Potential December 12th-13th threat

[Rob]

Well I'm no expert in middle Tenn. climo thats for sure. I'm surprised we don't have more mets online from Tennessee, its state with enough big cities and diverse climate. I'll do my best if time permits tonight.

What county are you in?

We have a great online forum here for Tennessee, but we do not have a lot of MET support from surrounding offices on our forum. Looking at wv imagery you can really see this sucker diving. 700rh moisture is pretty stout roating around with several impulses that should drive moderate snow at times.

[FoothillsNC]

0z NAM "SnowDepth" forecast maps from Wright Weather paints a nice stripe of 1-4" snow across just about all of WNC mountains by 7am Sunday. This would be snow with the front.

Those maps a fun to look at. The only thing it means to me is that the 0z NAM was cooler this run and that is confirmed when looking at the AVL sounding versus the previous NAM run. This frontal snow margin is major thin.

I didn't look at soundings but overall it was looking a smidge warmer to me at 850. And did you notice the nice 2" snowfall across most of northern Florida! I felt stupid for even looking at the snow forecast on it. That said, I hope the GFS comes in atleast about like its 12 Z run. Already the winds are turning east and the dwpoints are rising. Mine went from 25 to 30 in the last 2 hours, wiht the temp rising as well...I know the wetbulbs will bottom out in the mountains at some point. LIke another poster said , it could be a rain to sleet to snow, to mix to rain back to snow scenario there. The nam did up its qpf near Asheville.

[AirNelson39]

Great write up! And sounds like a reasonable logic to me

Hi Carver's (love the Gap, Roan High Bluff and the Balds, btw). I'm a land surveyor in Kingsport. Everyone at my office refers to this as the "Eastman Dome" effect. For those who don't know, Kingsport is home to the Tennessee Eastman Company which is a huge chemical plant (I believe it currently employs over 8000 folks). We've always figured that the amount of super heated steam Eastman puts in the air contributes to the lack of snow Kingsport tends to get when compared to the surrounding region. I live in Church Hill and we normally get worse weather than Kingsport even though we're at a lower elevation. It might be a conincidence, but it sounds good anyway.

Longtime lurker/first time poster, btw. My daughter (Sophomore in HS) wants to become a Meteorologist and I've always been interested in weather. Working outside for the last 20 years of my life has given me an even greater interest in the forecast. Of course much of what y'all post is Greek to me but I do enjoy the hard work and information that you all share. Thank you!

Doing the Surveyor Snow Dance here in NE TN...

[MotoWeatherman]

I didn't look at soundings but overall it was looking a smidge warmer to me at 850. And did you notice the nice 2" snowfall across most of northern Florida! I felt stupid for even looking at the snow forecast on it. That said, I hope the GFS comes in atleast about like its 12 Z run. Already the winds are turning east and the dwpoints are rising. Mine went from 25 to 30 in the last 2 hours, wiht the temp rising as well...I know the wetbulbs will bottom out in the mountains at some point. LIke another poster said , it could be a rain to sleet to snow, to mix to rain back to snow scenario there. The nam did up its qpf near Asheville.

I didn't see the Florida thing. What run was that from and what hour?

Here is AVL sounding at 6z per the new 0z NAM. Almost a complete wetbulb snow sounding. I was going off my memory of the previous run and for some reason I thought the previous run sounding was warmer. I did notice when looking at the Wright Weather southeast close up maps the NAM did pop some pockets of zero 850 along the WNC mtns at different spots between 6z and 12z. I didn't notice any of those pockets from the previous run. Those details don't show up on the NCEP maps but they do on the Wright Weather Southeast maps.

