159
FXUS62 KGSP 130554
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
154 AM EDT SUN JUL 13 2025
SYNOPSIS
EXPECT SCATTERED THUNDERSTORMS AND HEAVY DOWNPOURS AROUND THE REGION
EACH DAY OF THE COMING WEEK. A FEW STORMS COULD PRODUCE DAMAGING
WIND GUSTS, PARTICULARLY TODAY AND MONDAY. DAILY HIGH TEMPERATURES
WILL BE SEVERAL DEGREES ABOVE NORMAL AT THE BEGINNING OF THE WEEK
BUT TREND BACK TO AROUND NORMAL TUESDAY THROUGH THURSDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 145 AM EDT SUNDAY: LINGERING CONVECTIVE DEBRIS STARTING TO
SCATTER OUT OF OVER THE WESTERN HALF OF THE CFWA, HELPING TO REVEAL
MAJOR MOUNTAIN VALLEY LOW STRATUS AND FOG ALREADY DEVELOPING. ALL
PRECIPITATION HAS DISSIPATED AND LEAVING PARTLY TO MOSTLY CLEAR
SKIES THROUGH THE REST OF THE OVERNIGHT PERIOD. CAN'T RULE OUT
GROUND FOG IN LOCATIONS THAT RECEIVED HEAVIER RAINFALL SATURDAY
AND NEAR BODIES OF WATER. EXPECT OVERNIGHT LOWS TO RUN AT OR A
FEW TICKS ABOVE NORMAL.
ONLY VERY SUBTLE CHANGES TO THE SYNOPTIC PATTERN AS A RIDGE OVER THE
GULF NOSES FURTHER NORTH IN TO THE REGION, ALLOWING FOR WARMER AND
DRIER AIR TO WORK INTO THE VERTICAL PROFILES. POSITIVELY-TILTED
TROUGH OVER THE CENTRAL CONUS WILL GRADUALLY WORK EASTWARD
DURING THE FORECAST PERIOD, DRAGGING AN ATTENDANT BOUNDARY WITH
IT. THE ACTUAL FRONTAL BOUNDARY WILL REMAIN WELL NORTHWEST OF THE
REGION. WITH MORE WARMER AND DRIER AIR ALOFT, EXPECT THE ATMOSPHERE
TO BE SLIGHTLY CAPPED. FACTOR IN A DOWNWARD TREND IN PWAT VALUES
(1.25"-1.75") AND CONVECTIVE COVERAGE SHOULD SHRINK COMPARED TO
THE PAST FEW DAYS. STILL EXPECT ISOLATED CONVECTIVE INITIATION OVER
THE RIDGETOPS AND BLUE RIDGE ESCARPMENT BY THE EARLY AFTERNOON AND
WILL SHIFT EAST INTO THE FOOTHILLS AND PIEDMONT BY OUTFLOWS AND
COLD POOL ORGANIZATION LATER INTO THE AFTERNOON AND EVENING. THE
ENVIRONMENT WILL STILL CONSIST OF 2000-3000 J/KG SBCAPE AND <20
KTS OF DEEP LAYER SHEAR, BUT WITH DRIER AIR ENTRAINMENT WITHIN
THE PROFILES, STORMS THAT DO DEVELOP WILL HAVE A HIGHER CHANCE OF
BECOMING STRONG TO SEVERE COMPARED TO SATURDAY AS DCAPE VALUES
WILL UPTICK TO 800-1200 J/KG, WITH POCKETS OF HIGHER THAN 1200
J/KG. WET MICROBURSTS WILL BE THE MAIN THREAT, WHICH IS TYPICAL
WITH SUMMERTIME PULSE CONVECTION. HI-RES GUIDANCE HAVE HINTED AT
BETTER CONVECTIVE COVERAGE ALONG AND EAST OF I-77 AS A POOL OF
HIGHER PWAT VALUES IS EVIDENT AND THE LEE TROUGH SHIFTING FURTHER
AWAY FROM THE APPALACHIANS. AS A RESULT, CHANCE POPS (25%-53%) ARE
INTRODUCED FOR THE CLT METRO AND I-77 CORRIDOR, WHILE ONLY SLIGHT
CHANCE (15%-24%) TO UNMENTIONABLE POPS (<14%) FOR LOCATIONS SOUTH
OF I-85 IN THE UPSTATE AND UPPER SAVANNAH REGIONS. WITH SLIGHTLY
HIGHER HEIGHTS AND THE LACK OF MORNING STRATUS, AFTERNOON HIGHS ARE
FORECASTED TO TOP OUT A FEW DEGREES ABOVE NORMAL. HEAT INDEX VALUES
SHOULD REACH TRIPLE DIGITS IN PORTIONS OF THE PIEDMONT ZONES, BUT
WILL REMAIN BELOW HEAT ADVISORY CRITERIA.
