391
FXUS62 KGSP 232328
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
728 PM EDT WED SEP 23 2026
WHAT HAS CHANGED
NO MAJOR CHANGES TO THE PUBLIC FORECAST.
THE AVIATION FORECAST WAS UPDATED TO REFLECT THE RECENT 00Z TAF
ISSUANCE.
KEY MESSAGES
1. A FEW THUNDERSTORMS WITH A THREAT FOR EXCESSIVE RAIN ARE
POSSIBLE THIS EVENING, MAINLY OVER THE SMOKIES, WITH RAIN ELSEWHERE
THROUGH THURSDAY.
2. TEMPERATURES WILL REMAIN COOL THROUGH THE WEEKEND WITH DRY
AIR RETURNING, THEN A GRADUAL RETURN TO NORMAL TEMPERATURES IS
EXPECTED INTO THE MIDDLE OF NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: A FEW THUNDERSTORMS WITH A THREAT FOR EXCESSIVE RAIN
ARE POSSIBLE THIS EVENING, MAINLY OVER THE SMOKIES, WITH RAIN
ELSEWHERE THROUGH THURSDAY.
IF THERE IS A MAIN CONCERN WITH THIS FORECAST, IT WOULD BE EXCESSIVE
RAIN THROUGH THE EVENING HOURS, MAINLY OVER SOUTHWEST NC AND THE
SMOKIES. COLD AIR DAMMING HAS TAKEN OVER MOST OF THE FORECAST AREA,
BUT THE WEDGE BOUNDARY CURLS AROUND NORTHEAST AND NORTH GA AND
OVER THE MTNS, LEAVING THE SOUTHWESTERN COUNTIES EXPOSED TO SOME
AFTERNOON HEATING. THE LATEST SPC MESOANALYSIS SHOWS SFC-BASED CAPE
OF ROUGHLY 1000-1500 J/KG AND STORMS ARE MAKING THE MOST OF IT. THE
SETUP IS NOT THE BEST FOR SEVERE WEATHER AS LAPSE RATES ARE SOMEWHAT
POOR AND DCAPE IS MARGINAL, BUT AN ISOLATED SEVERE STORM CAN NEVER
BE RULED OUT. EXCESSIVE RAIN IS THE GREATER THREAT AS CELL MOVEMENT
IS SLOW AND MOISTURE IS PLENTIFUL, BUT FORTUNATELY THAT AREA
CAN TOLERATE THE RAIN FOR THE TIME BEING, SO ACTUAL HYDRO ISSUES
REMAIN QUITE ISOLATED SO FAR. ELSEWHERE, THE COLD AIR DAMMING WEDGE
SHOULD GENERALLY PRECLUDE CONVECTION DEEP ENOUGH FOR THUNDERSTORMS
OR EXCESSIVE RAIN. LATER TONIGHT THERE COULD BE SOME INTERACTION
BETWEEN THE EASTERLY FLOW AGAINST THE BLUE RIDGE ESCARPMENT AND THE
OVERALL WESTERLY FLOW WITH THE UPPER LOW TO OUR NORTH. HOWEVER,
THE POTENTIAL FOR HEAVY RAIN HAS GONE DOWN IN RECENT GUIDANCE,
ESPECIALLY AWAY FROM THE ESCARPMENT. TEMPS WILL REMAIN COOL.
THE COLD AIR DAMMING REGIME SHOULD PERSIST WELL INTO THE DAY
ON THURSDAY WITH PRECIP CHANCES SLOWLY DIMINISHING INTO THE
AFTERNOON. THE PASSAGE OF THE UPPER SYSTEM IN THE AFTERNOON SHOULD
ACT TO START DRAINING THE COOL POOL EAST OF THE MOUNTAINS BY THE
END OF THE DAY. IT COULD EASILY REMAIN OVERCAST THROUGH SUNSET AS
SOME OF THE GUIDANCE DOESN'T BRING THE LOW LEVEL FLOW AROUND TO A
DOWNSLOPE DIRECTION UNTIL LATER THURSDAY EVENING. DRY AIR COMES
IN ALOFT FIRST, WHICH COULD SET US UP FOR A PERIOD OF DENSE FOG
LATE THURSDAY NIGHT OR EARLY FRIDAY MORNING.
KEY MESSAGE 2: TEMPERATURES WILL REMAIN COOL THROUGH THE WEEKEND WITH
DRY AIR RETURNING, THEN A GRADUAL RETURN TO NORMAL TEMPERATURES
IS EXPECTED INTO THE MIDDLE OF NEXT WEEK.
