435
FXUS62 KGSP 211812
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
212 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.
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 RAMPING UP ACROSS THE AREA AND WILL CONTINUE INTO THE
EVENING. DESPITE THE CLOUD COVER, INSTABILITY IS INCREASING WITH
1500 J/KG OF CAPE ACROSS MOST OF THE AREA. BULK SHEAR IS WEAK AND
THE BEST DCAPE IS OFF TO OUR EAST. CAN'T RULE OUT A FEW STRONG OR
POSSIBLY EVEN A SEVERE STORM, BUT THE OVERALL CHANCE IS LOW. 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 /18Z THURSDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: CONVECTION POPPING UP ACROSS PORTIONS OF THE
AREA WITH MORE COVERAGE EXPECTED THROUGH THE AFTERNOON AS A BACKDOOR
COLD FRONT DROPS INTO THE AREA. HAVE TEMPOS AND PROB30S TO COVER
THIS ACTIVITY. CONVECTION LINGERS INTO THE EVENING BEFORE BECOMING
MORE SHOWERY OR STRATIFORM OVERNIGHT. INITIALLY, RESTRICTIONS WILL
BE LIMITED TO THE CONVECTION; HOWEVER, AS THE FRONT CROSSES THE
AREA, MVFR THEN IFR CLOUDS MOVE IN FROM THE NE. MVFR VSBY
RESTRICTIONS DEVELOP OVERNIGHT AS WELL. COLD AIR DAMMING CONDITIONS
SET IN FRI WITH IFR CIGS AND MVFR VSBY AND PROB30S FOR LIFR CIGS AND
IFR VSBY WITH SHRA CONTINUING. GENERALLY SW WIND, NW AT KAVL, THIS
AFTERNOON BECOMES N TO NE THIS EVENING AND CONTINUES INTO SATURDAY.
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.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
RWH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page