589
FXUS62 KGSP 272320
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
720 PM EDT WED AUG 27 2025
SYNOPSIS
HIGH PRESSURE REMAINS IN CONTROL THROUGH MUCH OF THE REST OF THE
WEEK. COOLER AND DRIER WEATHER CONTINUES THROUGH THE WORKWEEK WITH
SOME INCREASE IN MOISTURE OVER THE WEEKEND THAT MAY RESULT IN
SCATTERED AFTERNOON AND EVENING SHOWERS AND STORMS.
NEAR TERM /THROUGH THURSDAY/
AS OF 715 PM EDT WEDNESDAY: STRATOCU HAS SCATTERED OUT OUTSIDE OF
THE MOUNTAINS BUT LINGERS ACROSS THE MOUNTAINS AS CIRRUS SPREADS IN
FROM THE NW. THE CLOUDS WILL LINGER ACROSS THE MOUNTAINS AND COULD
LIMIT FOG POTENTIAL AND POSSIBLY KEEP LOWS A LITTLE ON THE WARMER
SIDE OF GUIDANCE. STILL, HAVE DROPPED LOWS SLIGHTLY WITH A BLEND OF
THE NATIONAL BLEND AND MOS GUIDANCE AND MENTIONED SOME PATCHY VALLEY
FOG.
OTHERWISE, THE CENTER OF THE SURFACE HIGH SLIDES EASTWARD AND
POSITIONS OVER THE SOUTHEAST INTO THURSDAY. A STRONG TROUGH REMAINS
PARKED OVER THE EASTERN CONUS THROUGH THE PERIOD, SHUNTING RAIN
CHANCES AND KEEPING THE COOLER AND DRIER AIR IN PLACE. FOR THIS, NOT
EXPECTING ANYTHING IN TERMS OF PRECIPITATION THROUGH THE NEAR TERM.
AS THE CENTER OF THE HIGH MOVES OVERHEAD, WINDS BECOME VERY LIGHT TO
EVEN VRB BY TONIGHT AND INTO THURSDAY MORNING THEN GO LIGHT S TO SW
DURING THE AFTERNOON. OVERNIGHT TEMPS COULD BE A TAD WARMED DUE TO
LINGERING CLOUDS WITH A MIX OF 50S AND LOW 60S. THERE IS A
POSSIBILITY FOR SOME MOUNTAIN VALLEY FOG NEAR DAYBREAK, ESPECIALLY
AS THE WINDS BECOME CALMER. HIGHS WILL BE SLIGHTLY WARMER ON
THURSDAY BUT STILL AROUND 5 DEGREES BELOW NORMAL.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
AS OF NOON WED: AXIS OF 500MB TROUGH OVER THE EASTERN CONUS,
ENCIRCLING UPPER LOW OVER SOUTHERN ONTARIO/QUEBEC, SHOULD SWING EAST
OF THE CWA THURSDAY NIGHT. A SUBTLE ACCOMPANYING COLD FRONT CROSSES
THE AREA AS LOW-LEVEL WINDS VEER TOWARD NW. THE FRONT IS NOT
ASSOCIATED WITH APPRECIABLE CAA, BUT REINFORCES A GRADIENT BETWEEN
DRY CONTINENTAL AIR OVER OUR AREA AND A MORE HUMID AIRMASS TO OUR
SOUTH. EARLIER MODEL RUNS GENERATED SOME PRECIP RESPONSE ALONG THE
CONVERGENCE ZONE THU NIGHT, BUT THOSE MODELS HAVE TRENDED DRIER AND
POPS ARE NOW BELOW SLIGHT-CHANCE THEN AND FRIDAY MORNING. FRIDAY
STILL IS EXPECTED TO BE CLEARER THAN THURSDAY AND THE ADDITIONAL
SUNSHINE BRINGS TEMPS SLIGHTLY WARMER, BUT STILL A COUPLE DEGREES
BELOW NORMAL. AFTERNOON DEWPOINTS MAY MIX OUT A BIT MORE THAN THU AS
DRIER AIR IS PRESENT ABOVE THE PBL, ESPECIALLY OVER THE MOUNTAINS AND
IN THE WARMER I-77 CORRIDOR. A FEW SPOTS MIGHT SEE RH DROP INTO THE
30-35% RANGE AT PEAK HEATING.
MEANWHILE, A STALLED FRONTAL ZONE--THE BOUNDARY WHICH PASSED US
EARLIER IN THE WEEK--ARCS ACROSS THE DEEP SOUTH FRI AND SAT. A SFC
WAVE DEVELOPS ALONG THE FRONT IN THE ARKLATEX REGION FRIDAY, WHICH
TRACKS TO THE VICINITY OF THE FL PANHANDLE BY SATURDAY MORNING.
