869
FXUS62 KGSP 190010
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
710 PM EST THU DEC 18 2025
SYNOPSIS
WIDESPREAD RAIN MOVES EAST OF OUR REGION ON FRIDAY AS A COLD FRONT
TAKES THE RAIN TO THE EAST COAST. GUSTY WIND WILL LINGER OVER THE
AREA UNTIL FRIDAY EVENING. DRY HIGH PRESSURE TRANSITS ACROSS OUR
AREA EARLY IN THE WEEKEND THEN ANOTHER COLD FRONT CROSSES ON SUNDAY.
SMALL CHANCES OF MOUNTAIN PRECIPITATION IN THE MIDDLE OF NEXT WEEK,
OTHERWISE DRY.
NEAR TERM /THROUGH FRIDAY/
AS OF 700 PM THURSDAY:
KEY MESSAGE #1: DENSE FOG ADVISORY IN EFFECT UNTIL MIDNIGHT
FOR A PORTION OF THE AREA BETWEEN THE BLUE RIDGE ESCARPMENT AND
INTERSTATE 85.
IN-SITU COLD-AIR DAMMING CONTINUES ACROSS MOST OF THE CWA EAST/SOUTH
OF THE APPALACHIANS. FOLLOWING EARLIER ROUNDS OF RAINFALL, AN AREA
OF DENSE FOG DEVELOPED AROUND 3:30-4:30 PM THU AFTERNOON BETWEEN
CLARKESVILLE AND SPARTANBURG, WITH SOME DOT CAMS INDICATING DENSE
FOG IN THE ADJACENT PART OF NC BELOW THE ESCARPMENT. NO SCOURING
MECHANISM YET IN PLACE ASIDE FROM THE STRONG SW FLOW OVER THE WEDGE
PROMOTING A SLIGHT NORTHWARD CREEP IN THE WEDGE BOUNDARY. DENSE FOG
ADVISORY WAS ISSUED FOR THAT PORTION OF THE CWA THRU MIDNIGHT. SOME
SLIGHT IMPROVEMENT DID OCCUR CLOSER TO SUNSET WITH DEVELOPMENT OF
MORE SHOWERS, THOUGH NOW THAT THOSE HAVE EXITED/FIZZLED, VISIBILITY
HAS CREPT BACK DOWN. NOT SEEING A NEED TO EXPAND PRODUCT AT THIS
TIME THOUGH SOME AREAS OF 0.75 TO 1.5 MILE VSBY PERSIST FARTHER
NORTH AND EAST INTO THE NC PIEDMONT. DEVELOPMENT OF STEADIER RAIN
BY MIDNIGHT MAY HELP MIX OUT THE FOG WITH THE COLD FRONT ARRIVING
LATER IN THE NIGHT WHICH SHOULD SCOUR OUT THE WEDGE.
KEY MESSAGE #2: A COLD FRONT MOVES CROSSES THE AREA OVERNIGHT,
BRINGING MOSTLY RAIN AND A BRIEF BURST OF SNOW FOR ISOLATED
LOCATIONS IN THE MOUNTAINS.
