Potential December 12th-13th threat

[BullCityWx]

F-ck ZR in the 5 day, we have a MAJOR system to track in the short term that could bring surprises even to your area west of 77...

[FoothillsNC]

0z GFS literally says snow for Asheville at 6z Sunday

And if you back up to 0z Sunday for Asheville this wetbulb is below zero at all levels.

Date: 48 hour GFS valid 0Z SUN 12 DEC 10

Station: Kavl

Nice. Still time to monitor this but for a day or so I noticed the lack or strong warm advection in w NC on this and it brought back a couple memories of when it was supposed to rain ahead of a cold front, but once every few years you get one like this, where its just cold enough by skin of the teeth for wet snow. I recall the 1993 superstorm was dicey for Asheville and called my prof. back in college to ask what it looked like..the concensus just 24 hours away was mostly rain Asheville to start based on soundings and 850 temps witha transition to snow. My own theory is that during radically falling heights, if your in the mountains in an already marginal airmass, then snow can result. We'll see on this one.

[MotoWeatherman]

Bristol TN at 6z Sunday...looks like all snow per this run of the GFS. At least at 6z Sunday that is. At 0z Sunday the moisture is just moving and and by 12z it is long gone before wrap moisture moves in Sunday afternoon.

Date: 54 hour GFS valid 6Z SUN 12 DEC 10
Station: Ktri
Latitude:   36.48
Longitude: -82.40
-------------------------------------------------------------------------------
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    53                                                                 
 1  950   469                                                                 
SFC  945   515   0.3  -1.4  89  1.6  -0.4 197   3 277.9 278.5 275.6 288.0  3.66
 3  850  1363  -0.1  -2.8  82  2.8  -1.2 186  21 286.1 286.7 279.8 296.5  3.64
 4  800  1849   0.3  -1.0  91  1.3  -0.3 205  29 291.5 292.3 283.2 304.4  4.45
 5  750  2366  -0.6  -1.0  97  0.4  -0.8 222  40 295.9 296.8 285.2 309.9  4.73
 6  700  2916  -3.3  -3.8  97  0.5  -3.6 230  49 298.8 299.6 285.8 311.2  4.13
 7  650  3498  -6.8  -7.2  97  0.4  -7.0 233  53 301.3 301.9 285.9 311.7  3.42
 8  600  4119 -10.8 -11.3  96  0.5 -10.9 233  53 303.7 304.2 286.1 312.0  2.69
 9  550  4782 -15.2 -15.8  95  0.6 -15.4 228  52 306.0 306.4 286.2 312.4  2.02
10  500  5495 -20.5 -20.9  97  0.4 -20.6 224  53 308.0 308.3 286.3 312.7  1.44
11  450  6265 -26.3 -26.8  96  0.5 -26.4 221  60 310.1 310.3 286.5 313.3  0.95
12  400  7106 -32.6 -33.0  97  0.3 -32.7 228  76 312.6 312.7 286.9 314.6  0.60

[WeatherNC]

take it you live east of the interstate

[FoothillsNC]

F-ck ZR in the 5 day, we have a MAJOR system to track in the short term that could bring surprises even to your area west of 77...

got to give you kudos for keeping tabs on the data in the Pacific on this one. Already there's been some wild swings on this particular storm track and how it all evolves, and it probably can be traced back there.

[Rob]

Thinking of coming up to the mountains for this one. I could go to Gatlinburg and Hike LeConte and see some pretty wicked snowfall totals but I would rather relax and watch some snow pound down. A bit NE more up the apps would prob be better.... Oh where to go?

[BullCityWx]

take it you live east of the interstate

lol, no I'm west...i just dunno. I hope the cold air can win for once.

[MotoWeatherman]

Nice. Still time to monitor this but for a day or so I noticed the lack or strong warm advection in w NC on this and it brought back a couple memories of when it was supposed to rain ahead of a cold front, but once every few years you get one like this, where its just cold enough by skin of the teeth for wet snow. I recall the 1993 superstorm was dicey for Asheville and called my prof. back in college to ask what it looked like..the concensus just 24 hours away was mostly rain Asheville to start based on soundings and 850 temps witha transition to snow. My own theory is that during radically falling heights, if your in the mountains in an already marginal airmass, then snow can result. We'll see on this one.

