556
FXUS62 KGSP 061020
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
620 AM EDT WED AUG 6 2025
SYNOPSIS
A WEDGE OF COOL AND MOIST AIR WILL LINGER THROUGH MUCH OF
THE WEEK BEFORE A POTENTIAL COASTAL LOW ERODES THE WEDGE THIS
WEEKEND. WIDESPREAD RAIN WILL TAPER OFF THIS MORNING, WITH SHOWERS,
ALONG WITH SOME THUNDERSTORMS BECOMING MORE SCATTERED IN NATURE
EACH DAY THROUGH THE WEEKEND. ALTHOUGH A WARMING TREND IS EXPECTED
TO BEGIN TODAY, BELOW NORMAL HIGH TEMPERATURES ARE EXPECTED TO
CONTINUE THROUGH THIS WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 620 AM EDT WEDNESDAY...
KEY MESSAGES:
1) LOCALLY HEAVY RAINFALL MAY LEAD TO ISOLATED AREAS OF FLASH
FLOODING THIS MORNING, MAINLY ALONG AND SOUTH OF I-85
2) WARMER TODAY BUT STILL WELL BELOW NORMAL THANKS TO COLD AIR
DAMMING STICKING AROUND
3) DRIER CONDITIONS RETURN LATER THIS MORNING BUT ISOLATED
THUNDERSTORMS ARE POSSIBLE IN THE MOUNTAINS THIS AFTERNOON/EVENING
SHORTWAVES EMBEDDED WITHIN AN UPPER TROUGH WILL LIFT NORTHEAST
ACROSS THE FORECAST AREA THIS MORNING KEEPING RAIN AROUND, MAINLY
EAST OF THE NC MOUNTAINS. LOCALLY HEAVY RAINFALL LEADING TO ISOLATED
FLASH FLOODING WILL BE THE MAIN CONCERN THROUGH THIS MORNING,
ESPECIALLY WITH WET ANTECEDENT CONDITIONS LEADING TO LOWER FLASH
FLOOD GUIDANCE VALUES. AREAS OF MOST CONCERN FOR ISOLATED FLASH
FLOODING TO DEVELOP ARE ALONG/SOUTH OF I-85 AS 2-5 INCHES OF RAIN
FELL ACROSS THESE ZONES YESTERDAY. WITH THE FLASH FLOODING POTENTIAL
EXPECTED TO REMAIN ISOLATED, A FLOOD WATCH WAS NOT ISSUED. RAINFALL
AMOUNTS FROM 0.25" TO 1" CAN BE EXPECTED FOR MOST LOCATIONS SOUTH OF
I-40 THIS MORNING. LOCALLY HIGHER AMOUNTS OF 1.5 TO 2.5+ INCHES ARE
POSSIBLE WHERE HEAVIER DOWNPOURS TRACK AND/OR TRAIN, MAINLY ALONG
AND SOUTH OF 85.
DRIER CONDITIONS WILL GRADUALLY RETURN LATER THIS MORNING INTO THIS
AFTERNOON, ALTHOUGH SOME LIGHT RAIN MAY LINGER ALONG THE I-77
CORRIDOR THIS AFTERNOON AND A FEW ISOLATED THUNDERSTORMS MAY DEVELOP
ACROSS THE NC MOUNTAINS THIS AFTERNOON/EARLY EVENING. DID GO LOWER
THAN NBM REGARDING THUNDER CHANCES THROUGH PERIOD WITH COLD AIR
DAMMING STILL IN PLACE, WITH THE BEST CHANCE FOR THUNDER ACROSS THE
MOUNTAIN ZONES (OUTSIDE OF THE WEDGE). ALTHOUGH HIGHS WILL BE WARMER
TODAY, THEY WILL STILL END UP 6-10 DEGREES BELOW NORMAL ACROSS THE
WESTERN HALF OF THE CWA AND 10-15 DEGREES BELOW NORMAL ACROSS THE
EASTERN HALF. LOWS TONIGHT SHOULD END UP A FEW DEGREES WARMER BUT
WILL STILL END UP A FEW DEGREES BELOW NORMAL OUTSIDE OF THE
MOUNTAINS. PATCHY FOG MAY DEVELOP ACROSS THE MOUNTAINS OVERNIGHT
INTO DAYBREAK WEDNESDAY.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
KEY MESSAGES:
1) COLD AIR DAMMING WILL SLOWLY WEAKEN THROUGH THIS PERIOD, BUT
HIGH TEMPERATURES WILL REMAIN BELOW NORMAL.
