891
FXUS62 KGSP 091045
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
645 AM EDT FRI OCT 9 2026
WHAT HAS CHANGED
THE AVIATION DISCUSSION HAS BEEN UPDATED FOR THE 12Z TAF ISSUANCE.
KEY MESSAGES
1. FAIR WEATHER WILL PERSIST TODAY WITH NEAR NORMAL TEMPERATURES.
2. WIDESPREAD RAIN IS EXPECTED TO MOVE INTO THE REGION ON SATURDAY
AND CONTINUE THROUGH EARLY SUNDAY. EXCESSIVE RAINFALL WILL BE
POSSIBLE SATURDAY AFTERNOON THROUGH SUNDAY MORNING, ALONG WITH
A SMALL RISK FOR SEVERE THUNDERSTORMS.
3. GUSTY WINDS EXPECTED ACROSS THE MOUNTAINS OF NORTH CAROLINA
SATURDAY THROUGH EARLY SUNDAY MORNING, ESPECIALLY ABOVE 3500 FT.
DISCUSSION
KEY MESSAGE 1: FAIR WEATHER WILL PERSIST TODAY WITH NEAR NORMAL
TEMPERATURES.
ONE LAST QUIET DAY IS EXPECTED BEFORE THE SITUATION DETERIORATES
TONIGHT. A COLD FRONT ANALYZED MOVING SOUTH ACROSS THE FCST AREA
WILL CONTINUE TO SLIP SOUTHWARD THIS MORNING, AND IN ITS WAKE WE
CAN EXPECT A WEAK AND DRY COLD AIR DAMMING WEDGE TO DEVELOP THANKS
TO SFC HIGH PRESSURE MOVING PAST ACROSS THE CENTRAL APPALACHIANS
AND MID-ATLANTIC REGION. AS A RESULT, TEMPS DROP BACK TO AROUND
NORMAL AS THE WEDGE DEVELOPS AND CONTINUES TO BE OVERSPREAD BY HIGH
CLOUDINESS EXHAUSTED FROM ISAIAS MOVING NORTHWARD ACROSS THE GULF.
KEY MESSAGE 2: WIDESPREAD RAIN IS EXPECTED TO MOVE INTO THE REGION
ON SATURDAY AND CONTINUE THROUGH EARLY SUNDAY. EXCESSIVE RAINFALL
WILL BE POSSIBLE SATURDAY AFTERNOON THROUGH SUNDAY MORNING, ALONG
WITH A SMALL RISK FOR SEVERE THUNDERSTORMS.
HURRICANE ISAIAS IS FORECAST TO MOVE NORTH AND MAKE LANDFALL ALONG
THE CENTRAL GULF COAST FRIDAY NIGHT, THEN QUICKLY TRANSITION TO
AN EXTRATROPICAL LOW AS IT DRIFTS INLAND TOWARD WESTERN TN ON
SATURDAY. REFER TO THE LATEST GUIDANCE FROM THE NATIONAL HURRICANE
CENTER FOR MORE DETAILS. FORECAST CONFIDENCE IN RAIN CONTINUES
TO INCREASE AS A TROPICAL REMNANT MOVING NORTHWARD WEST OF THE
MOUNTAINS IS HIGHLY FAVORABLE FOR WIDESPREAD RAINFALL ACROSS OUR
REGION, THOUGH CONFIDENCE IN AMOUNTS REMAINS ELUSIVE.
