788
FXUS62 KGSP 310723
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
323 AM EDT SAT MAY 31 2025
SYNOPSIS
A FRONT STALLS OVER THE AREA THIS WEEKEND, KEEPING A CHANCE OF
ISOLATED TO SCATTERED SHOWERS AND STORMS, ESPECIALLY IN THE
MOUNTAINS. DRY HIGH PRESSURE BUILDS IN EARLY NEXT WEEK. TEMPERATURES
WILL BE SLIGHTLY BELOW NORMAL THROUGH THE WEEKEND, THEN RISE TO A
LITTLE ABOVE NORMAL NEXT WEEK AS A WARM AND HUMID AIR MASS RETURNS.
NEAR TERM /THROUGH TONIGHT/
AS OF 305 AM EDT SATURDAY: LOW CLOUDS REMAIN ACROSS THE MOUNTAINS IN
THE LOW LEVEL NW FLOW. A FEW SHOWERS WILL MOVE INTO THE NC NORTHERN
MOUNTAINS EARLY THIS MORNING AS WELL.
CYCLONIC UPPER FLOW REMAINS ACROSS THE AREA TODAY. A SHORT WAVE AND
UPPER JET MOVE INTO THE AREA TODAY IN THIS FLOW, ALONG WITH A WEAKER
BACK DOOR COLD FRONT. LINGERING LOW LEVEL MOISTURE ACROSS THE
MOUNTAINS AND I-40 CORRIDOR WILL COMBINE WITH THE FORCING FOR
ISOLATED TO SCATTERED AFTERNOON CONVECTION. MODERATE SHEAR IS
EXPECTED, BUT INSTABILITY SHOULD ONLY TOP OUT IN THE 500 J/KG RANGE.
DESPITE THE SHORT WAVE MOVING OVERHEAD, H5 TEMPS AREN'T ESPECIALLY
COLD LIMITING THE STEEPENING OF MID LEVEL LAPSE RATES. DCAPE VALUES
AREN'T ESPECIALLY HIGH EITHER. THAT SAID, FREEZING AND WET BULB ZERO
LEVELS ARE QUITE LOW. THEREFORE, ANY STORM THAT CAN GROW TALL ENOUGH
COULD BECOME STRONG TO SEVERE WITH SOME HAIL OR DAMAGING WINDS GIVEN
THE SHEAR AND LOW FREEZING LEVELS. GUIDANCE AGREES THE BETTER
CHANCES WILL BE ACROSS THE MOUNTAINS AND I-40 CORRIDOR BUT DISAGREE
ON WHETHER THE CELLS HOLD TOGETHER AND REACH THE CLT METRO.
THEREFORE, HAVE LIMITED POP TO THE MOUNTAINS AND I-40 CORRIDOR, BUT
EXPANSION SOUTHWARD MAY BE NEEDED. GUSTY WINDS ARE ALREADY IN PLACE
ACROSS THE HIGHER ELEVATIONS AND WILL DEVELOP ACROSS THE REST OF THE
AREA BY AFTERNOON. HIGHS BE UP TO 5 DEGREES BELOW NORMAL.
CONVECTION SHOULD DISSIPATE BY EARLY EVENING OUTSIDE OF THE
MOUNTAINS BUT WILL LINGER OVER THE NC MOUNTAINS BEFORE DISSIPATING
BY MIDNIGHT. THE GUSTY WINDS SHOULD FOLLOW A SIMILAR PATTERN. LOWS
WILL BE UP TO 5 DEGREES BELOW NORMAL.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
AS OF 255 AM EDT SATURDAY: BROAD CYCLONIC FLOW ALOFT REMAINS
OVERHEAD ON SUNDAY AS A SHORTWAVE ROUNDS THE BASE OF THE UPPER
TROUGH, SENDING A BACKDOOR FRONT FROM THE NORTH INTO THE CFWA. THE
PLACEMENT OF THE BOUNDARY WILL BE KEY TO WHAT DEVELOPS AS THIS COULD
BE A FOCUS FOR CONVECTIVE INITIATION. GENERALLY THE CAMS AND
DETERMINISTIC MODELS HAVE COME IN BETTER AGREEMENT AND DEVELOP
DIURNAL SHOWERS AND THUNDERSTORMS ACROSS THE AREA SUNDAY. DEEP LAYER
SHEAR OF 30-35 KTS AND 1000-1500 J/KG OF SBCAPE SUGGEST SOME
ORGANIZED CONVECTION SHOULD DEVELOP ALONG AND SOUTH OF THE BOUNDARY.
EXACT PLACEMENT WILL BE HARD TO PINPOINT UNTIL CLOSER TO THE EVENT,
BUT HIGHER POPS ARE CURRENTLY CONCENTRATED OVER MOST OF THE
MOUNTAINS AND IN THE PIEDMONT NEAR THE VICINITY OF THE NC/SC STATE
LINE. STEEPER MID-LEVEL LAPSE RATES, LOWER FREEZING LEVELS, AND
INVERTED-V PROFILES SUGGEST THAT LARGE HAIL AND DAMAGING WIND GUSTS
MAY DEVELOP WITH STRONGER STORMS. TEMPERATURES WILL BE A FEW TICKS
BELOW NORMAL FOR AFTERNOON HIGHS ON SUNDAY. THE FRONT IS EXPECTED TO
SAG SOUTH OF THE CFWA SUNDAY NIGHT AS A WEAK SURFACE HIGH PUSHES
INTO THE OH VALLEY AND DRIER AIR SETTLES IN. LINGERING CONVECTIVE
DEBRIS MAY OFFSET OTHERWISE GOOD DRY AIR ADVECTION AS OVERNIGHT LOWS
ARE FORECASTED TO STILL DIP A CATEGORY OR SO BELOW NORMAL FOR SUNDAY
NIGHT.