Date: 6 hour NAM valid 6Z SUN 12 DEC 10
Station: Kavl
Latitude:   35.43
Longitude: -82.55
-------------------------------------------------------------------------------
LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W
    mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg
-------------------------------------------------------------------------------
 0 1000    68                                                                 
 1  975   274                                                                 
 2  950   485                                                                 
 3  925   700                                                                 
SFC  920   743   2.1  -4.0  64  6.1  -0.4 110   7 281.8 282.4 276.9 290.6  3.07
 5  900   922   1.6  -3.4  69  5.0  -0.4 136  19 283.2 283.8 277.9 292.6  3.31
 6  875  1148   1.5                      146  26 285.3                        
 7  850  1382   2.1  -4.8  60  6.9  -0.7 156  31 288.4 288.9 280.3 297.5  3.15
 8  825  1623   2.6                      168  34 291.3                        
 9  800  1872   2.4  -2.4  71  4.8   0.3 180  36 293.7 294.4 283.6 305.5  4.01
10  775  2128   1.9                      189  40 295.9                        
11  750  2393   0.7  -0.8  90  1.5  -0.0 196  42 297.3 298.2 285.9 311.6  4.81
12  725  2664  -0.9                      200  44 298.4                        
13  700  2943  -2.4  -3.3  94  0.9  -2.8 204  45 299.8 300.6 286.3 312.7  4.29
14  675  3232  -3.3                      208  46 301.9                        
15  650  3530  -4.7  -6.9  85  2.2  -5.6 211  49 303.7 304.3 286.9 314.5  3.52
16  625  3837  -6.5                      212  49 305.0                        
17  600  4155  -8.7 -11.2  82  2.4  -9.6 211  48 306.0 306.5 286.9 314.5  2.71
18  575  4483 -10.9                      211  47 307.2                        
19  550  4823 -13.1 -15.2  84  2.1 -13.8 210  47 308.5 308.9 287.2 315.4  2.13
20  525  5176 -15.5                      211  47 309.8                        
21  500  5543 -18.0 -19.9  85  1.9 -18.5 212  48 311.1 311.4 287.5 316.3  1.58
22  475  5924 -20.6                      214  49 312.5                        
23  450  6321 -23.5 -25.2  86  1.7 -23.9 214  52 313.7 313.9 287.9 317.3  1.09

[FoothillsNC]

I didn't see the Florida thing. What run was that from and what hour?

Here is AVL sounding at 6z per the new 0z NAM. Almost a complete wetbulb snow sounding. I was going off my memory of the previous run and for some reason I thought the previous run sounding was warmer. I did notice when looking at the Wright Weather southeast close up maps the NAM did pop some pockets of zero 850 along the WNC mtns at different spots between 6z and 12z. I didn't notice any of those pockets from the previous run. Those details don't show up on the NCEP maps but they do on the Wright Weather Southeast maps.

Date: 6 hour NAM valid 6Z SUN 12 DEC 10
Station: Kavl
Latitude:   35.43
Longitude: -82.55
-------------------------------------------------------------------------------
LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W
	mb 	m 	C 	C    %   C 	C  deg knt   K 	K 	K 	K    g/kg
-------------------------------------------------------------------------------
 0 1000    68                                                             	
 1  975   274                                                             	
 2  950   485                                                             	
 3  925   700                                                             	
SFC  920   743   2.1  -4.0  64  6.1  -0.4 110   7 281.8 282.4 276.9 290.6  3.07
 5  900   922   1.6  -3.4  69  5.0  -0.4 136  19 283.2 283.8 277.9 292.6  3.31
 6  875  1148   1.5                      146  26 285.3                        
 7  850  1382   2.1  -4.8  60  6.9  -0.7 156  31 288.4 288.9 280.3 297.5  3.15
 8  825  1623   2.6                      168  34 291.3                        
 9  800  1872   2.4  -2.4  71  4.8   0.3 180  36 293.7 294.4 283.6 305.5  4.01
10  775  2128   1.9                      189  40 295.9                        
11  750  2393   0.7  -0.8  90  1.5  -0.0 196  42 297.3 298.2 285.9 311.6  4.81
12  725  2664  -0.9                      200  44 298.4                        
13  700  2943  -2.4  -3.3  94  0.9  -2.8 204  45 299.8 300.6 286.3 312.7  4.29
14  675  3232  -3.3                      208  46 301.9                        
15  650  3530  -4.7  -6.9  85  2.2  -5.6 211  49 303.7 304.3 286.9 314.5  3.52
16  625  3837  -6.5                      212  49 305.0                        
17  600  4155  -8.7 -11.2  82  2.4  -9.6 211  48 306.0 306.5 286.9 314.5  2.71
18  575  4483 -10.9                      211  47 307.2                        
19  550  4823 -13.1 -15.2  84  2.1 -13.8 210  47 308.5 308.9 287.2 315.4  2.13
20  525  5176 -15.5                      211  47 309.8                        
21  500  5543 -18.0 -19.9  85  1.9 -18.5 212  48 311.1 311.4 287.5 316.3  1.58
22  475  5924 -20.6                      214  49 312.5                        
23  450  6321 -23.5 -25.2  86  1.7 -23.9 214  52 313.7 313.9 287.9 317.3  1.09

