012
FXUS62 KGSP 032347
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
747 PM EDT SUN AUG 3 2025
SYNOPSIS
COLD AIR DAMMING SETUP WILL KEEP TEMPERATURES WELL BELOW NORMAL
THROUGH THE FIRST COUPLE OF DAYS INTO THE NEW WORKWEEK. A GRADUAL
WARMING TREND IS EXPECTED BY THE MIDDLE PART OF THE WEEK INTO THE
WEEKEND. SHOWER AND THUNDERSTORM CHANCES STICK AROUND EACH DAY
THROUGHOUT THE WEEK.
NEAR TERM /THROUGH MONDAY/
AS OF 545 PM EDT SUNDAY: SFC HIGH PRESSURE WILL REMAIN
NOSED SWWD INTO THE CWFA THROUGH MONDAY IN CAD OR CAD-LIKE
ORIENTATION. SHORTWAVE AXIS IS EVIDENT FROM WATER VAPOR IMAGERY
OVER EASTERN KY/TN AND SEEMS TO BE THE DRIVER FOR BROAD AREA OF
PRECIP MOVING ATOP THE SFC WEDGE. POPS GENERALLY SHOULD DIMINISH
IN THE PIEDMONT OF GA/SC AND THEN NC AS THE SHORTWAVE PROGRESSES
AND THE PRECIP EXITS. HOWEVER, EASTERLY FLOW IN THE SFC TO 925MB
LAYER WILL DRIVE PERSISTENT PRECIP DEVELOPMENT FOR A FEW MORE HOURS,
ALTHOUGH DRY ADVECTION AT THAT LEVEL SHOULD ALLOW THAT TO DECREASE
OVERNIGHT. 925-850MB MOISTURE PLUME WILL PERSIST OVER THE SW HALF
OF THE CWA TONIGHT INTO MONDAY, AROUND THE PERIPHERY OF THE DAMMING
HIHG AND INTO THE NEXT SHORTWAVE NOW IN THE MIDWEST. CONSIDERABLE
CLOUDINESS WILL LINGER REGIONWIDE THROUGH TONIGHT, BUT PARTICULARLY
IN THE SW AREAS WHERE LIGHT SHOWER CHANCES CONTINUE AND THEN
INCREASE INTO MORNING. WITH THE SWWD PUSH OF LOWER SFC DWPTS TODAY,
ESPECIALLY IN THE NC PIEDMONT, MINIMUM TEMPERATURES MONDAY MORNING
ARE EXPECTED TO BE WELL INTO THE LOWER 60S, ALTHOUGH SVRL LOCALES
ARE NOT TOO FAR AWAY FROM THOSE VALUES ATTM.
THE SENSIBLE WX ON MONDAY MAY WIND UP BEING NOT TOO TERRIBLY
DIFFERENT THAN TODAY FEATURING A SW TO NE GRADIENT WITH RESPECT
TO THE STRENGTH OF THE UPGLIDE FLOW FORCING SHOWER ACTIVITY.
SHOWERS SHOULD AGAIN BECOME NUMEROUS IN THE ESCARPMENT AND SW
CWFA WHILE THE NC PIEDMONT REMAINS JUST WITH A TOKEN PROBABILITY.