THERE ARE HINTS IN THE LATEST MODEL GUIDANCE OF THE BOUNDARY
STRUGGLING TO MAKE A FULL FROPA ACROSS THE SOUTHERN HALF OF THE CFWA
ON MONDAY. IN PARTICULAR, THE NAM DEVELOPS A COUPLE OF ISOLATED
SHOWERS AND THUNDERSTORMS ALONG AND SOUTH OF I-85, BUT NOT MUCH
SUPPORT ELSEWHERE, SO MENTIONABLE POPS ARE NOT CURRENTLY IN THE
FORECAST DUE TO LOW CONFIDENCE. OTHERWISE, MILD AND LOWER HUMID
CONDITIONS WILL BE IN STORE FOR MONDAY AS AFTERNOON HIGHS WILL BE A
CATEGORY OR LESS BELOW NORMAL. SURFACE HIGH ESTABLISHES MORE CONTROL
OF THE SENSIBLE WEATHER MONDAY NIGHT AS THE FRONT PUSHES WELL SOUTH
OF THE CFWA AND GOOD RADIATIONAL COOLING CONDITIONS DEVELOP. AS A
RESULT, OVERNIGHT LOWS SHOULD REMAIN A CATEGORY OR SO BELOW NORMAL.
LONG TERM /TUESDAY THROUGH FRIDAY/
AS OF 320 AM EDT SATURDAY: LONGWAVE UPPER RIDGING BEGINS TO REPLACE
THE CYCLONIC FLOW ALOFT BY TUESDAY AS WARMER THICKNESSES FILTER
IN AND SURFACE HIGH REMAINS IN CONTROL AT THE SURFACE. THE ECMWF
PROVED TO BE OUT TO LUNCH WITH THE 00Z FRIDAY RUN AS IS HAS BECOME
MUCH BETTER ALIGNED WITH THE OTHER DETERMINISTIC MODELS. EXPECT A
REBOUND IN TEMPERATURES AND HUMIDITY STARTING TUESDAY AND CONTINUE
TO RISE THROUGH THE REST OF THE WEEK. TEMPERATURES ARE FORECASTED
TO RUN A FEW TICKS ABOVE NORMAL FOR HIGHS AND LOWS TUESDAY AND
WEDNESDAY WITH DRY CONDITIONS.
THE UPPER RIDGE WILL SLIP EAST OF THE CFWA THURSDAY INTO FRIDAY,
WHICH IS A SLOWER IN PROGRESSION COMPARED TO PREVIOUS MODEL RUNS AS
THE FLOW ALOFT BECOMES MORE ZONAL. WITH THE SURFACE HIGH SHIFTING
OFFSHORE IN BERMUDA FASHION, LOW-LEVEL SOUTHWESTERLY FLOW WILL
INCREASE AHEAD OF A COLD FRONT TO THE WEST AND SUMMERTIME CONDITIONS
RETURN IN A BIG WAY FOR THE SECOND HALF OF NEXT WEEK. EXPECT
TEMPERATURES TO RISE A CATEGORY OR SO ABOVE NORMAL BY THURSDAY
AND LAST THROUGH NEXT WEEKEND, WITH A SLIGHT UPTICK IN DIURNAL
SHOWERS AND THUNDERSTORMS, ESPECIALLY IN THE MOUNTAINS.
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: GENERALLY VFR EXPECTED THROUGH THE PERIOD.
LOW VFR CLOUDS WILL CONTINUE ACROSS THE MOUNTAINS THROUGH THE DAY.
SOME OF THESE CLOUDS MAY SPILL EAST THIS MORNING BUT MORE LIKELY
THIS AFTERNOON. ISOLATED SHOWERS AND POSSIBLY STORMS WILL DEVELOP
ACROSS THE MOUNTAINS, AND POSSIBLY KHKY, THIS AFTERNOON. CHANCE TOO
LOW FOR A TAF MENTION AT THIS POINT. EXPECT WESTERLY WINDS TO
INCREASE BY MORNING AND BECOME GUSTY BY AFTERNOON. GUIDANCE CAN'T
QUITE AGREE ON THE DIRECTION AT KCLT. HAVE GONE WITH A MODEL BLEND
AND KEEP IT WNW, BUT A DUE WEST CROSSWIND IS QUITE POSSIBLE. WINDS
DIMINISH THROUGH THE EVENING.
OUTLOOK: SHOWERS AND A FEW THUNDERSTORMS POSSIBLE AGAIN SUNDAY. DRY
HIGH PRESSURE AND VFR CONDITIONS MONDAY THROUGH WEDNESDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...CAC
NEAR TERM...RWH
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...RWH
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