Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 311456
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1056 AM EDT FRI OCT 31 2014

.SYNOPSIS...
MOISTURE WILL INCREASE TODAY OUT AHEAD OF AN APPROACHING COLD
FRONT. THIS FRONT...AND A STRONG MID LEVEL AREA OF LOW PRESSURE IS
FORECAST TO TRACK ACROSS THE REGION TONIGHT INTO SATURDAY. A
STRONG SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OFFSHORE ON
SATURDAY...THEN TRACK QUICKLY NORTH BY SATURDAY NIGHT. CIRCULATION
AROUND THE COASTAL LOW WILL BRING A COLD CANADIAN AIR MASS TO THE
REGION THROUGH MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM...WATER VAPOR IMAGERY SHOWS A LEAD SHORTWAVE DIVING
INTO THE TROUGH AXIS ALONG THE APPALACHIANS LATE THIS MORNING. THE
MAIN PLAYER AT 500 MB IS DIGGING INTO IN/IL. THE FORECAST IS ON
TRACK FOR TODAY...EXCEPT THAT WESTERN MTN POPS FOR LIGHT RAIN
SHOWERS WILL BE INCREASED ALONG THE TN BORDER THROUGH MIDDAY WITH
THE EARLY UPPER WAVES.

OTHERWISE...THE STRONGLY DYNAMIC UPPER LOW WILL DROP DOWN ACROSS THE
WESTERN CAROLINAS TONIGHT TO A POSITION OVER THE WRN UPSTATE AT
DAYBREAK ON SATURDAY. THIS COMPACT SYSTEM SHOULD HAVE ALL MANNER OF
LOW/MID/UPPER FORCING THAT COMES INTO PLAY THIS EVENING AND
OVERNIGHT. MOISTURE SHOULD ALSO BE FAIRLY DEEP...SO THE POP RAMPS UP
TO CATEGORICAL OVER THE MTNS THIS EVENING...AND INTO THE LIKELY
RANGE ACROSS MOST OF THE FOOTHILLS AND WRN PIEDMONT...AND EVENTUALLY
CATEGORICAL OVER THE WRN PIEDMONT...WHERE FORCING IS MAXIMIZED ON
THE N SIDE OF THE UPPER LOW. PRECIP WAS LIMITED TO THE CHC RANGE
OVER THE WRN UPSTATE AND NE GEORGIA AS SOME DOWNSLOPE FLOW MAY
INHIBIT PRECIP DEVELOPMENT.

THE DISTRIBUTION OF PARTIAL THICKNESS ACCOMPANYING THE UPPER LOW
WILL BE DECIDEDLY WINTER-LIKE. STRONG COLD ADVECTION THIS EVENING
SHOULD ALLOW PRECIP TO CHANGE OVER FROM RAIN TO SNOW FROM RIDGETOPS
DOWN TO THE VALLEYS ACROSS THE NC MTNS BY THE EARLY MORNING HOURS.
EAST OF THE MTNS...THE LATEST GFS SUGGESTS A SLIGHT UPWARD TREND IN
TEMP AND DEWPT BY DAYBREAK SATURDAY PERHAPS BECAUSE THE OPERATIONAL
MODEL WAS WETTER...WHICH WAS GENERALLY FOLLOWED. THAT SHOULD BUMP
THE SFC WET BULB TEMPS UP A BIT MORE...MEANING LESS OF A CHANCE OF
SEEING ANY SNOW E OF THE FOOTHILLS THRU 12Z SATURDAY. WILL GIVE A
NOD TO THE COOLER NAM BUFKIT PROFILES THAT SUGGEST A POSSIBILITY OF
A WET SNOWSHOWER AROUND DAYBREAK OVER THE NC FOOTHILLS AND WRN
PIEDMONT...BUT THIS MIGHT NOT YET MAKE THE CUT AND APPEAR IN THE
FCST. SNOW STILL LOOKS LIKE A GOOD BET OVER THE MTNS MAINLY NEAR THE
TN BORDER...WITH UPWARDS OF 2-4 INCHES POSSIBLE BY SUNRISE. SOME OF
THE SNOW MAY WRAP AROUND INTO THE UPPER SAVANNAH RIVER BASIN AND NE
GEORGIA AROUND SUNRISE. HOWEVER...THOSE LOCATIONS HAVE THE LOWEST
PROBABILITY OF ANY PRECIP REACHING THE GROUND...AT THE LOW END OF
THE CHC RANGE. AN ADVISORY WILL NOT BE ISSUED YET FOR THE REST OF
THE SRN MOUNTAINS OF NC AND NE GEORGIA...INSTEAD WILL TAKE A LOOK AT
THE MORNING MODEL RUNS FOR MORE GUIDANCE AND CONFIDENCE.

