161
FXUS62 KGSP 072335
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
735 PM EDT THU AUG 7 2025
SYNOPSIS
COLD AIR DAMMING WILL GRADUALLY WEAKEN OVER THE NEXT FEW DAYS,
WITH HIGH TEMPERATURES FORECAST TO REMAIN 4 TO 5 DEGREES BELOW
NORMAL THROUGH THE WEEKEND. THEY WILL WARM TO NEAR NORMAL BY
EARLY NEXT WEEK. ISOLATED TO SCATTERED AFTERNOON SHOWERS AND A
FEW THUNDERSTORMS ARE EXPECTED EACH DAY.
NEAR TERM /THROUGH FRIDAY/
AS OF 730 PM EDT THURSDAY: THE SYNOPTIC PATTERN REMAINS LARGELY
UNCAGED WITH A STOUT UPPER RIDGE CENTERED OVER THE DESERT SOUTHWEST
INTO THE SOUTHERN PLAINS. ON THE POLEWARD SIDE OF THE RIDGE, A
ROBUST NORTHERN STREAM TROUGH IS SLIDING OUT OF THE INTER-MOUNTAIN
WEST AND INTO THE NORTHERN PLAINS. FARTHER EAST, WEAK AND BROAD
TROUGHING REMAINS DRAPED DOWN THE APPALACHIANS SANDWICHED BETWEEN
THE WESTERN RIDGE AND ANOTHER RIDGE OFF THE COAST OVER THE ATLANTIC.
A WEAK WAVE MAY CLOSE OFF INTO AN UPPER LOW THROUGH TONIGHT OVER THE
AREA, BUT OTHERWISE FORCING FOR ASCENT REMAINS NEBULOUS AT BEST. AT
THE SURFACE, SPRAWLING HIGH PRESSURE IS SITUATED ACROSS NEW ENGLAND
INTO THE MID ATLANTIC WITH AN INVERTED TROUGH ALONG THE COAST.
WITHIN THIS TROUGH, GUIDANCE TRIES TO DEVELOP A WEAK TROPICAL/HYBRID
TYPE LOW JUST OFFSHORE. THE RESULT WILL BE FOR AN INCREASING
PRESSURE GRADIENT ACROSS THE EASTERN CAROLINAS WHICH WILL FURTHER
REINFORCE NORTHEAST FLOW INTO THE WESTERN CAROLINAS AND NORTHEAST
GEORGIA. A WEDGE OF DRY AIR WILL CONTINUE TO BE DRIVEN INTO THE AREA
WITH PWATS FALLING TO AT OR BELOW 1.5".
ANY AFTERNOON SHOWERS AND/OR STORMS SHOULD WANE OVERNIGHT, BUT A
STRAY SHOWER/DRIZZLE WILL BE POSSIBLE MAINLY ALONG AND EAST OF THE I-
77 CORRIDOR. THE ARRIVAL OF DRY AIR AND DEPARTURE OF THE WEAK UPPER
LOW WILL YIELD AN EVEN DRIER FORECAST TOMORROW WITH ONLY ISOLATED
SHOWERS ACROSS EASTERN ZONES AND ISOLATED TO WIDELY SCATTERED
MOUNTAIN SHOWERS AND STORMS, MAINLY NEAR THE TENNESSEE LINE. SHOULD
SUFFICIENT CLEARING OF CLOUD COVER OCCUR TOMORROW, TEMPERATURES WILL
FINALLY START TO REBOUND MORE WITH SLOW AIRMASS MODIFICATION
OCCURRING. THIS WOULD SUPPORT AFTERNOON HIGHS IN THE LOW, TO MAYBE
MID 80S.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/
AS OF 1244 PM EDT THURSDAY...
KEY MESSAGES:
1) COLD-AIR DAMMING BREAKS DOWN AND WARMER TEMPERATURES BEGIN
BUILDING.
2) ISOLATED TO SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS OVER
THE WEEKEND.
BROAD, EASTERN-CONUS RIDGING WILL AMPLIFY OVER THE WEEKEND AS A
SUBTROPICAL LOW DEEPENS OFF THE NC-VA COAST, PULLING NORTHEAST
THROUGH THE PERIOD AND DISLODGING A SURFACE HIGH PREVIOUSLY
LINGERING OFF THE NEW ENGLAND COASTLINE. THE RESULT STILL APPEARS
TO BE A LOSS OF SYNOPTIC SUPPORT FOR COLD AIR DAMMING...AND A STEADY
WEAKENING OF SURFACE HIGH PRESSURE RIDGING DOWN INTO THE CAROLINAS
BY THE END OF THE WEEKEND. SANS ANY ROBUST MECHANISM TO SCOUR
OUT THE WEDGE, HOWEVER, EXPECT ITS DETERIORATION TO BE GRADUAL.
