646
FXUS62 KGSP 290512
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
112 AM EDT SUN JUN 29 2025
SYNOPSIS
A TYPICAL SUMMER PATTERN CONTINUES INTO EARLY NEXT WEEK WITH
SEASONABLE TEMPERATURES AND DAILY CHANCES FOR AFTERNOON AND EARLY
EVENING THUNDERSTORMS. A COLD FRONT APPROACHES THE AREA ON TUESDAY
AND DRIER WEATHER MAY RETURN FOR THE HOLIDAY WEEKEND.
NEAR TERM /THROUGH TODAY/
AS OF 1215 AM EDT SUNDAY: A FEW DECAYING STORMS ARE STILL TRYING TO
HANG ON AS THEIR OUTFLOW BOUNDARIES SHOOT SOUTHWARD. THESE STUBBORN
STORMS IN THE SOUTHERN ZONES HAVE BEEN PAINSTAKINGLY SLOW TO
DIMINISH BUT SHOULD CALM DOWN IN THE NEXT HOUR. SATELLITE SHOWS A
BROAD AREA OVER THE UPSTATE OF CONVECTIVE CLOUD DEBRIS SCATTERING
SLOWLY. THERE IS ALSO A FEW AREAS IN THE MOUNTAIN VALLEYS LIGHTING
UP WITH FOG ALREADY. THIS WILL CONTINUE TO INCREASE THROUGH THE
NIGHT AND DISAPPEAR AFTER DAYBREAK.
OTHERWISE, WHILE GUIDANCE IS SHOWING THE AIR MASS WON'T BE AS
UNSTABLE SUNDAY, IT WILL STILL BE MODERATELY UNSTABLE. PW VALUES
REMAIN HIGH WITH EVEN LESS MID LEVEL DRY AIR LEADING TO LOWER DCAPE
AND SFC DELTA THETA-E VALUES. HOWEVER, FORCING WILL BE ENOUGH FOR
MORE DIURNAL CONVECTION FAVORING THE MOUNTAINS AND FOOTHILLS WITH
SCATTERED COVERAGE ELSEWHERE. SEVERE CHANCE IS LOWER BUT HEAVY RAIN
CHANCE HIGHER GIVEN THE PREVIOUSLY MENTIONED CONDITIONS. TRAINING OR
ANCHORING OF CELLS WILL BE POSSIBLE ONCE AGAIN. HIGHS WILL BE NEAR
NORMAL ACROSS THE MOUNTAINS AND A FEW DEGREES ABOVE NORMAL
ELSEWHERE.
SHORT TERM /TONIGHT THROUGH TUESDAY/
AS OF 1221 PM SATURDAY: THE FORECAST CONTINUES TOMORROW NIGHT WITH
BROAD BERMUDA RIDGE EXTENDING ACROSS THE ATLANTIC AND INTO THE
SOUTHEAST COAST. FARTHER UPSTREAM, A NORTHERN STREAM TROUGH WILL BE
SWINGING ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THE TROUGH
IS PROGGED TO SLIDE ACROSS THE MIDWEST ON MONDAY AND ACROSS THE
GREAT LAKES INTO NEW ENGLAND ON TUESDAY. WEAK DEEP-LAYER SOUTHWEST
FLOW WILL KEEP A MOIST SUB-TROPICAL AIRMASS ENTRENCHED ACROSS THE
AREA WITH PWATS OF 1.75-2". A PERSISTENCE FORECAST SEEMS LIKELY ON
MONDAY WITH SCATTERED TO NUMEROUS DIURNALLY DRIVEN THUNDERSTORMS
WITH THE GREATEST RAIN CHANCES ACROSS THE MOUNTAINS. OUTFLOW
BOUNDARIES PUSHING OUT OF THE MOUNTAINS MAY INITIATE NEW SCATTERED
CONVECTION MAINLY ALONG AND NORTH OF I-85 WITH GENERALLY ISOLATED TO
WIDELY SCATTERED COVERAGE FARTHER SOUTH/EAST. THE FORECAST TURNS
WETTER ON TUESDAY AS THE PREVIOUSLY MENTIONED TROUGH PASSES NORTH OF
THE AREA AND DRAGS A COLD FRONT WITHIN THE TROUGH AXIS TOWARDS THE
AREA. DEEP MOISTURE POOLING AHEAD OF THE BOUNDARY ALONG WITH A
SLIGHT UPTICK IN FLOW/WEAK FORCING WILL PROVE SUFFICIENT TO
INSTIGATE NUMEROUS TO WIDESPREAD AFTERNOON/EARLY EVENING STORMS