FREEZE WARNINGS REMAIN OUT FOR TONIGHT WITH THE MTN GROWING SEASON
ENDING TOMORROW.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 320 AM EDT FRIDAY...THE LATEST 00Z SHORT RANGE MODELS
CONTINUE TO INDICATE THAT AN ANOMALOUS UPPER LOW JUST SOUTH OF OUR
CWA 12Z SAT WILL MOVE OFF THE SE COAST BETWEEN 21Z SAT AND 00Z SUN
WITH AN UNSEASONABLY COLD AIRMASS FILTERING IN BEHIND THE LOW IN
ITS WAKE. MODELS HAVE TRENDED A BIT WETTER...ESPECIALLY EAST OF
THE MTNS ON EARLY SAT AS BETTER DEFORMATION ZONE OVER THE NORTHERN
PERIPHERY OF THE UPPER LOW SETS UP OVER THE WESTERN CAROLINAS
PIEDMONT. HOWEVER...LATEST MODEL TEMPS OUT SIDE OF THE MTNS APPEAR
A BIT WARMER THAN THE PREVIOUS MODEL RUNS. HENCE...HAVE UPDATED WX
GRIDS TO HIGHLIGHT MORE OF LIQUID PRECIP OVER THE PIEDMONT. STILL
WITH COLDER TEMPS OVER THE MTNS...EXPECT HEAVY SNOW ACCUMS TO
OCCUR THROUGH EARLY SUN MAINLY ALONG THE TN BORDER. TOTAL SNOWFALL
FROM THIS EVENT WILL RANGE FROM 8" OVER THE NORTHERN NC MTNS TO
12" OVER THE SMOKIES. ELSEWHERE OVER THE NC MTNS WILL SEE BETWEEN
1 AND 2 INCHES OF SNOW. HENCE...WILL CONTINUE TO HIGHLIGHT A
WINTER STORM WARNING OVER THE TN BORDER COUNTIES AND A WINTER
WEATHER ADVISORY OVER BUNCOMBE...NORTHERN HALF OF JACKSON...AND
GRAHAM COUNTIES.

GUSTY NW WINDS OF 20-40 MPH WILL DEVELOP ON SAT IN LIGHT OF
TIGHTENING SURFACE PRESSURE GRADIENT BETWEEN A DEVELOPING SURFACE
LOW OFF THE SE COAST AND STRONG HIGH PRESSURE TO OUR WEST.
AS THE UPPER LOW MOVES OFF TO THE EAST...POPS TAPER OFF FROM WEST TO
EAST THROUGH SAT EVENING. TEMPERATURES ON SAT WILL REMAIN WELL BELOW
NORMAL (AROUND 15-20 BELOW NORMAL). SUN LOOKS MOSTLY DRY AS THE
CANADIAN HIGH SETTLES OVER THE REGION. NW SNOW OVER THE NC MTNS WILL
TAPER OFF BY EARLY SUN AS DRY AIRMASS MOVES IN. MORNING LOW TEMPS ON
SUNDAY WILL BE QUITE COLD...RANGING FROM LOW TO MID 30S OVER THE
PIEDMONT TO 20S IN THE MTNS/VALLEYS. WITH THE PRESENCE OF DECENT NW
CAA WINDS...WIND CHILL READING WILL REMAIN IN THE 10S IN THE MTNS
WITH 20S ELSEWHERE. HOWEVER...TEMPS ON SUN AFTERNOON WILL BE WARMER
THAN SAT...BUT STILL LOOKING AROUND 7-15 DEGREES BELOW NORMAL.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 250 AM EDT FRIDAY...LATEST GLOBAL MODELS CONTINUE TO AGREE
THAT AN UPPER RIDGE AXIS IS FORECAST TO CROSS THE FORECAST AREA ON
MONDAY AND OFF TO THE EAST COAST BY TUE. SWLY FLOW ALOFT WILL THEN
SET UP BY TUE NIGHT AS A POSITIVELY TILED UPPER TROUGH APPROACHES
FROM THE CENTRAL CONUS. THIS UPPER TROUGH WILL CROSS THE REGION ON
THU FOLLOWED BY NWLY FLOW THU NIGHT.