well now I'm confused because those pockets did n't show up for me in WNC on this run, but did on the previous runs, if I recall. I may have to clear my cache, but since I never view snow maps, I don't that that was an error in the Fl. snow. I'lll look again. Also had Alabama with 8" around Montgomery or that area.

[FoothillsNC]

the latest RUC has all snow in western NC. It starts around midnight far SW NC, and then by 2 am has ne GA in snow, andby 3:00 am has most all of western NC and extreme n. Central to Ne GA in snow , ends it around 12Z.. I can't say I follow it that much but was just viewing a some stuff I rarely have time to watch.

[NEGa]

the latest RUC has all snow in western NC. It starts around midnight far SW NC, and then by 2 am has ne GA in snow, andby 3:00 am has most all of western NC and extreme n. Central to Ne GA in snow , ends it around 12Z.. I can't say I follow it that much but was just viewing a some stuff I rarely have time to watch.

great. thanks man. so i can blame you for staying up late for rain now all day the models have been showing ne ga right on the line and it continues at least its interesting and something to watch. although as soon as i make my rain post i will go to bed

i cant remember for sure (this was last winter, after all) but i think once a storm started the ruc did a good job with the 'phantom' precip that a lot of n ga would get that didnt show up on radar.

[FoothillsNC]

great. thanks man. so i can blame you for staying up late for rain now all day the models have been showing ne ga right on the line and it continues at least its interesting and something to watch. although as soon as i make my rain post i will go to bed

and soon as you hit the hey, the transition occurs, then you wake up and its over, sun coming out. Seriously, your so close its not funny. I'd hate to be at 32.5 with getting 3/4 an inch of rain, but thats a very good possibility. Another possibility is wetbulbing at 31 or so and still have rain or mix, not snow. And of course one more is that its just cold enough to snow, which is too close to say for sure. But several runs of the models had the northern tier of counties esp. near blairsville to Mountain City to Blue Ridge with a chance atleast . Almost certain to start as snow and about 2 hours before any transition , if any. Meant start as rain.

[MotoWeatherman]

well now I'm confused because those pockets did n't show up for me in WNC on this run, but did on the previous runs, if I recall. I may have to clear my cache, but since I never view snow maps, I don't that that was an error in the Fl. snow. I'lll look again. Also had Alabama with 8" around Montgomery or that area.

Here is a cut of the new NAM at 6z. At 9z that zero blob expands up the MTNs.

[NEGa]

and soon as you hit the hey, the transition occurs, then you wake up and its over, sun coming out. Seriously, your so close its not funny. I'd hate to be at 32.5 with getting 3/4 an inch of rain, but thats a very good possibility. Another possibility is wetbulbing at 31 or so and still have rain or mix, not snow. And of course one more is that its just cold enough to snow, which is too close to say for sure. But several runs of the models had the northern tier of counties esp. near blairsville to Mountain City to Blue Ridge with a chance atleast . Almost certain to start as snow and about 2 hours before any transition , if any.

lolol i was wondering if anyone would pick up on that of course i cant go to sleep just when the rain starts, i have to wait for the temps/dewpoints to do their thing...and end up at 32.5 THEN go to bed although seriously yes, the temps/dewpoints etc. are just right this close >< so even if its a cold rain, i might see a few flakes or some sleet mixed in.

hopefully the moisture tomorrow afternoon will overcome the downsloping and flakes will be a flying. the temp is down to 38.5 with a dewpoint of 23

[FoothillsNC]

Here is a cut of the new NAM at 6z. At 9z that zero blob expands up the MTNs.

well I looked again at SV and didnt' see it and still don't on the Plymouth site. Thats for 6z? valid time.

[NEGa]

friend just texted on the other side of town..sleet! going out to investigate.

