Potential Thanksgiving Event

[Solak]

New 'slight risk of severe weather' has crept a little more inland.

 

http://www.spc.noaa.gov/products/outlook/archive/2013/day1otlk_20131126_1630.html

[calculus1]

Here's the latest GFS version of the 700mb RH for tomorrow.  Might there be some flakes for those outside of the mountains?

 

 

And here are the 850mb temps for the same time stamp:

 

[metalicwx366]

New 'slight risk of severe weather' has crept a little more inland.

http://www.spc.noaa.gov/products/outlook/archive/2013/day1otlk_20131126_1630.html

I'm included in the slight risk now.

[BullCityWx]

Here's the latest GFS version of the 700mb RH for tomorrow.  Might there be some flakes for those outside of the mountains?

 

 

And here are the 850mb temps for the same time stamp:

 

 

Judging by the RH on the soundings, I'd lean towards no. With temps crashing though, I wouldnt be surprised to see freezing rain/drizzle or maybe even graupel. 

[BullCityWx]

Date: 30 hour Eta valid 18Z WED 27 NOV 13

Station: KCLT

Latitude: 35.22

Longitude: -80.93

-------------------------------------------------------------------------------

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

SFC 982 206 1.7 -1.6 78 3.4 0.4 318 15 276.3 276.9 274.4 285.8 3.45

2 950 475 -1.2 -3.1 87 1.9 -1.9 319 23 276.0 276.5 273.9 284.8 3.19

3 900 903 -4.8 -5.9 92 1.1 -5.1 327 35 276.6 277.0 273.6 284.2 2.74

4 850 1352 -5.2 -6.3 92 1.0 -5.6 331 36 280.6 281.1 275.9 288.6 2.81

5 800 1829 -5.0 -5.5 96 0.5 -5.2 302 23 285.9 286.4 279.1 295.0 3.17

6 750 2335 -5.8 -6.4 96 0.6 -6.0 273 25 290.3 290.9 281.1 299.6 3.16

7 700 2875 -7.0 -9.6 82 2.6 -7.9 254 30 294.7 295.2 282.4 302.7 2.64

8 650 3451 -8.6 -14.2 64 5.6 -10.4 242 37 299.2 299.6 283.5 305.3 1.96

9 600 4070 -10.2 -19.8 45 9.6 -12.9 230 45 304.3 304.6 284.8 308.6 1.32

10 550 4737 -12.9 -27.2 29 14.4 -16.0 227 54 308.8 309.0 285.8 311.4 0.75

11 500 5456 -17.6 -36.6 17 19.1 -20.5 227 61 311.6 311.7 286.3 312.8 0.33

12 450 6234 -24.1 -44.4 13 20.4 -26.2 225 63 313.0 313.0 286.6 313.6 0.16

13 400 7081 -30.4 -50.6 12 20.2 -31.9 219 70 315.5 315.5 287.3 315.8 0.09

14 350 8020 -34.7 -61.6 5 26.8 -36.0 211 85 321.9 321.9 289.3 322.0 0.03

15 300 9088 -38.6 -66.2 4 27.6 -39.6 209 94 331.0 331.0 292.0 331.0 0.02

16 250 10326 -43.8 -71.8 3 28.0 -44.6 210 94 340.9 340.9 294.6 341.0 0.01

17 200 11802 -49.7 -67.4 11 17.8 -50.1 211 90 354.1 354.1 297.5 354.2 0.02

18 150 13653 -56.3 -74.4 9 18.1 -56.6 215 86 373.0 373.0 301.1 373.1 0.01

19 100 16185 -61.6 -82.9 4 21.3 -61.8 234 61 408.8 408.8 306.3 408.8 0.00

TRP 0

WND 0

[BullCityWx]

As best I understand it, to get snow to fall you want high relative humidity values throughout the column but especially in the -15C region. As you can see in that sounding, the region that is at or below -15C(the growth zone for snow flakes) has completely dried out. I believe you can get graupel with that sounding but somebody might need to correct me on that.

[NCCatawba]

The NAM brings 0.5" of wintry accumulation tomorrow for areas near the north-west Piedmont/foothills. NWS Raleigh thinks wet snow flakes may mix with rain. Low impact atm.

[griteater]

As best I understand it, to get snow to fall you want high relative humidity values throughout the column but especially in the -15C region. As you can see in that sounding, the region that is at or below -15C(the growth zone for snow flakes) has completely dried out. I believe you can get graupel with that sounding but somebody might need to correct me on that.

No expert on it, but you typically need moisture at temps that are lower than -10C.  -12C to -18C is best (dendrite snow growth zone), with max snow growth at -15C.  On the moisture, 80% RH is saturated with respect to ice...I'm pretty sure you just need 80% or higher RH.  In contrast, 100% RH is considered saturated with repect to water. 

