Potential December 12th-13th threat

[DaculaWeather]

Though I'm not really qualified to compliment folks who do this for a living, I thought it was a great write-up as well.

HA HA!!! I just saw your signature! That's great! I'm a Vol fan too, grew up in Nashville and went to UT Knoxville. Go Vols!

[FoothillsNC]

Their write-up is excellent, but there is a difference in their forecast and their "advisory" vs. a winter storm warning. Unless I misunderstand the criteria required their wording suggest we should be under a winter storm warning, but their forecast is for a winter weather advisory. (speaking for the NE TN valleys) Maybe 3-6 no longer qualifies the valleys for a WSW. What am I missing?

I don't know but I bet there is some nuance you're missing. Then again it may be an oversight or not correct wording, they may change it. I don' t know their policy. It could be like GSP's which has a lot of details and options.

[Carvers Gap]

Their write-up is excellent, but there is a difference in their forecast and their "advisory" vs. a winter storm warning. Unless I misunderstand the criteria required their wording suggest we should be under a winter storm warning, but their forecast is for a winter weather advisory. (speaking for the NE TN valleys) Maybe 3-6 no longer qualifies the valleys for a WSW. What am I missing?

I had a similar thought as well. Does this have anything to do w/ the changes in warning criteria?

[rosie]

...WINTER WEATHER ADVISORY IN EFFECT FROM 2 PM SUNDAY TO 7 AM EST

MONDAY...

A WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR THE NORTHEAST

GEORGIA MOUNTAINS FOR SUNDAY AFTERNOON AND SUNDAY NIGHT. THE AREA

IS GENERALLY ALONG AND NORTH OF A LINE FROM CLEVELAND...TO

DAHLONEGA...TO JASPER...AND EAST OF A LINE FROM COHUTTA...TO

ELLIJAY...TO JASPER.

[isohume]

Actually, looks like its pretty remarkably close to the Ukmet and op. ECMWF as well.  All the models I'm seeing show this outbreak equally as cold, if not substantially colder for western NC mountains on this upslope, and def. on the Tennessee side. Should be some great powder with extreme ratios again.  A sneak peak at the new 12Z Euro has -16 in nw NC at 66 and 72 hours. Not bad at all.(and was too warm on the last outbreak)

Yeah you're right...the 12Z runs have come into better agreement with the partial thicknesses.  The SREF now supports the GFS pretty good with the NAM coming into agreement in the llvls. 

GFS: 1503/1233

SREF: 1501/1247

NAM: 1482/1233

Looks like avg snowfall ratios get up to 20:1 regardless of model tho. Just a very cold airmass once again.  

[FoothillsNC]

the 18z still has it just cold enough probably in W. NC for the prefrontal snows, followed by the good upslope. The middle part of Tenn and eastern esp. NE TN are going to be hit hard as well. Look at the 5H center come directly overhead Nashville and doesnt' start to weaken til shortly therafter. Probably going to be some heavy windwhipped snows with that along and north of 40 in Tenn with that.

[DaculaWeather]

FXUS62 KFFC 112118

AFDFFC

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PEACHTREE CITY GA

418 PM EST SAT DEC 11 2010

.SYNOPSIS...

DEEP UPPER TROUGH WILL ROTATE THROUGH THE EASTERN U.S. NEXT 48 HOURS

BRINGING A SIGNIFICANT SURGE OF COLD AIR INTO THE SE U.S. THIS WILL

QUICKLY LIFT OUT BY MID-WEEK AS STRONG ZONAL FLOW EVOLVES ACROSS THE

CENTRAL AND SOUTHERN U.S. ARCTIC AIR AND MUCH BELOW NORMAL

TEMPERATURES EARLY IN THE WEEK WILL QUICKLY BE REPLACED BY

MILD...ABOVE NORMAL TEMPERATURES DURING THE LATER HALF OF THE WEEK.

ABUNDANT CLOUD COVER AND AT LEAST SLIGHT CHANCES OF RAIN WILL EXIST

FOR THE LATER HALF OF THE WEEK.

19

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...

IMMEDIATE CONCERN IS STRONG SHORT WAVE....LOCATED ACROSS THE

NORTHERN PLAINS...THAT WILL EVOLVE INTO A DEEP...FULL LATITUDE

MERIDIONAL TROUGH ACROSS THE EASTERN U.S. THROUGH MON.

CONSEQUENTLY...RAPID AND STRONG CYCLOGENESIS WILL OCCUR ACROSS THE

EASTERN GREAT LAKES INTO NEW ENGLAND. THE DEEP MERIDIONAL...HENCE

POLAR CONNECTION OF THIS SYSTEM WILL DELIVER A SIGNIFICANT SURGE OF

ARCTIC AIR INTO THE SE U.S. AS A RESULT...ALTHOUGH IT WILL BE BRIEF.

STRONG WAA AND IMPRESSIVE DYNAMICS...LIFT...VERTICAL MOTION WILL

ACCOMPANY THIS SYSTEM OVERNIGHT IN A NARROW APPROXIMATE 100-MILE

WIDE WINDOW ALONG AND IMMEDIATELY IN ADVANCE OF THE COLD FRONT.

THERE ARE A VARIETY OF CONCERNS TO CONSIDER IN THE SHORT TERM AS A

RESULT OF THIS SYSTEM. FIRST...RAINFALL. MODEL QPF IS GENERALLY IN

THE 1.0 TO 1.5 INCH. HPC QPF...GENERALLY IN THE 0.5 TO 1.0 INCH.

