536
FXUS62 KGSP 280745
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
345 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 3:15 AM EDT WEDNESDAY: WE REMAIN MOSTLY SHOWER-FREE AT
THIS TIME WITH BROAD BANDS OF SHOWERS TO OUR WEST AND OUR EAST.
THE PRECIP TO OUR WEST IS JUST NOW BEGINNING TO MOVE OVER OUR
WESTERNMOST ZONES, YET THE LATEST CAM RUNS STILL HAVE THIS AC-
TIVITY DIMINISHING/SCT OVER THE NEXT FEW HRS AS MOVES ACROSS OUR
CWA. REGARDLESS, WE WILL LIKELY GET SOME ADDITIONAL LIGHT SHOWERS
AS INCREASINGLY SHALLOW UPGLIDE WILL PERSIST INTO THE MORNING
WITH THE WEDGE NOT EXPECTED TO ERODE UNTIL MID TO LATE MORNING.
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 /08Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: A COOL-AIR DAMMING WEDGE REMAINS IN PLACE
ACROSS THE REGION. OUR FCST AREA IS CURRENTLY BETWEEN TWO BROAD
BANDS OF PRECIP, ONE TO OUR EAST AND ONE TO OUR WEST. THE BAND TO
OUR WEST WILL LIKELY IMPACT SOME OF OUR TERMINALS OVER THE NEXT
FEW HRS, SO I HAVE TEMPOS FOR -RA AT MOST TERMINALS. OTHERWISE,
EXPECT CIGS TO REMAIN IFR THRU MUCH OF THE MORNING WITH VISBY
BEING MORE UNCERTAIN. AT PRESENT, MOST TERMINALS ARE REPORTING
VFR VISBY, BUT THIS WILL LIKELY FLUCTUATE THRU THE MORNING DEPEN-
DING 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. IN ADDITION, THE LATEST NEAR-TERM GUIDANCE CONTINUES TO
GENERATE SCT SHOWERS ACROSS OUR AREA THIS EVENING, WITH THUNDER
LOOKING MORE LIKELY OVER THE MTNS. THUS, I INCLUDED PROB30S FOR
SHRA AT ALL OUR TAF SITES (EXCEPT KAVL), BEGINNING AROUND 20 TO
22Z. AT KAVL, I HAVE A PROB30 FOR TSRA FROM 18 TO 24Z TODAY.
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.
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...JPT
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...JPT
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