GaWx

Something of that sort happened in this area in January of 1800. I’m not making this up. Was a multi-hundred year snowstorm obviously.

A weak low crossing central FL (not N FL) like the 12Z UK does is what we want to root for. History of past winter storms here agrees.

12Z UKMET gives us 2” of qpf with our temperatures at 32 or lower from very late Mon night (1/21) til 24 hours later (near sunrise Wed morning 1/22)!! The good news is that a fair bit is snow is implied. The 850s are only +1 to +2 for the first 9 hours or so (which tends to be cold enough for sleet more often than ZR) before dropping to potential snow levels of 0C to as low as -1C for part of the time. So, this may all be almost all sleet and snow on the 12Z UKMET and would be historic. Of course the odds are low (standard disclaimer out 144 hours), but we’re getting closer!

If there were to actually be a winter storm here early to mid next week, I wouldn’t at all be giving up on snow or sleet here despite the higher risk for ZR: 12Z GEFS looks quite nice for us and much of the deep SE…check out the 0.4” way down at Jacksonville: 11 of the 30 members give us snow within 1/21-2 with 8 of the 30 at 1”+ with 5 of those 2”+! So, this isn’t just 1 or 2 crazy members skewing it. This is about as good a look we’re going to get on the GEFS while still out 6 days: @pcbjr @Awesomesauce81

12Z CMC: no thank you for this modeled disaster of 1.78” of ZR at Hunter/2.32” at SAV but fortunately this is highly likely overdone and also CMC has a low level cold bias, especially considering that the low passes by not too far offshore: Sleet:

12Z GFS has Brooksville (BKV way down in west C FL) getting rain at 10AM on Tue (1/21) while at 35F with a dewpoint of 29F. That shows how close a call even way down there this could be if there is anything 1/21:

Snow for SE coast CHS NE late on Tue night/Wed morning (1/22): so GFS is back to coastal wintry within 1/21 like the prior 10 we’re before today’s 6Z blank:

12Z GFS has snow for a portion of coastal SC and NC Tue night!

I’m ok with it too as painful as it is to see this.

The 12Z Icon gives SAV area 6-8” of snow (7.9” at further inland airport and 6.3” at Hunter near the city). This looks like legit snow on the clown map since 850s are near or just below 0C and 2m temps are in upper 20s and then fall to mid 20s during it. Adjusting down for what Kuchera may have had, it would likely be closer to 5-7”. Whereas that would be amazing and I’d obviously love to see it, SAV hasn’t received that much snow since way back on March 3, 1837! So, SAV getting anywhere near this much snow is, needless to say, extremely unlikely especially since this is still 6.5 days away. https://www.weather.gov/chs/todayinwxhistory

The 6Z GFS was the 1st run since way back at the Jan 12 12Z run with no significant SE coastal wintry precip. during 1/21-2. So, there had been 10 GFS runs in a row like that just prior to today’s 6Z. And not only that but there’s no precip of any kind in any of the SE US 1/21-2! Interesting! 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, 18Z Jan 15 0Z but not on 6Z (1st since 12Z Jan 12) A delay of anything in the SE til after 1/22 means a higher risk of not having enough cold air for a storm to intermingle with for widespread SE wintry precip since 1/20-2 is when the coldest of the air has been plunging down and fresh enough for a winter storm. Near perfect timing is crucial for the SE as we know!

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.