EXPECTING GENERALLY 1.0 INCH AMOUNTS NORTH OF I-20...WITH SLIGHTLY

LESSER AMOUNTS TO THE SOUTH. FFG VALUES MOSTLY IN THE 1.5-2.O INCH/3

HR RANGE...AND THIS AMOUNT OF RAINFALL IS NOT EXPECTED GIVEN SPEED

OF MOVEMENT OF SYNOPTIC SYSTEM. THUS...NO FLOOD PRODUCTS WILL BE

ISSUED. SECOND...SEVERE WEATHER POTENTIAL. NARROW RIBBON OF VERY

STRONG DYNAMICS...60-65KT LLJ...HELICITY NEAR 1000 M2/S2 WILL

PRECEDE STRONG COLD FRONT IN THE 06Z-12Z TIME FRAME.

HOWEVER...INSTABILITY IS COMPLETELY LACKING WITH ANTECEDENT DRY

ARCTIC AIR MASS IN PLACE. DEWPOINTS ARE ONLY ABLE TO RECOVER INTO

THE 30S NORTH AND LOW 40S SOUTH. ALTHOUGH SHEAR AND POTENTIAL FOR

ROTATING STRONG SHOWERS AND QLCS HAS TO BE CONSIDERED...ESPECIALLY

CONSIDERING RECENT EVENTS. HOWEVER...IN THIS CASE FEEL THAT THE

COMPLETE LACK OF INSTABILITY PRECLUDES THE THREAT OF SEVERE.

PREVIOUS SUCH EVENTS WERE NOT PRECEDED BY AN ARCTIC AIR MASS SUCH

HAS BEEN IN PLACE MOST OF THIS WEEK. FURTHERMORE...GIVEN THE LACK OF

INSTABILITY...DO NOT EXPECT CLOUDS TO BUILD HIGH ENOUGH TO SUPPORT

LIGHTNING...THUS WILL CONTINUE TO LEAVE THUNDER OUT OF THE

FORECAST...ALTHOUGH AN EMBEDDED RUMBLE OF THUNDER CANNOT BE

COMPLETELY RULED OUT. THIRD CONCERN...WINTER WEATHER. GFS

INDICATING MUCH GREATER POTENTIAL FOR WINTER WX THAN

NAM/ECMWF...EVEN IN ADVANCE OF THE MAIN SURGE OF COLD AIR. 12Z GFS

HAS SFC TEMPS/850MB TEMPS BELOW FREEZING ACROSS THE NE

MOUNTAINS...WHICH IS NOT VERIFYING WELL AT ALL. CURRENT SFC TEMPS

ACROSS NE GA ARE WELL INTO THE 40S...E.G...OBS FROM BLAIRSVILLE AT

48..CLEARLY MUCH CLOSER TO THE NAM12 SOLUTION. THUS...WILL NOT BUY

OFF ON THE GFS INDICATION OF FROZEN PCPN ACROSS THE NE MOUNTAINS

EVEN THIS EVENING AND BEFORE COLD FRONTAL PASSAGE. BULK OF MOISTURE

WILL EXIT THE REGION QUICKLY FOLLOWING FRONTAL PASSAGE AS NARROW

RIBBON OF N-S ORIENTED PVA/OMEGA EXITS TO THE EAST. NOT EXPECTING

ANY FROZEN PCPN WITH THE MAIN PCPN BAND. HOWEVER...AS STRONG

LOW-LEVEL CAA SPREADS ACROSS THE CWA FROM NW-SE SUN...NOTE 850MB

TEMPS PLUMMETING FROM NEAR 0C AT 12Z TO -14C ACROSS N GA BY 00Z

MON...COMBINED WITH STRONG NW SFC WINDS/OROGRAPHIC LIFT ALONG NW

FACING SLOPES...AND SIGNIFICANT WRAP AROUND MOISTURE...-SHSN ARE

LIKELY. MODEL SNOWFALL MOSTLY 1 INCH OR LESS IN THESE AREAS...WITH

THE EARLY 3-4 INCHES DEPICTED ALONG THE RIDGES BEING IGNORED.

AGAIN...THE NAM12 SNOWFALL OF 1 INCH OR LESS MUCH MORE REALISTIC.

GIVEN THESE FACTORS COMBINED WITH SFC TEMPS BY SUN AFTERNOON AOB

BELOW FREEZING IN THESE AREAS COMBINED WITH AN ATMOSPHERIC COLUMN

COMPLETELY SUPPORTIVE OF ALL SNOW...WILL ISSUE A WINTER WEATHER

ADVISORY FOR THE NE MOUNTAIN ZONES FROM 18Z SUN - 12Z MON. THINKING

IS THAT 0.5 TO 1.0 INCH OF SNOW IS POSSIBLE IN THESE AREAS...WHICH

WILL BE ENOUGH TO CAUSE A HAZARD...ESPECIALLY ON MOUNTAINOUS/HIGHER

ELEVATIONS ROADWAYS. FINALLY...A STRONG PRESSURE GRADIENT WILL

DEVELOP BEHIND THE FRONT AS STRONG SFC CYCLOGENESIS OCCURS TO THE NE

OF THE REGION. MOS AND GRIDDED DATA SUPPORT LOCAL WIND ADVISORY

CRITERIA ACROSS THE ENTIRE CWA AFT 15Z SUN...SO WILL ISSUE A WIND

ADVISORY FOR N GA. ISSUES WITH WIND CHILLS CAN BE DEALT WITH ON

LATER SHIFTS...SINCE ANY CONCERN WITH WIND CHILL WOULD NOT BE UNTIL

MON MORNING. CURRENTLY...WIND CHILL CRITERIA IS NOT MET EXCEPT

BRIEFLY IN THE NE MOUNTAINS.

