851
FXUS62 KGSP 050543
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
143 AM EDT SUN OCT 5 2025
SYNOPSIS
HIGH PRESSURE REMAINS IN CONTROL OVER THE NEXT FEW DAYS WITH NEAR-
NORMAL TEMPERATURES. CONTINUED WARMING IS EXPECTED TUESDAY AND
WEDNESDAY, AHEAD OF A COLD FRONT. INCREASING CLOUDS AND BETTER
RAIN CHANCES WILL BE IN STORE FOR WEDNESDAY IN ASSOCIATION WITH
THE COLD FRONT. COOLER TEMPERATURES EXPECTED BEHIND THE FRONT FOR
THE LATTER HALF OF THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 120 AM EDT SUNDAY...
KEY MESSAGES:
1) MOUNTAIN VALLEY FOG/LOW STRATUS POSSIBLE EACH MORNING
2) ABOVE NORMAL TEMPERATURES EXPECTED THROUGH THE NEAR TERM
3) RAIN CHANCES RETURN THIS AFTERNOON ALONG AND WEST OF I-26
SEEING BROKEN TO OVERCAST CIRRUS STREAMING NORTHWARD ACROSS THE
FORECAST AREA THIS MORNING AS STRATOCU CONTINUE TO SPREAD ACROSS THE
MOUNTAINS AND FOOTHILLS. THIS CLOUD COVER MAY ACT TO LIMIT MOUNTAIN
VALLEY FOG/LOW STRATUS LATER THIS MORNING, SO CONFIDENCE REMAINS LOW
ON THE FORMATION OF PATCHY TO LOCALLY DENSE FOG AND LOW STRATUS.
MORNING LOWS WILL END UP ~4-8 DEGREES ABOVE NORMAL THANKS TO THE
INCREASING CLOUD COVER.
UPPER ANTICYCLONE WILL REMAIN CENTERED OVER EASTERN NC/VA THROUGH
THE PERIOD BUT WILL GRADUALLY WEAKEN STARTING TONIGHT AS AN UPPER
TROUGH NUDGES EASTWARD TOWARDS THE GREAT PLAINS. AT THE SFC, HIGH
PRESSURE CENTERED OVER THE WESTERN ATLANTIC WILL SLOWLY DRIFT EAST
AS A COLD FRONT TRACKS ACROSS THE CENTRAL UNITED STATES. THIS WILL
ALLOW LOW-LEVEL FLOW TO TURN E'LY (EAST OF THE MOUNTAINS) AND SE'LY
(ACROSS THE MOUNTAINS) THROUGHOUT THE MORNING AND EARLY AFTERNOON
HOURS, LEADING TO AN INFLUX OF MOISTURE FROM THE ATLANTIC. THIS WILL
HELP KEEP CLOUD COVER AROUND THROUGH THE PERIOD, AS WELL AS BRING
RAIN CHANCES BACK TO THE FORECAST AREA THIS AFTERNOON, MAINLY ALONG
AND WEST OF I-26. THE WESTERN SC UPSTATE AND NE GA APPEAR TO HAVE
THE BEST CHANCE TO SEE ISOLATED TO SCATTERED SHOWERS DEVELOP WITH
THE HIGHEST POPS (25% TO 30%) IN PLACE ACROSS THESE ZONES. 00Z CAMS
ARE NOT IN THE GREATEST AGREEMENT REGARDING COVERAGE, BUT THEY
GENERALLY AGREE THAT THE HIGHEST RAIN CHANCES WILL REMAIN SOUTH AND
WEST OF THE GSP CWA. WITH LIMITED INSTABILITY AVAILABLE DURING PEAK
HEATING, THUNDER IS NOT EXPECTED TO ACCOMPANY THESE SHOWERS. HIGHS
THIS AFTERNOON WILL BE SIMILAR TO YESTERDAY, ENDING UP A FEW DEGREES
ABOVE NORMAL. LOWS MONDAY MORNING WILL END UP ~8-12 DEGREES ABOVE
NORMAL THANKS TO LINGERING CLOUD COVER. MOUNTAIN VALLEY FOG/LOW
STRATUS MAY DEVELOP OVERNIGHT INTO DAYBREAK MONDAY BUT CLOUD COVER
MAY LIMIT THIS POTENTIAL.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