MOST OF THE CONVECTION SHOULD GRADUALLY DISSIPATE AFTER SUNSET WITH
THE LOSS OF PEAK DIURNAL HEATING. LINGERING CONVECTIVE DEBRIS,
AVAILABLE LOW-LEVEL MOISTURE, AND LOCATIONS THAT RECEIVE HEAVY
RAINFALL WILL BE PRONE TO ANOTHER ROUND OF LOW STRATUS AND FOG
OVERNIGHT SUNDAY, ESPECIALLY IF THE CONVECTIVE DEBRIS CLEARS
OUT EARLY ON DURING THE OVERNIGHT PERIOD. OVERNIGHT LOWS WILL BE
SIMILAR TO TONIGHT WITH LOW 70S ACROSS THE PIEDMONT AND MID TO
UPPER 60S ACROSS THE MOUNTAINS AND FOOTHILLS.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
AS OF 1230 AM SUNDAY: A WEAK UPPER ANTICYCLONE WILL BE CENTERED OVER
THE GULF COAST REGION MONDAY, AS A WEAK SHORTWAVE PASSES BY TO OUR
NORTH ASSOCIATED WITH A SLOWING COLD FRONT IN THE LOWER OHIO VALLEY.
INVERTED TROUGH MEANWHILE WILL DRIFT WEST INVOF THE BAHAMAS. THE
RESULT IS NEBULOUS UPPER FORCING OVER OUR AREA BUT A BROAD ZONE OF
LOW TO MIDLEVEL CONVERGENCE CENTERED OVER CENTRAL NC/SC/GA AND THUS
PERHAPS JUST TO OUR EAST AND SOUTH. DIURNAL INSTABILITY WILL BE THE
MAIN DRIVER OF SHOWERS/STORMS, WITH COVERAGE ENHANCED ABOVE CLIMO
ON ACCOUNT OF THE CONVERGENCE AND MODESTLY HIGH PWATS. MODEL QPF
RESPONSE HAS INCREASED SLIGHTLY IN OUR CWA COMPARED TO RUNS FROM A
DAY AGO, AND NOTABLY THERE APPEARS A BETTER CHANCE OF ACTIVITY TO
CONTINUE AFTER SUNSET; PEAK CHANCES FOR MONDAY APPEAR TO BE NEAR
00Z FOR OUR SOUTHEASTERN HALF. TEMPS LOOK TO BE AT OR SLIGHTLY
ABOVE SUNDAY'S VALUES, BUT DEWPOINTS COULD BE SLIGHTLY HIGHER SO A
FEW LOWER PIEDMONT SPOTS BRIEFLY SEE HEAT INDEX EXCEED 105. SHEAR
IS WEAK; DESPITE MOIST PROFILES, VERY HEAVY DOWNPOURS AND WATER
LOADING STILL MAINTAIN SOME WET MICROBURST RISK.
AS THE NORTHERN SHORTWAVE MOVES FURTHER EAST THE TRAILING FRONT
SEEMS TO FINALLY STALL JUST TO OUR NORTH. PARTIAL THICKNESSES FALL
SEEMINGLY AS A RESULT OF THE INVERTED TROUGH MOVING WESTWARD AND
REPLACING THE UPPER RIDGE. TEMPS SHOULD TREND COOLER, BACK TO AROUND
CLIMO, EVEN IF THE FRONT TECHNICALLY STAYS TO OUR NORTH. CONVERGENCE
STILL COULD BE ENHANCED BY THE INVERTED TROUGH. THE COOLER TEMPS
BUT SIMILAR IF NOT HIGHER DEWPOINTS RESULT IN LOWER LCLS. CAPE
AND POPS INCREASE ACCORDINGLY. VIA THE CONVERGENCE ZONE ANOTHER
SLOW NOCTURNAL DECLINE IS EXPECTED TUE NIGHT.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
AS OF 115 AM SUNDAY: THE INVERTED TROUGH MAY HAVE SOME ENHANCING
INFLUENCE WEDNESDAY, BUT OTHERWISE THE DOMINANT FEATURE FOR THE
MEDIUM RANGE LOOKS TO BE THE BERMUDA HIGH. WEDNESDAY LOOKS LIKE THE
"COOLEST" DAY AS PARTIAL THICKNESSES REACH THEIR NADIR ON MOST
OF THE GLOBAL MODELS, POSSIBLY ALSO OWING TO CLOUD COVER WITH
CONVECTIVE COVERAGE NEAR THE TROUGH AXIS. A GRADUAL WARMING TREND
THEN OCCURS AS THE BERMUDA HIGH RETROGRADES OVER THE SOUTHEAST
COAST. RELATIVELY HIGH AFTERNOON DEWPOINTS WILL KEEP LCLS LOW AND
SUPPORT ABOVE-CLIMO POPS AGAIN THU.