PLAN TO LEAN TOWARD THE WARMER MET MOS FOR TONIGHTS MINS GIVEN

WAA...CLOUDS...RAIN...AND TEMPS MOSTLY IN THE 50S NOW...THEN TOWARD

THE COLDER MAV MOS FOR THE REMAINDER OF THE SHORT TERM. SIMILAR

EVENTS OF -14 TO -16C TEMPS AT 850MB USUALLY RESULTS IN SFC MAX

TEMPS REMAINING AOB FREEZING NEAR THE WINTER SOLSTICE IN THESE

PARTS. THUS...N GA SHOULD REMAIN AOB FREEZING MON...AND ONLY MID TO

UPPER 30S CENTRAL AREAS. LOWS MON MORNING WILL BE FAIRLY UNIFORM IN

THE MID AND UPPER TEENS NORTH TO LOWER 20S SOUTH. TUE MORNING WILL

SEE BETTER RADIATIONAL COOLING AND A WIDER DISCREPANCY OF MIN TEMPS

FROM ONE LOCATION TO ANOTHER.

.LONG TERM /TUESDAY THROUGH SATURDAY/...

THE DEEP EASTERN U.S. UPPER TROUGH WILL QUICKLY LIFT OUT TUE AND BE

REPLACED WITH A FLAT ZONAL FLOW ALONG WITH A SLOWLY BROADENING

SUBTROPICAL RIDGE ACROSS THE WESTERN GULF AND SOUTHERN PLAINS.

STRONG LOW-LEVEL WAA WILL EVOLVE IN THE WAKE OF THE DEPARTING ARCTIC

AIR MASS. A WEAK SHORT WAVE/ASSOCIATED SFC LOW WILL SKIRT TO THE

NORTH IN THE INCREASING ZONAL FLOW WED-THU...BRINGING ABUNDANT

MID-LEVEL CLOUDS AND LOW CHCS FOR -RA TO N GA. TEMPS SHOULD BE WARM

ENOUGH FOR ALL LIQUID PCPN AT THAT POINT. WITH THE AXIS OF THE UPPER

RIDGE REMAINING WELL WEST OF THE REGION...THE UPPER FLOW WILL REMAIN

PREDOMINATELY NW. TEMPS WILL RECOVER FROM THE EARLY WEEK FRIGID

LEVELS...BUT SHOULD REMAIN JUST BELOW SEASONAL NORMS AT BEST GIVEN

PREDOMINANCE OF NW FLOW ALOFT OVERALL. HOWEVER...AFTER MIN TEMPS

BOTTOM OUT IN THE 10-15F RANGE EARLY TUE...TEMPS WILL BE MUCH MILDER

FOR THE REMAINDER OF THE WEEK...RECOVERING MOSTLY TO LOWS IN THE 30S

AND HIGHS IN THE 50S DURING THE LATER HALF OF THE WEEK. THE WARMEST

TEMPS WILL BE SEEN THU IN ADVANCE OF THE WEEK OHIO VALLEY SHORT

WAVE...WITH SOMEWHAT OF A SETBACK IN TEMPS FOR FRI INTO THE

WEEKEND...BUT NOTHING EVEN CLOSE TO WHAT IS EXPECTED SUN-TUE. THERE

ARE CONSIDERABLE DIFFERENCES AMONG THE ECMWF/GFS WITH RESPECT TO

TIMING OF PCPN AND COOLING DURING THE LATER HALF OF THE WEEK.

CONFIDENCE IN ANY ONE SOLUTION IS LOW. FOR NOW...HAVE ADVERTISED NO

MORE THAN LOW CHC POPS WED-FRI AND COMPROMISED BETWEEN THE COLD MEX

MOS TEMPS AND THE MUCH WARMER ECMWF GRIDDED DATA. BEYOND NEXT

WEEKEND...THE DIFFERENCES BETWEEN THE ECMWF AND GFS CONTINUE TO GROW

LARGER. THE ECMWF DEVELOPS ANOTHER VERY DEEP EASTERN U.S. TROUGH AND

SIGNIFICANT SURGE OF ARCTIC AIR INTO THE SE U.S. MEANWHILE...THE GFS

DOES A COMPLETE FLIP-FLOP WITH A WESTERN U.S. TROUGH AND A

SUBTROPICAL RIDGE ACROSS THE SE U.S...WHICH WOULD BRING UNSEASONABLY

WARM TEMPS TO THE SE U.S AND PERHAPS THUNDERSTORMS.

AGAIN...CONFIDENCE VERY LOW BEYOND WED AT THIS POINT.

[EmersonGA]

Just got back from Newfound Gap. The snow got good around 3000 feet. The sheltered valleys stiil had snow plastered trees. The NW sides if the tree trunks were still covered. It is cold as crap up top and snow is still piled everywhere. Hopefully we see the changeover early so I can see some good snow before we leave tomorrow.

[kvskelton]

Personally, I'll be surprised if Kingsport gets more than two inches. We'll see. (edit) Kingsport does much better when a low pressure tracks through central NC. I always find it interesting when Weber City, VA, is under a WSW and Kingsport, TN, is under a WWA. I know it's arbitrary as far as borders and has to do more w/ elevation, but it's still interesting. BTW, those cities sit next to each other. For all intents and purposes, Weber City would be like a northern 'burb to Kingsport.

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...

[1bert1]

the 18z still has it just cold enough probably in W. NC for the prefrontal snows, followed by the good upslope. The middle part of Tenn and eastern esp. NE TN are going to be hit hard as well. Look at the 5H center come directly overhead Nashville and doesnt' start to weaken til shortly therafter. Probably going to be some heavy windwhipped snows with that along and north of 40 in Tenn with that.

From Blacksburg. NW NC Mountains

FURTHER SOUTHWEST COLD ENOUGH AIR REMAINS IN THE NC MTNS WITH AN

ISOTHERMAL LAYER THAT A FEW INCHES OF SNOW COULD FALL ACROSS THE NC

MTNS INTO FAR SW VA.

ADVISORIES FOR MIXED PRECIP ACROSS THE NORTH...AND SNOW IN

THE HIGH COUNTRY OF THE NW NC MTNS WILL BE ENDING SUNDAY MORNING.

