Potential December 12th-13th threat

[MotoWeatherman]

LOL....12z GFS has 999mb low over Asheville on 12z Sunday and it's the only low.

Which of course translates to much more snow over TN and better snow shower chances across north Alabama and Georgia Sunday.

[SBUWX23]

What are the surface winds showing in this time period for you?

It is giving my area slight wnw around 5...

Would like to know about past events that had snow upfront then a massive cold outbreak after-wards. I assume this has happened before?

The infamous Jan 25, 2000 brought down historic cold for NC I know BUT it was rather cold before the system anyway. NO I am not saying this is happening again.

[Local Yokel Wx]

Regardless of the snow chances we have based on the track of the low, there is little arguement that the mtns will see an amazing Upslope flow event. Perhaps more so than this past one. The ratios will be insane and the wind as well. Perhaps a trip to my friends house in Avery is in order Monday night to catch some nice x country skiing Tuesday.

Sometimes I wish my job was to chase snow b/c if I keep taking days off from work for it it might as well be!

[strongwxnc]

Takes me 1 hour to get from mby to the Avery county line up 221....

Just make make that trip....

Regardless of the snow chances we have based on the track of the low, there is little arguement that the mtns will see an amazing Upslope flow event. Perhaps more so than this past one. The ratios will be insane and the wind as well. Perhaps a trip to my friends house in Avery is in order Monday night to catch some nice x country skiing Tuesday.

Sometimes I wish my job was to chase snow b/c if I keep taking days off from work for it it might as well be!

[Brick Tamland]

Why would anyone want a miserable cold if there is no precip around? I dont get it.

I agree. Nothing exciting about this, just a higher power bill.

[MotoWeatherman]

GFS sounding for Atlanta GA for 7pm Sunday. Enough moisture for snow showers. For entertainment purposes only of course as we have a long way to go.

Date: 4.5 day GFS valid 0Z MON 13 DEC 10
Station: Katl
Latitude:   33.65
Longitude: -84.42
-------------------------------------------------------------------------------
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    80                                                             	
SFC  977   270  -0.1  -1.5  90  1.4  -0.6 304  19 274.9 275.5 273.8 284.5  3.51
 2  950   491  -1.5  -2.6  92  1.1  -1.9 313  39 275.7 276.2 273.9 284.8  3.31
 3  850  1369  -5.4  -7.5  85  2.1  -6.1 340  53 280.5 280.9 275.5 287.7  2.55
 4  800  1843  -7.0  -9.4  83  2.4  -7.8 339  48 283.7 284.1 276.9 290.5  2.34
 5  750  2345  -9.3 -11.7  83  2.4 -10.1 337  44 286.5 286.8 277.9 292.6  2.08
 6  700  2875 -12.8 -14.4  87  1.7 -13.2 334  41 288.3 288.6 278.4 293.6  1.78
 7  650  3437 -15.4 -18.4  77  3.1 -16.1 326  38 291.6 291.8 279.4 295.8  1.37
 8  600  4037 -19.3 -22.3  76  3.1 -19.9 324  36 293.8 294.0 280.1 297.2  1.06
 9  550  4678 -24.0 -26.4  80  2.5 -24.4 323  31 295.7 295.8 280.6 298.2  0.80
10  500  5366 -29.6 -32.3  77  2.7 -29.9 321  27 297.0 297.0 280.7 298.6  0.51
11  450  6107 -35.8 -39.1  72  3.3 -36.0 317  19 298.3 298.3 281.0 299.3  0.29

[Marion_NC_WX]

What are the surface winds showing in this time period for you?

It is giving my area slight wnw around 5...

During the peak of the rainfall Sunday Morning the winds are calm at 10M but howling SSW 36 at 850mb.

The winds at the surface and 850 turn WNW around 15z and then howling northwest after 21z Sunday. Infact the 850 winds at 21z Sunday are 70 mph. The winds at the surface and 850 stay true northwest through Tuesday morning with surface winds between 15-25 mph the whole time. Monday's 8 degree temp will be accompanied with 18 mph winds.

[MotoWeatherman]

Congrats Knoxville at 7pm Sunday. Plenty of moisture in that sounding. This will likely change many times before Sunday...

