594
FXUS62 KGSP 081053
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
653 AM EDT THU OCT 8 2026
WHAT HAS CHANGED
THE AVIATION DISCUSSION HAS BEEN UPDATED FOR THE 12Z TAF ISSUANCE.
KEY MESSAGES
1. QUIET WEATHER WITH ABOVE-NORMAL TEMPERATURES AGAIN TODAY,
THEN A COOL-DOWN BACK TO NORMAL FOR FRIDAY.
2. WIDESPREAD RAIN IS EXPECTED TO MOVE INTO THE REGION ON SATURDAY
AND CONTINUE THROUGH SUNDAY. EXCESSIVE RAINFALL WILL BE POSSIBLE
SATURDAY NIGHT AND SUNDAY, ALONG WITH A SMALL RISK FOR SEVERE
THUNDERSTORMS MAINLY SUNDAY AFTERNOON.
DISCUSSION
KEY MESSAGE 1: QUIET WEATHER WITH ABOVE-NORMAL TEMPERATURES AGAIN
TODAY, THEN A COOL-DOWN BACK TO NORMAL FOR FRIDAY.
VERY LITTLE CHANGE ON THE FRONT END OF THIS FORECAST, OTHER THAN
PERHAPS THE CENTER OF THE REINFORCING HIGH COMING A LITTLE FARTHER
SOUTH AND INTO THE FCST AREA ON FRIDAY. HIGH TEMPS TODAY WILL
BE SEASONALLY WARM AND BETTER THAN FIVE DEGREES ABOVE NORMAL,
AIDED BY SOME MODEST DOWNSLOPE WARMING ON THE LEADING EDGE OF
THE MID/UPPER ANTICYCLONE APPROACHING FROM THE WEST. A WEAK COLD
FRONT WILL CROSS THE AREA THURSDAY NIGHT AND USHER IN A SLIGHTLY
COOLER AIR MASS FOR FRIDAY AS THE POSITION OF THE REINFORCING HIGH
FAVORS THE DEVELOPMENT OF A DRY COLD AIR DAMMING WEDGE. A STREAM
OF THICKENING HIGH CLOUDS EXHAUSTED FROM TS ISAIAS WILL ALSO HELP
TO KNOCK THE TEMPS BACK TO NORMAL. IT IS POSSIBLE THE HIGH TEMP
FORECAST FOR FRIDAY AFTERNOON COULD BE ON THE HIGH SIDE IF HIGH
CLOUDS ARRIVE THICKER AND SOONER. THE QUIET WEATHER WILL COME TO
AN END AFTER MIDNIGHT FRIDAY.
KEY MESSAGE 2: WIDESPREAD RAIN IS EXPECTED TO MOVE INTO THE REGION
ON SATURDAY AND CONTINUE THROUGH SUNDAY. EXCESSIVE RAINFALL WILL
BE POSSIBLE SATURDAY NIGHT AND SUNDAY, ALONG WITH A SMALL RISK
FOR SEVERE THUNDERSTORMS MAINLY SUNDAY AFTERNOON.
OUR ATTENTION TURNS QUICKLY TO THE SOUTHWESTERN TO CENTRAL GULF
WHERE HURRICANE ISAIAS IS EXPECTED TO STRENGTHEN TO A HURRICANE
LATER TODAY AND TAKE A MORE NORTHWARD TRACK TOWARD THE NORTHERN GULF
COASTAL REGION TONIGHT AND FRIDAY. REFER TO THE LATEST GUIDANCE FROM
THE NATIONAL HURRICANE CENTER FOR MORE DETAILS. THE STORM ISN'T
EXPECTED TO START AFFECTING THE WESTERN CAROLINAS UNTIL THE PRE-DAWN
HOURS SATURDAY AT THE EARLIEST, AS MOISTURE SURGES NORTHWARD AS THE
CENTER COMES ASHORE IN THE MIDDLE OF THE NORTHERN GULF COAST. SO,
PRECIP CHANCES RAMP UP STEADILY FROM THE SOUTH IN THE PRE-DAWN HOURS
SATURDAY AND REACH THE CATEGORICAL RANGE EVERYWHERE BY LATE THAT
EVENING.