[FoothillsNC]

Here is a cut of the new NAM at 6z. At 9z that zero blob expands up the MTNs.

thats weird b/c I'm using 1 degree increments and it didnt' show up on 6z but does on the 9z.

[MotoWeatherman]

well I looked again at SV and didnt' see it and still don't on the Plymouth site. Thats for 6z? valid time.

Yes...0z NAM at hour 6 which is 6z Sunday. Who knows?? It's from Wright Weather so not sure how they pull their maps versus other providers.

[NEGa]

nothing here yet, but its sleeting 5 miles away. foothills, i am liking that map

[FoothillsNC]

nothing here yet, but its sleeting 5 miles away. foothills, i am liking that map

well I'm hoping for you friend. You have a decent shot, I remember last March you overperformed in a good way (while I was mostly rain and mid 30's all day). A little elevation can really help. Lets see what the GFS says. I honestly like its resolution better than the nam, and its actually outperformed it too lately.

[HurricaneTracker]

the latest RUC has all snow in western NC. It starts around midnight far SW NC, and then by 2 am has ne GA in snow, andby 3:00 am has most all of western NC and extreme n. Central to Ne GA in snow , ends it around 12Z.. I can't say I follow it that much but was just viewing a some stuff I rarely have time to watch.

Not sure I see what you are seeing. The 02Z run of the RUC has a rain or freezing rain sounding for much of the night and doesn't sufficiently cool the intense warm nose it advertises until almost 12Z Sunday. Ii don't need 0.75" of freezing rain...

[NEGa]

well I'm hoping for you friend. You have a decent shot, I remember last March you overperformed in a good way (while I was mostly rain and mid 30's all day). A little elevation can really help. Lets see what the GFS says. I honestly like its resolution better than the nam, and its actually outperformed it too lately.

thanks, and yes just the little elevation here can make a huge difference, as i have discovered, over the past going on 8-years back in ga. hopefully you get in on the action too (the forecast low right now is mid 30s). looks like those echos moving into the upstate are sleet

and yeah, i feel bad with todays weenieism after last march lol..but hey that was LAST winter! this is a new one so bring it on

the gfs has done better with temps here during these cold snaps, i believe. hopefully i can give a good report, along with rosie and dawsonwx, and we can send it on over to the carolinas

[DCMetroWinston]

how are you defining western nc, just the mountains, or the western piedmont too?

[NEGa]

how are you defining western nc, just the mountains, or the western piedmont too?

not sure who this is directed to, but i imagine if you are referring to snow in western nc, it will mostly be in the mtns (for tonight, at least)

[phil882]

the latest RUC has all snow in western NC. It starts around midnight far SW NC, and then by 2 am has ne GA in snow, andby 3:00 am has most all of western NC and extreme n. Central to Ne GA in snow , ends it around 12Z.. I can't say I follow it that much but was just viewing a some stuff I rarely have time to watch.

Maybe this is not the latest RUC, but it still seems like its a tad above freezing even at 11z

thats weird b/c I'm using 1 degree increments and it didnt' show up on 6z but does on the 9z.

Yea Plymouth does some sort of weird resolution increase in the in-between 3 hour intervals. The normal 6 12 and 18 hour periods are normal resolution, but for 3, 9, 15 hour periods the resolution is increased.

[MotoWeatherman]

how are you defining western nc, just the mountains, or the western piedmont too?

I've been referring to the mountains. I'm sure most of the others have too.

[FoothillsNC]

Not sure I see what you are seeing. The 02Z run of the RUC has a rain or freezing rain sounding for much of the night and doesn't sufficiently cool the intense warm nose it advertises until almost 12Z Sunday. Ii don't need 0.75" of freezing rain...

I was looking strictly at the winter precip animaton on wright weather. It was solid blue.

how are you defining western nc, just the mountains, or the western piedmont too?

