Lookout

speaking of that..the 12z icon goes nuts over tn thanks to that snow cover..5 to 15 below unfortunately looks like it screws ga/sc snow wise (east of atlanta/gainesville). does keep temps in the 20s for highs though, even here in the heart of the screwzone.

gfs and euro ensembles look pretty decent for the nw half. ....but of course areas to the east of 85 look pretty much screwed with the leeside screwzone in full effect...which means i'll likely have to make a trip to see it. But an inch or two looks possible and north/west of an atlanta to gainesville to clayton line. In fact some of the euro ensembles show several inches for the mountains. Would love to see this thing put down a few inches ahead of this arctic airmass to maximize the low temp potential. Although the euro doesn't look nearly as impressive with the outbreak as it once did.

if the 12z gfs is right with highs in the teens up your way, it would be impressive if it wasn't the coldest day lol. Even the downslope screwzone might stay below freezing. for several runs now the gfs has been showing dewpoints that if came to pass would surely be some of the lowest we have ever seen.....and to see it over such a large area is even more impressive. Although WAA commences after this, Have to believe the gfs is too warm though with morning lows the next day with high pressure becoming situated directly over head in the carolinas thursday night/friday morning with dewpoints still in the negative teens.

yep, everything was always dependent on enough precip falling to take advantage and unfortunately it was just bone dry. Story of the winter so far south of nc...just can't get anything to come together right. Still this was a fascinating day here with the warm front and something happened that is pretty rare...the warm front moved through but then pushed back slightly south. Normally of course once it comes through it keeps going or at least doesn't come back. Athens observations bear it out...the warm front moved just north of here and then came back south. Temps went from the mid 40s to the upper 60s and damn near 70 only to fall back into the low to mid 50s the past few hours. Meanwhile just to the south it's still in the mid to upper 60s. A few miles to the north temps mostly stayed in the 40s. Indeed at one point, one observation site just a couple of miles away from athens airport was 10 degrees warmer. Personally, cad/wedges aren't just about ice/snow so this is pretty neat to me. Here is athens observations this afternoon. 23 Jan 5:51 pm 53 44 71 ENE 9 10.00 OVC046 29.02 1012.0 29.88 23 Jan 4:51 pm 57 46 67 ENE 10 10.00 OVC049 29.04 1012.8 29.90 23 Jan 3:51 pm 69 49 49 S 9 10.00 FEW049,BKN090 29.07 1013.6 29.93 23 Jan 2:51 pm 68 49 50 S 9G20 10.00 BKN046,BKN090 29.11 1015.0 29.97 23 Jan 1:51 pm 60 48 64 NE 10 10.00 FEW037 29.16 1016.9 30.03 23 Jan 12:51 pm 54 44 69 ENE 10 10.00 FEW030 29.23 1019.4 30.10 55 39 23 Jan 12:33 pm 53 43 69 NE 8 10.00 SCT013 29.25 30.12 23 Jan 12:16 pm 52 43 71 ENE 10 10.00 BKN010,OVC015 29.28 30.15 23 Jan 11:51 am 51 43 74 E 13 10.00 OVC008 29.29 1021.8 30.16 23 Jan 10:51 am 46 38 73 ENE 6 10.00 OVC009 29.34 1023.5 30.21 23 Jan 9:51 am 42 34 73 E 10 10.00 OVC008 29.36 1024.1 30.23 23 Jan 9:27 am 41 33 73 E 9 10.00 OVC009 29.39 30.26 23 Jan 8:51 am 41 33 73 E 9 10.00 OVC010 29.39 1025.2 30.26 23 Jan 8:41 am 41 33 73 E 9 10.00 OVC010 29.39 30.26 Yep, if i had not gone to gainesville the past few years , i wouldn't have seen a thing. Been a pretty bad winter weather drought around these parts.

Although i've never been optimistic about this system and still don't believe we get much of anything, i'd rather they be showing it squashed than to the north. Even though it's not looking good at the moment, The lack of run to run consistency should be enough to not rule it or anything out right now.

It's the southeast....we always find ways to screw things up or finding ways for warm air to rule the day. meh....the next run will probably be dry and 50s lol. Euro has been all over the place in the medium and long range of late.

Yep, chances of light freezing rain (or sleet at first as gsp mentioned) have gone up. Considering the cold conditions, it won't take much to cause some slick spots on area roads tue night/wed am after this cold spell..especially in the western carolinas/extreme northern ga where temps should be below freezing or near freezing before any precip arrives. nam/3km nam is now keeping temps stuck in the 30s all day in cad areas as i expected the other day..and i wouldn't be surprised if they are still too warm since even the nam suite are showing 15 to 20 degree rise in dewpoints without much temp response. I would imagine there will be some dewpoint recovery even without precip due to southerly flow just off the surface, but it's probably a little overdone or at least not showing enough temp falls. (assuming there is enough precip). Actual lows and highs wednesday will depends on how much precip actually falls and if it will be enough to fully take advantage of the dry air/low wetbulbs. Assuming there are at least light showers around wed, i wouldn't be surprised to see it take to mid day or early afternoon to get above freezing in spots and then stay stuck in 33 to 35 range until the front passes in the heart of cad territory. Depending on model run/model, they have all hinted at an axis of heavier totals across far north ga into the upstate...on the order of 0.10 to 0.20 though mid to late morning when temps should still be below freezing. Considering the light nature of the precip which should promote freezing on elevated surfaces, could be some respectable light glazing and pretty scenes in those areas if comes to pass. I was a little surprised it was that many but in general those that have snow were big hits. But I remain highly skeptical though since we are dealing with a northern stream systems which a lot of times the models get wrong at this range.

