064
FXUS62 KGSP 172356
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
756 PM EDT THU JUL 17 2025
SYNOPSIS
DAILY THUNDERSTORM CHANCES CONTINUE THROUGH THE UPCOMING WEEKEND. A
FEW STORMS COULD PRODUCE DAMAGING WIND GUSTS AND LOCALIZED FLASH
FLOODING. HOT AND HUMID CONDITIONS STICK AROUND THROUGH THE
FORECAST PERIOD.
NEAR TERM /THROUGH FRIDAY/
AS OF 750 PM EDT THURSDAY: A STRONG SURFACE HIGH REMAINS PARKED
OVER THE ATLANTIC AND THE WESTERN SIDE AMPLIFYING, KEEPING THE FLUX
OF MOISTURE IN PLACE. OFF TO THE NORTH, AN AREA OF LOW PRESSURE
MOVES OUT TO THE FAR NE, WHICH HAS DRAGGED A VERY WEAK FRONTAL
BOUNDARY INTO THE MOUNTAINS, WHICH IS AIDING IN SLIGHTLY MORE
LIFT FOR CONVECTIVE DEVELOPMENT THIS EVENING, WHILE COVERAGE HAS
DROPPED OFF DRASTICALLY EAST OF THE MOUNTAINS. ALL OTHER INGREDIENTS
REMAIN IN PLACE MUCH LIKE THE PAST WEEK. GUIDANCE HAS PWATS IN THE
1.75-2.00 INCH RANGE AND RELATIVELY WEAK STEERING FLOW ALOFT. THE
POTENTIAL FOR TRAINING AND/OR BACK-BUILDING STORMS CONTINUES, POSING
A CONTINUED THREAT OF LOCALLY TORRENTIAL RAINFALL RATES AND POSSIBLE
ISOLATED/LOCAL FLASH FLOODING. OVERNIGHT, POPS DECREASE QUICKLY, BUT
CANNOT RULE OUT A POP-UP SHOWER OR THUNDERSTORM BEFORE MIDNIGHT. FOR
FRIDAY, A SURFACE HIGH MIGRATES EAST FROM THE CENTRAL CONUS ALONG
WITH THE HIGH OVER THE ATLANTIC. IN BETWEEN THE TWO HIGHS SITS THE
CWA, ALLOWING FOR CONTINUED MOISTURE ADVECTION AND THE TYPICAL
DIURNALLY DRIVEN CONVECTION CHANCES. AGAIN, THE HIGHER CHANCES
ARE OVER THE MOUNTAINS (60-80%) AND ELSEWHERE 20-40%. TEMPERATURES
REMAIN IN THE LOW 90S TODAY BUT HEAT UP MORE FOR FRIDAY. THE HEAT
INDEX LOOKS TO BE A BIT MORE OF AN ISSUE STARTING TOMORROW. MANY
LOCATIONS EAST OF THE MOUNTAINS COULD SEE HI VALUES IN THE 100-104
RANGE, BUT REMAINS JUST BELOW HEAT ADVISORY CRITERIA AT THIS TIME.
