354
FXUS62 KGSP 291117
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
617 AM EST SAT NOV 29 2025
SYNOPSIS
BELOW NORMAL HIGH TEMPERATURES STICK AROUND THROUGH NEXT WEEK. DRY
AND COLD HIGH PRESSURE REMAINS IN CONTROL THROUGH TODAY BEFORE A
COLD FRONT BRINGS PRECIPITATION CHANCES SUNDAY. DRIER CONDITIONS
DEVELOP BRIEFLY MONDAY BEFORE A LOW PRESSURE SYSTEM FROM THE GULF
BRINGS BETTER PRECIPITATION CHANCES MONDAY NIGHT AND TUESDAY. DRY
HIGH PRESSURE RETURNS WEDNESDAY INTO THURSDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 603 AM EST SATURDAY...
KEY MESSAGES:
1) QUIET BUT COLD WEATHER TONIGHT AND SATURDAY, WITH FRIGID LOWS
IN THE 20S THIS MORNING, AND HIGHS ONLY CLIMBING INTO THE 40S
THIS AFTERNOON.
2) INCREASING CLOUD COVER SATURDAY AND SATURDAY NIGHT AS IN SITU
COLD-AIR DAMMING DEVELOPS.
3) WINTRY MIX DEVELOPS OVER THE BLUE RIDGE SATURDAY NIGHT, WITH
ISOLATED LIGHT ICE ACCUMULATIONS POSSIBLE. WINTER WEATHER ADVISORY
NOW IN EFFECT FOR AVERY COUNTY BEGINNING 1 AM SUNDAY.
STILL SEEING WIDESPREAD CIRRUS STREAMING ACROSS THE CWA THIS
MORNING, ALBEIT WITH A LITTLE LESS COVERAGE OVER THE NC PIEDMONT
THAN ORIGINALLY ANTICIPATED. WINDS OVER MUCH OF THE AREA HAVE
REMAINED A LITTLE STEADIER THAN EXPECTED, WHICH HAS RESULTED IN
TEMPERATURES RUNNING 1-3 DEGREES WARMER THAN FORECAST. STILL,
SEEING WIDESPREAD TEMPS IN THE 20S ALREADY, AND EVEN THE WARMEST
OF SITES ARE APPROACHING 30 DEGREES WITH AT LEAST ANOTHER 1-2
HOURS OF COOLING BEFORE HITTING THEIR NADIR.
OTHERWISE...SURFACE HIGH PRESSURE WILL QUICKLY MIGRATE EASTWARD
ACROSS THE MID-ATLANTIC TODAY, REACHING THE ATLANTIC COAST BY LATE
AFTERNOON OR EVENING, AND CONTINUING NORTHEASTWARD INTO THE NIGHT.
HIGH TEMPERATURES WILL ONLY CLIMB INTO THE MID-40S THIS AFTERNOON.
BY TONIGHT, WE'LL HAVE A BRIEF WINDOW DURING WHICH THERE'S A SIGNAL
FOR SOME SYNOPTICALLY-SUPPORTED COLD-AIR DAMMING DEVELOPMENT...BUT
WITH THE HIGH CONTINUING EASTWARD AND SURFACE-CAA WEAK TO BEGIN
WITH, THAT WINDOW WILL BE *VERY* BRIEF. NONETHELESS, AS LOW-LEVEL
ISENTROPIC ASCENT BEGINS AFTER SUNSET, THERE WILL ALREADY BE A
SOMEWHAT COOL SURFACE LAYER BENEATH IT.