THERE IS SOME SPREAD AMONG MODELS, AND BETWEEN THE GFS AND EC
ENSEMBLE MEMBERS, AS TO HOW DEEP THE BERMUDA RIDGE ENDS UP OVER
OUR REGION. THE NEXT FRONTAL SYSTEM WILL PASS THE GREAT LAKES
CIRCA THURSDAY; GFS AND GDPS SUGGEST THE RIDGE WILL HOLD OFF THAT
SYSTEM FROM OUR AREA UNTIL THE ASSOCIATED SHORTWAVE IS REINFORCED
BY A SECONDARY TROUGH DIGGING INTO THE NORTHERN PLAINS AND WESTERN
GREAT LAKES LATE FRI OR EARLY SAT. THE EC BRINGS THE CONVERGENCE
ZONE INTO OUR AREA A BIT SOONER. THE UPSHOT OF ALL THIS IS THAT THE
GFS AND GDPS SOLUTIONS FEATURE MORE TYPICAL POPS (I.E., MAINLY OVER
THE MOUNTAINS) WHEREAS THE EC MAINTAINS ENHANCED VALUES REFLECTING
LESS TERRAIN INFLUENCE. GIVEN THE TIMING DIFFERENCES CONFIDENCE
DECREASES FRI-SAT.
HEAT INDEX STILL COULD PEAK AT 100 TO 105 IN THE WARMER PIEDMONT
AREAS FRI-SAT. SLOW-MOVING CELLS PRODUCING HEAVY RAINFALL WILL
REMAIN A DAILY CONCERN PARTICULARLY WHERE SOILS SATURATE FOLLOWING
REPEATED ROUNDS OF SHOWERS/STORMS OVER THE COURSE OF THE WEEK.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: SOME LINGERING CONVECTIVE DEBRIS IS EVIDENT
ACROSS THE WESTERN TERMINALS, BUT SIGNS OF SCATTERING HAS REVEALED
MOUNTAIN VALLEY LOW STRATUS AND FOG. ANY LOW STRATUS OR FOG OUTSIDE
OF THE MOUNTAIN VALLEYS WILL BE SPARSE, WHICH IS SHOWN IN THE
LATEST TAF UPDATE. KEPT THE TEMPO FOR 1SM AND OVC004 MENTION AT
KAVL FOR MOUNTAIN VALLEY INFLUENCE AND 5SM AT KHKY DUE TO ELEVATED
FOG CHANCES NEAR BODIES OF WATER. OTHERWISE, FAIRLY QUIET THROUGH
DAYBREAK FOR THE TERMINALS. VFR CONDITIONS WILL PREVAIL FOR THE
DAYTIME PERIOD WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
EXPECTED, ESPECIALLY FOR THE NORTH CAROLINA TAF SITES. INCLUDED
A PROB30 FOR TSRA AND ASSOCIATED RESTRICTIONS AT ALL TERMINALS
EXCEPT KAND, WHERE TSRA CHANCES ARE THE LOWEST. LIGHT AND VARIABLE
WINDS THROUGH DAYBREAK, WILL PICK UP OUT OF THE NORTH-NORTHWEST
BY PEAK HEATING. ANOTHER ROUND OF LOW STRATUS AND FOG CAN'T BE
RULED OUT OVERNIGHT SUNDAY, ESPECIALLY OVER THE MOUNTAIN VALLEYS
ONCE AGAIN. WINDS ALSO GO BACK TO LIGHT AND VARIABLE SUNDAY NIGHT.
OUTLOOK: TYPICAL SUMMERTIME WEATHER IS EXPECTED INTO EARLY NEXT
WEEK, WITH SCATTERED TO NUMEROUS THUNDERSTORMS MAINLY IN THE
AFTERNOON/EVENING AND FOG AND/OR LOW STRATUS POSSIBLE EACH MORNING.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...CAC
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...CAC
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