A POTENT SHORTWAVE TROUGH IS CURRENTLY SLIDING ACROSS THE LOWER
MISSISSIPPI VALLEY WITH AN ATTENDANT SURFACE LOW TRANSITING THE
GREAT LAKES. THE TROUGH IS FORECAST TO TAKE ON A NEGATIVE TILT AS
IT SWINGS ACROSS THE APPALACHIANS THIS EVENING AND OVERNIGHT WITH
THE SURFACE LOW GRADUALLY DEEPENING AS WELL. SUBSEQUENT LOW-LEVEL
MASS RESPONSE HAS FOSTERED ROBUST WIND FIELDS WITH A 50KT LOW-LEVEL
JET PROGGED TO TRANSLATE ACROSS THE FORECAST AREA. HEIGHT FALLS
OVERSPREADING THE AREA IN CONCERT WITH WARM ADVECTION AND ISENTROPIC
ASCENT HAS ALLOWED FOR A LARGE AREA OF SCATTERED TO WIDESPREAD
SHOWERS TO SPREAD NORTH ACROSS MUCH OF THE AREA. THIS HAS ALSO
LOCKED IN AN IN-SITU COLD AIR DAMMING WEDGE EXTENDING FROM THE
FOOTHILLS INTO PORTIONS OF THE I-85 CORRIDOR. WITH THE SURFACE
HIGH SHIFTING OFFSHORE THE WEDGE WILL GRADUALLY ERODE THROUGH THE
DAY AND THIS EVENING IN THE FACE OF INCREASING WARM ADVECTION AND
MIXING ALONG THE WEDGE BOUNDARY. THE TRADITIONAL LOCATIONS NESTLED
IN THE IMMEDIATE FOOTHILLS OF MCDOWELL, BURKE AND CALDWELL COUNTIES
WILL LIKELY REMAIN UNDER SOME DEGREE OF CAD THROUGH THE DURATION
OF THE EVENT, HOWEVER.
EVENTUALLY, A STRONGLY FORCED CONVECTIVE LINE ANCHORED JUST AHEAD
OF THE SURFACE COLD FRONT RACING ACROSS TENNESSEE WILL APPROACH THE
MOUNTAINS LATE THIS EVENING. HEAVIER RAINFALL RATES WILL LIKELY
ACCOMPANY THIS ACTIVITY AND A STRAY RUMBLE OF THUNDER CANNOT BE
COMPLETELY RULED OUT. A COUPLE LOCALLY STRONG WIND GUST WITH THE
LINE WILL ALSO BE POSSIBLE ACROSS THE IMMEDIATE TENNESSEE BORDER
BEFORE THE LINE BEGINS TO LOSE STRUCTURE OVER THE MOUNTAINS. AT
LEAST SOME DEGREE OF A BROKEN LINE OF SHOWERS WILL PERSIST EAST
OF THE MOUNTAINS THROUGH THE OVERNIGHT AND ATTENTION WILL HAVE TO
BE CLOSELY PAID AS TO HOW FAR NORTH THE WEDGE BOUNDARY RETREATS
AND WHERE IT RESIDES. 12Z CAMS INDICATE THE POTENTIAL FOR MID
TO UPPER 50S DEWPOINTS TO ENCROACH ON THE I-85 CORRIDOR. SHEAR
PROFILES ARE MORE THAN SUPPORTIVE OF ORGANIZED CONVECTION, BUT
INSTABILITY WILL BE HELD IN CHECK OWING TO POOR LAPSE RATES AND
NEUTRAL STABILITY. NONETHELESS, AROUND 100 J/KG OF MLCAPE CANNOT
BE COMPLETELY DISCOUNTED AND STRONGLY FORCED EVENTS CAN OFFSET
MARGINAL THERMODYNAMIC PROFILES VIA INTENSE DYNAMICAL FORCING TO
HELP MAINTAIN CONVECTIVE ELEMENTS IN OTHERWISE POOR ENVIRONMENTS.
CONVECTIVE INTERACTIONS WITH WEDGE BOUNDARIES HAVE ALSO BEEN KNOWN
TO CAUSE MISCHIEF, THUS WHILE THE CHANCES FOR SEVERE WEATHER ARE
VERY LOW, A VERY SMALL BUT NON-ZERO CHANCE FOR A BRIEF DAMAGING
WIND GUST OR ISOLATED TORNADO CANNOT BE DISCOUNTED.
KEY MESSAGE #2: GUSTY WINDS CONTINUE ON FRIDAY, ESPECIALLY AT
HIGHER ELEVATIONS, ALONG WITH A RETURN OF DRY CONDITIONS.
