391
FXUS62 KGSP 211059
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
659 AM EDT THU MAY 21 2026
WHAT HAS CHANGED
THE AVIATION DISCUSSION WAS UPDATED TO REFLECT THE 12Z TAF ISSUANCE.
KEY MESSAGES
1. A COLD FRONT WILL DROP DOWN FROM THE NORTHWEST LATE TODAY AND
TONIGHT, USHERING IN A CHANGE IN OUR WEATHER FOR THE MEMORIAL
DAY WEEKEND. THE NEW PATTERN WILL SUPPORT A PERIOD OF COOLER AND
MORE UNSETTLED WEATHER THAT COULD ULTIMATELY PUT A DENT IN OUR
DROUGHT AS IT PERSISTS INTO THE MIDDLE OF NEXT WEEK. AT THIS TIME,
THE RISK OF SEVERE THUNDERSTORMS AND FLOODING RAIN APPEARS LOW.
DISCUSSION
KEY MESSAGE 1: A COLD FRONT WILL DROP DOWN FROM THE NORTHWEST LATE
TODAY AND TONIGHT, USHERING IN A CHANGE IN OUR WEATHER FOR THE
MEMORIAL DAY WEEKEND. THE NEW PATTERN WILL SUPPORT A PERIOD OF
COOLER AND MORE UNSETTLED WEATHER THAT COULD ULTIMATELY PUT A DENT
IN OUR DROUGHT AS IT PERSISTS INTO THE MIDDLE OF NEXT WEEK. AT
THIS TIME, THE RISK OF SEVERE THUNDERSTORMS AND FLOODING RAIN
APPEARS LOW.
A DAY OF CHANGE IS IN STORE FOR THE WESTERN CAROLINAS AND NORTHEAST
GEORGIA AS A TUTT LOW OFF THE SOUTHEAST COAST FADES AWAY TO THE
SOUTHEAST AND WE COME MORE UNDER THE INFLUENCE OF BETTER SOUTH TO
SOUTHWEST FLOW ALOFT. ALREADY, WE ARE SEEING SHOWERS AND ISOLATED
THUNDERSTORMS PERSISTING NEAR THE BLUE RIDGE ESCARPMENT AS THEY TAKE
ADVANTAGE OF A LIGHT SOUTHERLY UPSLOPE LOW LEVEL FLOW OF SLOWLY
INCREASING MOISTURE. AFTER A QUIET WEEK, THAT SHOULD BE A CLUE
THAT CHANGES ARE UNDERWAY. THE EXPECTATION IS FOR THE CONVECTION TO
EVENTUALLY WEAKEN AND DISSIPATE BY DAYBREAK, AFTER WHICH THE BALANCE
OF THE MORNING WOULD BE QUIET, ALLOWING FOR A WARMUP WITH TEMPS
ROUGHLY TEN DEGREES ABOVE NORMAL ONCE AGAIN BY EARLY AFTERNOON,
THOUGH NOT AS HOT AS THE LAST FEW DAYS. BY THIS AFTERNOON, A COLD
FRONT WILL BE DROPPING IN FROM THE NORTHWEST, THOUGH WITHOUT MUCH
SUPPORT ALOFT. THE RAP DEVELOPS ROUGHLY 1500 J/KG OF SFC-BASED CAPE
TO FUEL THE DEVELOPMENT OF SCATTERED THUNDERSTORMS BEGINNING IN
THE MID/LATE AFTERNOON BUT SHEAR WILL BE WEAK, WHICH SHOULD LIMIT
HOW STRONG THE STORMS GET. AN ISOLATED SEVERE STORM WOULD NEVER BE
COMPLETELY RULED OUT IN A SITUATION LIKE THIS, HOWEVER. OVERALL,
THE PRECIP CHANCES FOR THE DAY ARE RELATIVELY HIGH, THOUGH AT ANY
GIVEN TIME THE COVERAGE OF SHOWERS AND STORMS WILL BE SCATTERED,
IN OTHER WORDS THE DAY IS NOT EXPECTED TO BE A WASHOUT.