WILL ISSUE ELEVATION DE PENDANT WINTER STORM WARNINGS FOR ALL WESTERN

SLOPE COUNTIES...FROM WATAUGA AND ASHE COUNTIES IN NC...NORTH ACROSS

SMYTH...TAZEWELL AND BLAND COS IN VA...TO MERCER...SUMMERS AND

GREENBRIER IN WV. WILL KEEP THOSE WARNINGS GOING THROUGH MONDAY

NIGHT. FAVORED LOCATIONS...SUCH AS BEECH MTN...LANSING...MT

ROGERS...QUINWOOD AND RAINELLE WILL LIKELY SEE A FOOT OR MORE OF

SNOW BY TUESDAY MORNING.

SUNDAY NIGHT- SIGNIFICANT SNOW ACCUMULATIONS ARE EXPECTED ON WEST OR

NORTHWEST FACING SLOPES OF THE MTNS...WITH A PROLONGED PERIOD OF

STRONG COLD ADVECTION...AND GOOD TRAJECTORIES OFF LAKE MICHIGAN.

WESTERN SLOPE SNOW SHOWERS MAY GET GOING EARLY IN THE EVENING IN THE

MTNS WITH STRONG COLD ADVECTION...BUT MODELS HOLD OFF DEEPER

MOISTURE BEHIND THE FRONT UNTIL MIDNIGHT OR LATER. IN ADDITION TO

THE SNOW SHOWERS IN THE MTNS...WINDS WILL INCREASE TO 15 TO 25 MPH

WITH STRONGER GUSTS TOWARD MORNING...AND THE COMBO WILL BRING WINDS

CHILLS DOWN TO AROUND ZERO.

MONDAY/MONDAY NIGHT- WILL BE BITTERLY COLD WITH STRONG COLD

ADVECTION CONTINUES...ALONG WITH ACCUMULATING SNOW SHOWERS ON

WESTERN SLOPES IN THE MTNS. WINDS INCREASE...WITH MODELS INDICATING

A 50+ KNOT LOW LEVEL JET. WIND GUSTS WILL LIKELY BE STRONG ENOUGH

FOR A WIND ADVISORY ALONG AND EITHER SIDE OF THE BLUE RIDGE

MTNS...WITH GUSTS OF AT LEAST 50 MPH EXPECTED. I USED THE COLDER MAV

TEMPS FOR HIGHS MONDAY AND LOWS MONDAY NIGHT SINCE THIS WILL BE AN

ARCTIC AIRMASS. THAT KEPT HIGHS BELOW FREEZING FOR MUCH OF THE CWA

MONDAY...AND IN THE TEENS IN HIGHER ELEVATIONS OF THE MTNS. LOWS

WILL BE IN THE SINGLE DIGITS IN THE MTNS MONDAY NIGHT...WITH TEENS

IN THE PIEDMONT. WIND CHILLS MONDAY WILL REMAIN AROUND ZERO IN THE

MTNS...AND TEENS IN THE PIEDMONT. WIND CHILLS MONDAY NIGHT WILL BE 5

TO 15 BELOW ZERO IN THE MTNS...AND SINGLE DIGITS IN THE PIEDMONT.

TUESDAY- THE UPSLOPE SNOW SHOWERS WILL BE WINDING DOWN WITH VERY

LITTLE LOW LEVEL MOISTURE LEFT.

[HWY316wx]

FXUS62 KFFC 112118

AFDFFC

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PEACHTREE CITY GA

418 PM EST SAT DEC 11 2010

.SYNOPSIS...

DEEP UPPER TROUGH WILL ROTATE THROUGH THE EASTERN U.S. NEXT 48 HOURS

BRINGING A SIGNIFICANT SURGE OF COLD AIR INTO THE SE U.S. THIS WILL

QUICKLY LIFT OUT BY MID-WEEK AS STRONG ZONAL FLOW EVOLVES ACROSS THE

CENTRAL AND SOUTHERN U.S. ARCTIC AIR AND MUCH BELOW NORMAL

TEMPERATURES EARLY IN THE WEEK WILL QUICKLY BE REPLACED BY

MILD...ABOVE NORMAL TEMPERATURES DURING THE LATER HALF OF THE WEEK.

ABUNDANT CLOUD COVER AND AT LEAST SLIGHT CHANCES OF RAIN WILL EXIST

FOR THE LATER HALF OF THE WEEK.

19

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...

IMMEDIATE CONCERN IS STRONG SHORT WAVE....LOCATED ACROSS THE

NORTHERN PLAINS...THAT WILL EVOLVE INTO A DEEP...FULL LATITUDE

MERIDIONAL TROUGH ACROSS THE EASTERN U.S. THROUGH MON.

CONSEQUENTLY...RAPID AND STRONG CYCLOGENESIS WILL OCCUR ACROSS THE

EASTERN GREAT LAKES INTO NEW ENGLAND. THE DEEP MERIDIONAL...HENCE

POLAR CONNECTION OF THIS SYSTEM WILL DELIVER A SIGNIFICANT SURGE OF

ARCTIC AIR INTO THE SE U.S. AS A RESULT...ALTHOUGH IT WILL BE BRIEF.

STRONG WAA AND IMPRESSIVE DYNAMICS...LIFT...VERTICAL MOTION WILL

ACCOMPANY THIS SYSTEM OVERNIGHT IN A NARROW APPROXIMATE 100-MILE

WIDE WINDOW ALONG AND IMMEDIATELY IN ADVANCE OF THE COLD FRONT.

THERE ARE A VARIETY OF CONCERNS TO CONSIDER IN THE SHORT TERM AS A

RESULT OF THIS SYSTEM. FIRST...RAINFALL. MODEL QPF IS GENERALLY IN

THE 1.0 TO 1.5 INCH. HPC QPF...GENERALLY IN THE 0.5 TO 1.0 INCH.