Not sure if it's been mentioned but The long range aside, i think there could be a decent insitu wedge and a chance of some very light freezing rain in north ga/western carolinas tuesday night/early wed.. Yes the high moves into a bad spot but we will have the airmass left over from this upcoming cold shot and it will be pretty cold/dry initially. The old gfs is way too warm and would mean zero chance. However the icon, canadian, and euro all hint or show outright the possibility of some light freezing precip. Despite the bad high placement and no additional caa, winds will be easterly in the low levels and should lock in the cold pool...assuming there is enough precip to cool it down. Once again it might depend on how warm things get tuesday. Gfs says not a chance in hell so won't even bother while the other models show 35 to 41 in general but cooling back down to low to mid 30s by evening in ga and upper 20s/low 30s in the carolinas with dewpoints rising from single digits/low teens tue to teens/20s by evening. The euro keeps being the most aggressive with precip tuesday night showing light freezing rain in far ne ga/upstate by 9pm. Overall it's only a small chance and even if it happens it won't amount to a whole lot since precip amounts look very light (less than a tenth) and temps quickly warm up but figured i'd mention it anyway. Don't be surprised if we get stuck in the mid to upper 30s all day since in setups like this, the cold pools are really hard to dislodge/warm up.

fv3 has been warmer and warmer with this one......now has just a run of the mill cold. Only upper 20s here to low to mid 20s in nc. Probably will get more than ga/sc in the end.

yeah the canadian is bad news honestly for everyone in cad territory with so much precip. Wetbulbs are in the upper 20s to near 30 right as precip arrives and the depth of the cold air is sufficient to keep it subfreezing for a good chunk of it,..through 925mb. Put simply the canadian looks like our classic ice storm for ga/sc./nc. Nothing like the december storm in terms of the setup...where in this case the cold air is already well established before any of the precip arrives. Of course it's the canadian so tonight it's likely to show something totally different but for this run at least, it looks slick.

yep, much further south. although they handle the low much different, both solutions look icy for many. at least this system has one thing the last one didn't, actually respectably low dewpoints/dry air, and evap cooling potential.

Fascinating. Never ceases to amaze me how the topography effects things around there/here. Sure makes it difficult to get a grasp on what to expect. I've often thought how nice it must be to be in the ohio valley or plains where it's a lot more straight forward. new hrrr is looking really promising, especially for south carollna where they got nothing. a bit colder and dropping a couple of tenths liquid With temps at 32/33.

Yeah that sucks. How do you normally do when wedges break down? Do you warm up faster or slower than gsp/anderson? Temp here has actually dropped back to 34 after getting to 35. Still have a 10mph or so ne wind with heavy mist/drizzle. Hard to see me rising 4 or 5 degrees overnight.

Good post. I have No idea why anyone even looks at snow accumulation maps unless temps start below freezing and you know for sure everything will stick. Over ne ga, the hrrr showed too much sleet. It showed gainesvlle getting 6 hours of it but in reality they only got a little bit during the heavier rates. And it showed sleet making down to here and unless there was a little in the heavier showers, i never saw any. It was pretty obvious it was in error as it showed the max temp above ground getting to near 40 at the time it was showing it and the warm layer was deep. The fv3 over did the snow a bit a little bit but otherwise did an ok job as snow got down to cornelia and surrounding areas for an hour or two. Nam on the other hand failed to show it. Nam was too warm yesterday but in the end was about right as far as the lowest temps went. FV3 was actually a degree or two TOO cold. lol...What makes it worse is the best chance is further to the south AND the rich will get richer as those who got a lot today will get even more. So that means there could be a zone that has been exceptionally screwed and tortured where they watched areas to the north get snow last night/this morning and then watch areas to the south get some tonight/tomorrow morning. In my case, I fear i'm going to be in a situation where it's snowing a couple of counties over while it's dry here. I'd be happy just seeing a little bit falling through the air but will be lucky to even get that.

It looks like it. Across the board the models are colder from 925mb to the surface there. Essentially the models push the cold pool with the wedge to the south. Here is the nam's 925mb showing just that. Also here is the nam's 2 meter temps and as you can see, it has really warm temps over the ne corner/nw upstate. GFS is a few degrees colder and the hrrr is showing temps in the 32 to 34 range. although the gfs/hrrr are colder at the surface, they all show warming above it similar to below. That said, If precip develops and it's sort of widespread, i wonder if that would make it a bit colder than they are showing. the 18z nam was wetter than the 12z and it was a bit colder as a result at 925mb at least. A bit unusual but they have consistently showed this.