CONVERSELY, WITH THE POTENTIAL FOR MORE INSOLATION, LOWER 80S ARE
IN THE FORECAST FOR THE I-77 CORRIDOR WHILE THE UPPER SAVANNAH
VALLEY MAY FALL SHORT OF 75 FOR MAXIMUM TEMPERATURES.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
AS OF 120 PM EDT SUNDAY: AN UPPER TROUGH WILL SHIFT OVER THE MS
VALLEY, WHILE SHARPENING WITHOUT MUCH MOVEMENT AND PULLING IN
BETTER MOISTURE ACROSS THE CWA MONDAY NIGHT INTO TUESDAY. THIS
IS THANKS TO A DEEPENING UPPER ANTICYCLONE OVER THE SOUTHWESTERN
CONUS AND ANOTHER OVER WESTERN ATLANTIC. AT THE SURFACE, AN
IN-SITU CAD WILL PERSIST AS A WEAK SURFACE HIGH CONTINUES TO
NOSE IN FROM THE NORTHEAST, ONLY TO BE REINFORCED MONDAY NIGHT
INTO TUESDAY AS A SECOND CANADIAN HIGH SHIFTS OVER ATLANTIC
CANADA AND NEW ENGLAND. THE SREF CONTINUES TO SUPPORT A LI INDEX
BETWEEN 4-6, INDICATING SUPPORT FOR HIGHER STATIC STABILITY TO
HELP KEEP PERSISTENT CAD-LIKE CONDITIONS WITH A STEADY NORTHEASTERLY
COMPONENT AT THE SURFACE. THE AFOREMENTIONED UPPER TROUGH, HOWEVER,
WILL START TO BREAKDOWN IN BETWEEN THE TWO ANTICYCLONES BY THE
LATTER HALF OF THE PERIOD, WHILE DEEP LAYER WAA WITH SOUTHEAST
TO SOUTHWESTERLY FLOW FILTERS IN ATOP THE SURFACE LAYER. THIS MAY
HELP TO KEEP THE CAD DOME INTACT THROUGH WEDNESDAY, WHILE BETTER
MOISTURE TRANSPORT AND UPGLIDE HELP TO INCREASE POPS THROUGHOUT
THE FORECAST PERIOD. THE GFS REMAINS A DRY OUTLIER WITH KEEPING
MOST OF THE QPF RESPONSE CLOSER TO THE WEDGE BOUNDARY SOUTH AND
WEST OF THE CWA, WHILE THE REST OF THE DETERMINISTIC GUIDANCE
PRODUCES GOOD QPF RESPONSE ACROSS THE AREA MONDAY NIGHT THROUGH
WEDNESDAY. CURRENT PROFILES INDICATE BETTER MIXING IN THE
LOW-LEVELS WITH INVERTED-V PROFILES AND A LI INDEX CLOSER TO 0
AND BELOW (-1 TO -3) BY WEDNESDAY, WHICH SUGGEST THAT THE CAD
EROSION PROCESS SHOULD BEGIN BY THE END OF THE WORKWEEK NEAR THE
START OF THE EXTENDED PERIOD. TEMPERATURES WILL CERTAINLY CONTINUE
THE CAD TREND WITH OVERNIGHT LOWS MONDAY AND TUESDAY REMAINING A
CATEGORY OR SO BELOW NORMAL, WHILE AFTERNOON HIGHS ON TUESDAY AND
WEDNESDAY GRADUALLY REBOUND COMPARED TO THE NEAR-TERM, LIKELY DUE
TO SOME SCATTERING CLOUDS AS STRONG AUGUST SOLAR HEATING REACHES
THE SURFACE AT TIMES. AFTERNOON HIGHS REMAIN 8-12 DEGREES BELOW
NORMAL TUESDAY AND 5-10 ON WEDNESDAY.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
AS OF 200 PM EDT SUNDAY: THE FLOW ALOFT AND AT THE SURFACE BEGINS TO
MAKE SUBTLE CHANGE BY THE END OF THE WORKWEEK AS A STALLED FRONTAL
BOUNDARY REMAINS DRAPED SOUTH OF THE CWA AND THE SURFACE HIGH
SLOWLY SLIDES OVER THE NORTHERN ATLANTIC. A COASTAL LOW FEATURE
IS EVIDENT IN MOST OF THE LATEST GUIDANCE BY THURSDAY AND LIFTS
NORTH GOING INTO THE WEEKEND. THIS WOULD ESSENTIALLY ERODE ANY CAD