THE INFLUENCE OF THE LOW AND ITS ASSOCIATED UPPER TROUGH WILL
LIMIT DEEPER MOISTURE OVER MOST OF THE FORECAST AREA OVER THE
WEEKEND...WITH THE EXCEPTION OF THE NC MOUNTAINS, AND PERHAPS PARTS
OF THE SAVANNAH RIVER VALLEY AND PARTS OF THE SOUTHERN UPSTATE.
HERE, THE 12Z OPERATIONAL GUIDANCE AS WELL AS LONG-RANGE ENSEMBLES
SUPPORT THE DEVELOPMENT OF 500-1000 J/KG SBCAPE BOTH AFTERNOONS,
WITH THE BEST COVERAGE LIKELY OVER THE MOUNTAINOUS TERRAIN, WHERE
THERE'LL BE THE BEST OPPORTUNITY FOR INITIATION. COVERAGE APPEARS
HIGHER OVERALL FOR SUNDAY, BY WHICH POINT THE NEAR-COMPLETE LOSS OF
INVERTED SURFACE RIDGING WILL PERMIT A RETURN OF ATLANTIC MOISTURE
AT THE LOW LEVELS. WHAT CONVECTION DEVELOPS EACH AFTERNOON SHOULD
POSE ONLY A LIMITED RISK OF SEVERE WEATHER...THOUGH DCAPE CLIMBS
HIGH ENOUGH IN A FEW MODELS (RDPS, ECMWF) TO SUPPORT ISOLATED
STRONG TO SEVERE CELLS.
LONG TERM /MONDAY THROUGH THURSDAY/
AS OF 103 PM EDT THURSDAY...
KEY MESSAGES:
1) TEMPERATURES CONTINUE TO WARM THROUGH THE NEW WORKWEEK, RETURNING
TO NORMAL AUGUST CONDITIONS BY MID-WEEK.
2) AFTERNOON SHOWERS AND THUNDERSTORMS ARE EXPECTED EACH DAY
THROUGH THE PERIOD.
SUBTROPICAL RIDGING WILL BEGIN TO REBOUND OVER THE SOUTHEASTERN
UNITED STATES MONDAY AND BEYOND, WHILE REMNANTS OF THE SURFACE RIDGE
OVER THE ATLANTIC WILL BE ABSORBED AS THE BERMUDA HIGH BECOMES
RE-ESTABLISHED OVER THE WESTERN ATLANTIC. THE RESULT FOR THE
CAROLINAS WILL BE A RETURN TO SEASONAL CONDITIONS. BY TUESDAY OR
CERTAINLY WEDNESDAY, HIGHS ARE EXPECTED TO BE BACK AROUND NORMAL -
IN THE LOWER 90S OR UPPER 80S ACROSS THE LOW TERRAIN - AND DIURNAL
SHOWER AND THUNDERSTORM CHANCES WILL RETURN, WITH WEAK STEERING
FLOW AND MOIST PROFILES SUPPORTIVE OF PROLIFIC RAINFALL PRODUCTION.
COVERAGE WILL INCREASE STEADILY EACH AFTERNOON, WITH SCATTERED TO
NUMEROUS STORMS EXPECTED IN THE AFTERNOON FROM MID-WEEK ONWARD.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: DECK OF LOW STRATUS WILL CONTINUE TO
HANG OUT ACROSS THE AREA THROUGH THE OVERNIGHT AND FIRST HALF
OF FRIDAY. GUIDANCE TRIES TO LIFT THIS DECK AND SCATTER IT OUT
LATER FRIDAY AFTERNOON AND EVENING. NOT VERY CONFIDENT IN THIS AS
GUIDANCE HAS NOT HAD A GOOD HANDLE ON THE PATTERN RECENTLY. MVFR
CIGS ARE EXPECTED TO BE WIDESPREAD BY THE OVERNIGHT HOURS THROUGH AT
LEAST DAYBREAK. VFR MAY RETURN FRIDAY AFTERNOON AND THAT IS WHAT'S
CURRENTLY IN THE TAF, BUT IS SUBJECT TO CHANGE. NORTHEASTERLY WINDS
EXPECTED THROUGH THE PERIOD AT 5-10 KTS, WITH SLIGHTLY LOWER VALUES
OVERNIGHT. KAVL WILL MAINTAIN A SOUTH TO SOUTHEASTERLY COMPONENT
THROUGH THE PERIOD. CAN'T RULE OUT AN OCCASIONAL LOW-END GUST
DURING PEAK HEATING.
OUTLOOK: THE WEDGE REMAINS IN PLACE THROUGH AT LEAST THE FIRST
HALF OF THE WEEKEND, KEEPING PERIODIC RESTRICTIONS AND -RA CHANCES
AROUND. DAILY DIURNAL SHOWERS AND THUNDERSTORMS CAN BE EXPECTED,
MAINLY ACROSS THE MOUNTAINS THE REST OF THIS WEEK INTO THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...MPR
NEAR TERM...TW
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...CAC
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