EXPECTING GENERALLY 1.0 INCH AMOUNTS NORTH OF I-20...WITH SLIGHTLY

LESSER AMOUNTS TO THE SOUTH. FFG VALUES MOSTLY IN THE 1.5-2.O INCH/3

HR RANGE...AND THIS AMOUNT OF RAINFALL IS NOT EXPECTED GIVEN SPEED

OF MOVEMENT OF SYNOPTIC SYSTEM. THUS...NO FLOOD PRODUCTS WILL BE

ISSUED. SECOND...SEVERE WEATHER POTENTIAL. NARROW RIBBON OF VERY

STRONG DYNAMICS...60-65KT LLJ...HELICITY NEAR 1000 M2/S2 WILL

PRECEDE STRONG COLD FRONT IN THE 06Z-12Z TIME FRAME.

HOWEVER...INSTABILITY IS COMPLETELY LACKING WITH ANTECEDENT DRY

ARCTIC AIR MASS IN PLACE. DEWPOINTS ARE ONLY ABLE TO RECOVER INTO

THE 30S NORTH AND LOW 40S SOUTH. ALTHOUGH SHEAR AND POTENTIAL FOR

ROTATING STRONG SHOWERS AND QLCS HAS TO BE CONSIDERED...ESPECIALLY

CONSIDERING RECENT EVENTS. HOWEVER...IN THIS CASE FEEL THAT THE

COMPLETE LACK OF INSTABILITY PRECLUDES THE THREAT OF SEVERE.

PREVIOUS SUCH EVENTS WERE NOT PRECEDED BY AN ARCTIC AIR MASS SUCH

HAS BEEN IN PLACE MOST OF THIS WEEK. FURTHERMORE...GIVEN THE LACK OF

INSTABILITY...DO NOT EXPECT CLOUDS TO BUILD HIGH ENOUGH TO SUPPORT

LIGHTNING...THUS WILL CONTINUE TO LEAVE THUNDER OUT OF THE

FORECAST...ALTHOUGH AN EMBEDDED RUMBLE OF THUNDER CANNOT BE

COMPLETELY RULED OUT. THIRD CONCERN...WINTER WEATHER. GFS

INDICATING MUCH GREATER POTENTIAL FOR WINTER WX THAN

NAM/ECMWF...EVEN IN ADVANCE OF THE MAIN SURGE OF COLD AIR. 12Z GFS

HAS SFC TEMPS/850MB TEMPS BELOW FREEZING ACROSS THE NE

MOUNTAINS...WHICH IS NOT VERIFYING WELL AT ALL. CURRENT SFC TEMPS

ACROSS NE GA ARE WELL INTO THE 40S...E.G...OBS FROM BLAIRSVILLE AT

48..CLEARLY MUCH CLOSER TO THE NAM12 SOLUTION. THUS...WILL NOT BUY

OFF ON THE GFS INDICATION OF FROZEN PCPN ACROSS THE NE MOUNTAINS

EVEN THIS EVENING AND BEFORE COLD FRONTAL PASSAGE. BULK OF MOISTURE

WILL EXIT THE REGION QUICKLY FOLLOWING FRONTAL PASSAGE AS NARROW

RIBBON OF N-S ORIENTED PVA/OMEGA EXITS TO THE EAST. NOT EXPECTING

ANY FROZEN PCPN WITH THE MAIN PCPN BAND. HOWEVER...AS STRONG

LOW-LEVEL CAA SPREADS ACROSS THE CWA FROM NW-SE SUN...NOTE 850MB

TEMPS PLUMMETING FROM NEAR 0C AT 12Z TO -14C ACROSS N GA BY 00Z

MON...COMBINED WITH STRONG NW SFC WINDS/OROGRAPHIC LIFT ALONG NW

FACING SLOPES...AND SIGNIFICANT WRAP AROUND MOISTURE...-SHSN ARE

LIKELY. MODEL SNOWFALL MOSTLY 1 INCH OR LESS IN THESE AREAS...WITH

THE EARLY 3-4 INCHES DEPICTED ALONG THE RIDGES BEING IGNORED.

AGAIN...THE NAM12 SNOWFALL OF 1 INCH OR LESS MUCH MORE REALISTIC.

GIVEN THESE FACTORS COMBINED WITH SFC TEMPS BY SUN AFTERNOON AOB

BELOW FREEZING IN THESE AREAS COMBINED WITH AN ATMOSPHERIC COLUMN

COMPLETELY SUPPORTIVE OF ALL SNOW...WILL ISSUE A WINTER WEATHER

ADVISORY FOR THE NE MOUNTAIN ZONES FROM 18Z SUN - 12Z MON. THINKING

IS THAT 0.5 TO 1.0 INCH OF SNOW IS POSSIBLE IN THESE AREAS...WHICH

WILL BE ENOUGH TO CAUSE A HAZARD...ESPECIALLY ON MOUNTAINOUS/HIGHER

ELEVATIONS ROADWAYS. FINALLY...A STRONG PRESSURE GRADIENT WILL

DEVELOP BEHIND THE FRONT AS STRONG SFC CYCLOGENESIS OCCURS TO THE NE

OF THE REGION. MOS AND GRIDDED DATA SUPPORT LOCAL WIND ADVISORY

CRITERIA ACROSS THE ENTIRE CWA AFT 15Z SUN...SO WILL ISSUE A WIND

ADVISORY FOR N GA. ISSUES WITH WIND CHILLS CAN BE DEALT WITH ON

LATER SHIFTS...SINCE ANY CONCERN WITH WIND CHILL WOULD NOT BE UNTIL

MON MORNING. CURRENTLY...WIND CHILL CRITERIA IS NOT MET EXCEPT

BRIEFLY IN THE NE MOUNTAINS.