I was in class at UCNA that day taking a test Friday afternoon and it started to snow. Talk about a distraction...LOL. At about 4pm I drove from Asheville to Waynesville to Franklin TN to Clayton GA and then home to ATL. It was snowing from AVL all the way to Franklin before it turned to rain.

OK...now back on topic....

[FoothillsNC]

the strong NAO remains through the run. The cold air bisects the nation mostly for a while, with zonal flow, but theres a couple more interesting periods where snow or freezing precip is possible after the Thursday event. Of course the details will change and probably some longwave positions knowing the GFS at those ranges. The one piece of good news is the strong PNA ridge out west and bowl shape trough covering most of the country by the end of the run, if it verifies. Nice possibilites, and not much of a torch for the Southeast on this run. The one thing I'm expecting is going to be a long, sustained cloudy period for the Southern states, starting Wednesday, and probably continuing a while.

[Rob]

I was in class at UCNA that day taking a test Friday afternoon and it started to snow. Talk about a distraction...LOL. At about 4pm I drove from Asheville to Waynesville to Franklin TN to Clayton GA and then home to ATL. It was snowing from AVL all the way to Franklin before it turned to rain.

OK...now back on topic....

I live in Franklin Tn... Well 1 miles from the border. I went to High School there... Not much of a snow belt here unfortunately. Middle Tennessee has really been without over the years.

[FoothillsNC]

lol, no I'm west...i just dunno. I hope the cold air can win for once.

You hoping on the Saturday night/Sun morn? the late week event? I'm thinking we may have a shot at something Wednesday night or Thursday...not too worried about surface temps, but question the amount of moisture that gets in here. A little snow to start would be nice but I know the warm aloft usually wins out here.

[MotoWeatherman]

I live in Franklin Tn... Well 1 miles from the border. I went to High School there... Not much of a snow belt here unfortunately. Middle Tennessee has really been without over the years.

Ooppps...I mean to Type Franklin NC.....sorry..

[SBUWX23]

got to give you kudos for keeping tabs on the data in the Pacific on this one. Already there's been some wild swings on this particular storm track and how it all evolves, and it probably can be traced back there.

Theres a big CSTAR project here in collaboration with several WFOs about the predictability of these types of events and wave packet research is on going at Stony Brook Unviersity as one of my colleagues is writing his thesis on them. Check out this website for some wave packet data.

http://xs1.somas.sto...l/Wave/main.htm

Here is a hovmoller from the 12z run: http://ferrel.msrc.s...y_12Z/plot1.gif

and the envelope analysis http://xs1.somas.stonybrook.edu/~chang/personal/Wave/12hrly_12.htm If you scroll through the run you can see the impact the trough in the Pacific has on our trough in question.

[BullCityWx]

Well this is just terrible all around:

GFSX MOS (MEX)
KAKH   GFSX MOS GUIDANCE  12/10/2010  0000 UTC                       
FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192      
FRI  10| SAT 11| SUN 12| MON 13| TUE 14| WED 15| THU 16| FRI 17 CLIMO
X/N  47| 27  53| 40  48| 19  34| 14  35| 15  45| 30  54| 41  61 32 53
TMP  36| 30  44| 43  34| 20  24| 16  25| 17  36| 32  48| 43  52      
DPT  21| 23  33| 37  18|  9   1|  3   4|  6  13| 24  40| 38  39      
CLD  PC| PC  OV| OV  OV| CL  CL| CL  CL| CL  OV| OV  OV| OV  OV      
WND   2|  2   5|  3  12|  8  13|  4   6|  2   5|  2   4|  2   7      
P12   3|  4  14| 87  47|  5   6|  1   0|  6  17| 32  35| 21  23999999
P24    |     14|     89|      6|      1|     17|     50|     26   999
Q12   0|  0   0|  2   1|  0   0|  0   0|  0   0|  1    |             
Q24    |      0|      3|      0|      0|      0|       |             
T12   0|  0   0|  1   0|  0   0|  0   0|  0   0|  1   1|  1   1      
T24    |  0    |  1    |  2    |  0    |  0    |  1    |  4          
PZP  10| 10   7|  9   3|  6   5|  6   7|  9   9| 22  14| 10   7      
PSN  32| 35   0|  0  34| 80  84| 75  73| 66  53| 21   0|  0   0      
PRS   0|  0   3|  1  22|  0   0|  0   0|  0   7|  0   4|  2   1      
TYP  RS| RS   R|  R  RS|  S   S|  S   S|  S   S|  Z   R|  R   R      
SNW    |      0|      0|      0|      0|      0|       |             