MODELS STILL VARY AS TO THE SPECIFIC TIMING OR LOCATION BUT MOSTLY DO
SHOW A BIT OF ISENTROPIC LIFT AND MOISTURE ADVECTION NORTH OF THE
BOUNDARY AND INTO OUR CWA BY EARLY SAT, ON PREDOMINANTLY EASTERLY TO
SOUTHEASTERLY 925-850MB FLOW NORTH OF THE SFC LOW. POPS RISE TO THE
CHANCE RANGE OVER MOST OF THE AREA, WITH HIGHEST VALUES ALONG THE
E/SE FACING BLUE RIDGE ESCARPMENT. A RUMBLE OF THUNDER CAN'T BE RULED
OUT, BUT PROFILES FAVOR EITHER SHALLOW CONVECTION OR SIMPLY
STRATIFORM RAIN. OUR REGION WILL REMAIN ON THE UPSTREAM SIDE OF THE
UPPER TROUGH BY THEN OVER THE NE CONUS, AND WEAK HIGH PRESSURE NOSES
IN FROM THE GREAT LAKES. BETWEEN THAT AND CLOUDS/PRECIP, SATURDAY
SHOULD TREND COOLER THAN FRI, WITH TEMPS IN MUCH OF THE WESTERN HALF
OF THE CWA REMAINING BELOW 80 THRU THE DAY.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
AS OF 1250 PM WED: STORY FOR THE MEDIUM RANGE CONTINUES TO BE THE
COMPETING INFLUENCES OF THE DRY CONTINENTAL SFC HIGH TO OUR NORTH,
WHICH LOOKS TO RIDGE DOWN THE EAST COAST IN CAD-LIKE FASHION,
AND THE STALLED FRONT AND SFC LOW TO OUR SOUTH.
THE EASTERLY-FLOW REGIME THAT DEVELOPS OVER THE WEEKEND AS A RESULT
OF THE ABOVE FEATURES IS LIKELY TO PERSIST THROUGH MONDAY, POSSIBLY
TUESDAY, BEFORE THE FLOW BACKS TO MORE OF A NE'LY DIRECTION. THAT
SHOULD REDUCE FORCING FROM EITHER ISENTROPIC OR MECHANICAL LIFT
ONCE IT OCCURS. CONFIDENCE REMAINS HIGH ENOUGH FOR THE REGIME
TO CONTINUE SUNDAY THAT POPS REMAIN SIMILAR TO SATURDAY'S. AS
CONSENSUS FOR THE BACKING FLOW INCREASES MON AND TUE AS FRONTAL
WAVE AMPLIFIES--OR AS A SECOND CYCLOGENESIS OCCURS AS ON THE 27/00Z
EURO--CHANCES DIMINISH. WEAK INSTABILITY WILL CONTINUE EACH DAY AND
A DIURNAL COMPONENT IS STILL REFLECTED IN POPS. GREATEST POTENTIAL
FOR RAIN RATES AND THUNDER SUNDAY WHEN MEAN INSTABILITY FROM LREF
MEMBERS IS HIGHEST (BUT STILL FAIRLY LOW FOR AUGUST).
MAX TEMPS REMAIN BELOW NORMAL THRU THE PERIOD. MONDAY, LABOR DAY,
ENDS UP WITH THE LOWEST DAYTIME TEMPS AS THE DRY HIGH EXERTS THE
MOST INFLUENCE: HIGHS IN THE MID-70S ACROSS THE PIEDMONT AND LOWER
70S IN SOME MOUNTAIN VALLEYS. TEMPS REBOUND SLIGHTLY TUE SEEMINGLY
AS A RESULT OF CLEARER SKIES.
AVIATION /23Z WEDNESDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: VFR STRATOCU HAS SCATTERED OUT OUTSIDE OF THE
MOUNTAINS BUT CONTINUE ACROSS THE MOUNTAINS, WITH INCREASING CIRRUS
ACROSS THE AREA. VFR STRATOCU LINGERS OVERNIGHT ACROSS THE MOUNTAINS
INTO KHKY AND POSSIBLY ELSEWHERE. MOUNTAIN VALLEY FOG POSSIBLE
OVERNIGHT AND HAVE INCLUDED AT TEMPO FOR MVFR AT KAVL, BUT THE
STRATOCU MAY LIMIT FOG FORMATION. THE STRATOCU LINGERS ACROSS THE
MOUNTAINS AND KHKY THROUGH THE DAY WITH SCT POSSIBLY BKN STRATOCU
ELSEWHERE. WINDS BECOME LIGHT AND VARIABLE THIS EVENING AND
OVERNIGHT. WINDS PICK UP FROM THE S TO SW DURING THE AFTERNOON.
OUTLOOK: DRY CONDITIONS REMAIN THROUGH FRIDAY. SHOWERS AND
THUNDERSTORMS, AND ASSOCIATED RESTRICTIONS, MAY RETURN FOR THE
WEEKEND INTO MONDAY. FOG AND/OR LOW STRATUS MAY DEVELOP EACH NIGHT,
MAINLY IN THE MOUNTAIN VALLEYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...CP/RWH
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...RWH
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