225
FXUS62 KGSP 281359
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
959 AM EDT WED MAY 28 2025
SYNOPSIS
COOL HIGH PRESSURE WILL MOVE OFF THE EAST COAST THROUGH TODAY
RESULTING IN MUCH WARMER TEMPERATURES IN MOST LOCATIONS. LOW
PRESSURE MOVES ALONG A FRONT CROSSING OUR AREA THURSDAY NIGHT AND
FRIDAY WITH MORE SHOWERS AND THUNDERSTORMS EXPECTED. DRIER WEATHER
MOVES OVER OUR AREA FOR THE WEEKEND AND INTO NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 945 AM EDT WEDNESDAY: WESTERLY FLOW IS STARTING TO SCOUR
OUT THE LOW CLOUDS AND RESIDUAL WEDGE THIS MORNING. OVERALL,
THE FORECAST LOOKS ON TRACK, WITH A GRADUAL SCATTERING OUT OF
CLOUDS AND SHOWERS EXITING TO THE EAST THRU MIDDAY. AS THE WEDGE
ERODES, TEMPS WILL REBOUND INTO THE UPPER 70S TO NEAR 80 EAST OF
THE MOUNTAINS. THE LATEST CAMS STILL NOT VERY EXCITED ABOUT DIURNAL
CONVECTION LATER TODAY, AS WE BECOME MODESTLY UNSTABLE. MINOR TWEAKS
WERE MADE TO THE POPS, GENERALLY A SLIGHT DOWNWARD ADJUSTMENT.
OTHERWISE, A LARGE 500MB LOW WILL CONTINUE TO SPIN TO OUR NW WHILE
HEIGHTS OVER THE SOUTHEAST BEGIN TO REBOUND AS THE DAY PROGRESSES.
AT THE SFC, WEAK/DISORGANIZED LOW PRESSURE WILL LIFT NORTH OF OUR
AREA TODAY AND HELP PUSH THE SFC HIGH OFF THE ATLANTIC COAST. AT
THE SAME TIME, 850MB FLOW VEERS TO WLY AND HELPS SCOUR OUT THE CAD
WEDGE. AS THE CLOUDS GRADUALLY SCT OUT LATER THIS MORNING AND AFTN,
WE SHOULD SEE A PRONOUNCED REBOUND IN TEMPS THIS AFTN. NONETHELESS,
HIGHS ARE STILL EXPECTED TO REMAIN ABOUT A CATEGORY BELOW NORMAL FOR
LATE MAY. THERE WILL BE SOME SFC-BASED INSTABILITY ACROSS OUR CWA
THIS AFTN/EVENING, GENERALLY MORE OVER OUR SOUTHERN AND WESTERN
ZONES. HOWEVER, THERE DOES NOT APPEAR TO MUCH IN THE WAY OF A
ROBUST TRIGGER ACROSS OUR AREA TO INITIATE CONVECTION. NONETHELESS,
ISOLATED TO WIDELY SCT SHOWERS AND THUNDERSTORMS ARE EXPECTED FROM
THE LATE AFTN THRU THE EVENING, WITH THE BEST COVERAGE EXPECTED
OVER THE MTNS AND INTO THE FOOTHILLS. IN ADDITION, A FEW STORMS
COULD BECOME STRONG TO SEVERE AND PRODUCE SMALL HAIL AND DAMAGING
WIND GUSTS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
KEY MESSAGES:
1) A FEW STRONG-TO-SEVERE THUNDERSTORMS POSSIBLE FRIDAY WITH A COLD
FRONT
2) TEMPERATURES NEAR NORMAL EARLY IN THE PERIOD
3) TEMPS RETURN TO BELOW NORMAL FRI/FRI NIGHT
AS OF 245 AM WEDNESDAY: AN UPPER LOW CENTERED OVER THE UPPER MISS
VALLEY AT THE START OF THE PERIOD, WILL MIGRATE ESE...PICKING UP
SPEED AS IT BEGINS TO OPEN UP AND MOVE ACROSS THE OHIO VALLEY BEFORE
CARVING OUT A RATHER DEEP...ALBEIT PROGRESSIVE LONG WAVE TROUGH
CENTERED ALONG THE EASTERN SEABOARD BY THE END OF THE PERIOD. THIS
WILL DRIVE A COLD FRONT TOWARD THE SOUTHERN APPALACHIANS AND
VICINITY FRIDAY...WHICH WILL BE THE NEXT SIGNIFICANT WEATHER-MAKER
FOR OUR AREA. IN THE INTERIM, HEIGHTS WILL BEGIN SLOWLY FALLING
ACROSS THE REGION ON THURSDAY. ALTHOUGH THIS WILL CREATE AN OVERALL
FAVORABLE REGIME FOR CONVECTIVE DEVELOPMENT...SIGNIFICANT DRYING
ALOFT IS FORECAST TO RESULT IN PRECIPITABLE WATER VALUES UNDER 1.0"
FOR MUCH OF THE DAY. WHILE MODERATE DESTABILIZATION IS FORECAST...AS
TEMPS FINALLY RETURN TO AROUND LATE-MAY NORMALS...REDUCED MOISTURE
SHOULD LIMIT THE COVERAGE TO WIDELY SCATTERED-AT-MOST...WITH POPS
GENERALLY IN THE 20-30% RANGE.