AS OF 119 AM EDT SUNDAY: UPPER RIDGE AXIS AND AREA OF HIGH PRESSURE
RIDING UNDERNEATH WILL BE IN THE MIDST OF DRIFTING OFFSHORE THE
EASTERN SEABOARD BY THE START OF THE NEW WORKWEEK. IN THIS SETUP,
BETTER LOW-LEVEL EAST-SOUTHEASTERLY WAA FILTERS IN, WHILE HELPING
TO DETERIORATE ANY LINGERING WEDGE AS THE SYNOPTIC SUPPORT DIMINISHES
WITH THE RETREATING HIGH, AND STRONGER BOUNDARY LAYER MIXING LEADING
TO SCATTERING OF LOW-LEVEL CLOUDS. DEEP FRONTAL ZONE STRETCHED FROM
THE CENTRAL GULF COAST, THROUGH THE FLORIDA PENINSULA, AND OVER
THE BAHAMAS GRADUALLY LIFTS NORTH AND WILL PRODUCE GOOD CONVECTION
ALONG THE GULF COAST, WHICH WILL LIMIT BETTER MOISTURE TRANSPORT
THIS FAR NORTH. HOWEVER, MOIST UPGLIDE COULD INDUCE SOME SHOWER
COVERAGE OVER THE SOUTHWESTERN ZONES MONDAY INTO MONDAY NIGHT,
BUT COVERAGE IS SPARSE BASED ON MODEL GUIDANCE, WITH CONFIDENCE
BEING TOO LOW FOR A MENTIONABLE POP AT THIS TIME. SUBTLE HEIGHT
FALLS ON TUESDAY IN RESPONSE TO A LONGWAVE UPPER TROUGH THAT WILL BE
SITUATED FROM THE HUDSON BAY THROUGH THE GREAT LAKES REGION AND INTO
THE OH VALLEY. THE ASSOCIATED COLD FRONT WILL ENCROACH THE CWFA AS
A RESULT, BUT REMAIN NORTHWEST THROUGH TUESDAY NIGHT. SOME OF THE
MODEL GUIDANCE HAVE PRODUCED BETTER QPF RESPONSE BY TUESDAY NIGHT
NEAR THE NC/TN BORDER, BUT THE BRUNT OF THE PRECIP WILL REMAIN IN
THE BEGINNING PORTIONS OF THE EXTENDED PERIOD.
TEMPERATURES ON MONDAY WILL BE AT OR SLIGHTLY ABOVE NORMAL AS
LOW-LEVEL WAA FILTERS IN, BUT BETTER CLOUD COVER MAY HINDER
THE FULL POTENTIAL OF AFTERNOON HIGHS CLIMBING HIGHER DESPITE
ANOMALOUSLY HIGH THICKNESSES. BETTER INSOLATION AND COMPRESSIONAL
WARMING ON TUESDAY WILL HELP AFTERNOON HIGHS RISE A CATEGORY OR
SO ABOVE NORMAL AS A RESULT. OVERNIGHT LOWS FOR MONDAY AND TUESDAY
NIGHT WILL BE 5-10 DEGREES ABOVE NORMAL THANKS TO THE ONGOING WAA,
LEADING TO ELEVATED DEWPOINTS.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
AS OF 139 AM EDT SUNDAY: THE AFOREMENTIONED COLD FRONT WILL BEGIN
ITS TRACK ACROSS THE CWFA ON WEDNESDAY. AHEAD OF THE FRONT, GOOD
COMPRESSIONAL HEATING WILL LEAD TO AFTERNOON HIGHS REMAINING A
CATEGORY OR SO ABOVE NORMAL. BETTER FORCING AND DEEP LAYER SHEAR
STILL REMAINS NORTH OF THE AREA, BUT ENOUGH SHEAR AND SOME FORM OF
INSTABILITY MAY GET SOME LOOSELY ORGANIZED CONVECTION GOING, BUT NOT
EXPECTING A REAL SEVERE THREAT AT THIS TIME. MODEL GUIDANCE STILL
SUGGEST A FULL FROPA OCCURRING DURING THE FIRST HALF OF THURSDAY
AS A STOUT CONTINENTAL HIGH (~1030+MB) DRIFTS ACROSS THE GREAT
LAKES REGION WEDNESDAY NIGHT INTO THURSDAY AND SETTING UP SHOP
