were during a super El Niño: 1998 and 2016. 1987 was during a moderate El Niño though a moderate Nino tends to be chilly.

After a quite mild first half, it looks like Dec will end up within 1-2 F of normal in much of the SE thanks to a very impressively cold 12/16-12/28! Looking ahead for the SE, it looks like a mainly mild 12/30-1/7 or so before a potential change back to cooler domination starting during the 2nd week in January. Pattern signals are looking favorable for this then with an Aleutian low progged by model consensus to pop the W ridge/ +PNA. This along with the GEFS progging the current +NAO to fall back to neutral/the AO to drop back to negative and the consensus progging the MJO to move to the low to at most moderate amp left side (cold favoring) during the 1st week of January and continuing into the 2nd week tells me that this upcoming mild is likely going to be temporary. My 3rd year cold ENSO analogs had suggested as I stated in the winter forecast thread that one cold month, one near normal, and one mild month would be the scenario to bet on. With Dec being the near normal month, this would suggest one cold and one mild month to come. We'll see. Edit: 12Z EPS falling in line with the above thinking and looking favorable for cold to return during 2nd week of Jan

Look at what has occurred in parts of central and even south FL this morning from the first (weaker) of the two post cold front upper level disturbances! Also from MLB NWS: ISSUED AT 1049 AM EST SUN DEC 25 2022 A SMALL BAND OF PRECIPITATION FORMED OVER EASTERN OSCEOLA COUNTY AND PUSHED ACROSS CENTRAL BREVARD COUNTY AND OFFSHORE LATE THIS MORNING. TEMPERATURES WERE COLD ENOUGH TO PRODUCE A WINTRY MIX OF LIGHT SNOW AND SLEET, FROM VIERA TO MERRITT ISLAND, COCOA BEACH AND CAPE CANAVERAL. MAINLY TRACE AMOUNTS HAVE OCCURRED WITH RAPID MELTING. Here's a link to video evidence of wintry precip: https://twitter.com/realTimB/status/1607043178372243457/mediaViewer?currentTweet=1607043178372243457&currentTweetUser=realTimB In addition, Immokalee in SOUTH FL a little before this reported "MIX PCPN" at 10 AM! IMMOKALEE MIX PCPN 39 27 How often does it rain with it as cold as 41 in West Palm Beach at noon?!? W PALM BEACH LGT RAIN 41 32 70 NW13

From noon, KSAV ended up warming a much faster than models 7 F from noon to a high of 33. But that was still a record low high for the date. Also, the 33 with mainly sunshine means only two mainly sunny days since the 1870s had colder highs in December: 27 on 12/25/1983 and 32 on 12/29/1894. Hunter AAF and my house also had highs of 33. I took two walks (one last evening and one two hours ago) with temperatures in the 28-30 area and wind chills in the teens. Yes, I was the only crazy nut walking around in the two parks I went to, but I loved every minute of them! These were about the coldest I've ever taken in this area. I'm now at 28.8.

Low of 19 this morning. The temp here just before noon was 28.4. At KSAV, it was only 26 at noon. The 12Z GFS, which was about the warmest model run, had them then at 30. So 4 too warm and it projects a high of 32. The only model too cold then was the CMC's 25, too cold by one. It projects a high near 28. The ICON is near perfect with its 26-27 at noon. It projects a high of 30. So, the consensus is for a rise of 2-3 from noon with no more than a 4 rise. All of this implies a good chance of a KSAV high no more than 30 as it stands now. When was the last time KSAV had a high of 30 or lower with mostly sunny skies? Jan 21st of 1985 (27)! The last sunny Dec day at least that cold was 12/25/1983 (27). No other Dec day with no precip other than 12/25/1983 going back to the 1870s had a high of 30 or colder!! What's also amazing is that Ft. Pulaski right on the coast was only 25 and buoys 41004/8, well offshore SC/GA, were only 29/31 at noon!! And that was over SSTs of 70/60!

It was 31 here and throughout the area at 9PM. It hit 32 here near 8:30. The forecast low at KSAV is 17, which would be the coldest since 1/24/03!