ONCE THE FRONT SLIPS SOUTHWARD THIS EVENING, A SFC HIGH OVER EASTERN
CANADA WILL NOSE DOWN EAST OF THE MTNS AND ESTABLISH A COLD AIR
DAMMING WEDGE ACROSS THE REGION BY DAYBREAK FRIDAY. DEVELOPING LOW
LEVEL ISENTROPIC UPGLIDE EARLY IN THE DAY SHOULD DEVELOP ENOUGH LOW
CLOUDINESS TO LOCK IN THE COOLER AIR MASS THAT WILL BE NOTICEABLE
COMPARED TO OUR WEEK THUS FAR. FOR NOW, OUR FORECAST HAS HIGH TEMPS
IN THE 70S EAST OF THE MTNS, UNDERCUTTING WHAT IS IN THE NBM BY
SEVERAL DEGREES, BUT THAT COULD EASILY BE TEN DEGREES TOO WARM IF
WE END UP WITH EXTENSIVE LIGHT RAIN. THE NEW GUIDANCE SUGGESTS THE
WEDGE IS LIKELY TO PERSIST THROUGH SATURDAY EVEN AS THE TRANSITORY
PARENT HIGH MOVES OFF THE CANADIAN MARITIMES. TEMPS WERE ONCE AGAIN
LOWERED FROM THE MODEL BLEND. SUPPORT FOR CAD FADES SUNDAY AS THE
SOUTHWESTERLY FLOW ALOFT INCREASES.
FROM THAT POINT ONWARD, UNSETTLED WEATHER WILL CONTINUE AS THE GULF
REMAINS OPEN WITH A MEAN UPPER TROF AXIS OVER THE SRN PLAINS/MS
VALLEY REGION AND A MEAN RIDGE OFF THE EAST COAST. SO, FROM MEMORIAL
DAY ONWARD, WE ARE LOOKING AT A FAVORABLE PERIOD OF ABOVE CLIMO
PRECIP PROBS AND RAINFALL COVERAGE. IF THIS PERSISTS AS INDICATED
BY SOME GUIDANCE, WE COULD EVENTUALLY GET TO THE POINT WHERE FLASH
FLOOD RISK CREEPS UPWARD, BUT FOR NOW WE WILL MANAGE EXPECTATIONS.
AVIATION /12Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: KAVL CONTINUES TO BE THE TROUBLE SPOT AT THE
START, WITH AN AREA OF SHOWERS AND EMBEDDED THUNDERSTORMS MOVING
UP FROM NORTHEAST GA. THIS ACTIVITY IS EXPECTED TO DIMINISH IN
COVERAGE AND INTENSITY OVER THE NEXT HOUR OR TWO, BUT A TEMPO FOR
MVFR RESTRICTIONS WILL BE INCLUDED AT 14Z JUST IN CASE. OTHERWISE,
VFR AT THE OTHER TERMINALS UNTIL THIS AFTERNOON WHEN NEW CONVECTION
DEVELOPS. THE CAMS HAVE SCATTERED COVERAGE FOR THE MOST PART
THROUGH THE EARLY EVENING, SO WE CONTINUE TO OPT FOR PROB30 GROUPS
TO CONTAIN THE TSRA CHANCES AND ASSOCIATED RESTRICTIONS. WIND
WILL BE MAINLY SW AND LIGHT THROUGH THE AFTERNOON. AT SOME POINT
THIS EVENING, A FRONTAL BOUNDARY WILL DROP SOUTH ACROSS THE FCST
AREA, SO WIND MAY GO VARIABLE UNTIL THE BOUNDARY PASSES, AT WHICH
POINT IT GOES NE AND THE COLD AIR DAMMING WEDGE DEVELOPS. FLIGHT
RESTRICTIONS WILL DEVELOP QUICKLY BEHIND THE WEDGE BOUNDARY, DOWN
TO MVFR IN LATE EVENING AND IFR IN THE EARLY MORNING HOURS. CAN'T
RULE OUT LIFR STRATUS AND LIGHT RAIN BY THE END OF THE PERIOD.
OUTLOOK: COLD-AIR DAMMING ACROSS THE AREA BY DAYBREAK FRIDAY,
AND MAY PERSIST THRU SATURDAY. THE CAD WILL LIKELY PRODUCE
WIDESPREAD MVFR TO IFR CEILINGS THROUGH THE DAY FRIDAY AND INTO
SATURDAY. PERIODS OF MAINLY DIURNAL CONVECTION WILL ALSO CONTINUE
ATOP THE CAD WEDGE AND INTO NEXT WEEK, EVEN AS THE CAD ERODES. THE
POTENTIAL FOR OVERNIGHT FOG/LOW CLOUDS WILL INCREASE THROUGH THE
PERIOD AS WELL.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
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