EXCESSIVE RAIN AND LOCALIZED FLASH FLOODING ARE STILL THE MAIN
CONCERNS. IF WE FOLLOW THE TREND SHOWN CLEARLY BY THE CAMS, THE
TROPICAL MOISTURE WILL MOVE IN EARLIER THAN SHOWN PREVIOUSLY,
SUCH THAT THE LEADING EDGE OF THE RAIN WILL BE WORKING ITS WAY
INTO THE DRY AIR ACROSS OUR REGION AS EARLY AS SUNSET TODAY. IT
MIGHT TAKE A FEW HOURS FOR THE LIGHT RAIN TO REACH THE GROUND,
BUT IT IS LOOKING MORE LIKE RAIN WILL BE FALLING BY DAYBREAK
SATURDAY ACROSS THE WESTERN TWO-THIRDS OF THE FORECAST AREA,
AND THEN EVERYWHERE BY THE EARLY AFTERNOON. ONCE THE RAIN STARTS
TO FALL, IT SHOULD LOCK IN THE COLD AIR DAMMING WEDGE EARLY IN
THE DAY, KEEPING THE REGION ROUGHLY TEN DEGREES BELOW NORMAL AND
RESULTING IN A LOW DIURNAL RANGE IN TEMPERATURE. GETTING BACK TO
THE EXCESSIVE RAIN POTENTIAL...THE SITUATION OBVIOUSLY HAS A LOT
GOING FOR IT, WITH DEEP TROPICAL MOISTURE MOVING UP AND OVER THE
WEDGE AND THEN ENCOUNTERING THE MTNS, ALONG WITH EXCELLENT FORCING
AS WHAT'S LEFT OF ISAIAS MOVES NORTHWARD TO THE WEST OF THE MTNS
SATURDAY NIGHT. IN FACT, THE TREND IN THE MODEL QPF IS UPWARD
ON THIS CYCLE, BUT THE QUESTION REMAINS IF THE AMOUNTS WILL BE
ENOUGH TO RAISE MORE OF A FLOODING THREAT. FORTUNATELY, WE ENTER
THIS EVENT ON A DRY SPELL. THE POTENTIAL FOR HEAVY RAIN RAMPS UP
SATURDAY AFTERNOON AS A LOW LEVEL JET WITH 40-60KT OF UPSLOPE FLOW
AT 850 MB ARRIVES. THE 00Z RUN OF THE RRFS SUGGESTS THAT RAIN WILL
BEGIN TO PILE UP IN THE HEADWATERS OF THE FRENCH BROAD AND SAVANNAH
RIVER BASINS BY LATE AFTERNOON, WITH THE BEST 6 HOUR PROBABILITY
MATCHED MEAN VALUES SATURDAY EVENING AND EARLY SUNDAY MORNING OVER
THE SOUTHEAST FACING SLOPES OF THE BALSAM AND BLACK MOUNTAINS,
AND NEAR THE ESCARPMENT. THE FCST QPF REFLECTS MORE OF A FOCUS
TOWARD THE BLUE RIDGE ESCARPMENT AND SOUTHEAST UPSLOPE AREAS,
WHILE RAISING AMOUNTS SLIGHTLY IN THOSE LOCATIONS, WITH MAXIMA
IN THE 4-6 INCH RANGE OVER A 60 HOUR PERIOD. CONFIDENCE IS 50/50
AS TO WHETHER OR NOT THIS WILL BE ENOUGH TO TRIGGER FLOODING TO
WARRANT ISSUING A WATCH THIS EARLY, SO WE ARE LEANING AWAY FROM
IT AND PREFER TO WAIT ONE MORE FORECAST CYCLE. THE NEW GUIDANCE
MOVES THE SYSTEM THROUGH QUICKER, SO THE STEADIER PRECIP IS ALREADY
MOVING OUT TO THE NORTH BY LATE MORNING SUNDAY. PRECIP CHANCES ARE
PARED BACK TO THE TN BORDER BY SUNDAY EVENING AS THE FLOW TURNS
OUT OF THE WEST AND NORTHWEST.