WNC I usually mean mountains only, not foothills or western Piedmont, generallly speaking.

the new 00Z GFS is about the same, maybe an hour or 2 slower overall, and a fewmiles further north with the 5H over KY now midday tomorrow, instead of Nashville. It doesn't drop snow shower to ATL but right to the nw suburbs. However, BHM does get into it. For WNC, still has pockets of 0 at 850 scattered and keeps it there I thinkthe 6z frame was pretty large, so the bottom line to take away is its still the same tough call. It did drop over .50" , it keeps expanding over WNC now most of WNC is above .50" qpf, and northern GA has over .75". Also the 2m temps are right at freezing over several pockets of extreme NE Ga to sw NC and again nw NC. Its really splitting degrees by fractions now. I guess the bottom line is different places could come out with different stories. I tend to think most of WNC ends up with a greater than 50/50 chance of mostly snow on the front side, but no guarantee....could be slop/mix. Really the same for extreme NE GA. Also, if it isnt' snow, ZR could be the problem. I'm sure it will occur in some deeper valleys.

[FoothillsNC]

Yea Plymouth does some sort of weird resolution increase in the in-between 3 hour intervals. The normal 6 12 and 18 hour periods are normal resolution, but for 3, 9, 15 hour periods the resolution is increased.

Thanks, I didn't know that. I'm not positive which version of the RUC i was looking it, just assumed it was the latest animation.

[MotoWeatherman]

I was looking strictly at the winter precip animaton on wright weather. It was solid blue.

WNC I usually mean mountains only, not foothills or western Piedmont, generallly speaking.

the new 00Z GFS is about the same, maybe an hour or 2 slower overall, and a fewmiles further north with the 5H over KY now midday tomorrow, instead of Nashville. It doesn't drop snow shower to ATL but right to the nw suburbs. However, BHM does get into it. For WNC, still has pockets of 0 at 850 scattered and keeps it there I thinkthe 6z frame was pretty large, so the bottom line to take away is its still the same tough call. It did drop over .50" , it keeps expanding over WNC now most of WNC is above .50" qpf, and northern GA has over .75". Also the 2m temps are right at freezing over several pockets of extreme NE Ga to sw NC and again nw NC. Its really splitting degrees by fractions now. I guess the bottom line is different places could come out with different stories. I tend to think most of WNC ends up with a greater than 50/50 chance of mostly snow on the front side, but no guarantee....could be slop/mix. Really the same for extreme NE GA. Also, if it isnt' snow, ZR could be the problem. I'm sure it will occur in some deeper valleys.

I agree Robert. The Wright weather GFS maps for 6z and 9z for 850mb look almost identical to the new NAM with the zero pockets. Well this is just a few hours away so we shall know real soon.

[NCSNOW]

oz gfs looks more hopefull for NC northern counties/ southern VA to catch some wrap around flurries/snow showers Sunday night.

[Carvers Gap]

Unless I'm missing something, the 0z GFS is showing the northern TN Valley getting into the upslope action as well as the mountains, which get clocked. Verbatim, maybe 2-4 inches in the northern Valley. The NAM is much less bullish. Nonetheless, it would be great to see some snow falling in that wind...I'm still iffy on this due to missing out many times in the past w/ upslope events.

[tnweathernut]

Unless I'm missing something, the 0z GFS is showing the northern TN Valley getting into the upslope action as well as the mountains, which get clocked. Verbatim, maybe 2-4 inches in the northern Valley. The NAM is much less bullish. Nonetheless, it would be great to see some snow falling in that wind...I'm still iffy on this due to missing out many times in the past w/ upslope events.

not sure I follow, that's been forecasted for a couple of days now. 2 inches seems likely IMO. .

[MotoWeatherman]

Unless I'm missing something, the 0z GFS is showing the northern TN Valley getting into the upslope action as well as the mountains, which get clocked. Verbatim, maybe 2-4 inches in the northern Valley. The NAM is much less bullish. Nonetheless, it would be great to see some snow falling in that wind...I'm still iffy on this due to missing out many times in the past w/ upslope events.

This isn't just an upslope event for you. You will benefit from the wrap around the upper low providing much more moisture than is normally seen with just a frontal passage upslope event.

[FoothillsNC]

This isn't just an upslope event for you. You will benefit from the wrap around the upper low providing much more moisture than is normally seen with just a frontal passage upslope event.

I agree. East central Tn and north and east of there will have an added bonus this go round. All this precip is from the GFS after 12Z Sun, which from the Apps, west, should be snow. Its actually pretty high for the GFS, which is kinda low usualy. Also, the ratios will be higher than normal, so several inches is a good bet.