338
FXUS62 KGSP 020624
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
124 AM EST TUE DEC 2 2025
SYNOPSIS
LOW PRESSURE LIFTS ACROSS THE FORECAST AREA TODAY BRINGING
WIDESPREAD PRECIPITATION. BEHIND THE SYSTEM, HIGH PRESSURE WILL
RESULT IN CHILLY AND DRY CONDITIONS WEDNESDAY INTO THURSDAY.
UNSEASONABLY COLD AND UNSETTLED WEATHER IS EXPECTED FRIDAY AS
ANOTHER SYSTEM BRINGS MORE PRECIPITATION TO THE AREA.
NEAR TERM /THROUGH TONIGHT/
AS OF 1237 AM EST TUESDAY...
KEY MESSAGES:
1) WINTER WEATHER ADVISORY IN EFFECT FOR THE NORTHERN AND
CENTRAL APPALACHIANS, OWING TO ONGOING FREEZING RAIN AND LIGHT
ICE ACCUMULATIONS.
2) RAINFALL WILL CONTINUE THROUGH THE FIRST PART OF TUESDAY BEFORE
WE DRY OUT DURING THE AFTERNOON AND EVENING.
3) DRY BUT VERY COLD CONDITIONS SHOULD RETURN TUESDAY NIGHT.
VIRTUALLY THE ENTIRE FORECAST AREA IS NOW SEEING AT LEAST LIGHT
DRIZZLE AS PROFILES MOISTEN BENEATH A BAROCLINIC ZONE DRAPED ACROSS
THE SOUTHEAST. SOME LOCATIONS ALONG I-77 MAY STILL BE DRY ENOUGH
THAT PRECIP MAY NOT BE REACHING THE SURFACE, BUT GENERALLY THINK
THAT RAIN IS NOW MAKING TO THE GROUND EVERYWHERE. ACARS DATA
DEPICTS A MOIST, DEEPENING WARM NOSE ABOVE A STEEP LOW-LEVEL
INVERSION, INDICATIVE OF STRENGTHENING IN-SITU COLD AIR DAMMING
DRIVEN BY INTENSIFYING RAINFALL. THE RESULT IS ANOTHER ROUND
OF PATCHY FOG AND LOW STRATUS, THOUGH SO FAR IT'S FAR LESS MURKY
OUT THERE THAN IT WAS THIS TIME LAST NIGHT. MEOSANALYSIS WOULD
SUGGEST THAT ISENTROPIC ASCENT OVER THE DEVELOPING WEDGE HAS STILL
NOT PEAKED, WITH THE STRONGEST 850MB WINDS AND MOISTURE ADVECTION
STILL ANALYZED OVER NORTH GEORGIA AND PROGGED TO CONTINUE INTO
OUR SOUTHERN AND WESTERN ZONES OVER THE NEXT 2-3 HOURS.
THIS SETUP STILL LOOKS LIKE IT'LL CONTRIBUTE TO FREEZING RAIN
ACROSS THE CENTRAL AND NORTHERN BLUE RIDGE BETWEEN NOW AND DAYBREAK.
ALREADY, SOME REPORTS OF ICE HAVE BEGUN COMING IN FROM ACROSS OUR
NORTHERNMOST MOUNTAIN ZONES, AND WOULD EXPECT THIS TO CONTINUE MORE
OR LESS THROUGH DAYBREAK. HIGHER PEAKS ARE LIKELY TO BE INSIDE
THE WARM NOSE, SO FREEZING RAIN ACCUMULATIONS ARE ACTUALLY LIKELY
TO BE HIGHER/MOST WIDESPREAD ACROSS MID-LEVEL SLOPES BELOW 4000FT
OF ELEVATION...AND ABOVE THE LARGER MOUNTAIN VALLEYS, WHICH BY
VIRTUE OF A BORDERLINE TEMPERATURE FORECAST MAY NOT RELIABLY FALL
BELOW FREEZING AT ALL TONIGHT. EXPECTATIONS FOR OVERALL COVERAGE
OF ICE REMAIN MORE OR LESS THE SAME, WHICH IS TO SAY LITTLE TO
NO ACCUMULATING ICE IS EXPECTED WEST OF I-26, WITH MUCH BETTER
COVERAGE EAST OF I-26 AND ESPECIALLY NORTH OF THE I-40 CORRIDOR.