THAT'S LEFT LINGERING, BUT OVERALL CONFIDENCE REMAINS LOW ON HOW
THE SYNOPTIC PATTERN FULLY EVOLVES DURING THE FORECAST PERIOD. A
PERSISTENT COLD POOL LIKELY REMAINS INTACT, WHILE TRUE CAD ERODES
THANKS TO STRONG AUGUST SOLAR HEATING AND LI VALUES LOWERING,
INDUCING MUCH LOWER STATIC STABILITY. SURFACE DIVERGENCE WILL
SUPPORT CAD EROSION AS WELL IF THE COASTAL LOW GETS GOING AND
LIFTS NORTH OVER THE MID-ATLANTIC COAST AS IS DEPICTED IN SOME
DETERMINISTIC RUNS. THE FLOW ALOFT WILL BE FAIRLY SATURATED AS
CONTINUED SOUTHERLY FLOW FILTERS IN, WHILE DRY NORTHEASTERLY
FLOW ADVECTS IN THE SURFACE LAYER. TEMPERATURES GRADUALLY WARM
THROUGH THE PERIOD, BUT REMAIN SLIGHTLY BELOW NORMAL AS A RESIDUAL
COLD POOL TRIES TO HOLD ON WITH PERSISTENT NORTHEASTERLY FLOW AT
THE SURFACE TO GO ALONG WITH ELEVATED POPS. SOUNDINGS DO SUPPORT
BETTER INSOLATION AND BOUNDARY LAYER MIXING BY THURSDAY THROUGH THE
WEEKEND, WHICH LIKELY IS CONTRIBUTING TO THE WARMING TREND AS WELL.
AVIATION /00Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: AXIS OF -SHRA SHOULD PASS EAST OF KCLT WITHIN
THE FIRST HOUR OF THE TAF PERIOD. COLD-AIR DAMMING REGIME CONTINUES
AROUND THE AREA TONIGHT MAINTAINING CIGS THRU THE NIGHT AS WELL AS
-DZ IN THE EVENING MAINLY AT KCLT/KHKY/KAVL, AND NE WINDS AROUND
THE AREA (EXCEPT SE OR CALM AT KAVL). A FEW SPRINKLES CAN'T BE
RULED OUT IN UPSTATE SC BUT LIKELY OF MINIMAL IMPACT. EASTERLY
UPSLOPE FLOW WILL KEEP -SHRA GOING AT KAVL WHICH WILL MAINTAIN
REDUCED VSBY. WHILE MOSTLY VFR IS PRESENT AT ISSUANCE TIME AROUND
THE AREA, SOME AREAS THAT HAVE HAD -DZ HAVE DEVELOPED RESTRICTIVE
CIGS. GIVEN THE CAD REGIME, SIGNIFICANT CHANGES ONE WAY OR THE OTHER
ARE UNLIKELY TONIGHT DESPITE SOME DRIER AIR POTENTIALLY ADVECTING IN
NEAR THE SFC, AND SO HAVE LEANED PESSIMISTIC WITH FLIGHT CATEGORY
OVERNIGHT ESP AT KAVL AND KAND, THE FARTHEST REMOVED FROM THE
SOURCE OF DRY AIR. IMPROVEMENT BACK TO VFR IN THE MORNING. BEST
OVERALL PRECIP CHANCES ARE IN THE AFTERNOON AS ELEVATED INSTABILITY
DEVELOPS OVER REMAINING COLD POOL, RESULTING IN PROB30. CAD WEAKENS
ENOUGH TO PERMIT A FLIP TO ESE WINDS AT KCLT LATE IN THE AFTN.
OUTLOOK: PRECIP CHANCES CONTINUE TO INCREASE MONDAY NIGHT INTO
TUE. ALTHOUGH TEMPERATURES ONLY GRADUALLY WARM BACK UP OVER
THE REMAINDER OF THE WEEK, PRECIPITATION CHANCES TREND TOWARD
A MORE TYPICAL SUMMERTIME REGIME BY WED WITH CHANCES MAINLY IN
THE AFTERNOONS AND EARLY EVENINGS. PERIODIC RESTRICTIONS REMAIN
POSSIBLE THRU LATE WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...CAC
NEAR TERM...CSH/WIMBERLEY
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...WIMBERLEY
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