Date: 4.5 day GFS valid 0Z MON 13 DEC 10
Station: Ktys
Latitude:   35.82
Longitude: -83.98
-------------------------------------------------------------------------------
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    82                                                                 
SFC  960   407  -2.2  -2.5  98  0.3  -2.3 317  10 274.1 274.7 272.9 283.1  3.30
 2  950   491  -2.7  -3.4  95  0.7  -3.0 323  19 274.5 275.0 272.9 283.0  3.13
 3  850  1363  -7.6  -8.4  94  0.7  -7.9 350  41 278.2 278.6 273.9 284.9  2.39
 4  800  1834  -9.1  -9.9  94  0.8  -9.3 351  39 281.5 281.9 275.6 287.9  2.25
 5  750  2331 -11.5 -12.1  95  0.6 -11.6 347  38 284.1 284.5 276.6 290.0  2.01
 6  700  2857 -14.9 -15.2  98  0.3 -15.0 344  37 286.0 286.3 277.2 291.0  1.68
 7  650  3414 -17.5 -17.7  98  0.2 -17.5 340  37 289.2 289.5 278.4 293.6  1.46
 8  600  4011 -20.1 -20.4  97  0.4 -20.1 334  36 292.9 293.1 279.9 296.8  1.25
 9  550  4651 -24.2 -24.9  95  0.6 -24.4 330  35 295.3 295.5 280.6 298.2  0.93
10  500  5338 -29.3 -31.1  84  1.8 -29.6 325  35 297.3 297.4 281.0 299.1  0.57
11  450  6081 -35.6 -37.1  86  1.5 -35.7 316  31 298.5 298.6 281.2 299.7  0.35

[DaculaWeather]

Just keep us on top of the Atlanta stuff! Thanks!

[John1122]

Things have definitely taken a positive turn over the last 24 hours, this 12z is pretty spectacular for a large section of Tennessee. Almost the entire state would see snow cover at the same time. It's a rare storm that pulls that off.

[Gastonwxman]

Couple of interesting things I've gathered. First is the GENS model (not sure how useful this one is). Go under the 6hr. precip. section and hrs. 84-126.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gens/06/model_m.shtml

And here's the UKMET if anyone is just curious:

http://www.meteo.psu.edu/~gadomski/UKHEMI_0z/ukloop.html

[Local Yokel Wx]

Takes me 1 hour to get from mby to the Avery county line up 221....

Just make make that trip....

Takes me about 2 hrs to Linville from Cullowhee. I take the exit after Old Fort coming over Black Mtn and a few shortcuts later Im a 1/3 of the way up 221. Screw 181 for snow as it becomes sketch after a certain while. Im 2/2 this year and looking to make my snow chase record 3/3 Monday night into Tuesday!

[Mr Bob]

Dr No seems to be of the mindset that TN will mainly see snow showers; inclined to go with that over the GFS at this point (don't I always)...however, the cold will be brutal...going to be lucky to get much above 20 on Monday in most of eastern and central TN...I wish it were August again if it is not going to snow.

[tnweathernut]

LOL....12z GFS has 999mb low over Asheville on 12z Sunday and it's the only low.

Which of course translates to much more snow over TN and better snow shower chances across north Alabama and Georgia Sunday.

Euro at 96 (same time frame).................. has a 996 low over northeast indiana

[dalejr88]

Euro at 96 (same time frame).................. has a 996 low over northeast indiana

This models are a joke. If i had to pick one i would flip coins. lol

[dalejr88]

This models are a joke. If i had to pick one i would flip coins. lol

12z UKMET is much further east then the 12z EURO. Agreement just isn't there right now.

[WeatherNC]

Best bet is to split the difference between the two models at this point... 12z ECMWF has support, namely from our friends in Canada. GFS also has support, from our friends in the UK. Split the difference and you end up with a TN Valley to NE track, which really has not changed much over the past 48hrs given the general consensus.

12z GFS members 108hrs

[SBUWX23]

12z ECM is much colder than the 12z GFS also the beginning of next week.

[Nomad]

As much as I'm going to get called a weenie for saying this, I think it'll end up closer to the GFS (between GFS/Euro, but much closer to GFS). It looks like it has ensemble support and UK support. If I remember correctly, the Euro can at times be a little too phase-happy which is why we have vastly different solutions on the table (confirmation?). I'm not familiar with the Canadian model and its biases...

[Amos83]

Best bet is to split the difference between the two models at this point... 12z ECMWF has support, namely from our friends in Canada. GFS also has support, from our friends in the UK. Split the difference and you end up with a TN Valley to NE track, which really has not changed much over the past 48hrs given the general consensus.

12z GFS members 108hrs

Well you know what they say about Canada..... the best thing to come from there is ice

[Mr Bob]

This models are a joke. If i had to pick one i would flip coins. lol

Good insight...Thanks.