THE REAL ACTION SHOULD TAKE PLACE AFTER MIDNIGHT TONIGHT, AS
CONTINUED ISENTROPIC ASCENT RESULTS IN THE DEVELOPMENT OF A WARM
NOSE, AND A STRONG LLJ CENTERED AROUND THE 850MB LEVEL PASSES TO
OUR NORTHWEST...USHERING IN BETTER MOISTURE CONTENT AND MOISTENING
PROFILES FROM THE TOP DOWN. PRECIPITATION MAY NOT START IN EARNEST
OVER THE MOUNTAINS UNTIL A COUPLE HOURS BEFORE DAYBREAK, BUT SOME
CAMS AS WELL AS GENERAL PATTERN RECOGNITION WOULD SUPPORT PATCHY WAA
DRIZZLE AS EARLY AS 1 AM. IT THUS APPEARS THAT DESPITE THE LACK OF
SYNOPTICALLY-SUPPORTED COOLING, SOME LOCATIONS ALONG THE SAVANNAH
RIVER VALLEY AND ACROSS THE APPALACHIANS COULD SEE SOME DIABATIC
COOLING, WHICH FOR THE MOUNTAINS AT LEAST, SHOULD BRING VALLEYS TO
NEAR OR BELOW FREEZING A FEW HOURS BEFORE DAYBREAK. THEREFORE,
LIGHT ICE ACCUMULATIONS ARE EXPECTED TO DEVELOP, PARTICULARLY ON
ELEVATED SURFACES, ACROSS PARTS OF THE MOUNTAINS. CONFIDENCE AND
COVERAGE ARE HIGHEST IN THE NORTHERN BLUE RIDGE, ESPECIALLY AVERY
COUNTY, WHERE A WINTER WEATHER ADVISORY WILL BE ISSUED BEGINNING
AT 1 AM SUNDAY MORNING AND CONTINUING THROUGH 9 AM, BY WHICH TIME
VIRTUALLY THE ENTIRE COUNTY SHOULD BE ABOVE FREEZING, PRECLUDING
FURTHER ICING. TEMPERATURES SHOULD CONTINUE TO RISE AFTER DAYBREAK
SUNDAY, SO FOR ANY ZONES WHERE FREEZING RAIN IS OCCURRING, A QUICK
CHANGEOVER TO LIQUID RAIN IS EXPECTED THAT WILL CONTINUE INTO THE
EARLY AFTERNOON SUNDAY AHEAD OF AN ADVANCING COLD FRONT.
SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/
AS OF MIDNIGHT SATURDAY MORNING:
KEY MESSAGE 1: PRECIP WILL TAPER OFF SUNDAY AFTERNOON, MOST LIKELY
ENDING AS RAIN EVEN IN THE MOUNTAINS.
SUNDAY AFTERNOON, PREFRONTAL SHOWER ACTIVITY WILL PROGRESS ACROSS THE
PIEDMONT. AN LOW-LEVEL INVERSION LOOKS TO PERSIST, ATTRIBUTABLE TO
THE WEAK CAD, WITH A STRONGER SUBSIDENCE INVERSION DEVELOPING DURING
THE AFTERNOON KEEPING MOISTURE SHALLOW. VERY SHALLOW CONVECTION MAY
OCCUR ABOVE THE WEDGE BUT OVERALL QPF IS SMALL. POPS DIMINISH AS CAMS
AND GLOBAL MODELS LARGELY DEPICT THE REMAINING PRECIP FIZZLING OUT AS
IT PASSES EAST OF THE MOUNTAINS. MOST MODELS DEPICT SW WINDS DURING
THE AFTERNOON, BUT WITH CLOUDS NOT LOOKING TO BREAK UNTIL SUNDAY
NIGHT, MAX TEMPS ARE LIMITED TO THE UPPER 40S TO NEAR 50 IN THE UPPER
PIEDMONT, AND LOWER 50S SE OF I-85. TEMPS WILL BE WARM ENOUGH FOR ALL
RAIN IN THE MOUNTAINS AFTER 18Z. THE MOUNTAIN VALLEYS AND FOOTHILLS
MAY BE PARTICULARLY WARM WITH DOWNSLOPE FLOW DEVELOPING. THE
MOISTURE IN THE NW FLOW LAYER BEHIND THE FRONT IS SHALLOW SO POPS ARE
TOO SMALL TO MENTION NEAR THE TN BORDER, BUT FLURRIES OR SOME LIGHT
RIME ICING COULD OCCUR AS TEMPS FALL IN THE LATE AFTN AND EVENING.
TEMPS TREND COLDER IN THE MOUNTAINS AND I-40 CORRIDOR SUN NIGHT, BUT
END UP SLIGHTLY WARMER ELSEWHERE, THOUGH MINS STILL LOOK SEVERAL
BELOW NORMAL FOR MON MORNING.
KEY MESSAGE 2: A LIGHT WINTRY MIX APPEARS LIKELY IN PORTIONS OF THE
MOUNTAINS AND NORTHERN FOOTHILLS MONDAY NIGHT OR EARLY TUESDAY
MORNING.
THE FORECAST EVOLUTION OF THE NEXT SYSTEM HAS NOT CHANGED APPRECIABLY
FROM THAT DISCUSSED 24 HOURS AGO. HIGH PRESSURE WILL MIGRATE FROM THE
MIDWEST/OH VALLEY TO THE NY/PA/NJ AREA OVER THE COURSE OF MONDAY.
