437
FXUS62 KGSP 261435
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1035 AM EDT MON MAY 26 2025
SYNOPSIS
COOL HIGH PRESSURE MOVING ACROSS THE GREAT LAKES AND NEW YORK WILL
CAUSE UNSEASONABLY COOL WEATHER ON TUESDAY FOR THE WESTERN CAROLINAS
AND NORTHEAST GEORGIA WITH A BRIEF WEDGE PATTERN. WIDESPREAD SHOWERS
WILL FOLLOW FROM WEST TO EAST ALONG A STATIONARY FRONT LOCATED JUST
SOUTH OF OUR AREA THROUGH MID WEEK. A SLOW MOVING WEAK COLD FRONT
WILL DRIFT ACROSS OUR REGION THURSDAY AND FRIDAY BRINGING IN DRIER
WEATHER FOR THE WEEKEND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
AS OF 1030 AM: AFTER AN UPTICK IN SHOWER COVERAGE THIS MORNING,
COVERAGE IS BECOMING MORE SPOTTY AS AN UPPER WAVE MOVES EAST OF THE
AREA. COVERAGE MAY INCREASE ACROSS THE MOUNTAINS THIS AFTERNOON WITH
ANOTHER WAVE MOVING IN, BUT COVERAGE REMAINS SCATTERED ELSEWHERE.
THE LOWER PRECIP COVERAGE, AND SOME BREAKS IN THE CLOUDS, WILL KEEP
THE HIGH TEMP FORECAST TRICKY. IN FACT, TEMPS HAVE RISEN AND ARE
SLIGHTLY HIGHER THAN EXPECTED. THEREFORE, HAVE RAISED HIGHS SLIGHTLY
AS SOME WARMING WILL CONTINUE BEFORE CLOUDS FILL BACK IN AND SHOWERS
REDEVELOP. SOME WEAK INSTABILITY IS DEVELOPING IN THE EXPECTED
LOCATIONS, UPPER SAVANNAH RIVER VALLEY, THE LAKELANDS, AND NC
MOUNTAINS WEST OF AVL. THEREFORE, THE THUNDER MENTION IN THOSE
LOCATIONS STILL LOOKS GOOD.
OTHERWISE, THE UPPER FLOW ACROSS THE REGION IS FORECAST TO BACK FROM
WNW THIS MORNING TO WSW BY THE END OF THE PERIOD, AS A SHORT WAVE
RIDGE PROGRESSES EAST OF THE APPALACHIANS. CONFLUENT FLOW BETWEEN
THIS RIDGE AND A TROUGH PULLING AWAY FROM THE NORTHEAST COAST WILL
SUPPORT A SPRAWLING AREA OF SURFACE HIGH PRESSURE FROM THE GREAT
LAKES THROUGH NEW ENGLAND. AS THE CENTER OF THIS HIGH OOZES
SOUTHEAST...INVERTED RIDGING WILL SHARPEN DOWN THE EASTERN SLOPES OF
THE APPALACHIANS...WITH ONGOING WEAK IN SITU COLD AIR DAMMING
EVOLVING INTO A STRONGER HYBRID AFFAIR FROM NORTH TO SOUTH ACROSS
OUR CWA THROUGHOUT THE DAY. AS SUCH, MAX TEMPS ARE EXPECTED TO OCCUR
AROUND SUNRISE ACROSS THE NORTHERN ZONES TODAY, WITH EXTENSIVE LOW
CLOUD COVER AND MODEST SURFACE COLD ADVECTION RESULTING IN STEADY OR
PERHAPS VERY SLOWLY FALLING TEMPS. FARTHER SOUTHWEST...THE TEMP
FORECAST IS FAR TRICKIER...AS LOW CLOUDS INITIALLY INHIBIT
INSOLATION...BUT THE HEATING/TEMPERATURE BUST POTENTIAL IS HIGH IF
SOME THINNING OF THE CLOUDS CAN OCCUR. THIS COULD ALSO RESULT IN
SOME DESTABILIZATION ACROSS THE UPPER SAVANNAH RIVER VALLEY AND FAR
SOUTHWEST NC.
SHOWERS REMAIN LIGHT AND SPOTTY ACROSS THE AREA THIS MORNING, AND
THERE ISN'T A WHOLE LOT FOR ONE TO HANG ONE'S HAT ON IN TERMS OF
TARGETING HIGHER PRECIP CHANCES THROUGH THE PERIOD...OTHER THAN IT
WILL BE QUITE MOIST AND THERE WILL BE SOME WEAK FORCING... MAINLY IN
THE FORM OF ISENTROPIC LIFT AND MECHANICAL/UPSLOPE LIFT.
ADDITIONALLY, CONVERGENCE WILL INCREASE AS THE SURFACE RIDGE
SHARPENS FROM THE NE...EFFECTIVELY ACTING AS A BACKDOOR COLD FRONT.