2) CHANCES FOR WIDESPREAD PRECIPITATION END, BUT ISOLATED-TO-
SCATTERED, MAINLY DIURNAL SHOWERS AND A FEW THUNDERSTORMS ARE
EXPECTED.
AS OF 1255 AM EDT WEDNESDAY: THE AXIS OF A WEAKENING UPPER TROUGH
WILL BE POSITIONED ACROSS THE FORECAST AREA AT THE START OF THE
SHORT TERM, AND IS FORECAST TO PUSH EAST OF THE CWA BY FRIDAY
MORNING. DEEP MOISTURE WILL THEREFORE STEADILY SHUNT EAST OF THE
AREA ON THURSDAY, BRINGING AN END TO THE POTENTIAL FOR ANY
WIDESPREAD PRECIPITATION. HOWEVER, LOW LEVEL MOISTURE WILL LINGER
WITHIN INVERTED RIDGE AXIS/REMNANT (& WEAKENING) COLD AIR DAMMING.
CONDITIONS WITHIN THE DAMMING REGION WILL REMAIN RELATIVELY COOL AND
STABLE DURING THE AFTERNOON, BUT MODERATE DESTABILIZATION IS
EXPECTED AROUND THE PERIPHERY OF THE CWA, ESPECIALLY ACROSS THE
MOUNTAINS OF FAR SOUTHWEST NC. SCATTERED SHOWERS AND THUNDERSTORMS
ARE FORECAST BOTH THU AND FRI AFTERNOONS IN THESE AREAS. DESPITE THE
STABLE CONDITIONS WITHIN THE HEART OF THE CWA, LINGERING EASTERLY
UPSLOPE FLOW ATOP THE REMNANT COOL POOL WILL NEVERTHELESS SUPPORT
POTENTIAL FOR SHOWER DEVELOPMENT, WITH SMALL POPS (20-30%) WARRANTED
EVEN IN THESE AREAS. THE GRADUAL WARMING TREND IN MAX TEMPS WILL
CONTINUE, BUT FORECAST HIGHS EACH DAY ARE 7-10 DEGREES BELOW CLIMO
ACROSS MUCH OF THE AREA.
LONG TERM /SATURDAY THROUGH TUESDAY/
KEY MESSAGES
1) COLD AIR DAMMING FINALLY COMES TO AN END.
2) FORECAST TEMPERATURES SLOWLY INCREASE BUT REMAIN BELOW NORMAL
UNTIL TUESDAY.
3) THE DIURNAL CONVECTIVE CYCLE RETURNS.
