841
FXUS62 KGSP 270151
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
951 PM 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 /THROUGH TUESDAY/
AS OF 940 PM: COLD-AIR DAMMING WEDGE APPEARS TO BE ENTRENCHED ACROSS
THE CWA. LIGHT STRATIFORM PRECIP WITHIN THE WEDGE, SOME OF WHICH
IS TOO SHALLOW TO SEE ON RADAR. TYPICAL WEDGE IN THIS SENSE. SOME
SHOWERS ARE PRESENT NEAR THE PERIPHERY OF THE WEDGE, NAMELY ACROSS
THE MOUNTAINS WEST OF I-26 AND THE UPPER SAVANNAH RIVER VALLEY. SB
OR MU CAPE IS TOO SMALL TO WARRANT A MENTIONABLE THUNDER CHANCE;
THE CURRENT SHOWERS PROBABLY WILL DIMINISH AS THEY MOVE EAST INTO
STILL MORE UNSTABLE AIR ATOP THE WEDGE, BUT MORE COULD GENERATE IN
THAT AREA THRU THE NIGHT. STRATIFORM, UPGLIDE-DRIVEN PRECIP WILL
RAMP UP LATER TONIGHT AS LOW-LEVEL WINDS VEER IN RESPONSE TO WEAK
LOW MOVING UP THE WEST SIDE OF THE APPALACHIANS; NAM AND RECENT
CAMS SUGGEST A WAVE OF BETTER SHOWERS/QPF SHIFTING ACROSS THE CWA
IN THE LATE OVERNIGHT TO MID-MORNING PERIOD AS FORCING MAXIMIZES,
WHICH SHOULD HELP LOCK IN THE WEDGE STRONGLY FOR TUESDAY. REVISED
POP TRENDS INTO MIDDAY PER HI-RES MODEL CONSENSUS. LOWS AROUND
5 DEGREES BELOW NORMAL. MAINLY RAIN AND DRIZZLE WITH THE MORNING
PRECIP ACTIVITY; AN ISOLATED, ELEVATED TSRA POSSIBLE DURING THE
AFTERNOON AS MUCAPE INCREASES. HIGHS AROUND 20 DEGREES BELOW NORMAL
TUESDAY WITH A TYPICAL WEDGE GRADIENT.
BRIEF, HEAVY RAIN IS POSSIBLE IN ANY T-STORM. SOME MODERATE TO
POSSIBLY BRIEF, HEAVY RAIN IS POSSIBLE OVERNIGHT AS ISENTROPIC LIFT
AND UPSLOPE FLOW STRENGTHENS. NO SIGNIFICANT FLOODING IS EXPECTED,
BUT SOME PONDING IN LOW LYING AREAS IS POSSIBLE.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
AS OF 140 PM MONDAY: MESSY PATTERN CONTINUES INTO THE SHORT TERM.
MOSTLY A QUASI-ZONAL PATTERN KEEPING FLOW ALOFT MOSTLY WESTERLY
THROUGH THE PERIOD. EMBEDDED IN THE FLOW ARE A SERIES OF SHORTWAVES
THAT COULD HELP TRIGGER SOME SHOWERS, BUT TRUE CONVECTION LOOKS
MINIMAL. TUESDAY NIGHT, GUIDANCE HAS SHOWERS AND A FEW RUMBLES OF
THUNDER POSSIBLE THROUGH AT LEAST WEDNESDAY MORNING. THE CAD IS ALSO
EXPECTED TO WEAKEN WEDNESDAY, BRINGING WARMER TEMPERATURES, BUT A
DECREASE IN MOISTURE. THIS SHOULD SUPPRESS MUCH OF THE RAIN CHANCES
THROUGH WEDNESDAY NIGHT. BY THURSDAY, PWATS ONCE AGAIN INCREASE AS
SURFACE WINDS TURN MORE SOUTHERLY. SOME SPLIT IN THE GUIDANCE AS THE
GFS HAS ANOTHER SHORTWAVE PASSING ACROSS THE SOUTHEAST THURSDAY,
WHICH COULD INCREASE PRECIP CHANCES ONCE AGAIN. HOWEVER, THE EURO
AND CANADIAN MODELS ARE MUCH DRIER. SO FOR THE MISALIGNMENT OF
GUIDANCE, CONFIDENCE REMAINS LOW. WINDS REMAIN LIGHT AS WELL.