TEMPERATURES WILL FOLLOW A VERY NON-DIURNAL CURVE, WHICH IS TO
SAY WE'RE LIKELY ALREADY AT OUR COLDEST IN MOST PLACES, WITH
CONTINUING STRONG WAA LIKELY TO LEAD TO SLOW BUT STEADY WARMING
THROUGH DAYBREAK AND BEYOND. A WINTER WEATHER ADVISORY REMAINS IN
PLACE FOR THE SOUTHERN FRENCH BROAD VALLEY, NORTHERN BLUE RIDGE,
AND NC BLUE RIDGE ESCARPMENT ZONES THROUGH 10 AM TODAY, BY WHICH
POINT TEMPERATURES AT EVEN THE COLDEST SPOTS SHOULD BE RELIABLY
WARM ENOUGH TO PRECLUDE FURTHER ICE ACCUMULATION AND CONVERT
REMAINING PRECIPITATION TO AN ENTIRELY-RAIN FORECAST.
RAINFALL WILL MOVE STEADILY EASTWARD THROUGH LATE MORNING...WITH
ESSENTIALLY THE ENTIRE FORECAST AREA FORECAST TO BE DRY BY EARLY
AFTERNOON. CLOUD COVER COULD LINGER THROUGH MUCH OF THE DAY, BUT
THE INFLUENCE OF WAA ACROSS THE AREA WILL HELP OFFSET ANY LOSS
OF DAYTIME HEATING; HIGH TEMPERATURES ARE THEREFORE EXPECTED TO
REACH THE LOW 50S ACROSS THE NON-MOUNTAIN ZONES, ONLY REMAINING IN
THE 40S ACROSS THE NC MOUNTAINS. BY TOMORROW EVENING, WE SHOULD
SEE CONSISTENT CLEARING THAT'LL CONTINUE INTO TUESDAY NIGHT.
BETWEEN A SOMEWHAT COOLER POSTFRONTAL AIR MASS IN PLACE TOMORROW
NIGHT, AND A FEW HOURS OF GOOD RADIATIVE COOLING AFTER MIDNIGHT
ONCE CAA ABATES AND WINDS DIE DOWN, LOWS WEDNESDAY MORNING ARE
LIKELY TO DROP INTO THE MID-20S ACROSS MOST OF THE LOW TERRAIN,
EXCEPT FOR THE SAVANNAH RIVER VALLEY, WHICH MAY HOVER AROUND 30.
SHORT TERM /WEDNESDAY THROUGH THURSDAY/
AS OF MIDNIGHT TUESDAY MORNING:
KEY MESSAGE 1: DRY WEATHER WEDNESDAY WITH TEMPERATURES TRENDING
SLIGHTLY COOLER IN MOST PIEDMONT LOCATIONS.
WEAK SFC HIGH PRESSURE WILL MIGRATE ACROSS THE SOUTHEAST WEDNESDAY,
THOUGH 500MB FLOW ALREADY WILL BE SLIGHTLY CYCLONIC AS THE NEXT
TROUGH DIGS INTO THE NORTHERN GREAT LAKES REGION. DESPITE SUNNY SKIES
WEAK CAA CONTINUES AND MAX TEMPS WILL BE HELD 2-3 DEGREES COOLER THAN
TUESDAY IN MOST LOCATIONS EAST OF THE MOUNTAINS, THE GREATEST CHANGE
BEING IN AREAS THAT EXPERIENCE STRONG DOWNSLOPING/WARMING TUESDAY
AFTERNOON. TEMPS WILL BE ABOUT THE SAME WITHIN THE MOUNTAINS OR
PERHAPS SLIGHTLY WARMER.
KEY MESSAGE 2: A WEAK FRONT SETTLING THROUGH THE AREA THURSDAY COULD
SPAWN A FEW SHOWERS IN OUR FAR SOUTH, AND SHOULD BRING COOLER TEMPS
TO THE MOUNTAINS AND WARMER TEMPS EAST.
DYNAMIC FORCING WITH THE AFOREMENTIONED TROUGH WILL REMAIN FAR OFF TO
OUR NORTH THROUGH THURSDAY, AND THE ASSOCIATED FRONT LOOKS TO REACH
THE CWA WITH MINIMAL OOMPH. MIDLEVEL COVER WILL REACH THE AREA EARLY
IN THE DAY WHICH WILL LIMIT WARMING IN THE MOUNTAINS, WITH CAA
DEVELOPING THERE DURING THE DAY ALSO. WITH THE PREVIOUS AIRMASS
MODIFYING, AND WITH DOWNSLOPING BEGINNING ALOFT WITH THE ARRIVING
FRONT, TEMPS SHOULD TREND SLIGHTLY WARMER EAST OF THE MOUNTAINS.