[Jon]

NWS RAH mentions backside snow for the first time today in their 1:30PM AFD...obvisouly paying attention to the model inconsitancy and showing the possibility of wintry precip east of the mountains in NC.

.LONG TERM /SATURDAY THROUGH THROUGH WEDNESDAY/...

-- Changed Discussion --AS OF 130 PM WEDNESDAY...

THE SURFACE HIGH DOMINATING THIS WEEKS WEATHER MOVES OFFSHORE EARLY

THIS WEEKEND. IT HAS BEEN NOTED THAT SOUTHERLY FLOW AHEAD OF AN

APPROACHING COLD FRONT WILL OFTEN CAUSE MODELS TO UNDER-FORECAST THE

OVERNIGHT MIN TEMPS. LOOKS LIKE A GOOD POSSIBILITY OF THIS OCCURING

ON SATURDAY NIGHT WITH H85 WINDS STRENGTHENING TO >50KTS WITH A 15

METER RISE IN LOW LEVEL THICKNESSES. AS SUCH...WILL BUMP THE MINS UP

INTO THE UPPER 30S TO LOWER 40S.

MEANWHILE...THERE IS DECENT MODEL CONSENSUS ON THE GENERAL FLAVOR OF

THE SYSTEM PROGGED TO WIND UP ALONG THE ATLANTIC SEABOARD THIS

WEEKEND...WITH A SUNDAY FROPA ON TAP FOR CENTRAL NC. THERE IS AROUND

A 6 HOUR MODEL TIMING ISSUE...HOWEVER...WITH THE GFS PROVIDING THE

FASTER SOLUTION WHICH HAS THE SURFACE FRONT EXITING THE COAST AROUND

SUNSET. SEE NO REASON TO QUIBBLE WITH THE ONGOING FORECAST WHICH HAS

LIKELY POPS COVERING THE 12Z-00Z TIME FRAME SUNDAY. FINE TUNING THE

WEST-EAST TIMING CAN BE DONE IN LATER ISSUANCES. WILL RAISE THE

INITIAL POPS IN THE WEST SATURDAY NIGHT TO CHANCE CATEGORY GIVEN THE

STRENGTH OF THE LOW LEVEL FLOW AND RAPID FRONTAL PROGRESSION. HIGHS

SUNDAY WILL SHOW A STRONG WEST TO EAST GRADIENT AS WARM AIR

ADVECTION WILL BE CUT OFF A FEW HOURS EARLIER IN THE WEST...50S WEST

TO LOW 60S EAST.

SUNDAY NIGHT COULD BE PROBLEMATIC DUE TO THE INTENSE COLD AIR

ADVECTION WHICH CRANKS UP CONCURRENT WITH THE NEGATIVELY-TILTING

UPPER SHORT WAVE ROTATING ACROSS THE AREA. CONCEPTUALLY...THIS WOULD

PROVIDE WRAP AROUND PRECIP PERHAPS STARTING AS RAIN SHOWERS BEFORE

CHANGING OVER TO SNOW BEFORE ENDING. ITS NOT REALLY CLEAR JUST HOW

THE FEATURE TIMING WILL SHAKE OUT...HOWEVER...AS THE FAST

PROGRESSION SHOWN BY THE GFS WOULD INITIATE THIS CHANGEOVER ONLY

SHORTLY BEFORE THE MOISTURE IS CHASED OUT. AT THIS POINT...WILL

RAISE POPS IN THE NORTHWEST AND ALONG THE NORTHERN COUNTY TIER IN

THE SUNSET TO MIDNIGHT TIME FRAME...LEAVING PRECIP TYPE AS LIQUID

PENDING LATER MODEL RESOLUTION AND CONSENSUS. MINS WILL RANGE FROM

MID 20S NORTHWEST TO AROUND FREEZING SOUTHEAST.

MONDAY THROUGH WEDNESDAY...AN ARCTIC AIRMASS SETTLES INTO PLACE

ACROSS THE EASTERN CONUS WITH A HIGH AMPLITUDE TROF OFF THE EAST

COAST. WIND CHILLS DURING THE `HEAT` OF THE DAY WILL BE IN THE 20S

AS HIGHS WILL BE IN THE 30S THROUGH THE PERIOD. MINS TUESDAY WILL BE

IN THE UPPER TEENS TO LOW 20S...AND A SURFACE RIDGE AXIS OVER THE

AREA MID WEEK WILL PROMOTE BETTER RADIATION CONDITIONS WEDNESDAY

MORNING...PRODUCING MINS FROM 15 TO 20. THE GFS IS HINTING THAT SOME

UPPER PACIFIC MOISTURE COULD BE RIDING THE JET STREAM SOUTHEAST

ACROSS THE AREA LATER TUESDAY AND TUESDAY NIGHT AND PERHAPS

PROVIDING SOME CLOUD COVERAGE...TOO FAR OUT TO HANG MUCH CONFIDENCE

ON.-- End Changed Discussion --

[FoothillsNC]

the 12z Euro is even further south with its closed lobe, so the anamolies are literally off the charts in the Southeast and Midatlantic. Tuesday the entire state of NC will likely be in the 20's for highs, except possibly ILM area, and of course the mountains with AVL not cracking 20. I'm going for AVL)17 HKY )20 GSO)19 RDU)21 CLT)24 on max temps. Nighttime lows aren't shown to be that extreme, or even colder than this outbreak because of the winds most likely. The wind chills are going to be pretty severe with such a tight gradient and vortex to our north, and with the surface high holding so far back, its a continuous drainage of cold air and wind Monday and Tuesday into Wednesday.

The zero at 850 clears all of Florida except Key West. Also, some sound effect snow in NC is possible.

[SBUWX23]

NWS RAH mentions backside snow for the first time today in their 1:30PM AFD...obvisouly paying attention to the model inconsitancy and showing the possibility of wintry precip east of the mountains in NC.

.LONG TERM /SATURDAY THROUGH THROUGH WEDNESDAY/...

-- Changed Discussion --AS OF 130 PM WEDNESDAY...

THE SURFACE HIGH DOMINATING THIS WEEKS WEATHER MOVES OFFSHORE EARLY

THIS WEEKEND. IT HAS BEEN NOTED THAT SOUTHERLY FLOW AHEAD OF AN

APPROACHING COLD FRONT WILL OFTEN CAUSE MODELS TO UNDER-FORECAST THE

OVERNIGHT MIN TEMPS. LOOKS LIKE A GOOD POSSIBILITY OF THIS OCCURING

ON SATURDAY NIGHT WITH H85 WINDS STRENGTHENING TO >50KTS WITH A 15

METER RISE IN LOW LEVEL THICKNESSES. AS SUCH...WILL BUMP THE MINS UP

INTO THE UPPER 30S TO LOWER 40S.

MEANWHILE...THERE IS DECENT MODEL CONSENSUS ON THE GENERAL FLAVOR OF

THE SYSTEM PROGGED TO WIND UP ALONG THE ATLANTIC SEABOARD THIS

WEEKEND...WITH A SUNDAY FROPA ON TAP FOR CENTRAL NC. THERE IS AROUND

A 6 HOUR MODEL TIMING ISSUE...HOWEVER...WITH THE GFS PROVIDING THE

FASTER SOLUTION WHICH HAS THE SURFACE FRONT EXITING THE COAST AROUND

SUNSET. SEE NO REASON TO QUIBBLE WITH THE ONGOING FORECAST WHICH HAS

LIKELY POPS COVERING THE 12Z-00Z TIME FRAME SUNDAY. FINE TUNING THE

WEST-EAST TIMING CAN BE DONE IN LATER ISSUANCES. WILL RAISE THE

INITIAL POPS IN THE WEST SATURDAY NIGHT TO CHANCE CATEGORY GIVEN THE

STRENGTH OF THE LOW LEVEL FLOW AND RAPID FRONTAL PROGRESSION. HIGHS

SUNDAY WILL SHOW A STRONG WEST TO EAST GRADIENT AS WARM AIR

ADVECTION WILL BE CUT OFF A FEW HOURS EARLIER IN THE WEST...50S WEST

TO LOW 60S EAST.

SUNDAY NIGHT COULD BE PROBLEMATIC DUE TO THE INTENSE COLD AIR

ADVECTION WHICH CRANKS UP CONCURRENT WITH THE NEGATIVELY-TILTING

UPPER SHORT WAVE ROTATING ACROSS THE AREA. CONCEPTUALLY...THIS WOULD

PROVIDE WRAP AROUND PRECIP PERHAPS STARTING AS RAIN SHOWERS BEFORE

CHANGING OVER TO SNOW BEFORE ENDING. ITS NOT REALLY CLEAR JUST HOW

THE FEATURE TIMING WILL SHAKE OUT...HOWEVER...AS THE FAST

PROGRESSION SHOWN BY THE GFS WOULD INITIATE THIS CHANGEOVER ONLY

SHORTLY BEFORE THE MOISTURE IS CHASED OUT. AT THIS POINT...WILL

RAISE POPS IN THE NORTHWEST AND ALONG THE NORTHERN COUNTY TIER IN

THE SUNSET TO MIDNIGHT TIME FRAME...LEAVING PRECIP TYPE AS LIQUID

PENDING LATER MODEL RESOLUTION AND CONSENSUS. MINS WILL RANGE FROM

MID 20S NORTHWEST TO AROUND FREEZING SOUTHEAST.