AT THE SURFACE...A DRY HIGH PRESSURE CENTERED OVER THE SE STATES MON
WILL GRADUALLY SHIFT OFFSHORE THROUGH WED AS A WEAK COLD FRONT
APPROACHES FROM THE WEST. THE FRONT WILL CROSS THE REGION AROUND WED
NIGHT AND OFF TO OUR EAST BY FRI MORNING. MODELS INDICATE THAT THE
FRONT WILL DRY OUT AS IT REACHES THE MTNS. HENCE...HAVE CARRIED
SLIGHT TO LOW END CHANCE POP MAINLY ALONG THE TN BORDER DURING THE
FROPA. OTHERWISE...CONDITIONS LOOK DRY THROUGHOUT THE MEDIUM RANGE
PERIOD. TEMPERATURES WILL QUICKLY WARM UP TO NEAR CLIMO BY TUE.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
AT KCLT...BRIEF MORNING MVFR CIGS SCATTERED OUT VERY QUICKLY WITH
HEATING...SO VFR WILL REMAIN THROUGH THE DAY AS MID AND HIGH
CLOUDS INCREASE. BY MID/LATE AFTERNOON...THE WIND SHOULD BE LIGHT
AND VARIABLE AND MAY CHANGE BETWEEN NW AND SW OFTEN. AT THAT
TIME... A LOW CLOUD CEILING SHOULD MOVE IN FROM THE NW AHEAD OF
THE APPROACHING LOW...BUT STILL VFR. THE LATEST MODEL GUIDANCE IS
IN GOOD AGREEMENT WITH DEVELOPING LIGHT PRECIP INTO THE CLT METRO
AREA AROUND SUNSET. A CONSENSUS OF THE GUIDANCE SUGGESTS A
PREVAILING LIGHT RAIN...BUT WITH STILL A VFR CATEGORY
VISIBILITY...AFTER 02Z. WIND AT THAT TIME SHOULD SETTLE INTO A N
COMPONENT. NO ISSUES WITH PRECIP TYPE UNTIL AFTER 06Z
SATURDAY...WITH SNOW SHOWERS LIKELY MIXING IN AT TIMES EARLY SAT
MORNING.

ELSEWHERE...EXPECT VFR THROUGH THE DAYLIGHT HOURS TODAY. LIGHT AND
VARIABLE WINDS AND INCREASING MID/HIGH CLOUDS ARE EXPECTED THROUGH
MID MORNING. LOW VFR AND MID CLOUDS INCREASE THRU THE DAY WITH LOW
VFR CIGS EXPECTED BY AFTERNOON AT KAVL. WINDS TURN WSW THIS
AFTERNOON AHEAD OF THE APPROACHING COLD FRONT. HOWEVER...WINDS
REMAIN NLY AT KAVL. KAVL ALSO HAS THE BEST CHC OF SEEING ANY SHRA BY
LATE IN THE AFTERNOON...WHICH WAS INCLUDED AS A VCSH AT THIS TIME.
THE STEADIER RAIN SHOULD MOVE INTO THE MTNS BY SUNSET. HAVE INCLUDED
THE RAIN PREVAILING AFTER 02Z AT KAVL...AT WHICH TIME THE CEILING
SHOULD DROP TO MVFR. PRELIMINARY INDICATION IS THAT PRECIP COULD
CHANGE OVER TO SNOW SHOWERS AT KAVL AS EARLY AS 05Z.  A SIMILAR
PROGRESSION IS NOTED AT KHKY...BUT PRECIP WAS KEPT LIQUID. OTHER TAF
SITES ONLY HAVE A VCSH AFTER 02Z OR 03Z...OWING TO LOW CONFIDENCE.

OUTLOOK...LIGHT PRECIP WILL DEVELOP ACROSS THE ENTIRE AREA LATE
FRIDAY NIGHT. SOME RESTRICTIONS ARE POSSIBLE...ESPECIALLY IN THE
MOUNTAINS WHERE EVEN SOME SNOW SHOWERS ARE EXPECTED LATE FRIDAY
NIGHT AND SATURDAY. VFR BEYOND SUNDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FREEZE WARNING FROM 11 PM THIS EVENING TO 10 AM EDT SATURDAY
     FOR GAZ010.
NC...WINTER STORM WARNING FROM 8 PM THIS EVENING TO 8 PM EDT
     SATURDAY FOR NCZ033-048>052.
     FREEZE WARNING FROM 11 PM THIS EVENING TO 10 AM EDT SATURDAY
     FOR NCZ033-049-050-053-063>065.
     WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT
     SATURDAY FOR NCZ053-058-059.
SC...NONE.

&&

$$
SYNOPSIS...JOH
NEAR TERM...HG/PM
SHORT TERM...JOH
LONG TERM...JOH
AVIATION...HG/PM



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