Although there is some question about depth of the moisture, Models stubbornly warm the lowest levels over north ga/upstate overnight which is why some of that is shown as rain. despite northeasterly flow, which is a bit baffling to be honest. That said, some of the recent runs are a touch colder. Nam especially seems bizarre, showing temps rising into the upper 30s and even near 40 over the northwest upstate. There could be some weak downslope over far ne ga/nw upstate late but otherwise flow is remains NNE to NE throughout the low levels and if this happens it will surely be a first. I can't recall a single time where the temp starts above freezing already and rises several more degrees during the night with NE winds/flow so i'm curious how this shakes out. HRRR is much colder, especially in the upstate, showing temps staying right where they are now which seems like a no brainer. Models were pretty damn close with temps in the end here...got only to 32.7 here, which is a degree warmer than i thought it would get. So I can't totally discount it. Hopefully Places that were screwed and missed out will get a little something out of it. I would expect i would see some here too but the hrrr is dangerously close to showing most of the precip missing here. naturally.

hmm..not sure why but my last post went missing so here it is again. I'll be honest, i'm having issues with the 3km nam. For starters, it's too warm at the surface. Second, i find it next to impossible to believe there won't be more sleet than it shows over northeast ga where it essentially has none. Never mind it is warmer than even the hrrr at the surface. Third, it seems too warm aloft compared to the hrrr. Here is the 12z 3km nam 6 hour 850mb temp vs the 0z analyzed hrrr at 18z...

I'll be honest, i'm having issues with the 3km nam. For starters, it's too warm at the surface. Second, i find it next to impossible to believe there won't be more sleet than it shows over northeast ga where it essentially has none. Never mind it is warmer than even the hrrr at the surface. Third, it seems too warm aloft compared to the hrrr. Here is the 12z 3km nam 6 hour 850mb temp vs the 0z analyzed hrrr at 18z. So imho, i'd be cautious about it right now imo. The hrrr has done well in the past few winter storms here in ga so i'd put more weight on it right now.

fv3 still showing a changeover to very heavy snow for a few hours down to gainesville. Nam still says no and only shows a change to freezing rain toward sunrise. Hrrr still showing a changeover to heavy sleet. Going to be fascinating to see which model, the fv3 or nam, wins this one.

yeah the hrrr is always...always...too warm in these situations at the surface. With constant rain and the onset of cad, i don't expect any rise in temps across north ga which means by this afternoon the hrrr could end up being about 5 degrees too warm on average by this afternoon in spots. These 3 to 5 degree biases are right right on average in cad. I'm also think they are way too warm sunday night into monday at the surface and 950mb which is in part causing the models to spit out rain instead of snow. What makes it even more unlikely is the fact the models are showing temps rising into the mid to upper 30s at NIGHT with still NE flow. There is some downslope warming possible over parts of far north of ga but for everywhere else I'd be truly shocked if that happened. So don't be surprised if that is snow instead of rain monday in a lot of places.

a note on the 3km and 12km nam, currently it's running on average about 3 degrees too warm right now here in georgia and in a lot of areas seeing rain. If it held this average error into tonight, temps would get to freezing in gainesville/85 corridor between 0z and 03z where it gets these areas down to 34 by 03z.

Local temps are as low as 33 at sky valley and 38 at the dot station in clayton currently which is about where they should be. I haven't seen anything that has changed that would lead me to believe your changeover wouldn't be around mid day to early afternoon.

Well it's certainly by no means a lock and the chances are based on the fv3 and euro mainly...nam says no and the hrrr says it's sleet (or maybe some snow mixed in..it's hard to say since i'm near 100% positive it's surface temps are several degrees too warm as is usually the case in these situations and could be throwing it off). If it happens, it would be sometime between 01z/02z and 06z in ga and 09z in sc as the fv3 also brings the warm nose screaming in. it would be nice to see the nam come on board but the 12z run is holding firm.

I wonder if the intense precip rates could offset that warming somewhat or delay it? Speaking of those intense rates, most of the models are now showing enough heavy precip/cooling for a several window of very heavy snow or sleet across ne ga...maybe as far south as athens, before going back to sleet/freezing rain (mainly north of 85 until after 09z) overnight tonight as the warm nose aloft moves in. (just for reference it's all snow/subfreezing at 06z but warms to plus 3c at 750mb on the fv3 near cornelia at 09z). There does appear to be some dynamical cooling at play here with very intense precip rates and cooling occuring at the same time. ...in fact the 06z run it keeps it as sleet for areas like gainesville to hartwell for the duration of the storm after 03z. Would be quite the accumulation of it if that happens. i sure envy the upstate/western nc. The rates are going to be insane.

If i could have i would have took off to clayton again because i think they will do really well but unfortunately there are things going on keeping me from doing it. At any rate, i'd be excited if i was you. It looks like once mixed precip or snow starts mid morning tomorrow it shouldn't stop for a long time and It's just a matter of how much of which....although if that warm nose above 850 isn't as strong as advertised or rates are heavy enough it could very well end up being mostly snow...except the light freezing stuff after the dry air punches in aloft sunday.