PLAN TO LEAN TOWARD THE WARMER MET MOS FOR TONIGHTS MINS GIVEN

WAA...CLOUDS...RAIN...AND TEMPS MOSTLY IN THE 50S NOW...THEN TOWARD

THE COLDER MAV MOS FOR THE REMAINDER OF THE SHORT TERM. SIMILAR

EVENTS OF -14 TO -16C TEMPS AT 850MB USUALLY RESULTS IN SFC MAX

TEMPS REMAINING AOB FREEZING NEAR THE WINTER SOLSTICE IN THESE

PARTS. THUS...N GA SHOULD REMAIN AOB FREEZING MON...AND ONLY MID TO

UPPER 30S CENTRAL AREAS. LOWS MON MORNING WILL BE FAIRLY UNIFORM IN

THE MID AND UPPER TEENS NORTH TO LOWER 20S SOUTH. TUE MORNING WILL

SEE BETTER RADIATIONAL COOLING AND A WIDER DISCREPANCY OF MIN TEMPS

FROM ONE LOCATION TO ANOTHER.

.LONG TERM /TUESDAY THROUGH SATURDAY/...

THE DEEP EASTERN U.S. UPPER TROUGH WILL QUICKLY LIFT OUT TUE AND BE

REPLACED WITH A FLAT ZONAL FLOW ALONG WITH A SLOWLY BROADENING

SUBTROPICAL RIDGE ACROSS THE WESTERN GULF AND SOUTHERN PLAINS.

STRONG LOW-LEVEL WAA WILL EVOLVE IN THE WAKE OF THE DEPARTING ARCTIC

AIR MASS. A WEAK SHORT WAVE/ASSOCIATED SFC LOW WILL SKIRT TO THE

NORTH IN THE INCREASING ZONAL FLOW WED-THU...BRINGING ABUNDANT

MID-LEVEL CLOUDS AND LOW CHCS FOR -RA TO N GA. TEMPS SHOULD BE WARM

ENOUGH FOR ALL LIQUID PCPN AT THAT POINT. WITH THE AXIS OF THE UPPER

RIDGE REMAINING WELL WEST OF THE REGION...THE UPPER FLOW WILL REMAIN

PREDOMINATELY NW. TEMPS WILL RECOVER FROM THE EARLY WEEK FRIGID

LEVELS...BUT SHOULD REMAIN JUST BELOW SEASONAL NORMS AT BEST GIVEN

PREDOMINANCE OF NW FLOW ALOFT OVERALL. HOWEVER...AFTER MIN TEMPS

BOTTOM OUT IN THE 10-15F RANGE EARLY TUE...TEMPS WILL BE MUCH MILDER

FOR THE REMAINDER OF THE WEEK...RECOVERING MOSTLY TO LOWS IN THE 30S

AND HIGHS IN THE 50S DURING THE LATER HALF OF THE WEEK. THE WARMEST

TEMPS WILL BE SEEN THU IN ADVANCE OF THE WEEK OHIO VALLEY SHORT

WAVE...WITH SOMEWHAT OF A SETBACK IN TEMPS FOR FRI INTO THE

WEEKEND...BUT NOTHING EVEN CLOSE TO WHAT IS EXPECTED SUN-TUE. THERE

ARE CONSIDERABLE DIFFERENCES AMONG THE ECMWF/GFS WITH RESPECT TO

TIMING OF PCPN AND COOLING DURING THE LATER HALF OF THE WEEK.

CONFIDENCE IN ANY ONE SOLUTION IS LOW. FOR NOW...HAVE ADVERTISED NO

MORE THAN LOW CHC POPS WED-FRI AND COMPROMISED BETWEEN THE COLD MEX

MOS TEMPS AND THE MUCH WARMER ECMWF GRIDDED DATA. BEYOND NEXT

WEEKEND...THE DIFFERENCES BETWEEN THE ECMWF AND GFS CONTINUE TO GROW

LARGER. THE ECMWF DEVELOPS ANOTHER VERY DEEP EASTERN U.S. TROUGH AND

SIGNIFICANT SURGE OF ARCTIC AIR INTO THE SE U.S. MEANWHILE...THE GFS

DOES A COMPLETE FLIP-FLOP WITH A WESTERN U.S. TROUGH AND A

SUBTROPICAL RIDGE ACROSS THE SE U.S...WHICH WOULD BRING UNSEASONABLY

WARM TEMPS TO THE SE U.S AND PERHAPS THUNDERSTORMS.

AGAIN...CONFIDENCE VERY LOW BEYOND WED AT THIS POINT.

Good Lord! What has gotten into the FFC? That was actually more than 3 sentences!!! :weight_lift:

I mean, sheesh.... FINALLY... some REAL disco out of the FFC.

[Lookout]

the 18z still has it just cold enough probably in W. NC for the prefrontal snows, followed by the good upslope. The middle part of Tenn and eastern esp. NE TN are going to be hit hard as well. Look at the 5H center come directly overhead Nashville and doesnt' start to weaken til shortly therafter. Probably going to be some heavy windwhipped snows with that along and north of 40 in Tenn with that.

I have noticed on the last several runs of the nam that it continues to show a band of snow that crosses the NC foothills and eventually across the piedmont. It hardly shows up or not at all on the precip maps but it does on it's simulated composite radar. Will be interesting to see if there is one.

Just an amazing temperature gradient behind the front. 850mb temps go from 0c to -10c in just a few tens of miles tomorrow. Don't see that very often around these parts. I sure hope I can at least see a few flurries. Winds are west to even almost WSW tomorrow here behind the front, which would mean less downslope drying and might allow a few more to come this way but I won't get my hopes up.

GFS does have a good bit of moisture even up to above 700mb at 0z tomorrow. Note the wind direction in the boundary layer with a south of west direction. It should be noted though the nam has winds more westerly. We'll see I guess.