I found three more but don't know that any can be trusted or even recognized, especially since they're all well up in elevation (over 3,600 feet) just like Helena: links to last 7 days: 1) Ruby Valley Field (KRVF) : 1066.62 on 12/22 at 7:35 AM MST https://www.weather.gov/wrh/timeseries?site=Krvf&hours=168 Dec 22, 7:35 am -31 -38 67 N 0 SCT026 SCT031 1066.62 25.65 30.59 2) Ennis Big Sky Airport (KEKS): 1065.65 on 12/22 at 9:55 AM MST: https://www.weather.gov/wrh/timeseries?site=Keks&hours=168 Dec 22, 9:55 am -29 -38 60 N 0 10.00 CLR 1065.65 25.02 30.51 3) Ravalli County Airport (KHRF}: 1059.57 on 12/22 at 8 AM MST: https://www.weather.gov/wrh/timeseries?site=Khrf&hours=168 Dec 22, 8:00 am -24 -29 75 SE 5 10.00 BKN031 BKN039 1059.57 26.81 30.64

I have 39.2 after being only in the lower 40s earlier this afternoon.

From best I can tell, I'm guessing no records and high 1050s, which would not be a record despite still quite possibly being the strongest high since 12/1983. I can tell you that the highest for MT, IF this link to hourlies at Helena has accurate SLP data, is at least 1056.5 mb (this says that occurred at 8:53. AM MST on 12/22): https://w1.weather.gov/data/obhistory/KHLN.html 2208:53Calm1.25Fog/MistFEW002-31NANANANA30.711056.5

Although model consensus is keeping any surface low pressure too far offshore to give the deep SE wintry precip 12/26-7, the clipper associated with the 2nd upper level disturbance is giving accumulating snow (mainly light) to some areas well inland in the SE per the consensus between the PM of 12/26 and the AM of 12/27. The 12Z UKMET fwiw gives a portion of N AL and much of N central to N GA accumulating snow late Mon afternoon through Mon evening with as much as 1-1.5" Anniston, AL, to LaGrange, GA, and 0.5" in the SW ATL burbs to near the airport. Previous runs had nothing like this. Temperatures preceding this on Monday only rise to the middle to upper 30s after lows well below freezing. The 850s are a bit below freezing. Thus, the air and ground will be plenty cold enough. So, Monday afternoon and night could get quite interesting in parts of the SE. The disturbance leading to this clipper is not even going to reach the Pacific NW/SW Canada coast for another 36 hours. So, lots of uncertainty remains for something only 3.5 days away. Edit: But the 12Z Euro says it is still too dry for snow.

Today's 12Z model consensus, if anything, is a bit further from SE significant wintry precip 12/26-7 vs yesterday's runs. With it now being one day closer, the already pretty low chances have dropped further. I would have expected something more showing up by the 12Z runs today, like a closer to the SE coast surface low formation, if the trend were heading toward a threat. Yesterday was sort of headed toward that but today has backed off.

I just noticed that the following thread is addressing the very strong cold coming in starting tomorrow:

Although the 0Z Euro still doesn't give the SE wintry precip, the 2nd disturbance is stronger (more closed off) and a little further west for the same timeframe vs the 12Z. This results in the sfc low forming near the Bahamas on 12/27 being a little further west. As a result, rain gets further north in FL to St. Augustine vs Daytona on the 12Z run and to the coastal waters of the Carolinas vs 100 miles offshore on the 12Z. This run does nothing to sway me away from the possibility of later runs giving the SE wintry precip from this.

Latest highest SLP in MT is ~1053 mb. Keep in mind that this isn't based on station measured pressures as they have to be converted to SLP and much of MT is up several thousand feet. These SLPs will be rising considerably tonight. I can already say that the UKMET is going to verify way too low. This makes me wonder about how it converts to SLPs. Something's off bigtime. Map with current SLPs: https://www.spc.noaa.gov/exper/mesoanalysis/new/viewsector.php?sector=11&parm=pmsl&underlay=1&source=1#

Aren't you from the guy from world famous Waycross who moved to Hawaii because you had joined the military? And you were going to do something related to meteorology. Welcome back! I remember you had a Peppermint Patty avatar like mine. For those who weren't around then, many active members here were changing their avatars to favorite Peanuts characters for a reason I can't recall.