[BullCityWx]

You hoping on the Saturday night/Sun morn? the late week event? I'm thinking we may have a shot at something Wednesday night or Thursday...not too worried about surface temps, but question the amount of moisture that gets in here. A little snow to start would be nice but I know the warm aloft usually wins out here.

Sunday Afternoon is where I have my hopes pinned...I hate looking forward to the next system because thats when it seems I always get burned.

[Blue Ridge]

Foothills, I love your theory about the potential pre-frontal snow. I remember a few events during which this occurred. The last I recall was several years ago; I believe Asheville had a lengthy spell of TSSN.

MRX is obviously sticking with rain-to-snow, but they're just as uncertain as the rest of us:

...A WINTER STORM WILL AFFECT THE REGION THIS WEEKEND INTO EARLY NEXT WEEK...A STRONG LOW PRESSURE SYSTEM IS EXPECTED TO TRACK ACROSS THE GREAT LAKES REGION THIS WEEKEND. RAIN WILL SPREAD ACROSS THE SOUTHERNAPPALACHIANS BEGINNING SATURDAY. A SURGE OF COLD AIR BEHIND A COLD FRONT IS EXPECTED TO CHANGE THE PRECIPITATION TO SNOW LATE SATURDAYNIGHT AND SUNDAY MORNING. A PERSISTENT FLOW OF COLD AIR FROM THE NORTHWEST WILL KEEP SNOW SHOWERS GOING FOR MUCH OF THE AREA THROUGH SUNDAY NIGHT...AND FOR THE HIGHER ELEVATIONS THROUGH MONDAY.THE EXACT TRACK OF THE LOW PRESSURE REMAINS UNCERTAIN...WHICH WILLGREATLY IMPACT SNOWFALL AMOUNTS. SIGNIFICANT SNOW ACCUMULATIONS WILL BE POSSIBLE ACROSS THE SMOKY MOUNTAINS...THE MOUNTAINS OF NORTHEAST TENNESSEE...AND THE HIGHER ELEVATIONS OF SOUTHWEST VIRGINIA. STRONG WINDS IN THE HIGHER ELEVATIONS MAY LEAD TO BLOWINGAND DRIFTING SNOW...AND VERY COLD WIND CHILL VALUES. SOME SNOW IS EXPECTED TO ACCUMULATE IN THE TENNESSEE VALLEY AND CUMBERLAND PLATEAU...WITH AMOUNTS FROM A DUSTING TO SEVERAL INCHES POSSIBLE.

[superjames1992]

Looks like the front clears Charlotte right before kickoff on Sunday...there's going to be some cold people by the end of the game.

Nope, the fans will be warm in their cars on their way home as the Panthers are being blown out. And I'll be at home shaking my head in despair yet another week.

It keeps Greensboro and Winston Salem below 32 through 174 hours. NC is going to be a wreck if moisture does begin to creep in here Wed night and Thursday.

Just in time for my meteorology final exam Thursday morning!

Damn this thread, though. I keep on coming back here even though I should be studying for my Chemistry final exam in eight hours (and I need to go to bed soon). Sometimes, I hate the internet.

[SBUWX23]

Theres a big CSTAR project here in collaboration with several WFOs about the predictability of these types of events and wave packet research is on going at Stony Brook Unviersity as one of my colleagues is writing his thesis on them. Check out this website for some wave packet data.

http://xs1.somas.sto...l/Wave/main.htm

Here is a hovmoller from the 12z run: http://ferrel.msrc.s...y_12Z/plot1.gif

and the envelope analysis http://xs1.somas.sto...e/12hrly_12.htm If you scroll through the run you can see the impact the trough in the Pacific has on our trough in question.

Another thing I want to add is there is targetted sensitivity areas out there and there is a Pacific project where they usually fly into those target areas to see if the data acquired improves predictability. I found out that unfortunately they are flying this event.