SHORT TERM /FRIDAY NIGHT THROUGH MONDAY/
AS OF 1245 PM EDT THURSDAY: A FAIRLY ACTIVE PATTERN IS EXPECTED OVER
THE WEEKEND THRU MONDAY, AS UPPER RIDGE RETROGRADES SLIGHTLY TO THE
NORTHERN GULF COAST, AND HEIGHTS FALL ACROSS THE MID-ATLANTIC. THIS
WILL ALLOW A QUASI-STATIONARY FRONT TO SLOWLY SAG SOUTHWARD ACROSS
THE OHIO VALLEY AND MID-ATLANTIC. A TYPICAL HOT AND HUMID AIR MASS
IN PLACE COMBINED WITH EXTRA FOCUS FOR CONVECTION NEAR THE FRONTAL
BOUNDARY WILL RESULT IN CATEGORICAL POPS IN THE NC MOUNTAINS
TO SOLID CHC POPS ACROSS THE I-85 CORRIDOR AND SOUTHEAST EACH
DAY. GENERALLY, POPS WILL BE THE TYPICAL DIURNAL AFTN TO EARLY
EVENING TIME FRAME, BUT SOME INCREASE IN SHEAR ALONG A "RING OF
FIRE" AROUND THE UPPER RIDGE MAY SUPPORT MCS ACTIVITY MAKING A RUN
FOR THE SOUTHERN APPALACHIANS EITHER SUNDAY OR MONDAY. CONFIDENCE
IS STILL LOW ON THAT. THERE MAY ALSO BE AN INCREASING FLASH FLOOD
THREAT, AS ELEVATED PWATS IN THE 2-2.25" RANGE WILL PERSIST ACROSS
THE AREA THRU MONDAY. THE AREA OF MOST CONCERN WILL BE IN THE NC
MOUNTAINS NEAR THE TN BORDER THANKS TO THE PERSISTENT WESTERLY
UPSLOPE FLOW. ANOTHER CONCERN WILL BE THE HEAT INDEX, AS DEWPTS
MAY NOT MIX OUT AS MUCH AHEAD OF THE SAGGING FRONT, WHILE TEMPS
GET INTO THE MID 90S ACROSS MOST OF THE PIEDMONT. THE NBM DEWPTS
MAY BE A TAD HIGH, BUT THE LATEST FORECAST IS FOR PLENTY OF 105-109
HEAT INDICES ACROSS THE LOWER PIEDMONT AND THE CHARLOTTE AREA EACH
AFTN THRU MONDAY.
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
AS OF 100 PM EDT THURSDAY: UPPER RIDGING BEGINS TO REASSERT
ITSELF FROM THE LOWER MS VALLEY TOWARD THE EAST TUESDAY INTO
WEDNESDAY. THIS WILL ALLOW DRIER AIR TO WORK IN FROM THE NORTH
AND BRING POPS BACK DOWN CLOSER TO CLIMO. TEMPS WILL REMAIN ABOVE
NORMAL, BUT DEWPTS SHOULD MIX OUT MORE AND BRING HEAT INDICES BACK
UNDER HEAT ADVISORY CRITERIA FOR MOST OF THE FORECAST AREA.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: MOUNTAIN CONVECTION HAS INCREASED IN
COVERAGE OVER THE PAST HOUR IN AREAS WEST AND NORTH OF KAVL. THIS
WARRANTS A VCSH AT KAVL UNTIL LATE EVENING. MEANWHILE, CONVECTION
IS ISOLATED-AT-MOST ACROSS THE REMAINDER OF THE AREA. ADDITIONAL
ISOLATED CONVECTION WILL BE POSSIBLE NEAR THE OTHER TAF SITES THIS
EVENING, BUT ANY MENTION OF CONVECTION FOR THIS EVENING HAS BEEN
REMOVED FROM ALL SITES EXPECT KAVL. OTHERWISE, VFR CONDITIONS
ARE FORECAST AT THE TAF SITES THROUGH THE PERIOD. AREAS OF
MOUNTAIN VALLEY FOG AND LOW STRATUS ARE LIKELY AROUND DAYBREAK
FRIDAY, BUT WILL MOST LIKELY BE CONFINED TO THE VALLEYS WEST AND
NORTH OF KAVL. SIMILAR TO THIS MORNING, CAN'T RULE OUT A BRIEF
PERIOD OF IFR/LMVFR STRATUS DEVELOPING AROUND SUNRISE FRIDAY, BUT
CONFIDENCE IN THIS IS VERY LOW AT THIS TIME. SW WINDS OF 5-10 KTS
THIS EVENING ARE EXPECTED TO GIVE WAY TO LIGHTER WINDS OVERNIGHT,
BEFORE INCREASING TO 5-10 KTS AGAIN BY FRI AFTERNOON.
OUTLOOK: THUNDERSTORM CHANCES EACH AFTERNOON/EVENING. LOW STRATUS
OR FOG ARE POSSIBLE EACH MORNING IN MOUNTAIN/RIVER VALLEYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...ARK
NEAR TERM...CP/JDL
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JDL
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