484
FXUS62 KGSP 312126
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
526 PM EDT SAT MAY 31 2025
SYNOPSIS
A FRONT STALLS OVER THE AREA TONIGHT, RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND STORMS ACROSS THE AREA SUNDAY, ESPECIALLY
IN THE MOUNTAINS. DRY HIGH PRESSURE BUILDS IN EARLY NEXT
WEEK. TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL THROUGH MONDAY,
THEN RISE TO A LITTLE ABOVE NORMAL NEXT WEEK AS A WARM AND HUMID
AIR MASS RETURNS.
NEAR TERM /THROUGH SUNDAY/
AS OF 520 PM: RADARS CONTINUE TO SHOW SHOWERS AND A FEW
THUNDERSTORMS MOVING ALONG IN A NW FLOW IN A FRONTAL ZONE LAID
OUT FROM EASTERN KY, ACROSS SOUTHWEST VA, TO CENTRAL NC. SOME
OF THIS CONVECTIVE ACTIVITY SHOULD CLIP THE NRN ZONES THRU
EARLY EVENING. NOT MUCH SFC-BASED CAPE TO WORK WITH, MAYBE 500
J/KG AT BEST, SO THIS SHOULD TEMPER THE ENTHUSIASM OF ANYTHING
THAT MANAGES TO WORK ITS WAY INTO OUR AREA FROM THE NW THROUGH
EARLY EVENING. HAVE MADE SOME MINOR ADJUSTMENTS TO PRECIP PROBS
TO ACCOUNT FOR THIS AND TO LINE UP WITH NEIGHBORS. MEANWHILE,
A BLANKET OF SMOKE ALOFT FROM THE WILDFIRES ON THE CANADIAN
PRAIRIES OF AB/SK WILL CONTINUE TO STREAM OVERHEAD AND CUT OFF
JUST ENOUGH INSOLATION TO KEEP THE TEMPS SLIGHTLY COOLER THAN
PREVIOUSLY THOUGHT. NO MAJOR CHANGES.
OTHERWISE...WATER VAPOR IMAGERY SHOWS A DEEP UPPER TROUGH
CENTERED OVER THE EAST COAST, BRINGING A FAST NORTHWESTERLY MID
TO UPPER LEVEL FLOW OVER THE CWA. SMOKE FROM WILDFIRES IN THE
CANADIAN PRAIRIE, PICKED UP BY SAID FLOW, HAS BEEN ADVECTED OVER
THE SOUTHEAST US--VISIBLE ON SATELLITE. CURRENTLY THAT APPEARS
TO BE ONLY AT HIGH ALTITUDE, WITH NO SFC OBS REPORTING REDUCED
VSBY. HRRR-SMOKE MODEL SUGGESTS A MOUNTAIN WAVE THIS AFTERNOON MAY
THE BRING SMOKE DOWNWARD AND PRODUCE NOTICEABLE CONCENTRATIONS AT
THE SURFACE, BUT CURRENTLY NOT CONFIDENT ENOUGH TO REFLECT IN THE
FCST. THE SMOKE DOES APPEAR TO HAVE REDUCED INSOLATION ENOUGH TO
KEEP OBS FROM WARMING AS MUCH AS ALMOST ALL GUIDANCE WOULD HAVE
SUGGESTED SO FAR TODAY, ALTHOUGH GUSTY WINDS MAY HAVE PLAYED A
ROLE IN THAT AS WELL. EXPECTING SMOKE CONCENTRATION TO REMAIN AT
OR ABOVE CURRENT VALUES THRU THE AFTERNOON, LOWERED MAX TEMPS A
BIT FROM THE PREVIOUS FCST.
THE AFOREMENTIONED FAST FLOW ALOFT IS RESPONSIBLE FOR THE GUSTY
WINDS SO FAR TODAY, AND ALSO WILL EXPOSE ANY CONVECTIVE UPDRAFTS
TO STRONG EFFECTIVE SHEAR. IT REMAINS QUESTIONABLE HOW DEEP THE
UPDRAFTS WILL BE ABLE TO GET--AND THE COOLING EFFECT OF THE SMOKE
LAYER PUTS CONVECTIVE INITIATION FURTHER INTO QUESTION. PROG
SOUNDINGS FROM THE HRRR AND HRW-FV3 DEPICT A CAPPING LAYER
AROUND 600MB OVER MOST OF THE CWA, WITH A MOIST LAYER AROUND 700MB
BENEATH. THAT SHOULD EASILY RESULT IN DECENT CUMULUS ABOVE THE PBL,
BUT LIKELY NOT DEEP ENOUGH FOR GOOD ICE NUCLEATION OR THUNDER. EVEN
WITHOUT THUNDER, GIVEN THAT A FEW SITES HAVE GUSTED TO 25-30 MPH
WITH NOT SO MUCH AS A SHOWER NEARBY, IF A SHOWER DOES DEVELOP
THE DOWNDRAFT COULD PRODUCE 30-35 MPH WINDS. CAMS DO NOT DEPICT
MUCH COVERAGE IN OUR CWA THIS AFTERNOON AND EVENING, BUT RETAINED
ISOLATED/SCATTERED SHOWER MENTION OVER THE MOUNTAINS AND I-40
CORRIDOR. THINK SHOWERS PRODUCING BRISK SUBSEVERE GUSTS ARE MUCH
MORE LIKELY THAN SEVERE T-STORMS; SPC REMOVED US FROM THE DAY 1
WITH THE MIDDAY UPDATE.
