599
FXUS62 KGSP 220001
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
801 PM EDT THU MAY 21 2026
WHAT HAS CHANGED
THE WET AND COOL FORECAST CONTINUES THROUGH THE MEMORIAL DAY HOLIDAY
WEEKEND. WET AND NEAR NORMAL THROUGH THE REST OF THE PERIOD.
THE AVIATION DISCUSSION WAS UPDATED FOR THE 00Z TAFS.
KEY MESSAGES
1. A COLD FRONT WILL DROP DOWN FROM THE NORTHWEST 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 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.
CONVECTION IS TRENDING WEAKER, BUT ADDITIONAL ROUNDS OF MAINLY
SHOWERS AND A FEW ISOLATED STORMS WILL CONTINUE THRU THE EVENING
AND INTO THE OVERNIGHT, AS A BACKDOOR COLD FRONT SLIPS IN FROM
THE NE. SOME BRIEF, HEAVY RAINFALL IS POSSIBLE WITH ANY STORM,
BUT UNLESS THERE IS SOME TRAINING, THE OVERALL FLOOD THREAT IS
LOW AS WELL.
ONCE THE FRONT SLIPS SOUTHWARD OVERNIGHT, 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 MAINLY 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 GUIDANCE CONTINUES TO SUGGEST 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 /00Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: CONVECTION IS TRENDING WEAKER AS WE HEAD
INTO THE EVENING, BUT THUNDERSTORMS STILL OVER KCLT AT TIME OF TAF
ISSUANCE. WILL KEEP A TEMPO GOING FOR KCLT FOR THE FIRST 3 HOURS OF
THE TAF. ELSEWHERE, LOSS OF INSTABILITY SEEMS TO SUPPORT REMOVING
TS MENTION FOR THIS EVENING. HOWEVER, CONVECTION IS EXPECTED TO
INCREASE IN COVERAGE AGAIN OVERNIGHT, AS A BACKDOOR COLD FRONT SAGS
THRU THE AREA FROM THE NE AND TRIGGERS NEW ACTIVITY. THIS SHOULD
BE MAINLY SHOWERS OR AREAS OF LIGHT RAIN THRU THE OVERNIGHT. AN
EMBEDDED TS HERE AND THERE WILL BE POSSIBLE, BUT COVERAGE TOO LOW
FOR MENTION IN TAFS. AS THE FRONT CROSSES THE AREA, MVFR THEN IFR
CLOUDS ARE EXPECTED TO MOVE IN FROM THE NE. MVFR VSBY RESTRICTIONS
DEVELOP OVERNIGHT AS WELL. COLD AIR DAMMING CONDITIONS WILL PERSIST
THRU THE DAY FRIDAY, WITH IFR CIGS AND MVFR VSBY AND ADDITIONAL
ROUNDS OF SHRA. WINDS WILL BECOME NE ACROSS THE PIEDMONT SITES
AND SE AT KAVL DUE TO THE CAD AND CONTINUE THRU THE END OF THE
TAF PERIOD.
OUTLOOK: COLD-AIR DAMMING PERSISTS THRU SATURDAY. THE CAD WILL
LIKELY PRODUCE WIDESPREAD MVFR TO IFR CEILINGS 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. ACTIVE DIURNAL CONVECTION EXPECTED TO CONTINUE
THRU THE FIRST HALF OF NEXT WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
ARK/RWH
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