THE SFC HIGH BEHIND THE FRONT EXPANDS EAST OUT OF THE MID-MS VALLEY
BY THE END OF THE DAY THURSDAY. THE FRONT IN TURN SHOULD STALL ALONG
ITS SOUTHERN PERIPHERY SOMEWHERE ACROSS GA/SC. MEANWHILE A SEPARATE
SHORTWAVE WILL EXIT THE SOUTHERN ROCKIES AND BEGIN TO ACTIVATE THE
PREVIOUS STALLED/COASTAL FRONT IN THE FAR DEEP SOUTH. IT IS HARD TO
DISCERN WHICH FRONT IS RESPONSIBLE FOR THE SMALL POPS DEPICTED BY
SOME MODELS OVER OUR LAKELANDS ZONES, BUT THE IDEA IS PLAUSIBLE
ENOUGH FOR A SLIGHT CHANCE IN THE OFFICIAL FORECAST, AS RAIN THURSDAY
AFTERNOON.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
AS OF 1230 AM TUE:
KEY MESSAGE 1: CONFIDENCE REMAINS VERY LOW IN THE FORECAST FOR
THURSDAY NIGHT THROUGH SATURDAY NIGHT, BUT PERIOD(S) OF LIGHT WINTRY
PRECIP CANNOT BE RULED OUT IN THAT TIMEFRAME, MAINLY IN THE NORTHERN
CWA.
GENERAL EXPECTATION IS THE SAME AS PREVIOUS CYCLES, THAT THE SURFACE
HIGH THAT REACHES THE AREA THURSDAY WILL CENTER OVER THE MID-ATLANTIC
COAST BY FRIDAY MORNING, AND THAT AMPLIFYING JET STREAK AND/OR THE
WEAK TROUGH CROSSING THE SOUTHERN ROCKIES WILL LEAD TO FRONTOGENESIS
ALONG THE BAROCLINIC ZONE ACROSS THE SE COASTAL PLAIN TO OUR SOUTH.
THE TIMING OF THAT PROCESS, CAUSING EVENTUAL DEVELOPMENT OF A
MILLER-A CYCLONE, HOWEVER REMAINS DIFFICULT TO PIN DOWN.
COLD-AIR DAMMING HAD SEEMED LIKE A GOOD BET GIVEN THE STRENGTH AND
POSITION OF THE HIGH, BUT RECENT GFS RUNS SHOW THE HIGH BEING WEAKER
AND MORE TRANSIENT, WITH LESS DIABATIC COOLING AND LATER ONSET OF POP
WHICH WOULD SUGGEST PRECIP IS LIKELY TO BEGIN AS RAIN FOR ALL BUT THE
COLDEST ESCARPMENT AREAS. THE ECMWF, WHICH HAD ONCE BEEN CONSISTENT
IN FRIDAY BEING DRY, IS NOW FASTER AND COLDER THAN THE GFS, CLEARLY
DEPICTING CAD AND FREEZING RAIN AND/OR SNOW OVER OUR NORTHERN
MOUNTAINS AND I-40 CORRIDOR. WITH THE WEDGE LOCKED IN, IT CONTINUES
TO PRODUCE SOME WINTRY PRECIP THROUGH FRIDAY. THE GFS EVENTUALLY DOES
PRODUCE QPF IN A SIMILAR PATTERN, JUST STARTING LATER AND ALMOST ALL
LIQUID. THE CANADIAN GDPS IS DRIER, SHOWING A WEAKER HIGH LIKE THE
GFS BUT ALSO KEEPING THE PRECIP ASSOCIATED WITH THE FRONTAL WAVE
MOSTLY TO OUR SOUTH. THE BEST CONSENSUS FOR PRECIP OCCURRENCE IS
FRIDAY AFTERNOON THROUGH VERY EARLY SATURDAY MORNING, AND AT LEAST
WEAK CAD APPEARS LIKELY, EVEN IF TEMPS REMAIN ABOVE FREEZING. TEMPS
FRIDAY LOOK TO BE QUITE CHILLY. WITH MOST AREAS IN THE LOWER 40S,
POSSIBLY NOT MAKING IT OUT OF THE 30S IF THE CAD IS AS STRONG AS THE
ECMWF DEPICTS. REGARDLESS OF WHICH SOLUTION VERIFIES, PRECIP CHANCES
SHOULD BE ON THE DECLINE EAST OF THE MOUNTAINS, AT LEAST TEMPORARILY,
LATE FRIDAY NIGHT AS THE MILLER-A FORMS AND PULLS AWAY FROM THE
COAST. NORTHWEST FLOW SNOW OR RIME ICE COULD DEVELOP NEAR THE TN
BORDER AT THAT TIME.