THE SURFACE COLD FRONT WILL RACE ACROSS THE AREA DURING THE
OVERNIGHT HOURS AND SHOULD BE OFF TO OUR EAST BY DAYBREAK. THIS WILL
BRING AN END TO ANY PRECIPITATION OUTSIDE OF A VERY BRIEF WINDOW
FOR A COUPLE ISOLATED SNOW SHOWERS ALONG THE TENNESSEE BORDER OF THE
NORTHERN MOUNTAINS. THE MAIN FOCUS THEN SHIFTS TO STRONG WIND GUSTS
THROUGH MUCH OF THE DAY ON FRIDAY. A TIGHT PRESSURE GRADIENT WILL
SETUP SHOP ACROSS THE MOUNTAINS WITH THE TYPICAL COLD ADVECTION
PORTIONS OF THE BLUE RIDGE ESCARPMENT EXPECTED TO SEE ADVISORY
LEVEL WIND GUSTS. THE WIND ADVISORY REMAINS WELL PLACED AND NO
CHANGES WERE NEEDED. A FEW HIGH ELEVATION LOCATIONS, SUCH AS THE
BLACK MOUNTAINS AND GRANDFATHER MOUNTAIN, WILL LIKELY SEE HIGH
WIND WARNING CRITERIA GUSTS, BUT COVERAGE OF HIGHER GUSTS SHOULD
REMAIN ON ISOLATED PEAKS AND HAVE THUS OPTED TO KEEP THE ADVISORY
AND HOLD OFF ON ANY UPGRADES TO HIGH WIND WARNING AT THIS TIME.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/
AS OF 1215 PM THURSDAY...
KEY MESSAGE #1: DRY HIGH PRESSURE AND DIMINISHING WINDS SATURDAY.
ANY LINGERING GUSTY WINDS WILL QUICKLY DIMINISH FRIDAY NIGHT AS THE
CENTER OF SURFACE HIGH PRESSURE SETTLES IN OVER THE AREA AND REMAINS
IN PLACE ON SATURDAY. DRY CONDITIONS EXPECTED WITH LOWS AROUND 5
DEGREES BELOW NORMAL AND HIGHS RANGING FROM NEAR TO 5 DEGREES ABOVE
NORMAL.
KEY MESSAGE #2: A MAINLY DRY COLD FRONT CROSSES THE AREA SUNDAY WITH
GUSTY WINDS.
HIGH PRESSURE SLIDES EAST SATURDAY NIGHT AS A COLD FRONT APPROACHES
FROM THE WEST, THEN CROSSES THE AREA DURING THE DAY SUNDAY. THERE IS
VERY LITTLE MOISTURE OR MOISTURE INFLOW ASSOCIATED WITH THE FRONT.
THERE MAY BE ENOUGH FOR SOME SPRINKLES AS THE FRONT MOVES THROUGH
DURING THE DAY, BUT ANY PRECIP WOULD BE SPOTTY AND VERY LIGHT. WINDS
DO PICK BACK UP AHEAD OF AND BEHIND THE FRONT, WITH WINDY CONDITIONS
ACROSS THE MOUNTAINS AND BREEZY ELSEWHERE, BUT WELL BELOW ADVISORY
LEVEL. LOWS SLIGHTLY ABOVE NORMAL WITH HIGHS NEAR NORMAL FOR THE
MOUNTAINS AND AROUND 5 DEGREES ABOVE NORMAL ELSEWHERE.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
AS OF 1240 PM THURSDAY...
KEY MESSAGE #1: DRY CONDITIONS FOR MOST LOCATIONS, ALTHOUGH SOME
PRECIPITATION MAY RETURN ACROSS THE NORTH CAROLINA MOUNTAINS AT
TIMES.
DRY HIGH PRESSURE BUILDS INTO THE AREA MONDAY THEN WEAKENS AND
SLIDES SOUTH TUESDAY AND WEDNESDAY AS A LOW PRESSURE SYSTEM MOVES BY
TO THE NORTH AND DRAGS A COLD FRONT SOUTH TOWARD THE AREA. THE
GUIDANCE DIFFERS ON THE EXACT LOCATION OF THE FRONT, BUT IT MAY BE
CLOSE ENOUGH FOR SOME LIGHT PRECIP TO DEVELOP ACROSS THE MOUNTAINS
EACH DAY AS MOISTURE MOVES AROUND THE PERIPHERY OF THE SURFACE HIGH.