OVER NEW ENGLAND BY THURSDAY NIGHT. LOW-LEVEL CAA SHOULD FILTER IN
BEHIND THE FRONT AND KEEP THE CWFA ON THE COOLER SIDE STARTING ON
THURSDAY, WITH A WEDGE-LIKE CONFIGURATION TRYING TO NOSE INTO THE
REGION. HOWEVER, LATEST TRENDS QUICKLY SHIFTS THE SURFACE HIGH AS
AN ANTICYCLONE DEEPENS OVER THE SOUTHERN PLAINS AND HELPS TO CARVE
A TROUGH OVER THE SOUTHEASTERN CONUS BY UPCOMING WEEKEND. MOST OF
THE GUIDANCE DOESN'T HAVE MUCH FANFARE WITH THE TROUGH, BUT LOWER
THICKNESSES SHOULD HELP TEMPERATURES REMAIN IN CHECK. TEMPERATURES
ARE FORECAST TO DROP 5-10 DEGREES BELOW NORMAL THURSDAY BEHIND THE
FRONT, WITH ONLY A GRADUAL REBOUND THROUGH THE END OF THE FORECAST
PERIOD WITH SLIGHTLY BETTER AIRMASS MODIFICATION.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: COVERAGE OF STRATOCU AND CIRRUS WILL
GENERALLY BE SCT TO BKN THROUGH THE 06Z TAF PERIOD BUT CIGS SHOULD
REMAIN VFR FOR MOST TERMINALS. HOWEVER, MOUNTAIN VALLEY FOG/LOW
STRATUS MAY DEVELOP AGAIN AT KAVL, WITH LAKE FOG/STRATUS POSSIBLY
DEVELOPING AGAIN AT KHKY THIS MORNING. THUS, MAINTAINED TEMPOS FOR
RESTRICTIONS AT BOTH TERMINALS FROM 09Z-13Z. CONFIDENCE ON THE
FOG/LOW STRATUS DEVELOPMENT REMAINS LOW AS STRATOCU HAS BEEN
GRADUALLY EXPANDING ACROSS THE MOUNTAINS THE LAST FEW HOURS AND MAY
EVENTUALLY MAKE IT UP TO KHKY. THIS CLOUD COVER WOULD HELP LIMIT
FOG/STRATUS DEVELOPMENT THROUGH DAYBREAK. ANY FOG/STRATUS THAT
MANAGES TO DEVELOP WILL LIFT SHORTLY AFTER SUNRISE. OTHERWISE, WINDS
EAST OF THE MOUNTAINS WILL REMAIN NE THROUGH MID-MORNING BEFORE
TOGGLING MORE ENE/E BY LATE THIS MORNING OR EARLY THIS AFTERNOON.
WINDS AT KAVL WILL REMAIN CALM TO LIGHT AND VRB THROUGH DAYBREAK,
PICKING UP OUT OF THE SE SHORTLY AFTER DAYBREAK. WIND SPEEDS TODAY
WILL BE A BIT STRONGER COMPARED TO YESTERDAY, WITH SPEEDS RANGING
FROM 5-10 KTS. COULD NOT ENTIRELY RULE OUT SOME LOW-END WIND GUSTS,
MAINLY AT KAND AND KGMU, BUT CONFIDENCE IS LOW. KAND ALSO HAS THE
BEST CHANCE TO SEE SHRA THIS AFTERNOON SO WENT AHEAD AND INTRODUCED
A PROB30 AT THE TERMINAL FROM 17Z-22Z. HOWEVER, CONFIDENCE ON SHRA
IS LOW AS GUIDANCE IS NOT IN GREAT AGREEMENT REGARDING COVERAGE THIS
AFTERNOON.
OUTLOOK: OTHER THAN THE CONTINUED LIKELIHOOD OF EARLY MORNING
MOUNTAIN VALLEY FOG/LOW STRATUS, GENERALLY VFR CONDITIONS ARE
EXPECTED THROUGH AT LEAST EARLY NEXT WEEK. CHANCES FOR SHOWERS AND
POSSIBLY RESTRICTIONS INCREASE TOWARD MID-WEEK AHEAD OF AN
APPROACHING COLD FRONT.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...CAC
NEAR TERM...AR
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...AR
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