THE EXCESSIVE RAIN POTENTIAL IS THE MAIN CONCERN, WHAT WITH
A CURRENT FORECAST FAVORABLE NORTHWARD TRACK WEST OF THE
MOUNTAINS. THAT BEING SAID, THERE'S A LOT OF FACTORS THAT COULD
COME INTO PLAY, AND SOME FAIRLY BIG DIFFERENCES ARE SEEN IN THE
QPF FROM VARIOUS SOURCES, SOME STILL POINTING TO A MORE BENEFICIAL
RAIN AND OTHERS SUGGESTING SOMETHING MORE PROBLEMATIC. THAT WE
ARE GOING INTO THE WEEKEND FROM A DRY STRETCH WILL BE A LIMITING
FACTOR, AND THE DRY AIR MASS IN PLACE COULD DELAY THE PRECIP ONSET
EARLY ON SATURDAY MORNING. MID/UPPER FORCING MAY DOMINATE EARLY
ON SATURDAY, BUT THE LOW LEVEL FORCING AND ISENTROPIC UPGLIDE
WILL TAKE OVER INTO SATURDAY EVENING AS MOISTURE IS TRANSPORTED
OVER TOP OF THE WEDGE. SATURDAY NIGHT LOOKS LIKE IT HOLDS THE BEST
COLLECTION OF INGREDIENTS FOR HEAVY RAIN, INCLUDING A STRENGTHENING
SOUTHEASTERLY LOW LEVEL JET, DEEP TROPICAL MOISTURE, AND PLENTY
OF FORCING. THE QPF HAS TRENDED SLIGHTLY UPWARD WITH THIS CYCLE,
PARTICULARLY OVER THE WESTERN PIEDMONT, BUT THE NBM STILL SHOWS
LESS THAN WPC. THE NBM HAS ONLY MODEST CHANCES OF GETTING GREATER
THAN 3 INCHES OF RAIN IN A 24 HOUR PERIOD, AND THAT IS CENTERED
ON THE USUAL SOUTHEASTERLY FLOW UPSLOPE MAXIMUM IN THE HEADWATERS
OF THE FRENCH BROAD AND SAVANNAH RIVER BASIN. THE FRIDAY RUNS OF
THE CAMS SHOULD BE MUCH MORE REVEALING, AND IT MIGHT TAKE UNTIL
WE SEE THAT GUIDANCE BEFORE WATCHES ARE CONTEMPLATED.
ASSUMING THE TRACK FORECAST WORKS OUT AS SHOWN IN THE LATEST
ADVISORY, WE WILL START TO LOSE THE BEST LOW LEVEL FORCING EARLY
SUNDAY AS THE FLOW AT 850MB VEERS MORE S TO SW. A DRY SLOT MAY
START TO WORK IN FROM THE WEST AND SOUTHWEST LATER IN THE DAY. BY
SUNDAY AFTERNOON, THE SITUATION COULD GET INTERESTING AS THE
CIRCULATION ASSOCIATED WITH ISAIAS ALLOWS FOR THE WEDGE BOUNDARY
TO LIFT NORTHWARD INTO THE FORECAST AREA. THE LREF INDICATES SOME
FAVORABLE OVERLAP OF BUOYANCY ABOVE 500 J/KG AND GREATER THAN
30 KT OF SHEAR SUNDAY AFTERNOON IN THE AREA SOUTH AND EAST OF
I-85. THIS IS HIGHLY UNCERTAIN, BUT WORTH MONITORING. EVENTUALLY,
AS WE HEAD INTO MONDAY, PRECIP CHANCES MOVE OFF TO THE EAST AS
SFC/UPPER RIDGING MOVES IN BEHIND THE SYSTEM.
AVIATION /12Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: DERIVED SATELLITE IMAGERY AND METARS
REVEAL FOG/LOW STRATUS IS FAIRLY WIDESPREAD WITHIN THE MOUNTAIN
VALLEYS, AS WELL AS OVER SOME FOOTHILLS RIVER VALLEYS AND LAKES
EARLY THIS MORNING. ALTHOUGH LIFR/VLIFR CONDITIONS DEVELOPED
AT KAVL AND KHKY EARLIER THIS MORNING, THIS HAS SINCE RETREATED,
ALTHOUGH SATELLITE INDICATES THE FOG/STRATUS IS BANK IS NO MORE
THAN A COUPLE OF MILES AWAY FROM BOTH SITES. TEMPOS FOR MVFR VISBY
AND SCT003 ARE CARRIED AT BOTH SITES THROUGH 13Z. MEANWHILE, LIFR
STRATUS ASSOCIATED WITH FOG OVER LAKES KEOWEE/HARTWELL HAS WAFTED
OVER KAND, AND A LIFR TEMPO IS ALSO NECESSARY THERE THROUGH 13Z.
OTHERWISE, VFR IS FORECAST THROUGH THE PERIOD, ALTHOUGH BRIEF
RESTRICTIONS CANNOT BE RULED OUT THIS MORNING AT KCLT/KGSP/KGMU,
BUT THIS IS LOOKING INCREASINGLY UNLIKELY. WINDS WILL GENERALLY
REMAIN LIGHT/VARIABLE UNTIL THIS EVENING, WHEN WINDS WILL BEGIN
GRADUALLY INCREASING OUT OF THE NE.
OUTLOOK: VFR CONDITIONS PREVAIL THROUGH FRIDAY. MOUNTAIN VALLEY
FOG AND LOW STRATUS ARE POSSIBLE EACH NIGHT. WIDESPREAD RAIN AND
ASSOCIATED RESTRICTIONS DEVELOP SATURDAY AND BEGIN IMPROVING BY
LATE SUNDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
JDL/PM
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