 

I suspect the soundings between 15z and 18z are slightly better, but not by much.

 

Hug this...

[Cheeznado]

Here in the ATL looks like the typical light snow mainly on the NW side of town tomorrow, the downsloping will make it hard to get much on the SE/E side. Would not be surprised to see a dusting or maybe even up to an inch up I-75 by 12Z. In Cobb county where I will be at work there is a chance for a decent small burst at about 4-6 AM.

[DaculaWeather]

Here in the ATL looks like the typical light snow mainly on the NW side of town tomorrow, the downsloping will make it hard to get much on the SE/E side. Would not be surprised to see a dusting or maybe even up to an inch up I-75 by 12Z. In Cobb county where I will be at work there is a chance for a decent small burst at about 4-6 AM.

You can't push just a little of that toward the NE side of town? :-)

[calculus1]

As best I understand it, to get snow to fall you want high relative humidity values throughout the column but especially in the -15C region. As you can see in that sounding, the region that is at or below -15C(the growth zone for snow flakes) has completely dried out. I believe you can get graupel with that sounding but somebody might need to correct me on that.

 

 

No expert on it, but you typically need moisture at temps that are lower than -10C.  -12C to -18C is best (dendrite snow growth zone), with max snow growth at -15C.  On the moisture, 80% RH is saturated with respect to ice...I'm pretty sure you just need 80% or higher RH.  In contrast, 100% RH is considered saturated with repect to water. 

 

I suspect the soundings between 15z and 18z are slightly better, but not by much.

 

Thank you both for your analysis of the proper RH levels at different levels of the atmosphere.  Very helpful.

[jrips27]

Here in the ATL looks like the typical light snow mainly on the NW side of town tomorrow, the downsloping will make it hard to get much on the SE/E side. Would not be surprised to see a dusting or maybe even up to an inch up I-75 by 12Z. In Cobb county where I will be at work there is a chance for a decent small burst at about 4-6 AM.

Stop getting me excited Cheez! I will gladly take a dusting, but an inch would be amazing. Hope you're right!

On the obs side of things, it looks like we're approaching the end of this main rain band.

[Stovepipe]

HRRR snowfall @ 7z:

 

[NavarreDon]

Looks like a extension is forthcoming.

 

[downeastnc]

Looks like a extension is forthcoming.

 

There has been two reported tornados already,  really sucks that the primary window for tornadic storms here in NC will be in the late overnight hrs.....luckily the chances are these will be weak EF0, EF1 type spin ups.

[Brick Tamland]

There has been two reported tornados already,  really sucks that the primary window for tornadic storms here in NC will be in the late overnight hrs.....luckily the chances are these will be weak EF0, EF1 type spin ups.

 

Doesn't NC lead the nation in overnight fatalities from tornadoes in the month of November?

[downeastnc]

Doesn't NC lead the nation in overnight fatalities in the month of November?

Well we did at one point but I dont know if we still hold that rather dubious record any longer.

[Brick Tamland]

[Bsudweather]

From the looks of things, it looks like a pretty good band of snow may move through the upstate tomorrow. My question is the down sloping if it will have a impact on this?

[wncsnow]

GSP afternoon Disco-

 

WINTER WEATHER...
THE WINTER STORM WATCH WILL BE UPGRADED TO A WINTER STORM WARNING
ALONG THE TN BOARDER COUNTIES. THE NAM SOUNDINGS CONTINUE TO SHOW
STRONG LLVL COLD ADVECTION UNDER UNDERNEATH OF A WARM
NOSE...RESULTING IN A PERIOD OF FREEZING RAIN OVER THE WRN SLOPES OF
THE NC MTNS STARTING AROUND MIDNIGHT. THE WARM NOSE WILL QUICKLY
COLLAPSE AS THE LOW MOVES NORTHEAST OF THE REGION...BUT I HAVE
CARRIED A FEW HOURS OF FREEZING RAIN IN THE GRIDS...ESP NEAR THE TN
LINE. HOWEVER...THE MAIN CONCERN WILL BE HEAVY SNOW AND STRONG
WINDS. BY 12 UTC PCPN SHOULD BE ALL SNOW ALONG THE TN LINE. THERE
WILL ALSO BE STRONG SYNOPTIC SCALE FORCING AT THIS TIME WHICH WILL
SUPPORT HEAVY SNOWFALL RATES...ESPECIALLY WHERE THE PCPN WILL BE
ENHANCED BY NW FLOW. BY LATE MORNING THE EVENT WILL TRANSITION INTO
PURE NW FLOW...THOUGH STRONG H8 WINDS AND DEEP MOIST LAYER WILL
SUPPORT ACCUMULATING SNOW WELL INTO THE EVENING HOURS. VERY WINDY
CONDITIONS WILL ALSO RESULT IN BLOWING AND DRIFTING SNOW...THOUGH
THE STRONGEST WINDS WILL PROBABLY DEVELOP JUST EAST OF THE HEAVIEST
SNOW.

A WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR MOST OF THE REST OF
THE NC MTNS. RAPIDLY COOLING TEMPERATURES WILL SUPPORT WIDESPREAD
BLACK ICE. IN ADDITION...THAT SHOT OF DEEP FORCING COULD SUPPORT AN
INCH OR TWO OF SNOW BEFORE PCPN ENDS LATE WED MORNING.

A PERIOD OF SNOW IS ALSO POSSIBLE ACROSS THE FOOTHILLS AND PIEDMONT.
IN FACT I THINK THERE IS A GOOD CHANCE THE I-85 CORRIDOR WILL SEE
SNOWFALL...BUT ONLY A BRIEF PERIOD AND IT SHOULDN/T STICK. I/VE
ADDED THIS TO THE GRIDS. WITH TOMORROW BEING THE BUSIEST TRAVEL DAY
OF THE YEAR WE WILL HAVE TO WATCH THIS VERY CLOSELY.
 

[John1122]

JKL says near blizzard conditions tomorrow, with especially heavy snow near the TN and VA border counties. MRX goes with 1-2 lower, 2-4 higher, 4-8 highest.

[BullCityWx]

Little bit of instability passing through the western carolinas tomorrow morning around 10AM.

[FLweather]

Little bit of instability passing through the western carolinas tomorrow morning around 10AM.

 

 

Nice! Seems to keep taking the trough axis further east.  Good thump of snow on the ULL....Could some accumulations be possible.

 

Rap below but congrats Macon,GA!

 

[NEGa]

From the looks of things, it looks like a pretty good band of snow may move through the upstate tomorrow. My question is the down sloping if it will have a impact on this?

 

if we can get it swing around and approach from the sw we might be ok, if its coming directly on a course from the mountains chances are down sloping may kick in. its about a 20 min drive or so from mby to the other side of the valley where i can see flakes falling...its depressing to look out the window and see it, then watch as is disappears as it heads this way lol

[Bsudweather]

if we can get it swing around and approach from the sw we might be ok, if its coming directly on a course from the mountains chances are down sloping may kick in. its about a 20 min drive or so from mby to the other side of the valley where i can see flakes falling...its depressing to look out the window and see it, then watch as is disappears as it heads this way lol

But it looks to me like it will be coming in from the SW. If I'm seeing it right it looks on models like a northern stream phasing a little with southern stream then moving right up I85 and anyone on the west side of it would see snow? Someone correct me if I'm wrong.

[NEGa]

But it looks to me like it will be coming in from the SW. If I'm seeing it right it looks on models like a northern stream phasing a little with southern stream then moving right up I85 and anyone on the west side of it would see snow? Someone correct me if I'm wrong.

you are right i think lol.  i just finished looking around and does appear my have a more sw direction which would be great (as long as the warm bubble pops haha)  the nw flow event starting tomorrow afternoon will probably dry up before mby.  tomorrow morning looks more interesting.  a shame another inch or 2 of rain and temps 33 or 34 but oh well thats the se

 

if it still looks decent later i might get up early on a day off just in case lmao

[Bsudweather]

you are right i think lol. i just finished looking around and does appear my have a more sw direction which would be great (as long as the warm bubble pops haha) the nw flow event starting tomorrow afternoon will probably dry up before mby. tomorrow morning looks more interesting. a shame another inch or 2 of rain and temps 33 or 34 but oh well thats the se

if it still looks decent later i might get up early on a day off just in case lmao

Yeah looks like it may be little later in the morning before it hits here in upstate. But talking about rain, man has it put it down! I've got 2.62" and still have moderate to heavy rain! I'm gonna be pushing 4" probably before this is over. If it had been snow we would have been shoveling for two weeks! Lol

[nchighcountrywx]

Here comes Mr Warm Front

2nd Image Courtesy of Mike Dross at Wright-Weather

[Brandonjva]

Cool animation http://models.weatherbell.com/news/wrf_2013112612_ref_nmm_east.gif

[kvegas-wx]

Cool animation http://models.weatherbell.com/news/wrf_2013112612_ref_nmm_east.gif

Well that shows several hours of snow across much of NC. Not sure I am buying it as we always get dry slotted quickly with these types of rapid movers up the EC. But if we see some token flakes then great!