337
FXUS62 KGSP 131025
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
625 AM EDT SAT SEP 13 2025
SYNOPSIS
DRY HIGH PRESSURE WILL PERSIST OVER THE REGION THROUGH THE WEEKEND.
A DEVELOPING LOW PRESSURE SYSTEM ALONG THE CAROLINA COAST MAY BRING
RAIN INTO THE AREA BY THE MIDDLE OF NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 620 AM EDT SATURDAY...
KEY MESSAGES:
1) DRY AGAIN EAST OF THE MOUNTAINS WITH SPOTTY SHOWERS POSSIBLY
RETURNING ACROSS THE MOUNTAINS THIS AFTERNOON OR EVENING
2) MOSTLY SUNNY AND WARM AGAIN TODAY
3) MOUNTAIN VALLEY FOG AND LOW STRATUS EXPECTED EACH MORNING
PATCHY TO DENSE MOUNTAIN VALLEY FOG AND LOW STRATUS DEVELOPED
OVERNIGHT AND WILL LINGER THROUGH THE NEXT HOUR OR TWO BEFORE
LIFTING AS DAYTIME MIXING GETS UNDERWAY. CLEAR SKIES ARE NOTED
ELSEWHERE THIS MORNING. OTHERWISE, NOT MUCH CHANGE REGARDING THE
PATTERN THROUGH THE NEAR TERM. UPPER TROUGHING LINGERS OVER THE
SOUTHEAST WHILE SFC HIGH PRESSURE SITS TIGHT OVER THE EASTERN US.
THIS WILL KEEP MOSTLY DRY AND WARM CONDITIONS AROUND, ALTHOUGH SOME
SPOTTY SHOWERS MAY RETURN THIS AFTERNOON OR EVENING ACROSS THE
MOUNTAINS. CONFIDENCE ON CONVECTION REMAINS LOW SO MAINTAINED A DRY
FORECAST FOR NOW. HIGHS TODAY WILL BE SIMILAR TO YESTERDAY.
AFTERNOON TEMPS EAST OF THE MOUNTAINS WILL REBOUND INTO THE LOWER TO
MID 80S. THE MOUNTAIN VALLEYS WILL ONCE AGAIN SEE TEMPS REACH INTO
THE UPPER 70S TO LOWER 80S, WITH TEMPS ACROSS THE HIGHER ELEVATIONS
RANGING FROM THE UPPER 60S TO UPPER 70S. MORNING LOWS WILL RANGE
FROM THE UPPER 50S TO LOWER 60S EAST OF THE MOUNTAINS AND THE LOWER
TO UPPER 50S ACROSS THE MOUNTAINS. MOUNTAIN VALLEY FOG AND LOW
STRATUS WILL DEVELOP AGAIN OVERNIGHT INTO DAYBREAK SUNDAY,
DISSIPATING SHORTLY AFTER SUNRISE AS DAYTIME MIXING DEVELOPS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
AS OF 110 AM EDT SATURDAY: AN UPPER LOW SPINS ALONG THE CAROLINA
COAST OR COASTAL PLAIN THROUGH THE PERIOD. AT THE SURFACE, A LOW
PRESSURE SYSTEM ASSOCIATED WITH THE UPPER LOW REMAINS OFF SHORE OR
NEAR THE CAROLINA COAST WITH RIDGE OF HIGH PRESSURE OVER OUR AREA
EMANATING FROM A CENTER OVER NEW ENGLAND. THIS KEEPS THE FORECAST
AREA DRY EACH DAY, ALTHOUGH AN ISOLATED DIURNAL SHOWER CAN'T BE
RULED OUT OVER THE MOUNTAINS. HIGHS NEAR OR SLIGHTLY ABOVE NORMAL
SUNDAY, DROP A DEGREE OR TWO ON MONDAY. LOWS A FEW DEGREES BELOW
NORMAL SUNDAY NIGHT RISE TO NEAR NORMAL MONDAY NIGHT.