THIS WILL PROVIDE THE MAIN SOURCE OF LIFT FOR ANY THUNDERSTORM
DEVELOPMENT ACROSS THE SOUTHERN AND WESTERN PART OF THE CWA...
ASSUMING ANY MODEST INSTABILITY IS REALIZED THERE. POPS ARE
GENERALLY IN THE 50-60% RANGE ACROSS THE ENTIRE AREA TODAY. FOR WHAT
IT'S WORTH...THE MAX TEMP FORECAST IS AROUND 15 DEGREES BELOW NORMAL
ACROSS ~THE NORTHEAST QUARTER OF THE CWA...AROUND 5 DEGREES BELOW
ACROSS THE SOUTHWEST 1/4, AND AROUND 10 DEGREES BELOW CLIMO ACROSS
THE REMAINDER OF THE AREA.
TONIGHT COULD SEE A BIT OF AN UPTICK IN PRECIP CHANCES AS HEIGHTS
FALL ON THE WEST SIDE OF THE RIDGE, WEAK ISENTROPIC AND MECH LIFT
PERSISTS, AND ADDITIONAL WAVE(S) OF CONVECTIVE CLUSTERS ORIGINATING
FROM THE UNSTABLE ENVIRONS ACROSS THE LOWER MISS AND TN VALLEYS
APPROACH OUR FORECAST AREA. LIKELY POPS ARE ADVERTISED ACROSS
ROUGHLY THE WESTERN 2/3 OF THE AREA, WITH SOLID CHANCES ELSEWHERE.
MIN TEMPS ARE FORECAST TO BE A FEW DEGREES BELOW NORMAL.
SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/
AS OF 3:05 AM EDT MONDAY...THE SHORT-TERM FCST PICKS UP AT 12Z ON
TUESDAY WITH HEIGHTS GRADUALLY INCREASING OVER OUR AREA AS AN UPPER
RIDGE AXIS MOVES OVERHEAD. OVER THE NEXT 24 TO 48 HRS, MULTIPLE WEAK,
EMBEDDED UPPER SHORTWAVES WILL TRANSLATE OVER OUR AREA. AT THE SAME
TIME, A LARGE UPPER LOW WILL DEVELOP JUST WEST OF THE GREAT LAKES AND
SLOWLY DRIFT EASTWARD. BY THE END OF THE PERIOD EARLY THURSDAY, MOST
OF THE GUIDANCE HAS THE LOW CENTERED OVER THE GREAT LAKES AND BEGINNING
TO OPEN BACK UP. AT THE SFC, A WEAK CAD PATTERN WILL BE IN PLACE OVER
THE WESTERN CAROLINAS BY THE START OF THE PERIOD EARLY TUESDAY. THE CAD
STILL APPEARS TO BE FAIRLY SHORT-LIVED AS A SFC LOW IS PROGGED TO SPIN
UP TO OUR WEST TUESDAY INTO WEDNESDAY AND THEN LIFT NE TOWARDS THE GREAT
LAKES ON WEDNESDAY. THIS WILL PUSH THE PARENT SFC HIGH FURTHER OFF THE
ATLANTIC COAST AND ERODE THE CAD. BY THE END OF THE PERIOD EARLY THURS,
A WEAK, TRAILING COLD FRONT ASSOCIATED WITH THE LOW WILL BE MOVING THRU
OUR AREA WITH WEAK SFC HIGH PRESSURE BEGINNING TO SPREAD OVER THE CWA
FROM THE WEST. THIS PATTERN WILL KEEP PRECIP CHANCES ELEVATED THRU THE
PERIOD. WE CAN EXPECT MOSTLY SHOWERS ACROSS OUR FCST AREA ON TUESDAY AS
INSTABILITY WILL BE LACKING FOR MOST OF OUR FCST AREA. THUNDER CHANCES
INCREASE ON WEDNESDAY AS THE CAD ERODES AND MORE INSTABILITY IS EXPECTED
ACROSS OUR CWA DURING THE AFTERNOON/EVENING. THE SEVERE POTENTIAL STILL
APPEARS LOW THRU THE PERIOD. OTHERWISE, HIGH TEMPERATURES START OUT WELL-
BELOW NORMAL ON TUESDAY WITH THE CAD IN PLACE, AND ARE STILL ABOUT A
CATEGORY BELOW NORMAL ON WEDNESDAY.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
AS OF 2:55 AM EDT MONDAY...THE EXTENDED FCST PICKS UP AT 12Z
ON THURSDAY WITH A LARGE UPPER LOW/TROF CENTERED OVER THE GREAT
LAKES REGION AND UPPER RIDGING MOVING FURTHER OFF THE ATLANTIC
COAST. OVER THE NEXT COUPLE OF DAYS, THE UPPER LOW/TROF OPENS
BACK UP AND AMPLIFIES SOUTHWARD TOWARDS OUR AREA. BY THE END OF
THE PERIOD EARLY NEXT WEEK, MOST OF THE LONG-RANGE GUIDANCE HAS
