GaWx

Yeah, that’s not comforting. If you don’t mind would you please post the 12Z EPS total freezing rain so I could compare my and other areas vs the new run?

Right you are, Tony! History says that that run’s ZR was extremely likely to have been overdone. Qpf for EPS: 0Z small drop vs 12Z 12Z was slightly wetter

0Z EPS, which is still more important than the operational this far out although operational slowly becoming more important as we inch closer: about same impressive amounts N areas but lower S areas except for N FL pen. due to what appears to be an even higher % of the total wintry precip as IP/ZR since this is purely snow:

0Z Euro: Snow Sleet: ZR:

This 0Z UKMET clown map is way overdone in the S/SE portion of the snow shown. For example, Statesboro, GA doesn’t get anywhere near 11.4” of snow because no more than 0.1” of qpf falls when 850s aren’t above 0C. It really is 1” tops. SAV gets no snow. CHS gets far less than 6.9” if any at all. Augusta and Macon get maybe half at best of the 13.6”/14.4” this shows.

0Z: CMC and UKMET like the ICON have large amounts of IP/ZR mainly to the south of the snow. GFS ZR not as bad (<0.45 everywhere).

1054 mb high there at corner of MO/KS/NE/IA would be near an all-time record high there. Thus I feel it is likely overdone.

0Z ICON has several inches of snow FL Pandandle/SE AL to C GA to NE SC/SE NC and significant IP/ZR further south. Much of this in SC/SE GA and S SC that is S of the snow is ZR, some of it major amounts of 0.75-1” and it’s not over as of the end of the run as there’s probably another 6-9 hours of precip to go with no warming flow off the ocean due to N winds. Thank goodness it is just a model that’s out 168 hours and realizing this kind of ice hasn’t happened there in much of that area in over 100 years.

And we still have a chance for a NW track trend from there though the Siberian high may prevent that. Euro AI didn’t do well too far in advance with the surface pressures and winds. Remember those runs with a clipper low and no wedge/warming S winds ahead of it and on back side of offshore high? That looked very suspect based on history and turned out wrong.

The 18Z Euro AI has the 546 thickness line, often a proxy for the snow/sleet line, way NW of the GFS and near the 12Z Euro from Rome, GA, to the TN/NC line. The majority of the qpf on that 12Z Euro was in the form of ZR for much of GA/SC/NC. So, my guess is that much of the 18Z Euro AI precip is similarly ZR over a good portion of GA/SC/NC near and SE of a line from ATL to GSP to RDU. That’s not surprising with the low close to the SE coast rather than well offshore. This as modeled is very likely not a major snowstorm for most here.

From KCHS first issued this afternoon: ATTENTION THEN TURNS TO THE VERY END OF THE FORECAST PERIOD WHERE THERE IS INCREASING CONFIDENCE IN A WIDESPREAD PRECIPITATION EVENT IN ASSOCIATION WITH A COASTAL LOW TRACK, POTENTIALLY BEGINNING AS EARLY AS TUESDAY. THIS EVENT WOULD BE UNFOLDING IN THE PRESENCE OF THE ARCTIC AIRMASS NOTED ABOVE, YIELDING THE POTENTIAL FOR WINTER WEATHER. MODEL GUIDANCE, BOTH OF THE DETERMINISTIC AND ENSEMBLE VARIETY, SUGGESTS A THREAT OF WINTER WEATHER FOR THE FORECAST AREA AND THE REGION AS A WHOLE. IT MUST BE STRESSED THAT CONSIDERABLE UNCERTAINTY REMAINS, ESPECIALLY REGARDING SUCH IMPORTANT ITEMS AS POSSIBLE PRECIPITATION TYPES, POSSIBLE PRECIPITATION AMOUNTS, AND SPECIFIC IMPACTED AREAS. Our local TV forecasters are wisely not yet mentioning this possibility due to too much uncertainty, especially with wintry precip being rare here (it’s been 7 years without even a trace).