IT REMAINS UNCLEAR WHETHER THE AFOREMENTIONED SOUTHERN SHORTWAVE WILL
PHASE WITH ANOTHER SHORTWAVE IN THE NORTHERN PLAINS, SO THERE COULD
BE ANOTHER OPPORTUNITY FOR COASTAL FRONT TO REACTIVATE SATURDAY
NIGHT, EXEMPLIFIED BY THE 02/00Z ECMWF. THE GFS HAD ONCE DEPICTED
THIS SORT OF THING. POPS DO RAMP BACK UP AS A NOD TO THIS
POSSIBILITY. P-TYPE IN THIS SCENARIO PROBABLY WOULD BE PREDOMINANTLY
RAIN, BUT MORE FZRA CAN'T BE RULED OUT IN THE MOUNTAIN/FOOTHILL
LOCATIONS WHERE COLDER TEMPS PERSIST. TEMPS SHOULD REBOUND BACK INTO
THE UPPER 40S OR LOWER 50S SATURDAY--STILL SEVERAL BELOW NORMAL.
KEY MESSAGE 2: LIGHT NORTHWEST FLOW SNOW IS POSSIBLE NEAR THE TN
BORDER LATE SUNDAY THRU EARLY MONDAY.
MOST MODELS DEPICT A CLIPPER-LIKE SHORTWAVE BLOWING ACROSS THE
APPALACHIANS BETWEEN LATE SUNDAY AND MONDAY MORNING, AND SMALL POPS
REDEVELOP NEAR THE TN BORDER. TEMPS APPEAR SUPPORTIVE OF SNOW AT THAT
TIME. THE GFS DEPICTS SOME LIGHT SNOW SHOWERS DEVELOPING IN THE NC
PIEDMONT MONDAY MORNING BUT THOSE OFTEN DON'T PAN OUT WITH A CLIPPER,
OR END UP JUST BEING FLURRIES AND A NOVELTY. TEMPS TREND SLIGHTLY
COOLER AGAIN ON MONDAY.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: WIDESPREAD MVFR CEILINGS CURRENTLY BETWEEN
FL020 AND FL030 ARE EXPECTED TO SLOWLY DETERIORATE OVER THE COURSE
OF THE TONIGHT, WITH A PRETTY STRONG SIGNAL FOR IFR CEILINGS BY
DAYBREAK AT MOST TERMINALS IN BOTH THE STATISTICAL GUIDANCE AND
MODEL SOURCES. THE POSSIBILITY REMAINS, BUT WITH LOWER CONFIDENCE,
ON LIFR CEILINGS DEVELOPING AROUND DAYBREAK. CURRENTLY SEEING
THE HEAVIEST RA SOUTH OF I-85, BUT WITH MUCH BETTER RETURNS WEST
OF THE SAVANNAH RIVER VALLEY AND INBOUND...THINK MOST SITES WILL
SEE INCREASING COVERAGE/INTENSITY OF RAIN BEGINNING WITHIN THE
NEXT 2-3 HOURS. IN CONJUNCTION WITH THIS, EXPECT VISIBILITY TO
FALL TO MVFR/IFR LEVELS BY AROUND 09Z. VIS SHOULD IMPROVE FAIRLY
QUICKLY ONCE THE SUN COMES UP, BUT CEILINGS WILL BE MUCH MORE
STUBBORN, WITH THE GLAMP AND SHORT-RANGE BLENDED GUIDANCE BOTH
SUGGESTED THAT KCLT AND THE UPSTATE SITES COULD REMAIN SOCKED INTO
IFR CONDITIONS WELL PAST NOON TUESDAY, DESPITE RAINFALL ENDING
EVERYWHERE BY LATE MORNING OR EARLY AFTERNOON. COULD BE WELL
INTO THE LATE AFTERNOON/EVENING HOURS BEFORE ENOUGH LOW-LEVEL
MOISTURE IS SCOURED OUT ENOUGH TO GET US FULLY BACK TO VFR.
LIGHT AND VARIABLE WINDS OVERNIGHT, AT LEAST SOMEWHAT FAVORING
AN ENE COMPONENT, WILL GRADUALLY BECOME MORE CONSISTENTLY NW BY
MID-DAY TUESDAY. EXPECT VFR CONDITIONS AND A STEADY NW WIND OF
5-7 KTS THE FIRST PART OF TUESDAY NIGHT, AND FOR WINDS TO THEN
BECOME LIGHT AND <3KTS ACROSS THE TERMINAL FORECAST AREA DURING
THE PREDAWN HOURS WEDNESDAY.
OUTLOOK: DRY, VFR CONDITIONS EXPECTED TO PERSIST THROUGH WEDNESDAY
AND THE FIRST PART OF THURSDAY. RAIN COULD RETURN AS EARLY AS
THURSDAY AFTERNOON, BUT MORE LIKELY THURSDAY NIGHT AND FRIDAY AS
THE NEXT SYSTEM ARRIVES. RAIN AND ASSOCIATED FLIGHT RESTRICTIONS
COULD CONTINUE INTO THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NCZ033-049-050-053-065-501-503-505-507-509.
SC...NONE.
SYNOPSIS...AR
NEAR TERM...MPR
SHORT TERM...JCW
LONG TERM...JCW
AVIATION...MPR
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