COLD FRONT WILL STALL SOUTH OF THE HIGH, AND DEEP SHORTWAVE CROSSING
THE OZARKS AND LOWER MS VALLEY MONDAY NIGHT AND INDUCING MILLER-A
CYCLOGENESIS. SURFACE HIGH IS IN A SOMEWHAT MORE FAVORABLE POSITION
FOR CAD WITH THIS EVENT; TEMPS WILL TREND SLIGHTLY COOLER FOR MONDAY
WITH WINDS REMAINING NE'LY OVER MOST OF THE AREA THRU THE DAY.
PRECIP CHANCES DEVELOP FROM SW TO NE AS THE FRONT ACTIVATES MONDAY
EVENING, STEADILY INCREASING THRU DAYBREAK TUESDAY, REMAINING IN THE
CATEGORICAL 80-95% RANGE UNTIL THE INCIPIENT LOW PULLS AWAY TUESDAY
AFTERNOON AND CHANCES DIMINISH FROM THE WEST. CONFIDENCE REMAINS
FAIRLY HIGH THAT SOUTH AND EAST OF THE BLUE RIDGE ESCARPMENT, THIS
WILL BE AN ALL-RAIN EVENT. TEMPS SHOULD BE MOSTLY OR ENTIRELY ABOVE
FREEZING IN THE MOUNTAINS IF POPS BEGIN AS SOON AS SOME MODELS
SUGGEST MONDAY EVENING, BUT DIABATIC COOLING LOOKS TO BRING THEM
BELOW FREEZING FOR A TIME AFTER PRECIP BEGINS. THOSE MODELS RESOLVING
P-TYPE SUGGEST MAINLY A RAIN OR FREEZING RAIN SPLIT BASED ON SFC
TEMP, GIVEN THE STRENGTH AND SATURATION WITHIN THE WARM NOSE ALOFT.
HOW EFFECTIVE THE DIABATIC COOLING IS AT ONSET TO LOCK IN SUBFREEZING
TEMPS THUS LOOKS THE PRIMARY DETERMINANT OF FORECAST IMPACTS. HAVE
CHOSEN TO ADVERTISE SLEET ALONG WITH FREEZING RAIN WHERE THE LATTER
WAS FAVORED BY OUR ALGORITHM, IN ORDER TO REFLECT "MIXY" IMPACTS,
GIVEN THAT WE OFTEN CAN'T ACCOUNT FOR ENOUGH SLEET, AND WITH SOME
QUESTION AS TO HOW MUCH QPF WILL TRANSLATE TO ICE ACCUMULATION. AREAS
THAT RECEIVE A FEW HOURS OF FREEZING RAIN--THE MOST LIKELY AREA BEING
THE MOUNTAINS AND FOOTHILLS NORTHEAST OF THE FRENCH BROAD--LOOK
LIKELY TO NEED A WINTER WX ADVISORY AS THE EVENT NEARS. HIGH
ELEVATIONS OF THE BALSAMS MIGHT SEE SOME FREEZING RAIN ALSO, ALTHOUGH
CURRENT FORECAST ACCUMS MAY REFLECT TOO EARLY OF AN ONSET THERE AND
THUS MAY BE SLIGHTLY INFLATED. MOISTENING AND WARMING TEMPS IN THE
MOUNTAINS ON THE BACK SIDE OF THE SYSTEM LOOK TO BRING P-TYPE OVER TO
ALL RAIN BY 8-9 AM IN MOST AREAS OF THE MOUNTAINS, THOUGH A FEW OF
THE HIGHEST PEAKS MAY QUICKLY TRANSITION TO SNOW AS CAA SETS IN BY
NOON OR SO. LIGHT ACCUMULATION OF NW FLOW SNOW NEAR THE TN BORDER
COULD OCCUR THRU EVENING BUT ALL POPS FALL BELOW SLIGHT-CHANCE BY
MIDNIGHT. SEVERAL DEGREES COLDER TUE NIGHT VERSUS THE PREVIOUS NIGHT.
LONG TERM /WEDNESDAY THROUGH FRIDAY/
AS OF 100 AM FRI:
KEY MESSAGE 1: DRY WEATHER AND MODERATING TEMPERATURES WEDNESDAY AND
THURSDAY.
QUASI-ZONAL UPPER PATTERN RETURNS BY EARLY WED WITH HIGH PRESSURE
MIGRATING ACROSS THE SOUTHEAST, COMPARATIVELY WEAK TO THE PREVIOUS
TWO HIGHS. WINDS WILL BE LIGHT WEDNESDAY BUT SKIES TREND CLEAR, AND
TEMPS REBOUND SLIGHTLY. MID TO UPPER LEVEL FLOW TURNS SLIGHTLY
CYCLONIC WED NIGHT AND A DRY COLD FRONT LOOKS TO PUSH ACROSS THE
AREA. SOME HIGH ALTITUDE CLOUD COVER MAY RETURN, BUT SKIES REMAIN
PARTLY CLOUDY. WESTERLY DOWNSLOPE FLOW DEVELOPS THU WITH THE
INCOMING, STRONGER HIGH, WHICH WILL ALLOW TEMPS TO INCREASE FURTHER
DESPITE THE CLOUDS, ESPECIALLY EAST OF THE MOUNTAINS. TEMPS WILL
REMAIN BELOW NORMAL, ALTHOUGH BACK TO WITHIN 2-3 DEGREES THEREOF IN
THE PIEDMONT.