IN SHORT, THE WEATHER LOOKS SPECTACULAR FOR THE FIRST WEEKEND OF
AUTUMN. WHAT A DIFFERENCE A WEEK MAKES. ONCE THE UPPER LOW WOBBLES
OFF THE COAST OF THE CAROLINAS AND MID-ATLANTIC, DRY HIGH PRESSURE
WILL RETURN ON A NORTHERLY FLOW ALOFT AHEAD OF AN UPPER RIDGE AXIS
THAT STAYS TO OUR WEST THROUGH THE WEEKEND. THERE COULD BE SOME
RESIDUAL CLOUDINESS ON FRIDAY MORNING, BUT NOT LIKELY, OTHERWISE
MOSTLY CLEAR SKY LOOKS LIKE A GOOD BET FOR SEVERAL DAYS. HIGH
TEMPS ARE EXPECTED TO STAY IN THE 70S FRIDAY, ON THE ORDER OF 5-10
DEGREES BELOW NORMAL, BUT THEN A GRADUAL WARM-UP SHOULD TAKE PLACE
AS THE AIR MASS MODIFIES. BY MONDAY, HIGHS SHOULD BE RIGHT AROUND
NORMAL, WHICH IS UPPER 70S TO LOWER 80S, GENERALLY SPEAKING. THE
LOW TEMPERATURES WILL BE MORE REMARKABLE, MOSTLY IN THE UPPER 40S
AND LOWER 50S FRIDAY THROUGH SUNDAY. THE HIGH ELEVATIONS WILL
BE QUITE COOL, POSSIBLY DOWN INTO THE 30S AT ELEVATIONS ABOVE
5000 FEET FRIDAY NIGHT. BY THE EARLY PART OF THE WEEK, LOWS WILL
RETURN TO THE LOW TO MID 50S. IT WON'T LAST, OF COURSE, BECAUSE
THE PATTERN LOOKS LIKE IT WILL EVOLVE AGAIN IN THE MIDDLE OF NEXT
WEEK TOWARD SOMETHING MORE DAMP, THOUGH DETAILS ARE VERY SKETCHY.
AVIATION /00Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: MOST AREAS REMAIN SOCKED INTO A COLD AIR
DAMMING WEDGE THIS EVENING, WITH THE OB SITES REPORTING A MIX
OF IFR AND LOW MVFR CEILINGS AND PATCHY LOW VISIBILITY IN AREAS
WHERE IT'S ACTIVELY RAINING. GUIDANCE DEPICTS ANOTHER ROUND OF
RAINFALL...CURRENTLY LOCATED OVER THE SOUTHWEST MOUNTAINS...MAKING
TRACKS EASTWARD THROUGH THE OVERNIGHT HOURS AND PRODUCING AT LEAST
BRIEF -RA AT ALL THE TAF SITES LEADING UP TO DAWN. SCATTERED RA OR
DZ MAY CONTINUE THROUGH THE FIRST HALF OF THURSDAY, AND RESTRICTIONS
ARE UNLIKELY TO LIFT FOR MOST OF THE AFTERNOON. WINDS WILL REMAIN
OUT OF THE NE, WITH GUSTS IN THE MID-TEENS POSSIBLE MOST OF THE DAY.
A DRAMATIC CHANGE IS IN STORE BY THURSDAY EVENING, WHEN MOST
GUIDANCE DEPICTS A SLUG OF DRY AIR WIPING OUT MUCH OF THE MOISTURE
AND RESULTING IN IMPROVING RESTRICTIONS THURSDAY EVENING INTO
THURSDAY NIGHT. CAN'T RULE OUT SOME PATCHY DENSE FOG THURSDAY
NIGHT, AS ANY LINGERING LOW-LEVEL MOISTURE RESPONDS TO INCREASINGLY
CLEAR SKIES OVERNIGHT. CONFIDENCE IS LIMITED, HOWEVER, AND AS
OF YET HAVEN'T ADDED MUCH DETAIL ABOUT THIS POSSIBILITY TO THE
00Z TAFS.
OUTLOOK: VFR SHOULD RETURN EVERYWHERE BY FRIDAY. VFR EXPECTED
THROUGH THE WEEKEND, THOUGH MOUNTAIN/RIVER VALLEY FOG/STRATUS
COULD STILL DEVELOP BEFORE DAYBREAK EACH DAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
MPR/PM
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