Based on my analysis today of individual members’ qpf, 2m temps, and snowfall, I now know for sure that the WB snowfall on the EPS, like on the GEFS, excludes IP and ZR. My biggest concern for here is for significant ZR potential. The 12Z EPS and 18Z GEFS means have ~0.14”/0.10” of qpf in the form of 10:1 calculated snow, which is itself very high for an ens mean for snow a week out for this area. But what these aren’t showing is that the mean qpf in the form of IP/ZR on the 12Z EPS is an additional whopping ~0.4” and on the 18Z GEFS is ~0.3”. This means that mean IP/ZR producing qpf is ~3 times that for snow on these two runs! So, just looking at snow means for especially from E NC through far N FL, where the IP/ZR is a bit more prevalent on the 18Z GEFS, is deceptive for this threat. I very roughly estimate that the IP/ZR qpf breakdown in the deep SE on the 18Z GEFS is 75% ZR. That implies that the mean ZR qpf could very well be 0.25-0.3”, which is quite high for an ensemble mean a week out. Hopefully there wont be a bad icestorm! But unfortunately for the deep SE, that is a significantly higher probability than a big snow based on these latest two ens means. Hopefully that will change.

18Z GEFS mean snow:

3 of the 50 EPS members show the heaviest snowfall in my area in ~185 years after I decreased two of them from the 10:1 calculation, which would be too high in those two cases.

12Z 1/3/24 EPS 7 days before 1/10 storm (ignore VA/KY and further north snow as that was from an earlier storm): 12Z 1/14/24 EPS 7 days before projected 1/21 storm:

I’ve saved a lot of EPS mean snow maps with lots of snow and this one easily takes the cake for the heaviest overall from E half of NC to the Gulf coast, especially this far out! This is massive for being 7 days out, especially in those areas. Some of the members start as snow as early as late afternoon on Mon (1/20).

1/7/1988. 4.2” officially of mainly sleet at KATL and maybe a little less in Dunwoody. Stayed on the ground for a long time! Opposite (sort of) occurred 2/1979. Was expected to be mainly snow and ended up almost all sleet (4.2” also at KATL!!) after no more than first hour or so of snow.

Thanks. Here’s my personal experience. I was in Dunwoody for the 2/2014 storm. It started as rain that quickly changed to ZR. Fortunately, the ZR lasted only a few hours and was fairly light. It changed to a long period of sleet (~1”, my 3rd highest there) followed by snow to end it. But the southside (airport to Tony) eastward to Augusta wasn’t so lucky as they had majority ZR and major problems. The Eisenhower Tree at Augusta National fell because of it. We’re you then in ATL area?

Thanks. Regardless, the Euro was too cold further out or 7-10 days before last week’s storm. Remember those runs with single digits at ATL, for example? Also, storm tracks for that storm out 7+ days were much further SE than what verified. But we’re now getting right to day 7/crucial forecast time. It did much better for last week’s storm at 96-140, consistent with what you said. But we’re not there yet. By late tomorrow we will be getting to 140. This as you’ve implied is a much different setup with a much colder Siberian high that is progged to be 20 mb stronger to our north/NW vs the weak and weakening high for last week’s storm.

No. It and the models as a whole are cold biased, which is why the storms often track NW and temps are often not as cold as one gets closer. But there are always exceptions. Nobody knows if this will be an exception, but it is a much different setup vs last week’s storm.

12Z Euro as you said now has a winter storm back (1st since 12Z run on 1/12): Snow: Sleet: ZR:

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, 6Z, 12Z So, 11 of last 14 and 8 in a row! The 12Z CMC has ZR later, on 1/23-4, with it still falling some areas especially just inland at the end (fortunately only light along coast SAV northeastward):

Here’s 12Z GFS sleet for all to look at and especially for @dsaur

See above as I added it centered on AL/GA/SC.

12Z GFS fwiw (taking with a huge grain) as a result of 24 hours straight of ZR has close to the worst icestorm on record in the SAV area with 1.45” (Hunter) and 1.63” (airport further inland) at reporting stations and a general 1.25-1.65” over much of the area away from the islands. The 6Z GFS also had a lot of ZR with 1.30” at airport and 0.66” at Hunter. Statesboro had a whopping 1.89”! Needless to say, I might be taking a 2nd Jan trip to snowy Atlanta (in this case for two reasons) if something like this were to somehow materialize: