Potential December 12th-13th threat

[Wild Weather Monger]

To the coast?

[NCSNOW]

0z Nam thumps TN and north AL @ 60 and looking good for N GA at 66. Check it out!

[SBUWX23]

0z Nam thumps TN and north AL @ 60 and looking good for N GA at 66. Check it out!

You may want to check the sim radar. The majority of the precip has ended at that time in AL. You have to remember the QPF is a 6-hour ending forecast.

[CandymanColumbusGA]

You may want to check the sim radar. The majority of the precip has ended at that time in AL. You have to remember the QPF is a 6-hour ending forecast.

Exactly SBUWX23... One has to remember the QPF is for the previous 6 hours... So if you want to get a feeling of what it's truly going to be like, look at where the 0C line at 850 is the previous frame and see if the precip has accumulated over THAT area.. If it has, then there is a slight chance of there being winter precip, if not, then mainly rain. Also, you cannot look at just the 850 mb 0C line... the atmosphere is 3D, and just because it's 0C at 850mb doesn't always equate to snow, because there could be a pesky warm nose just above 850mb.... Just something to keep in mind.

Also, I am forecasting mainly a rain event here in Columbus... Yesterday, we did see some flurries (saw them with my own two eyes!) and my chief told me he is thinking up to an inch of snow... not exactly sure where he was getting that thinking, but we MAY see flurries, specially if we have that cloud deck above us, and if it's moist enough at the surface to see a rogue snowflake or two.

[FoothillsNC]

one thing in the back of my mind for the NC mountains Sat night has been the temperature profile. It doesn't look that warm on any model, and if the NAM is more accurate, with its supposedly better resolution grid, then its even closer call than I thought. I know of two instances where a cold front came through and it was heavy wet snow, not rain, for the Mountains (actually one of those included Foothills as well down to near Shelby). Turns out the 850s were just cold enough to be snow, not rain. I'm not going to say that this is the case, but with extremely crashing heights, and this very unusual diggy trough, I wouldn't be surprised in the least to see Boone /Asheville wind up with a slushy mix turning to a thump of heavy snow during the synoptic lift of the this front. Safest bet would still be to call for rain, but I definitely recall seeing 2 major snowstorms during a similar situation , one of which was in 1994, and another was this decade. Both dropped over 6" of beautifuly, heavy laden snow. Crashing heights that are already borderline, funny things happen that shouldn't according to soundings.

Anyway, still a very nice cold plunge during Sunday afternoon. And the lake tap for Upslope snow is very much there, and I would include N. Ga for flurries and snow showers overnight Sun. night and Monday.

[NCSNOW]

You may want to check the sim radar. The majority of the precip has ended at that time in AL. You have to remember the QPF is a 6-hour ending forecast.

I just did. I was watching 500 mb maps. At 60 sitting at neutral and 66 starting to go negative, looked like Gold. Then check of the sims and reality. Still looks like TN /north AL could see some accum snow, if BL issues dont present issues.

[dsaur]

One of the better finds in recent memory Psalm!!! Thanks for sharing and no doubt the most interesting disco thus far on this event. Noted a couple WFO's brushing off the 12z EC yesterday referencing latent heat feedback, not sure of the accuracy in that as I have no clue as to the initialization parameters of the models, and algorithms used to calculate such. For those who do not know what latent heat is, and it's implifications on the physical systems around us, this is a great article explaining the process...

a little less complex then what we learned in P-chem, but for most it should be either a refresher, or basic grasp on the subject

http://www.theweathe...m/habyhints/19/

Wow! Thanks for this. Tony

[weatherfide]

I just did. I was watching 500 mb maps. At 60 sitting at neutral and 66 starting to go negative, looked like Gold. Then check of the sims and reality. Still looks like TN /north AL could see some accum snow, if BL issues dont present issues.

If you check Bufkit for the soundings you will see that all of the rain has moved well east before the temps crash. Snow flurries at best on this one for N. AL/N. GA.

[WeatherNC]

I just did. I was watching 500 mb maps. At 60 sitting at neutral and 66 starting to go negative, looked like Gold. Then check of the sims and reality. Still looks like TN /north AL could see some accum snow, if BL issues dont present issues.

Even though those H5 maps can paint the most accurate depiction of the UL's given the model, it can be deceiving and hard to interpret at times... This is the system,aka as primary H5 packet on IR coming down stream, which is just inside the NAM's "box." Those are -75C tops

Almost looks like someone launched a lateral H-bomb into it on WV, and take into account this is a 185kt 200mb jet progged to come onshore around Puget Sound in 24-36 hrs

images valid 10:30 pm EST

[FoothillsNC]

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"

[lilj4425]

So close yet so far away at hr60 on OzGFS: http://www.nco.ncep....0/fp0_060.shtml

[BullCityWx]

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.

[HKY18]

00z gfs looks close for the mtns and maybe the very western foothills? at hr 60. it looks like mostly rain though.

[FoothillsNC]

the 510thkns line is down to nrn SC on this run by 12Z Mon, most of NC is already to -16 at 850 which is extremely cold, and quite colder than this last wave. Getting the car to start Monday morning is going to be rough, and high temps are going almost nowhere during the day in Ala, Ga Tenn, the Carolinas. This is going to be an amazingly fast crashing of temps, one of the best cold fronts in long time, complete with winds, blizzard conditions on the mountains of Tenn, NC, and subzero wind chills in places.

[Rob]

I am starting to wonder if we will actually see accumulating snow here in Nashville now. Tonights 00Z Gfs once again makes the forecast a bit harder.

[SBUWX23]

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.

And some busted forecasts for Mondays and Tuesdays temperatures

[BullCityWx]

And some busted forecasts for Mondays and Tuesdays temperatures

Yep, sure does appear that way. Oh well, you live with MOS and you die with MOS. It seems like there's many days when thats just useless around here.

Noticed today some ponds are icing over in the countryside here so those temps are going to help out w/that.

[FoothillsNC]

Just wonder if the GFS is going to handle this cold outbreak as well as it did the other, and the 2 big ones from last season. This run is quite a bit colder and usually from 96 hours out is when it had a realistic handle on the 2m temps. Already, the highs are less than freezing from about Orangeburg SC to Columbus GA to just north of Jackson Miss. on Monday, and not much better on Tuesday. Those are high temps. The Tuesday am low gets the freezing line very near Naples Fl, and toward Lake Okachobee. Not quite Miami, but still darn impressive cold wave.

By Wednesday afternoon it has sleet and freezing rain over most of North Georgia including Atlanta, west to n Alabama. A little faster than earlier runs.

[BullCityWx]

Just wonder if the GFS is going to handle this cold outbreak as well as it did the other, and the 2 big ones from last season. This run is quite a bit colder and usually from 96 hours out is when it had a realistic handle on the 2m temps. Already, the highs are less than freezing from about Orangeburg SC to Columbus GA to just north of Jackson Miss. on Monday, and not much better on Tuesday. Those are high temps. The Tuesday am low gets the freezing line very near Naples Fl, and toward Lake Okachobee. Not quite Miami, but still darn impressive cold wave.

By Wednesday afternoon it has sleet and freezing rain over most of North Georgia including Atlanta, west to n Alabama. A little faster than earlier runs.

Just for entertainment purposes..lol..still holding onto a sn sounding at 144:

Date: 6 day AVN valid 0Z THU 16 DEC 10
Station: 35.31,-81.23
Latitude:   35.31
Longitude: -81.23
-------------------------------------------------------------------------------
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   138                                                                 
SFC  986   254  -1.3 -16.0  32 14.7  -5.2 216   6 272.9 273.1 268.7 276.1  1.11
 2  950   548  -1.2 -18.1  26 16.9  -5.6 230  10 275.9 276.1 270.4 278.8  0.96
 3  900   978  -0.9  -9.9  50  9.0  -3.9 251  10 280.6 280.9 274.7 286.3  2.00
 4  850  1436   0.3  -2.3  83  2.6  -0.8 262  18 286.5 287.1 280.2 297.4  3.81
 5  800  1922  -0.2  -1.5  91  1.3  -0.7 278  28 290.9 291.7 282.7 303.4  4.29
 6  750  2438  -1.7  -2.5  94  0.9  -2.1 282  41 294.7 295.5 284.2 307.2  4.23
 7  700  2985  -4.4  -5.0  95  0.6  -4.6 279  51 297.7 298.3 284.9 309.0  3.77
 8  650  3565  -8.0  -8.7  94  0.7  -8.3 276  59 299.9 300.5 285.0 309.2  3.04
 9  600  4185 -10.1 -14.0  73  3.9 -11.3 281  62 304.5 304.9 285.8 311.3  2.17
10  550  4852 -13.1 -17.6  69  4.4 -14.5 288  67 308.5 308.8 286.8 314.2  1.75
11  500  5573 -16.7 -19.1  82  2.4 -17.4 290  74 312.7 313.0 288.2 318.2  1.69
12  450  6359 -20.4 -21.5  91  1.1 -20.7 290  84 317.5 317.8 289.6 322.7  1.52
13  400  7221 -25.8 -27.2  87  1.5 -26.1 290  92 321.5 321.7 290.3 325.1  1.02
14  350  8176 -32.6 -35.5  75  2.9 -33.0 290  96 324.8 324.9 290.8 326.8  0.53
15  300  9242 -41.0 -45.2  64  4.2 -41.3 291  98 327.6 327.6 291.3 328.4  0.23
16  250 10454 -51.3 -54.7  67  3.4 -51.5 292 101 329.7 329.8 291.7 330.1  0.09
17  200 11868 -61.2 -63.9  70  2.7 -61.2 289 102 335.9 335.9 293.3 336.1  0.04
18  150 13632 -64.8 -69.4  53  4.7 -64.8 285  93 358.5 358.5 298.4 358.6  0.02
19  100 16087 -66.5 -78.8  16 12.3 -66.6 280  75 399.3 399.3 305.1 399.3  0.01
TRP                                             0                              
WND                                             0                              

[FoothillsNC]

Yep, sure does appear that way. Oh well, you live with MOS and you die with MOS. It seems like there's many days when thats just useless around here.

Noticed today some ponds are icing over in the countryside here so those temps are going to help out w/that.

This run is back to closeing off the 5H over the Tristate and England...makes a ton of difference on pushing the cold further south. If this run is right then CLT won't go much above 25 on Monday and no higher than 30 on Tuesday. Staying in the teens for Ashevile Monday with a potential blizzard if the upslope makes it there. Boone is no brainer on this. During the last outbreak they had a high of 18, easily going to stay under 15 with this one. Maybe 10 to 12 for a high.

[WeatherNC]

Yep, sure does appear that way. Oh well, you live with MOS and you die with MOS. It seems like there's many days when thats just useless around here.

Noticed today some ponds are icing over in the countryside here so those temps are going to help out w/that.

That is cold! -15C 850's are entrenched in NC for 42 hrs

[BullCityWx]

That is cold! -15C 850's are entrenched in NC for 42 hrs

And that will NOT help if there's freezing rain mid week....talk about a skating rink.

[FoothillsNC]

This run is a fun one to me. I don't know what to call for in the mountains Saturday night and Sunday morning with the frontal passage. Don't know how much upslope to expect (looks like a good tap this run though), the temps are much colder all across the Southeast, the vortex is back to closing off much further south and staying longer, and to top it off..the precip could arrive pretty early for Ala, Ga and western Carolinas as well as Tenn..with cold air on both sides of the mountains. Dont see that very often. Very interesting from all angles.

[Carvers Gap]

Departure from normal for December 2010 @ KTRI: -10.1

...And to think it will be cold again next week. 1989 comes to mind. Let's just hope the rest of the winter doesn't follow suit(like after December 1989). Nonetheless, I'll enjoy it while it lasts.

[MotoWeatherman]

This run is a fun one to me. I don't know what to call for in the mountains Saturday night and Sunday morning with the frontal passage. Don't know how much upslope to expect (looks like a good tap this run though), the temps are much colder all across the Southeast, the vortex is back to closing off much further south and staying longer, and to top it off..the precip could arrive pretty early for Ala, Ga and western Carolinas as well as Tenn..with cold air on both sides of the mountains. Dont see that very often. Very interesting from all angles.

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

[MotoWeatherman]

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
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   125                                                                 
 1  950   543                                                                 
SFC  924   764  -0.1  -5.0  70  4.8  -2.0 151   5 279.2 279.7 275.2 287.3  2.85
 3  850  1438   0.8  -7.1  56  7.8  -2.2 185  20 286.9 287.4 278.9 294.6  2.64
 4  800  1924   0.6 -12.6  36 13.2  -3.8 207  28 291.8 292.2 280.1 297.3  1.82
 5  750  2442   0.0 -11.3  42 11.4  -4.1 224  34 296.6 297.0 282.7 303.2  2.14
 6  700  2992  -2.1 -11.4  49  9.2  -5.5 237  36 300.1 300.5 284.2 307.2  2.29
 7  650  3577  -6.0 -11.0  68  5.0  -7.9 241  39 302.1 302.6 285.3 310.0  2.53
 8  600  4199 -10.5 -12.8  83  2.3 -11.3 241  45 304.0 304.4 285.8 311.5  2.38
 9  550  4863 -14.7 -15.5  94  0.8 -14.9 242  49 306.6 307.0 286.5 313.3  2.09
10  500  5579 -18.9 -19.1  99  0.1 -19.0 246  52 310.0 310.3 287.3 315.5  1.70
11  450  6356 -23.7 -23.7 100  0.0 -23.7 250  52 313.4 313.7 287.9 317.6  1.25
12  400  7207 -29.2 -29.2 100  0.0 -29.2 249  55 317.0 317.1 288.7 319.9  0.85
13  300  9194 -45.7 -45.7 100  0.0 -45.7 244  70 320.9 321.0 289.3 321.7  0.21
14  250 10378 -56.4 -56.5  98  0.1 -56.4 247  79 322.2 322.2 289.5 322.5  0.07

[FoothillsNC]

And that will NOT help if there's freezing rain mid week....talk about a skating rink.

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.

[MotoWeatherman]

Per 0z GFS....Boone at 0z Sunday

Date: 48 hour GFS valid 0Z SUN 12 DEC 10
Station: Ktnb
Latitude:   36.20
Longitude: -81.65
-------------------------------------------------------------------------------
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   126                                                                 
 1  950   542                                                                 
SFC  925   753  -1.0  -4.4  78  3.4  -2.3 149   7 278.3 278.8 274.9 286.6  2.98
 3  850  1435   0.0  -3.2  79  3.2  -1.3 176  26 286.1 286.8 279.7 296.3  3.55
 4  800  1921   0.5 -11.1  41 11.6  -3.6 197  34 291.6 292.0 280.3 297.8  2.04
 5  750  2438   0.1 -15.1  31 15.2  -5.0 215  38 296.7 296.9 282.0 301.5  1.57
 6  700  2988  -2.7 -12.8  46 10.1  -6.2 227  39 299.5 299.9 283.7 305.9  2.04
 7  650  3571  -6.7 -11.4  69  4.7  -8.4 236  40 301.4 301.8 284.9 309.0  2.46
 8  600  4192 -10.6 -12.3  87  1.8 -11.2 243  43 303.9 304.3 285.9 311.6  2.47
 9  550  4856 -14.8 -15.4  95  0.6 -15.0 244  45 306.5 306.9 286.5 313.2  2.09
10  500  5571 -19.4 -19.6  98  0.2 -19.5 246  46 309.4 309.7 286.9 314.6  1.61
11  450  6347 -24.4 -24.6  98  0.2 -24.5 247  46 312.5 312.8 287.6 316.4  1.15
12  400  7195 -30.0 -30.2  98  0.2 -30.1 245  49 315.9 316.1 288.3 318.6  0.77
13  300  9176 -46.1 -46.1 100  0.0 -46.0 241  69 320.4 320.5 289.1 321.2  0.20
14  250 10360 -56.7 -56.8  99  0.1 -56.8 242  81 321.7 321.7 289.3 322.0  0.07
15  200 11749 -62.0 -64.3  74  2.2 -62.1 252  81 334.5 334.5 293.0 334.7  0.03

And now at 6z Sunday...probably all snow per this run...

Date: 54 hour GFS valid 6Z SUN 12 DEC 10
Station: Ktnb
Latitude:   36.20
Longitude: -81.65
-------------------------------------------------------------------------------
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    63                                                                 
 1  950   480                                                                 
SFC  918   753   0.4   0.1  98  0.3   0.3 169   8 280.3 281.0 277.6 291.9  4.19
 3  850  1377  -0.0  -0.6  96  0.6  -0.3 184  31 286.1 286.9 280.6 298.4  4.31
 4  800  1862   0.0  -3.8  76  3.8  -1.6 200  40 291.2 291.8 282.1 301.7  3.62
 5  750  2380   0.1  -1.4  90  1.5  -0.6 219  45 296.7 297.5 285.4 310.4  4.61
 6  700  2931  -2.5  -3.5  93  1.0  -3.0 230  44 299.7 300.5 286.2 312.4  4.22
 7  650  3515  -6.0  -7.1  92  1.1  -6.5 233  41 302.1 302.8 286.3 312.7  3.44
 8  600  4138  -9.9 -11.4  89  1.5 -10.5 230  41 304.6 305.1 286.4 313.0  2.66
 9  550  4804 -14.3 -15.7  89  1.4 -14.7 227  46 307.1 307.5 286.6 313.6  2.04
10  500  5519 -19.6 -20.1  95  0.5 -19.7 231  52 309.2 309.5 286.8 314.2  1.55
11  450  6293 -24.9 -25.5  95  0.6 -25.1 234  63 311.9 312.1 287.2 315.5  1.06
12  400  7139 -31.5 -32.6  89  1.2 -31.6 234  71 314.1 314.2 287.5 316.2  0.62
13  300  9104 -47.4 -47.7  96  0.3 -47.4 247 101 318.6 318.6 288.5 319.3  0.17
14  250 10286 -55.2 -55.5  96  0.3 -55.2 247 114 324.0 324.0 290.1 324.4  0.08
15  200 11696 -59.5 -63.2  62  3.7 -59.6 250  91 338.6 338.6 294.0 338.7  0.04

[BullCityWx]

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.

That is a really, really weird run...it looks like there's freezing drizzle for some parts of the state for 36 hours.

[WeatherNC]

And that will NOT help if there's freezing rain mid week....talk about a skating rink.

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...