[FoothillsNC]

Theres a big CSTAR project here in collaboration with several WFOs about the predictability of these types of events and wave packet research is on going at Stony Brook Unviersity as one of my colleagues is writing his thesis on them. Check out this website for some wave packet data.

http://xs1.somas.sto...l/Wave/main.htm

Here is a hovmoller from the 12z run: http://ferrel.msrc.s...y_12Z/plot1.gif

and the envelope analysis http://xs1.somas.sto...e/12hrly_12.htm If you scroll through the run you can see the impact the trough in the Pacific has on our trough in question.

thanks I'll definitely check that out. Sounds pretty technical.

[SBUWX23]

thanks I'll definitely check that out. Sounds pretty technical.

It is plenty technical but I think these graphics are useful to get a sense on what is happening.

[WeatherNC]

Another thing I want to add is there is targetted sensitivity areas out there and there is a Pacific project where they usually fly into those target areas to see if the data acquired improves predictability. I found out that unfortunately they are flying this event.

Are they? That would seem similar to the project last year in which winter reconnoissance missions were flown in the Pac, but we have not seen confirmation those will be executed this season...

[SBUWX23]

Are they? That would seem similar to the project last year in which winter reconnoissance missions were flown in the Pac, but we have not seen confirmation those will be executed this season...

Im pretty sure they will be doing it this year too.

[Lookout]

Sunday Afternoon is where I have my hopes pinned...I hate looking forward to the next system because thats when it seems I always get burned.

Other than maybe some flurries/snow showers breaking containment, I think the book is about shut on anything significant happening outside the mountains.

Nope, the fans will be warm in their cars on their way home as the Panthers are being blown out.

I've been looking forward to beating the panthers all year. It's almost criminal for the nfl to make us wait this long to do it.

Actually, watch this be the dreaded trap game and we somehow make clausen or whatever his name is look like tom brady. Even if we win, if we don't blow you guys out, my hope about the post season will drop considerably.

[FoothillsNC]

tonights Euro is back to closing off the 516 dm vortex from northern Virginia to western Lakes by 84 hours. Its 2M temps are 30 or below roughly along I-85 in NC to Atl. ..which is slightly warmer than the GFS at this time. The GFS beat it on 2m temps this past outbreak, atleast in NC. The wind and snow are going to be the major story for east Tenn and west NC....excellent powder with blizz. conditions and temps in the teens on the 2M temps during the middle of the day. Not a nice travel day.

[Reb]

tonights Euro is back to closing off the 516 dm vortex from northern Virginia to western Lakes by 84 hours. Its 2M temps are 30 or below roughly along I-85 in NC to Atl. ..which is slightly warmer than the GFS at this time. The GFS beat it on 2m temps this past outbreak, atleast in NC. The wind and snow are going to be the major story for east Tenn and west NC....excellent powder with blizz. conditions and temps in the teens on the 2M temps during the middle of the day. Not a nice travel day.

How confident are you about Knoxville getting these blizzard conditions as well as snow totals? I have to work Monday all day and my job is on the road...Thanks Foothills

[phil882]

The 00Z GFS is one step closer to making this mostly a snow event in the mountains of NC, instead of a rain to snow. Ashevilles heights go from 558 at 48hr, just before precip starts, to 555 at the very start of precip, with 850's extremely close to zero then. By 54 hours, roughly the beginning of the precip the 850's shown are very near zero from crashing heights, and I mean crashing, and evaportive cooling. Also, the 2m shows pockets of freezing temps in western NC. Its a very intriguing setup and will make for good forecasting on this event since its so close. If its a pure snow event, with the extreme divergence ahead of the digging shortwave, and excellent strong lift, obviously the flakes will be falling fast and furious during the overnight Saturday night. One degree difference or a little elevation could make a big difference. The GFS doesn't drop too much qpf , only about .25 to .50" in wnc. Central Tenn gets atleast .75"