Date: 30 hour AVN valid 0Z MON 13 DEC 10
Station: KAHN
Latitude:   33.95
Longitude: -83.32
-------------------------------------------------------------------------------
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    33                                                                 
SFC  976   228  -2.7  -5.9  79  3.2  -3.8 251  15 272.4 272.8 270.7 279.3  2.52
 2  950   440  -3.4  -7.2  75  3.9  -4.7 259  32 273.8 274.2 271.3 280.2  2.33
 3  900   865  -6.9  -8.8  86  1.9  -7.5 269  45 274.4 274.8 271.4 280.5  2.18
 4  850  1308 -10.0 -11.3  90  1.3 -10.4 278  47 275.7 276.0 271.8 281.0  1.89
 5  800  1773 -12.7 -14.3  88  1.6 -13.1 287  44 277.6 277.9 272.4 282.2  1.58
 6  750  2263 -15.9 -17.9  85  1.9 -16.4 291  43 279.3 279.5 272.8 282.9  1.25
 7  700  2779 -19.2 -20.2  92  1.0 -19.4 289  41 281.2 281.4 273.7 284.5  1.10
 8  650  3332 -17.0 -20.9  71  4.0 -17.9 280  40 289.8 290.0 278.2 293.2  1.11

[MotoWeatherman]

Just checked out the 18z NAM and GFS and the flizzard watch across North Georgia still looks good for tomorrow afternoon/night. High county of NC should get pounded again with flow snow as moisture is very deep. Much of TN could get 1-3" with the wrap. I think a dusting to 1" is very possible north of Atlanta and north of I85. Best time for Georgia looks to be late afternoon and into the night when the best moisture wraps in. To me it looks like FFC has a good handle on the situation.

[Brian]

Good Lord! What has gotten into the FFC? That was actually more than 3 sentences!!! :weight_lift:

I mean, sheesh.... FINALLY... some REAL disco out of the FFC.

LOL--I know---sounds really well thought out, maybe they have heard how bad their reputation is. :snowman:

[Itunis]

Just checked out the 18z NAM and GFS and the flizzard watch across North Georgia still looks good for tomorrow afternoon/night. High county of NC should get pounded again with flow snow as moisture is very deep. Much of TN could get 1-3" with the wrap. I think a dusting to 1" is very possible north of Atlanta and north of I85. Best time for Georgia looks to be late afternoon and into the night when the best moisture wraps in. To me it looks like FFC has a good handle on the situation.

Cool stuff. Do you think you'll get your first measurable snow tomorrow? I think you're in the WWA for a whopping .5-1" lol.

[HWY316wx]

LOL--I know---sounds really well thought out, maybe they have heard how bad their reputation is. :snowman:

I have never had a problem with them being wrong, but I would just like to know their thinking behind their 3 sentences that they usually put out. With the dynamics of this system especially in the mountains, I think it calls for such disco out of the NWS. I applaud their thinking and I think it looks very reasonable.

[MotoWeatherman]

Cool stuff. Do you think you'll get your first measurable snow tomorrow? I think you're in the WWA for a whopping .5-1" lol.

I like my chances. Check out this sounding for Gainesville for 7pm tomorrow. Solid moisture thru 700mb. I am in the WWA for a whopper .5-1". With the cold coming behind this on Monday and Tuesday everything would stick around. Similar to how that .5" stuck around for 4-5 days earlier this year.

Date: 30 hour GFS valid 0Z MON 13 DEC 10
Station: Kgvl
Latitude:   34.32
Longitude: -83.83
-------------------------------------------------------------------------------
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    28                                                                 
SFC  956   382  -3.7  -5.2  90  1.5  -4.2 261  16 272.9 273.3 271.3 280.3  2.72
 2  950   435  -3.8  -5.5  88  1.7  -4.4 264  24 273.3 273.8 271.5 280.6  2.66
 3  850  1303 -10.0 -10.7  95  0.6 -10.2 284  46 275.6 276.0 271.9 281.2  1.99
 4  800  1768 -12.8 -13.6  94  0.8 -13.0 293  44 277.5 277.8 272.5 282.3  1.67
 5  750  2257 -15.9 -16.7  94  0.8 -16.2 298  43 279.3 279.5 273.1 283.3  1.37
 6  700  2773 -19.6 -20.1  96  0.4 -19.7 300  44 280.7 280.9 273.5 284.0  1.11
 7  650  3322 -18.9 -21.4  80  2.5 -19.4 299  44 287.6 287.8 277.0 290.8  1.06
 8  600  3919 -19.4 -23.0  73  3.6 -20.1 291  43 293.6 293.8 279.9 296.8  1.00
 9  550  4560 -23.8 -27.4  72  3.6 -24.4 287  41 295.8 296.0 280.6 298.2  0.73
10  500  5248 -29.1 -32.7  71  3.6 -29.6 281  38 297.5 297.6 281.0 299.2  0.49

[FoothillsNC]

I have noticed on the last several runs of the nam that it continues to show a band of snow that crosses the NC foothills and eventually across the piedmont. It hardly shows up or not at all on the precip maps but it does on it's simulated composite radar. Will be interesting to see if there is one.

Just an amazing temperature gradient behind the front. 850mb temps go from 0c to -10c in just a few tens of miles tomorrow. Don't see that very often around these parts. I sure hope I can at least see a few flurries. Winds are west to even almost WSW tomorrow here behind the front, which would mean less downslope drying and might allow a few more to come this way but I won't get my hopes up.

GFS does have a good bit of moisture even up to above 700mb at 0z tomorrow. Note the wind direction in the boundary layer with a south of west direction. We'll see I guess.