MOISTURE IS FORECAST TO RE-SURGE THU NIGHT IN ADVANCE OF THE FRONT,
WARRANTING A CONTINUATION OF CHANCE POPS THROUGH THE OVERNIGHT. THE
COLD FRONT SHOULD BEGIN PUSHING INTO THE AREA BY LATE FRIDAY
MORNING, ALLOWING FOR SUFFICIENT HEATING FOR MODERATE
DESTABILIZATION IN LIGHT OF MID-LEVEL LAPSE RATES OF AROUND 7 C/KM.
DEEP LAYER SHEAR IS FORECAST IN THE 40-50 KTS RANGE...MORE THAN
SUFFICIENT FOR DEVELOPMENT OF ORGANIZED CONVECTIVE STRUCTURES...AND
AT LEAST A MARGINAL RISK FOR SEVERE STORMS...ESPECIALLY ACROSS THE
PIEDMONT. OTHERWISE, THE FORECAST COMBO OF FORCING/MOISTURE/
INSTABILITY WARRANTS 70-80 POPS ACROSS MOST OF THE CWA. TEMPS ARE
EXPECTED TO RETURN TO A-LITTLE-BELOW-NORMAL DURING THE LATTER HALF
OF THE PERIOD...DUE TO THICKENING CLOUD COVER FRIDAY...AND
POST-FRONTAL COLD ADVECTION FRI NIGHT.
LONG TERM /SATURDAY THROUGH TUESDAY/
KEY MESSAGES
1) GENERALLY DRY, WITH ONLY SCATTERED MOUNTAIN SHOWERS OVER THE
WEEKEND
2) TEMPERATURES GRADUALLY WARM FROM A LITTLE BELOW NORMAL EARLY IN
THE PERIOD TO A LITTLE ABOVE LATE
AS OF 310 AM WEDNESDAY: OTHER THAN LINGERING NW FLOW/UPSLOPE
MOISTURE ACROSS FROM THE TN VALLEY INTO THE WESTERN SLOPES OF THE
SOUTHERN APPALACHIANS...CONDITIONS WILL DRY OUT OVER THE WEEKEND.
SMALL POPS WILL MAINLY BE CONFINED TO THE MOUNTAINS...ALTHOUGH A
SPEED MAX DIVING S/SE AROUND THE WESTERN PERIPHERY OF THE EASTERN
TROUGH COULD ALLOW FOR A FEW SHOWERS TO BREAK CONTAINMENT INTO THE
PIEDMONT SUNDAY AFTERNOON. TEMPS ARE FORECAST TO BE SLIGHTLY BELOW
NORMAL THROUGH THE WEEKEND. BY EARLY IN THE NEW WORK WEEK, UPPER
RIDGING WILL BEGIN STEADILY BUILDING INTO THE REGION FROM THE
WEST...RESULTING IN WARMING TEMPS AND KEEPING DEEP CONVECTION
GENERALLY SUPPRESSED. TEMPS WARM TO SLIGHT-ABOVE-NORMAL BY THE END
OF THE PERIOD, WHILE POPS ARE GENERALLY <20% MONDAY AND TUESDAY
AFTERNOON.
AVIATION /14Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: A COOL-AIR DAMMING WEDGE REMAINS IN PLACE
ACROSS THE REGION. SCT SHOWERS ARE CURRENTLY MAKING THEIR WAY
OVER THE SC UPSTATE AND ARE EXPECTED TO IMPACT KAND, KGMU, KGSP,
AND KCLT FOR THE FIRST FEW HRS OF THE TAF PERIOD. THIS HAS BEEN
HANDLED WITH TEMPOS FOR RA AND REDUCED VISBY. OTHERWISE, EXPECT
CIGS TO REMAIN IFR THRU MUCH OF THE MORNING WITH VISBY BEING MORE
UNCERTAIN. AT PRESENT, MOST TERMINALS ARE REPORTING MVFR TO VFR
VISBY, BUT THIS WILL LIKELY FLUCTUATE THRU THE MORNING DEPENDING
ON WHO GETS SHOWERS AND HOW LONG THEY LINGER. THE CAD EROSION
PROCESS IS EXPECTED TO BEGIN BY MID TO LATE MORNING AS WINDS VEER
AND THE LOW-LEVEL UPGLIDE DIMINISHES. EXPECT CIGS TO LIFT TO MVFR
BY LATE MORNING AT MOST TERMINALS, AND THEN VFR BY THE EARLY TO MID
AFTERNOON. THE LATEST NEAR-TERM GUIDANCE HAS BEEN LESS BULLISH WRT
SHOWER/T-STORM COVERAGE OUTSIDE THE MTNS THIS AFTN/EVENING. THUS,
I DECIDED TO REMOVE ANY MENTION OF SHOWERS AND/OR T-STORMS FOR THIS
AFTN/EVENING EXCEPT AT KAVL, WHERE I STILL HAVE A PROB30 FOR TSRA.
OTHERWISE, WINDS WILL REMAIN LIGHT AND FROM THE N TO NE THRU AT
LEAST MID-MORNING. THEY WILL VEER AROUND TO SW BY THE AFTN AND GO
LIGHT AND VRB TO CALM AGAIN LATER TONIGHT. WINDS AT KAVL WILL BE
MORE VRB THRU THE PERIOD.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES AND ASSOCIATED RESTRICTIONS
CONTINUE THRU THE REMAINDER OF THE WORK WEEK WITH DRIER CONDITIONS
EXPECTED BY THE START OF THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...JDL
NEAR TERM...ARK/JPT
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...JPT
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