DEPENDING ON HOW FAST THE CAD CAN ERODE, TEMPERATURES SHOULD REBOUND
INTO THE UPPER 70S AND LOW 80S BY THURSDAY.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
AS OF 200 PM MONDAY: BY THURSDAY NIGHT, THE MODELS START TO DIVERGE
IN AGREEMENT WITH WHAT MIGHT HAPPEN OR NOT. THE GFS REMAINS THE
WETTER SOLUTION WITH CHURNING A LOW OVER THE GREAT LAKES AND
EXTENDING A COLD FRONT SOUTHWARD TOWARD THE SOUTHEAST BY FRIDAY.
OTHER MODEL GUIDANCE IS LESS RESPONSIVE TO THIS SCENARIO AND DRIER.
SO, THE AMOUNT OF RAIN THAT MAY OR MAY NOT COME THROUGH IS A BIT UP
IN THE AIR. ENSEMBLE GUIDANCE PUTS ABOUT A 40-50% CHANCE OF
MEASURABLE RAINFALL ACROSS THE ENTIRE CWA ON FRIDAY, AHEAD OF A
POTENTIAL COLD FRONT. SHOULD THIS OCCUR, DRIER AIR LOOKS TO RETURN
FROM THE NW FOR THE WEEKEND. WEAK HIGH PRESSURE TRIES TO BUILD BACK
INTO THE NORTH ATLANTIC REGION AND EXTEND SOUTHWARD, POTENTIALLY
KEEPING THE AREA DRY. ALL IN ALL, A POSSIBLE COLD FRONT COULD SWING
THROUGH, BRINGING WIDESPREAD SHOWERS ON FRIDAY, BUT CONFIDENCE IS
LOW AT THIS TIME. TEMPERATURES LOOK TO RISE CLOSER TO NORMAL THROUGH
NEXT WEEKEND.
AVIATION /02Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: KEY ELEMENT OF THE FORECAST IS COLD-AIR
DAMMING WEDGE WHICH GENERALLY WILL KEEP IFR IN PLACE OVER THE
TERMINALS FOR MOST OF THE PERIOD AND BREEZY NE WINDS (EXCEPT SE AT
KAVL). SHOWERY PRECIP IS LIKELY THIS EVENING; SITES ALREADY AT IFR
DO NOT LOOK LIKELY TO GO TO LIFR AS A RESULT, BUT WHERE CIGS REMAIN
MVFR AT ISSUANCE, SHOWERS MAY BRING IFR VSBY/CIG WHICH IS HANDLED
IN TEMPO. PRECIP EXPECTED TO RETURN TO MORE -DZ IN CHARACTER BY
LATE EVENING AND IFR TO FILL IN. STRENGTHENING LIFT OVER THE WEDGE
WILL LEAD TO SOME LOWERING TOWARD DAYBREAK. SHRA LIKELY WILL MAKE
A COMEBACK FROM AROUND 12-18Z. THESE POSSIBILITIES COMBINE TO
PROMPT MORNING PROB30S AT ALL SITES EXCEPT KAND. CIGS NOT LIKELY
TO IMPROVE MUCH DURING THE AFTERNOON; ELEVATED INSTABILITY WILL
DEVELOP AT THE PERIPHERY OF THE WEDGE AND COULD LEAD TO MORE SHRA
OR EVEN TSRA AT THAT TIME. PROB30 USED FOR KAND THEN INSTEAD DUE
TO BEST PROXIMITY TO THE INSTABILITY.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES AND ASSOCIATED RESTRICTIONS
CONTINUE THROUGH THE WEEK THEN DIMINISH ON SATURDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...RWH/WIMBERLEY
SHORT TERM...CP
LONG TERM...CP
AVIATION...WIMBERLEY
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