MONDAY THROUGH WEDNESDAY...AN ARCTIC AIRMASS SETTLES INTO PLACE

ACROSS THE EASTERN CONUS WITH A HIGH AMPLITUDE TROF OFF THE EAST

COAST. WIND CHILLS DURING THE `HEAT` OF THE DAY WILL BE IN THE 20S

AS HIGHS WILL BE IN THE 30S THROUGH THE PERIOD. MINS TUESDAY WILL BE

IN THE UPPER TEENS TO LOW 20S...AND A SURFACE RIDGE AXIS OVER THE

AREA MID WEEK WILL PROMOTE BETTER RADIATION CONDITIONS WEDNESDAY

MORNING...PRODUCING MINS FROM 15 TO 20. THE GFS IS HINTING THAT SOME

UPPER PACIFIC MOISTURE COULD BE RIDING THE JET STREAM SOUTHEAST

ACROSS THE AREA LATER TUESDAY AND TUESDAY NIGHT AND PERHAPS

PROVIDING SOME CLOUD COVERAGE...TOO FAR OUT TO HANG MUCH CONFIDENCE

ON.-- End Changed Discussion --

Little suprised that wind chills only in the 20s and highs in the 30s? Even the GFS on Monday and Tuesday is indicating colder conditions than that. The 12z Euro is colder than the GFS. Seems like there was no credence to the ECM in this portion of the disco. The ECM solution will not have any wrap around snow chance in NC.

[BullCityWx]

Dr No seems to be of the mindset that TN will mainly see snow showers; inclined to go with that over the GFS at this point (don't I always)...however, the cold will be brutal...going to be lucky to get much above 20 on Monday in most of eastern and central TN...I wish it were August again if it is not going to snow.

Euro actually seems more in tune with climatology around here with limited wrap around.

[WeatherNC]

12z recap, GFS, UKMET, GGEM, and ECMWF all valid 12z Sunday

[FoothillsNC]

Little suprised that wind chills only in the 20s and highs in the 30s? Even the GFS on Monday and Tuesday is indicating colder conditions than that. The 12z Euro is colder than the GFS. Seems like there was no credence to the ECM in this portion of the disco. The ECM solution will not have any wrap around snow chance in NC.

"AS HIGHS WILL BE IN THE 30S THROUGH THE PERIOD. MINS TUESDAY WILL BE

IN THE UPPER TEENS TO LOW 20S.."

I don't follow the logic on their forecast for the Monday through Wednesday cold wave. Is this the new discussion? This current cold wave had 2 successive days of highs near freezing in the southern piedmont and 2 mornings of record lows, and some record low "max" temps as well. Not sure about the Raleigh area, but with this next cold outbreak forecasted on both models to be vastly colder than this one at all levels of the atmosphere, makes me wonder why they are going with warmer temperatures than what we just currently had? All guidance is pointing to Mon/Tues as being extremely cold statewide . I'd be surprised to see Raleigh get above 25 either Monday or Tuesday. (certainly no more than freezing) The nighttime lows will be a function of wind and dependent on radiation.

[SBUWX23]

I don't follow the logic on their forecast for the Monday through Wednesday cold wave. Is this the new discussion? This current cold wave had 2 successive days of highs near freezing in the southern piedmont and 2 mornings of record lows, and some record low "max" temps as well. Not sure about the Raleigh area, but with this next cold outbreak forecasted on both models to be vastly colder than this one at all levels of the atmosphere, makes me wonder why they are going with warmer temperatures than what we just currently had? All guidance is pointing to Mon/Tues as being extremely cold statewide . I'd be surprised to see Raleigh get above 25 either Monday or Tuesday. (certainly no more than freezing) The nighttime lows will be a function of wind and dependent on radiation.

This was just updated according to what was posted and I went back and checked last nights long term and its different. Temperatures seem close to GFS MOS guidance and we know thats drived towards climo. Even the GFS which seems warmer to me than the ECM is bringing in much colder air than this last outbreak.

[BullCityWx]

There's litle to no doubt its going to get super cold....when does anyone in the media/NWS plan on forecasting it??? This is the serious kind of cold people have to plan for.

[HKY18]

man the mtns are going to get hammered with upslope after this storm.