THE SECONDARY CONCERN WILL BE THE SEVERE WEATHER POTENTIAL, MAINLY
ON SUNDAY. ONCE THE MAIN RAIN SHIELD MOVES OUT, A STRENGTHENING SW
FLOW AT LOW LEVELS WILL ATTEMPT TO SCOUR OUT THE REMNANT WEDGE,
WHICH IS MOST LIKELY TO HAPPEN UP INTO PARTS OF THE CHARLOTTE
METRO REGION. WHAT IS INTERESTING IS THE LREF JOINT PROBS OF CAPE
ABOVE 500 J/KG AND SHEAR ABOVE 30, WHICH SHOWS SOME LIKELIHOOD
REACHING UNION COUNTY NC IN THE AFTERNOON AS THE DRY SLOT REACHES
OUR REGION WITH THE REMNANT LOW MAKING ITS CLOSEST PASS TO OUR
NW. UNFORTUNATELY, THE CAMS DON'T EXTEND THAT FAR IN TIME, SO WE
SHALL HAVE TO WAIT UNTIL WE SEE THE NEXT TWO MODEL CYCLES TO GET
A BETTER HANDLE ON THIS POTENTIAL.
ONCE THE SYSTEM LIFTS OUT MONDAY, THE REST OF THE FORECAST LOOKS
QUIET AS AN UPPER ANTICYCLONE MOVES OVER THE SOUTHEAST.
KEY MESSAGE 3: GUSTY WINDS EXPECTED ACROSS THE MOUNTAINS OF NORTH
CAROLINA SATURDAY THROUGH EARLY SUNDAY MORNING, ESPECIALLY ABOVE
3500 FT.
AS THE CIRCULATION ASSOCIATED WITH THE REMNANTS OF ISAIAS INTERACT
WITH A STRONG SFC HIGH OVER THE NORTHERN MID-ATLANTIC, EASTERLY
FLOW WILL INCREASE ACROSS THE REGION. THE AFOREMENTIONED LOW
LEVEL JET COULD REACH UPWARDS OF 40-60 KT, MAINLY LATE SATURDAY
AND SATURDAY NIGHT, BUT THIS WILL BE MOVING OVER TOP OF THE WEDGE
EAST OF THE MTNS. THOSE LOCATIONS WILL HAVE A COOL NORTHEASTERLY
BREEZE. HOWEVER, THE HIGH ELEVATIONS WILL STICK UPWARD ENOUGH TO BE
IMPACTED. THE FORECAST AS IT STANDS WILL SHOW WIND GUST POTENTIAL
NOT QUITE HIGH ENOUGH TO WARRANT AN ADVISORY, BUT IT WOULD BE
TOO EARLY TO ISSUE A WIND ADVISORY AT THIS TIME ANYWAY. WE WILL
CONTINUE TO MONITOR FURTHER DEVELOPMENTS.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS EXPECTED INTO THE EVENING WITH
DETERIORATING CONDITIONS OVERNIGHT. OVC CIRRUS CONTINUES THROUGH THE
MORNING WITH INCREASING MID CLOUDS DURING THE AFTERNOON. VFR
STRATOCU SPREADS IN THROUGH THE EVENING WITH CIGS FALLING TO THE LOW
VFR TO MVFR RANGE NEAR DAYBREAK. MVFR VSBY IN SCATTERED SHOWERS ALSO
POSSIBLE NEAR DAYBREAK. WIND PICKS UP SPEED THROUGH THE MORNING WITH
LOW END GUSTS POSSIBLE. KAVL THE EXCEPTION WITH LIGHT SE WIND
DEVELOPING. INCREASING NE WIND WITH GUSTS DEVELOPING OVERNIGHT. KAVL
SEES S TO SE WIND.
OUTLOOK: WIDESPREAD RAIN AND ASSOCIATED RESTRICTIONS DEVELOP
SATURDAY AND BEGIN IMPROVING BY LATE SUNDAY. GUSTY NE WIND, SE AT
KAVL, EXPECTED THROUGH SAT NIGHT WITH LIGHTER, BUT STILL GUSTY SW
WIND ON SUNDAY. VFR WITH GUSTY NW WIND ON MONDAY. VFR OUTSIDE OF
MOUNTAIN VALLEY FOG TUESDAY WITH LIGHT WINDS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
PM/RWH
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