725
FXUS62 KGSP 270459
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1259 AM EDT TUE MAY 27 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 TODAY/
AS OF 12:45 AM EDT TUESDAY: A COOL-AIR DAMMING WEDGE REMAINS IN
PLACE ACROSS THE FCST AREA AS WE HEAD INTO THE OVERNIGHT. PATCHES
OF STRATIFORM PRECIP CONTINUE TO MAKE THEIR WAY NE ACROSS OUR AREA
WITH A MUCH BROADER AREA OF PRECIP JUST NOW STARTING TO MOVE OVER
OUR FAR WESTERN ZONES. THIS ACTIVITY IS EXPECTED TO OVERSPREAD OUR
CWA THRU THE OVERNIGHT AND INTO THE MORNING AS ISENTROPIC UPGLIDE
INCREASES AND LOW-LEVEL WINDS VEER IN RESPONSE TO A WEAK LOW MOVING
UP THE WEST SIDE OF THE APPALACHIANS. THIS SET UP SHOULD HELP LOCK
IN THE WEDGE FOR TUESDAY. OTHERWISE, I REVISED THE POP TRENDS INTO
MIDDAY PER HI-RES MODEL CONSENSUS. LOWS OVERNIGHT SHOULD BE ROUGHLY
5 DEGREES BELOW NORMAL. MAINLY RAIN AND DRIZZLE WITH THE MORNING
PRECIP ACTIVITY, ALTHOUGH A FEW ISOLATED, ELEVATED THUNDERSTORMS
WILL BE POSSIBLE DURING THE AFTERNOON AS MUCAPE INCREASES. HIGHS
SHOULD REMAIN AROUND 20 DEGREES BELOW NORMAL ON TUESDAY WITH A
TYPICAL WEDGE GRADIENT WRT TEMPERATURES. AS FOR THE FLOODING POTEN-
TIAL, BRIEF, HEAVY RAIN IS POSSIBLE IN ANY THUNDERSTORM, BUT NO
SIGNIFICANT FLOODING IS EXPECTED. SOME PONDING IN LOW-LYING AREAS
IS MORE LIKELY.
SHORT TERM /TONIGHT 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 /06Z 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...JPT/WIMBERLEY
SHORT TERM...CP
LONG TERM...CP
AVIATION...JPT/WIMBERLEY
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