AS OF 1230 AM EDT WEDNESDAY: A NEBULOUS UPPER AIR PATTERN WILL
BE IN PLACE ACROSS THE SOUTHEAST THROUGH THE EXTENDED, GENERALLY
CHARACTERIZED BY A BROAD WEAKNESS IN THE SUBTROPICAL RIDGE. THE
LATEST GLOBAL MODELS ARE NOW IN AGREEMENT THAT A TROPICAL...OR
AT LEAST HYBRID CYCLONE WILL BE PULLING NORTHEAST AWAY FROM THE
MID-ATLANTIC COAST AT THE START OF THE PERIOD, WITH AN INVERTED
RIDGE REMAINING IN PLACE EAST OF THE APPALACHIANS THROUGH THE
WEEKEND. HOWEVER, NE FLOW IS FORECAST TO DEEPEN AS WEAKENING SURFACE
HIGH DRIFTS SOUTH INTO THE MID-ATLANTIC. THIS WILL DRIVE DRIER
AIR INTO THE REGION OVER THE WEEKEND, EFFECTIVELY ENDING COLD AIR
DAMMING AND ASSOCIATED IMPACTS. RESULTANT MODIFYING AIR MASS WILL
ALLOW FOR INCREASING DIURNAL INSTABILITY EACH DAY INTO EARLY NEXT
WEEK, WITH ASSOCIATED INCREASE IN DAILY SHOWER AND THUNDERSTORM
CHANCES, WITH SCATTERED-TO-NUMEROUS COVERAGE EXPECTED OVER THE
MOUNTAINS, AND SCATTERED ACTIVITY OVER THE PIEDMONT. MAX TEMPS
WILL BEGIN THE PERIOD AROUND 5 DEGREES BELOW NORMAL, WARMING TO
NEAR NORMAL BY DAY 7/TUESDAY. MIN TEMPS WILL BE AROUND NORMAL
THROUGH THE PERIOD.
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: LIGHT TO MODERATE RAIN, HEAVY AT TIMES,
CONTINUES LIFTING NORTHEAST, MAINLY EAST OF THE NC MOUNTAINS, AS OF
12Z. STILL SEEING MOSTLY MVFR TO IFR RESTRICTIONS ACROSS THE
TERMINALS WITH SOME OCCASIONAL VFR CIGS AND IFR VSBYS WITHIN +RA AS
OF 12Z. MVFR TO IFR CIGS SHOULD LINGER EAST OF THE MOUNTAINS THROUGH
THE 12Z TAF PERIOD, ALTHOUGH THE SC UPSTATE SITES COULD SEE VFR
RETURN BRIEFLY THIS AFTERNOON. ADDED A TEMPO TO ACCOUNT FOR THIS
POSSIBILITY IN THE 12Z TAFS. PATCHY FOG MAY LINGER AT KCLT THROUGH
LATE THIS EVENING BUT CONFIDENCE IS LOW. DRIER CONDITIONS WILL
RETURN LATER THIS MORNING, LINGERING ACROSS MOST OF THE TERMINALS
THROUGH THE REST OF THE 12Z TAF PERIOD. HOWEVER, ISOLATED TSRA MAY
DEVELOP ACROSS THE MOUNTAINS THIS AFTERNOON AND EVENING SO HAVE A
PROB30 FOR TSRA AT KAVL FROM 20Z-24Z. CIGS AT KAVL SHOULD IMPROVE TO
VFR BY THE EARLY AFTERNOON HOURS BEFORE DROPPING TO IFR AGAIN THIS
EVENING INTO THE OVERNIGHT HOURS WITH PATCHY FOG ALSO DEVELOPING.
WINDS WILL REMAIN NNE/NE EAST OF THE MOUNTAINS THROUGH THE 12Z TAF
PERIOD. WINDS AT KAVL WILL BE LIGHT AND VRB TO CALM EARLY THIS
MORNING, BECOMING E/ESE THIS AFTERNOON AND EVENING BEFORE GOING
LIGHT AND VRB TO CALM AGAIN OVERNIGHT. KCLT COULD SEE SPOTTY -RA
DEVELOP OVERNIGHT INTO DAYBREAK WEDNESDAY SO HAVE A PROB30 TO
ACCOUNT FOR THIS POTENTIAL.
OUTLOOK: THE WEDGE PATTERN PERSISTS OVER THE TERMINALS THROUGH THE
WORKWEEK KEEPING RAIN CHANCES AND PERIODIC RESTRICTIONS AROUND.
EMBEDDED THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON AND EVENING BUT
CONFIDENCE IS LOW.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...JDL
NEAR TERM...AR
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...AR
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