ACROSS MUCH OF THE AREA. STORMS MAY LOOSELY ORGANIZE INTO
CLUSTERS/LINEAR SEGMENTS ALONG COMPOSITE COLD POOLS. AS WITH ANY
SUMMER CONVECTION, A FEW STRONG TO ISOLATED SEVERE STORMS CANNOT BE
RULED OUT WITH THE MAIN THREAT BEING WET MICROBURSTS. THE
ENVIRONMENT WON'T BE OVERLY CONDUCIVE TO DAMAGING WINDS WITH POOR
LAPSE RATES, DCAPE, SURFACE DELTA THETAE AND VERTICAL TOTALS - THUS
ANY SEVERE THREAT SHOULD REMAIN FAIRLY ISOLATED.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
AS OF 1232 PM SATURDAY: THE LATEST SUITE OF GLOBAL MODEL GUIDANCE IS
IN FAIRLY GOOD AGREEMENT THAT THE FRONTAL BOUNDARY WILL SLIDE INTO
THE AREA ON WEDNESDAY WITH ANOTHER DAY OF FAIRLY HIGH COVERAGE OF
DIURNAL THUNDERSTORMS. BY THURSDAY, THE BOUNDARY BEGINS TO PUSH
SOUTH AND EAST OF THE AREA WITH MUCH LOWER THETAE AIR ARRIVING IN
ITS WAKE. THIS WOULD SHUNT THE GREATEST RAIN CHANCES SOUTH OF THE
AREA WITH A RETURN TO A MOSTLY DRY FORECAST. DEPENDING ON HOW FAR
SOUTH THE BOUNDARY MAKES IT, THE FORECAST MAY REMAIN DRY THROUGH THE
4TH OF JULY HOLIDAY WEEKEND. OF COURSE A FEW ISOLATED SHOWERS/STORMS
CAN NEVER BE RULED OUT OVER THE MOUNTAINS EVEN IN A POST-FRONTAL
AIRMASS. SHOULD THE BOUNDARY STALL OVER OR NEAR THE AREA, HOWEVER,
THE FORECAST WOULD STAY ACTIVE THROUGH THE HOLIDAY WEEKEND. CURRENT
MODEL TRENDS SUPPORT THE DRIER FORECAST, SO WILL KEEP RAIN CHANCES
IN LINE WITH THE NATIONAL MODEL BLEND WITH ONLY ISOLATED CHANCES
BEING ADVERTISED.
AVIATION /05Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS PREVAIL THROUGH THE TAF PERIOD
AT MOST SITES. SIMILAR TO THE LAST FEW DAYS, CALM TO LIGHT VRB WINDS
OVERNIGHT AND PICKING UP AGAIN SLOWLY IN THE LATE MORNING. HIGH
PRESSURE OFF TO THE WEST OF THE AREA ALLOWS FOR MORE SOUTHERLY WINDS
SUNDAY AFTERNOON, BUT LIGHT. KAVL REMAINS MOSTLY NW. ANOTHER ROUND
OF BR/FG POSSIBLE AT KAVL AND KHKY IN THE WEE HOURS THIS MORNING.
CONFIDENCE ISN'T HIGH ENOUGH TO PREVAIL AS THE AREA DID NOT RECEIVE
MUCH RAINFALL EARLIER IN THE DAY. SO WILL KEEP A TEMPO GOING FROM
09Z-12Z. SUNDAY AFTERNOON RINGS IN ANOTHER CHANCE FOR SCATTERED
SHOWERS AND TSRA, POSSIBLE ANYWHERE ESPECIALLY IN THE MOUNTAINS.
PROB30S AGAIN AT ALL TERMINALS FOR THE TSRA. ONCE SHOWERS AND
THUNDERSTORMS CLEAR UP, ANOTHER CALM NIGHT TO ROUND OUT THIS TAF
FORECAST.
OUTLOOK: DAILY CHANCES FOR AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS INTO NEXT WEEK. FOG AND/OR LOW STRATUS POSSIBLE EACH
MORNING IN THE USUAL MOUNTAIN VALLEYS AS WELL AS NEAR LAKES AND
RIVERS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...CP
NEAR TERM...CP/RWH
SHORT TERM...TW
LONG TERM...TW
AVIATION...CP
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