THE UPPER TROF STILL OVER THE EASTERN CONUS BUT RETREATING BACK
NORTH TO SOME DEGREE. AT THE SFC, THE EVOLUTION OF THE SYNOPTIC
PATTERN REMAINS SOMEWHAT UNCLEAR FOR MUCH OF THE PERIOD. IT'S
STILL LOOKING LIKE AS A SFC LOW LIFTS FURTHER NORTH ON THURSDAY,
IT WILL MOVE A WEAK COLD FRONT THRU OUR AREA. IN THE FRONT'S WAKE,
BROAD BUT WEAK HIGH PRESSURE TRIES TO SPREAD EASTWARD AND OVER THE
REGION, BUT ITS PROGRESS IS SLOW AND THERE APPEARS TO BE LIMITED
DRYING AS IT DOES. REGARDLESS, WE CAN EXPECT PRECIP CHANCES TO
TREND LOWER AS THE PERIOD PROGRESSES WITH GENERALLY DIURNALLY-
DRIVEN SLIGHT TO SOLID CHANCE POPS EACH DAY. THE SVR WX POTENTIAL
STILL APPEARS MINIMAL THRU THE PERIOD BUT COULD INCREASE EARLY ON
DEPENDING ON HOW THE ABOVE-MENTIONED SFC LOW EVOLVES ON THURSDAY.
OTHERWISE, TEMPERATURES ARE EXPECTED TO START OUT NEAR CLIMATOLOGY
ON THURSDAY AND WARM TO A FEW DEGREES ABOVE CLIMO BY EARLY NEXT WEEK.
AVIATION /15Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: VERY MESSY AVIATION WEATHER ACROSS THE
TERMINAL FORECAST AREA THIS MORNING, AS CIGS ARE HIGHLY VARIABLE IN
PLACE AND TIME IN A REGIME THAT IS VERY MOIST BUT OVERALL LACKING IN
ORGANIZED AREAS OF LIFT. EXPECT CIGS TO SETTLE AT IFR AT ALL SITES
BY LATE MORNING, WITH LIFR WELL WITHIN THE REALM OF POSSIBILITY
BETWEEN NOW AND NOON. ONCE THE LOW CIGS SETTLE IN, NOT MUCH
IMPROVEMENT IS EXPECTED THROUGH THE END OF THE PERIOD, ALTHOUGH SOME
OF THE UPSTATE SC TERMINALS COULD IMPROVE TO MVFR BRIEFLY DURING THE
AFTERNOON. ANY IMPROVEMENT THAT DOES OCCUR WILL LIKELY BE REVERSED
THIS EVENING, WITH CIGS IN THE 005-008 RANGE LIKELY TO CONTINUE
THROUGH AT LEAST TUE MORNING. GUIDANCE SOURCES ARE HITTING THE MVFR
VISBY RATHER HARD THROUGHOUT THE DAY...AND WOULDN'T RULE THAT OUT
ACROSS THE FOOTHILLS, WHERE SOME DRIZZLE MAY DEVELOP AS COLD AIR
DAMMING STRENGTHENS INTO THE AFTERNOON. WHILE SHOWERS CHANCES ARE IN
PLACE FOR THE ENTIRE PERIOD, CONFIDENCE IN TIMING OF ANY PERIOD OF
MORE WIDESPREAD/PERSISTENT RAINFALL REMAINS QUITE LOW BEYOND ~6
HOURS. THUS, THERE IS LIBERAL USE OF VCSH AND PROB30S FOR SHRA IN
THE FORECAST. CAN'T RULE OUT A TSRA THIS AFTERNOON NEAR KAND, BUT
CONFIDENCE IS LOW. WINDS WILL GENERALLY BE LIGHT AND VARIABLE THIS
MORNING, BUT WILL INCREASE FROM THE NE AT 5-10 KTS LATE THIS MORNING
INTO THE AFTERNOON, AS A SURFACE RIDGE STRENGTHENS ACROSS THE AREA.
WINDS MAY INCREASE TO THE 10-15 KTS RANGE WITH HIGHER GUSTS ACROSS
THE PIEDMONT LATE THIS AFTERNOON/EVENING.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH THE WEEK.
HIGHEST CHANCES ON TUESDAY WITH SLOWLY DIMINISHING COVERAGE THROUGH
THE LATTER HALF OF THE WEEK. EXTENDED PERIODS OF VSBY AND ESPECIALLY
CIG RESTRICTIONS ARE LIKELY TO CONTINUE THROUGH THE MIDDLE OF THE
WEEK AS COLD AIR DAMMING PERSISTS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...JPT
NEAR TERM...JDL/RWH
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...JDL
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