KEY MESSAGE 2: ANOTHER BRIEF FREEZING RAIN EVENT COULD OCCUR IN THE
MOUNTAINS THURSDAY NIGHT INTO FRIDAY MORNING, WITH CHANCES FOR RAIN
ELSEWHERE BY FRIDAY.
LOW PRESSURE DEVELOPING ALONG COASTAL FRONT IN/NEAR THE WESTERN GULF
POTENTIALLY WILL ACTIVATE THE FRONT AND BRING PRECIP CHANCES UP FROM
THE SOUTH, MOST LIKELY NOT UNTIL FRIDAY AFTERNOON OR NIGHT, BUT SOME
ENSEMBLE MEMBERS DEPICT PRECIP REACHING THE AREA AS SOON AS THURSDAY
NIGHT. IF THAT OCCURS LIGHT WINTRY PRECIP, CURRENTLY LOOKING MOST
LIKELY TO BE FREEZING RAIN, COULD DEVELOP IN A FEW SPOTS OF THE SW NC
MOUNTAINS. CONFIDENCE IS VERY LOW WITH WIDE SPREAD AMONG GUIDANCE
MEMBERS AS TO ONSET TIME OR EVEN THE EXISTENCE OF PRECIP, SO THE
FREEZING RAIN IS MENTIONED ONLY AS A SLIGHT-CHANCE FOR NOW. TEMPS
REMAINING A FEW DEGREES BELOW NORMAL THRU FRIDAY NIGHT.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS EXPECTED TO PREVAIL THROUGH
MOST OF TONIGHT. WIDESPREAD CIRRUS IS VISIBLE ON SATELLITE IMAGERY
AND SHOULD CONTINUE STREAMING INTO THE WESTERN CAROLINAS THIS
MORNING, THINNING SOMEWHAT BY MID-MORNING. WINDS, MOSTLY OUT OF
THE NORTH AT 2-4KTS, SHOULD PICK UP SOMEWHAT, CLIMBING TO 8-10KTS
DURING THE AFTERNOON. SOME PERIODS OF SE WINDS ARE EXPECTED DURING
THE DAYLIGHT HOURS AT ALL THE NON-MOUNTAIN TERMINALS. AN INCREASE
IN UPPER-LEVEL CLOUD COVER WILL BEGIN LATE THIS AFTERNOON, AND
SOME MID-LEVEL CLOUD COVER AORUND FL060-FL090 WILL WORK INTO THE
AREA FROM THE WEST AFTER SUNSET, BEFORE PRECIPITATION ASSOCIATED
WITH AN ADVANCING FRONTAL SYSTEM PICKS UP DURING THE LATTER HALF
OF TONIGHT...INITIALLY ACROSS APPALACHIA, BUT EVENTUALLY SPREADING
EASTWARD ACROSS THE ENTIRE TERMINAL FORECAST AREA BY 12Z SUNDAY.
ASSOCIATED MVFR FLIGHT RESTRICTIONS MAY DEVELOP AT KAVL AND OTHER
MOUNTAIN SITES BEFORE DAYBREAK SUNDAY; ELSEWHERE, THERE'S NOT
MUCH SIGNAL IN GUIDANCE FOR ANY WIDESPREAD RESTRICTIONS THROUGH
THE END OF THE 12Z TAF PERIOD.
OUTLOOK: RESTRICTIONS AND RAIN CHANCES CONTINUE SUNDAY BEFORE DRY
AND VFR CONDITIONS BRIEFLY RETURN MONDAY. ANOTHER ROUND OF RAIN
AND RESTRICTIONS ARE EXPECTED TUESDAY BEFORE DRY AND MAINLY VFR
CONDITIONS RETURN WEDNESDAY INTO THURSDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...WINTER WEATHER ADVISORY FROM 1 AM TO 9 AM EST SUNDAY FOR
NCZ033.
SC...NONE.
SYNOPSIS...AR
NEAR TERM...MPR
SHORT TERM...JCW
LONG TERM...JCW
AVIATION...MPR
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