CONFIDENCE IS LOW ON PRECIP CHANCES, SO THE VERY SMALL COVERAGE AND
POP OF THE NBM IS REASONABLE. TEMPS WOULD BE COLD ENOUGH THAT PRECIP
MOVING INTO THE MOUNTAINS LATE TUE NITE AND EARLY WED COULD INCLUDE
A SPOTTY MIX OF FREEZING RAIN. CONFIDENCE IS LOW ON PRECIP CHANCES
AND TYPES. RIGHT NOW, NO SIGNIFICANT ICE ACCRETION IS EXPECTED.
KEY MESSAGE #2: SEASONAL TEMPS MONDAY THEN A SIGNIFICANT WARM UP
THROUGH CHRISTMAS DAY.
TEMPS ON MONDAY WILL BE AROUND 5 DEGREES BELOW NORMAL, RISING TO
NEAR OR A LITTLE ABOVE NORMAL ON TUESDAY. THE BIGGER WARMING TREND
TAKES PLACE WEDNESDAY INTO CHRISTMAS DAY WITH LOWS AND HIGHS RISING
TO NEARLY 15 DEGREES ABOVE NORMAL.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: COLD-AIR DAMMING IS ASSOCIATED WITH
LARGELY LIFR CIGS ACROSS THE TERMINAL AREA. THOUGH RESTRICTIONS
ARE CURRENTLY LESS SEVERE AT KCLT, KAND AND POINTS SOUTH, NEARER
THE CAD BOUNDARY, THINK THESE WILL LARGELY LOWER AGAIN DURING
THE EVENING. BOUTS OF VSBY BELOW MINIMA POSSIBLE ESPECIALLY AT
KGSP/KGMU. FREQUENT -SHRA ARE EXPECTED TO REDEVELOP WHICH COULD
LEAD TO BRIEF IMPROVEMENT BUT OVERALL LIFR CONDITIONS PREVAIL
UNTIL COLD FRONT PASSES FROM WEST TO EAST EARLY FRIDAY MORNING;
IMPROVEMENT TO SCT-BKN MVFR LEVEL CLOUDS BY 08Z AT KAVL, 11Z AT
KCLT, WITH CIGS SCATTERING AND VFR PREVAILING BY SUNRISE. WINDS
TURN SW LATER THIS EVENING WHERE NOT ALREADY AND BECOME GUSTY
AT 20-30 KT PRIOR TO FROPA. CANNOT RULE OUT A BRIEF/ISOLATED TS
WITH BAND OF CONVECTION IMMEDIATELY AHEAD OF FRONT, AND ANY MORE
VIGOROUS SHOWERS OR TSRA POTENTIALLY WILL RESULT IN 40+ KT GUST;
THIS IS TOO ISOLATED TO REFLECT IN TAFS. LLWS CONDITIONS EXPECTED
TO BE MET HERE AND THERE AROUND THE REGION UNTIL WINDS FLIP TO
NW'LY BEHIND THE FRONT, BUT LLWS LIKELY TO RECUR DURING THE DAY
FRIDAY DUE TO MOUNTAIN WAVE IN THE LEE OF THE APPALACHIANS, NEAR
KAVL AND WEST OF KHKY. EXCEPT KAVL WHERE WINDS REMAIN GUSTY THRU
THE END OF THE PERIOD, GUSTS WEAKEN IN LATE AFTERNOON AND SHOULD
SUBSIDE AFTER SUNSET FRI.
OUTLOOK: VFR CONDITIONS CONTINUE THROUGH THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...DENSE FOG ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR GAZ010-017-
018.
NC...DENSE FOG ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ064-065-
507>510.
WIND ADVISORY FROM 7 AM TO 7 PM EST FRIDAY FOR NCZ033-048>053-
058-059-062-063.
SC...DENSE FOG ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR SCZ010-
101>109.
SYNOPSIS...DEO
NEAR TERM...JCW/TW
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...JCW
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