LONG TERM /TUESDAY THROUGH FRIDAY/
AS OF 145 AM EDT SATURDAY: THE MODEL UNCERTAINTY FOR THE MEDIUM
RANGE CONTINUES. THE GUIDANCE AGREES ON A LOW DEVELOPING NEAR THE
CAROLINA COAST ON TUESDAY AND SLOWLY MOVING NORTHEAST THROUGH
THURSDAY. HOWEVER A DIFFERENCE IN LOCATION AND RESULTING SENSIBLE
WEATHER REMAINS. THE GFS HAS BEEN CONSISTENT IN KEEPING THE LOW OFF
SHORE WITH A DRY FORECAST FOR OUR AREA. THE ECWMF HAS BEEN
CONSISTENT IN THE LOW DEVELOPING ALONG THE COAST AND MOVING INLAND
FAR ENOUGH FOR AN EASTERLY FLOW TO BRING MOISTURE AND PRECIPITATION
INTO THE AREA. THE CANADIAN WAS SIMILAR TO THE ECMWF BUT NOW HAS
THE LOW FARTHER EAST, BUT NOT FAR ENOUGH TO KEEP PRECIP OUT OF OUR
AREA, BUT LESS QPF THAN THE ECMWF. THE GFS AND CANADIAN ENSEMBLE
MEANS SHOW PRECIP DEVELOPING OVER THE AREA BUT ON THE LIGHTER SIDE.
THE GUIDANCE BLEND KEEPS MAINLY A SLIGHT CHANCE POP OVER THE AREA
WITH SOME CHANCE POP OVER THE NC PIEDMONT. GIVEN THE UNCERTAINTY THIS
CONTINUES TO BE THE PATH OF LEAST REGRET. TEMPS WILL BE BELOW NORMAL
TUE AND WED. SLIGHT CHANCE DIURNAL POP LINGERS OVER THE MOUNTAINS
THU AND FRI AS A WEAK LOW PRESSURE SYSTEM MOVES EAST ALONG THE OH
VALLEY. TEMPS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL BOTH DAYS.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: MOSTLY DRY AND VFR THROUGH THE 12Z TAF PERIOD
OUTSIDE OF MOUNTAIN VALLEY FOG AND LOW STRATUS DEVELOPING EACH
MORNING. AS OF 10Z KAVL IS REPORTING VLIFR CIGS AND VSBYS SO WILL
HOLD ONTO TEMPO AT THE TERMINAL THROUGH THE EARLY MORNING HOURS. FOG
AND LOW STRATUS WILL GRADUALLY LIFT AFTER SUNRISE AS MIXING
DEVELOPS. VFR CU FIELD SHOULD RETURN THIS AFTERNOON/EARLY EVENING,
WITH SOME SPOTTY SHOWERS POSSIBLY DEVELOPING ACROSS THE MOUNTAINS
AGAIN. WITH ACTIVITY EXPECTED TO REMAIN ISOLATED, MAINTAINED A DRY
FORECAST AT KAVL AS CONFIDENCE IS VERY LOW ON WHETHER A STRAY SHOWER
WILL TRACK DIRECTLY OVER THE TERMINAL. WINDS EAST OF THE MOUNTAINS
WILL BE MAINLY NE THIS MORNING AND AFTERNOON BEFORE TOGGLING MORE
ENE BRIEFLY THIS EVENING. WIND SPEEDS WILL BE A LITTLE STRONGER
TODAY EAST OF THE MOUNTAINS, RANGING FROM 5-9 KTS. WINDS EAST OF THE
MOUNTAINS WILL THEN TOGGLE BACK TO A MORE N/NNE DIRECTION LATE THIS
EVENING INTO TONIGHT WHILE BECOMING LIGHT. WINDS AT KAVL WILL BE
LIGHT AND VRB TO CALM THROUGH DAYBREAK BEFORE TOGGLING MORE NE AFTER
DAYBREAK AND EVENTUALLY MORE E/ENE THIS AFTERNOON INTO EARLY THIS
EVENING. WINDS AT KAVL WILL THEN GO LIGHT AND VRB TO CALM AGAIN LATE
THIS EVENING INTO TONIGHT. ANOTHER ROUND OF MOUNTAIN VALLEY FOG AND
LOW STRATUS WILL DEVELOP OVERNIGHT INTO DAYBREAK SUNDAY.
OUTLOOK: MOSTLY DRY AND VFR THROUGH EARLY NEXT WEEK, OUTSIDE OF THE
POTENTIAL FOR MOUNTAIN VALLEY FOG AND/OR LOW STRATUS EACH MORNING.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...RWH
NEAR TERM...AR
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...AR
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