Date: 30 hour AVN valid 0Z MON 13 DEC 10
Station: KAHN
Latitude:   33.95
Longitude: -83.32
-------------------------------------------------------------------------------
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    33                                                             	
SFC  976   228  -2.7  -5.9  79  3.2  -3.8 251  15 272.4 272.8 270.7 279.3  2.52
 2  950   440  -3.4  -7.2  75  3.9  -4.7 259  32 273.8 274.2 271.3 280.2  2.33
 3  900   865  -6.9  -8.8  86  1.9  -7.5 269  45 274.4 274.8 271.4 280.5  2.18
 4  850  1308 -10.0 -11.3  90  1.3 -10.4 278  47 275.7 276.0 271.8 281.0  1.89
 5  800  1773 -12.7 -14.3  88  1.6 -13.1 287  44 277.6 277.9 272.4 282.2  1.58
 6  750  2263 -15.9 -17.9  85  1.9 -16.4 291  43 279.3 279.5 272.8 282.9  1.25
 7  700  2779 -19.2 -20.2  92  1.0 -19.4 289  41 281.2 281.4 273.7 284.5  1.10
 8  650  3332 -17.0 -20.9  71  4.0 -17.9 280  40 289.8 290.0 278.2 293.2  1.11

I saw that little feature too, at times it was placed in SC sometimes NC, but now that you've jinxed my flakes, thanks. Ha. I'm very impressed overall with this whole system. All it has is potential yet, not much has happened, but by the end of it, Tn, Al, Ga and NC are going to get some measurable snow in every state I think. I'm really liking the looks of central to eastern Tennessee the more I think about it. Also, the upslope region of WnC with the -16 pocket of air and the crazy ratios that will be with that. Not to mention to see the GSF and NAM have that much qpf for upslope is very unusual...they usually under do it. So thats a flag right there for some pretty good widespread 6" amounts and no doubt somewhere some 1 foot plus amounts. Lots of Tennessee, atleast eastern half or 2/3 are going to a nice whitening of the ground I think. The strong winds should make for a surreal site I'd think. You guys enjoy it. Also, must mention just how good the overall setup is in about a week, maybe. But thats another thread. By the way, think Boone is set. They are 34 with a 22 dewpoint last hour.

[FoothillsNC]

Just checked out the 18z NAM and GFS and the flizzard watch across North Georgia still looks good for tomorrow afternoon/night. High county of NC should get pounded again with flow snow as moisture is very deep. Much of TN could get 1-3" with the wrap. I think a dusting to 1" is very possible north of Atlanta and north of I85. Best time for Georgia looks to be late afternoon and into the night when the best moisture wraps in. To me it looks like FFC has a good handle on the situation.

Anyone going to make a map for this event? I haven't seen any. I think its a pretty big deal, esp. for the eastern half of Tenn, n Ga and western NC. Even n. Alabama should get some dustings.

[Itunis]

Anyone going to make a map for this event? I haven't seen any. I think its a pretty big deal, esp. for the eastern half of Tenn, n Ga and western NC. Even n. Alabama should get some dustings.

Could you give us your template for the SE region so we have easy access to a decent blank map? Thanks.

[BullCityWx]

This run of the GFS gives us snow through hour 108

[BIG FROSTY]

I'm sitting at 38/21 wb- 32

NWS says lows in mid 30's now, where this morning they had low 30's Also they in morning package said I could get 1 inch tomorrow afternoon, now it's no accum and only slight chance of snow showers. BOO ! ! Just hoping to get a little mix tonight ?

[MotoWeatherman]

Anyone going to make a map for this event? I haven't seen any. I think its a pretty big deal, esp. for the eastern half of Tenn, n Ga and western NC. Even n. Alabama should get some dustings.

I want to but I don't know if ill be able to grab enough time to put one together. Wife already thinks I spend too time on the computer. Lol.

18z GFS still looks possible for AVL to be mostly snow. We shall see soon enough.

[tnweathernut]

Anyone going to make a map for this event? I haven't seen any. I think its a pretty big deal, esp. for the eastern half of Tenn, n Ga and western NC. Even n. Alabama should get some dustings.

Thanks for all your work foothills...........you always do a good job for us. Do you think the NWS calls for 3-6 are good here in the TRI? I was leaning on 1-2 earlier today, but this wrap around looks to be much above average for the valleys here, so I guess we have a shot at it.

Good luck to all!!!

[weatherheels]

Looks like we're out of the game this go round. I'm pulling for you guys in N. Georgia and in Tenn and everyone else hoping to see their first snow of the year! I hope it dumps on you all!

[Weather Czar]

Andy wood at fox Carolina put one out last night.

[NEGa]

Any accumulation is great!

you said it! i would be very very happy with a half an inch or so, 2" is a great snowfall!

[FoothillsNC]

Thanks for all your work foothills...........you always do a good job for us. Do you think the NWS calls for 3-6 are good here in the TRI? I was leaning on 1-2 earlier today, but this wrap around looks to be much above average for the valleys here, so I guess we have a shot at it.

Good luck to all!!!

Yes I like that call for Tenn. some sections will be over the 6" in mark probably but cant say exactly where. I do like the track of th 5H low as it continues strenghtening right now in Iowa/nrn Mo, and heading southeast toward Nashville by midday tomorrow before getting absorbed. That shoudl ensure a good burst of snow , and some great ratios for you. Take pics.

[NEGa]

Anyone going to make a map for this event? I haven't seen any. I think its a pretty big deal, esp. for the eastern half of Tenn, n Ga and western NC. Even n. Alabama should get some dustings.

um, seems like i saw one posted today from some dude named "robert" lol. his looked pretty good

temp is 41.2 now

[FoothillsNC]

um, seems like i saw one posted today from some dude named "robert" lol. his looked pretty good

temp is 41.2 now

Yeah it would be nice to see others. I know its a tough call about everywhere this time. I have some ideas for the Tennessee I need to upgrade there after my latest thinking, but may hold off til 00Z.