0z GFS literally says snow for Asheville at 6z Sunday

Date: 54 hour GFS 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    70                                                         		
 1  950   486                                                         		
SFC  918   764  -1.3  -2.2  93  1.0  -1.7 176   5 278.7 279.3 275.9 288.4  3.53
 3  850  1379  -0.2  -2.0  87  1.8  -0.9 193  25 286.0 286.7 280.0 297.1  3.88
 4  800  1865  -0.1  -1.8  88  1.7  -0.9 205  40 291.0 291.8 282.7 303.2  4.17
 5  750  2382   0.0  -0.3  98  0.3  -0.2 216  50 296.6 297.5 285.8 311.3  4.99
 6  700  2933  -2.8  -3.7  94  0.9  -3.2 222  51 299.4 300.1 286.0 311.9  4.17
 7  650  3517  -6.1  -7.3  91  1.2  -6.6 225  50 302.1 302.7 286.2 312.5  3.40
 8  600  4141  -9.0 -10.9  86  1.9  -9.7 230  52 305.7 306.2 286.9 314.4  2.77
 9  550  4809 -13.4 -14.2  94  0.7 -13.7 238  56 308.1 308.6 287.3 315.6  2.32
10  500  5527 -18.8 -19.3  96  0.4 -19.0 243  57 310.1 310.4 287.2 315.5  1.66
11  450  6302 -25.0 -25.3  98  0.3 -25.0 242  59 311.8 312.0 287.2 315.5  1.09
12  400  7146 -31.8 -32.1  97  0.3 -31.9 241  67 313.6 313.7 287.3 315.8  0.65
13  300  9111 -47.0 -47.2  98  0.2 -47.0 250 106 319.1 319.1 288.6 319.7  0.18

Those soundings are really nice... but BUFKIT shows a different profile for the same 0z run at the same time 6z. Which one is right? This implies a freezing rain / rain threat although with the strong WAA occuring, I'd be inclined to believe this would be mainly rain for the pre-fontal passage event.

Nice. Still time to monitor this but for a day or so I noticed the lack or strong warm advection in w NC on this and it brought back a couple memories of when it was supposed to rain ahead of a cold front, but once every few years you get one like this, where its just cold enough by skin of the teeth for wet snow. I recall the 1993 superstorm was dicey for Asheville and called my prof. back in college to ask what it looked like..the concensus just 24 hours away was mostly rain Asheville to start based on soundings and 850 temps witha transition to snow. My own theory is that during radically falling heights, if your in the mountains in an already marginal airmass, then snow can result. We'll see on this one.

There is some nice WAA occuring though with the very strong southwesterly flow ahead of this system. Notice how the dewpoints rise pretty quickly from 0z to 6z while the temperature fails to drop due to evaporational cooling. This implies some nice WAA allowing the temperatures to stay steady despite the moistening of the profile. The comparison to 1993 is a poor one in my opinion because that storm featured strong northeasterly flow just because the 850mb low passed to the east of WNC. This current system will have strong SW flow at 850mb since the 850mb low is well to the NW of WNC or anywhere in the southeast for that matter. I'm not saying we can't get any snow from the backside of this thing... but in my opinion, despite the questionable soundings, I don't think its very likely that KAVL will be picking up much if any snowfall pre-frontal passage.

How confident are you about Knoxville getting these blizzard conditions as well as snow totals? I have to work Monday all day and my job is on the road...Thanks Foothills

I think the "blizzard conditions" threat will mainly be confined to the higher elevations right along the TN/NC border. Knoxville might get some snowshowers and blustery conditions, but they are unlikely to

[Itunis]

Monday: Sunny and windy, with a high near 28.

Monday Night: Mostly clear, with a low around 15.

Tuesday: Sunny, with a high near 33.

Good work FFC! They dropped the mention of rain/snow for Sunday night, but they are correct that models have really backed off on any wraparound moisture making it south of the mountains. Oh well.

[John1122]

Looking like most of Middle and East Tennessee outside the Mtns will have a 1-3 incher with maybe a few 4 inch reports. The Eastern Mtns will probably pile up another foot or two.

[rosie]

Monday: Sunny and windy, with a high near 28.

Monday Night: Mostly clear, with a low around 15.

Tuesday: Sunny, with a high near 33.

Good work FFC! They dropped the mention of rain/snow for Sunday night, but they are correct that models have really backed off on any wraparound moisture making it south of the mountains. Oh well.

WSB shows snow in my area nearly all day Sun., what a joke!

[DaculaWeather]

FFC's only calling for a low of 34 Saturday night and 40 for a high here on Sunday. WSB might not be too far off for you.