COLD FRONT WILL PUSH EAST OF THE APPALACHIANS THIS EVENING AND
COULD SPAWN A FEW SHOWERS LATER THAN PEAK HEATING, PARTICULARLY
NEAR THE TN BORDER IN NW FLOW. NO PRECIP EXPECTED LATER IN
THE OVERNIGHT. ON SUNDAY, CONVERGENCE NEAR THE FRONT WILL BE
ASSOCIATED WITH AN INCREASE IN 850-700MB MOISTURE. THE CAP THAT
IS IN PLACE TODAY LOOKS TO ERODE BEFORE DIURNAL HEATING BEGINS,
ALTHOUGH LAPSE RATES WON'T BE ALL THAT REMARKABLE. DEEP CONVECTION
LOOKS MORE LIKELY OVERALL, WITH MODELS SEEMINGLY KEYING ON THE
CONVERGENCE ZONE IN DEPICTING A BAND OF COVERAGE MAINLY ACROSS
THE MIDDLE LATITUDES OF THE CWA. SHEAR WILL BE WEAKER THAN TODAY,
BUT WITH 0-6KM VALUES OF 30-40 KT LOOSELY ORGANIZED MULTICELLS
COULD DEVELOP. A SEVERE WIND THREAT COULD RESULT PARTICULARLY
ON THE COOL SIDE OF THE FRONT WHERE SOME DRY AIR WILL BE PRESENT
ALOFT. MAX TEMPS A FEW DEGREES WARMER THAN TODAY.
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
AS OF 215 PM EDT SATURDAY: THE SHORT TERM LOOKS DRY, AS A MILD
AREA OF HIGH PRESSURE SETTLES OVER THE REGION FROM THE NW. UPPER
RIDGING WILL BUILD IN BEHIND A DEPARTING UPPER TROUGH, AND THIS
WILL SET UP A WARMING TREND THRU THE MIDDLE OF THE WEEK. MONDAY
AND TUESDAY'S WEATHER LOOKS QUIET PLEASANT, WITH NEAR TO SLIGHTLY
BELOW NORMAL TEMPS UNDER CLEAR/SUNNY SKIES, LIGHT WIND, AND MODEST
HUMIDITY. HIGHS WILL BE MAINLY IN THE 70S TO LOWER 80S MONDAY,
AND ABOUT A CATEGORY WARMER ON TUESDAY. LOWS WILL IN THE 50S TO
LOWER 60S IN THE MOUNTAIN VALLEYS AND THE PIEDMONT.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
AS OF 225 PM EDT SATURDAY: AN UPPER RIDGE WILL BE AT ITS PEAK
ON WEDNESDAY ALONG THE EAST COAST, WHILE A WEAK TROPICAL WAVE
DEVELOPS NEAR FL. THE 12Z GFS CONTINUES TO BE DRY AND KEEPS THE
WAVE OVER FL, WHILE THE 12Z ECMWF AND CANADIAN SHOW THE WAVE DRIFT
NORTH ALONG THE CAROLINA COAST ON THURSDAY. THIS WAVE WOULD LIKELY
BE A LITTLE TOO FAR EAST FOR ANY PRECIP IN OUR CWFA, AND THE NBM
CONTINUES TO TREND DRIER. SO GOING WITH BASICALLY A DRY FORECAST
WEDNESDAY THRU THURSDAY, EXCEPT FOR A SLIGHT CHC IN THE MOUNTAINS,
WHICH MAY CONTINUE TO TREND DOWN WITH LATER FORECASTS. TEMPS WILL
WARM TO A FEW DEG ABOVE NORMAL WITH INCREASING DEWPTS, MAKING IT
FEEL MORE LIKE EARLY SUMMER. FLOW BECOMES MORE ZONAL FRIDAY INTO
NEXT WEEKEND, WITH A WEAK FRONTAL BOUNDARY APPROACHING THE CWFA
FROM THE NW. POPS INCREASE INTO THE CHANCE TO LIKELY RANGE THANKS
TO INCREASED DIURNAL SHOWER AND THUNDERSTORM ACTIVITY.
AVIATION /22Z SATURDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: VFR. CU FIELD THIS AFTERNOON WITH BASES
MOSTLY 035-050 OVER THE MOUNTAINS (KAVL) AND 060-080 OVER THE
OTHER SITES. WILDFIRE SMOKE AT HIGH ALTITUDE MAY FORM AN EFFECTIVE
BKN250 CIG OTHERWISE; SOME VSBY REDUCTION IS POSSIBLE AS A RESULT
OF THE SMOKE LATER THIS AFTN/EVENING BUT MOST LIKELY WILL REMAIN
P6SM. GUSTS OF 20-25 KT LIKELY AT ALL SITES THIS AFTN, HIGHER
AT TIMES AT KAVL. ISOLATED TO SCATTERED SHRA MAY DEVELOP NEAR
THE NC SITES THRU MID-EVENING, AND COULD EASILY PRODUCE 30-35 KT
GUSTS. CHANCE TOO SMALL TO MENTION. MAINLY WSW WINDS EARLY IN THE
PERIOD, FAVORING WNW BY AROUND 21Z. GUSTS MAY BRING WIND TO WNW
BRIEFLY EARLIER. CU FIELD AND ANY SHRA DIMINISH LATE EVENING IN
THE PIEDMONT; SOME SHRA COULD DEVELOP NEAR THE TN/NC BORDER LATER
INTO THE NIGHT. WINDS WILL TURN SW'LY AGAIN AFTER DIURNAL MIXING
BEGINS SUN. BETTER OVERALL CHANCE FOR SHRA/TSRA AFTER 18Z SUN,
PROMPTING PROB30 TSRA AT KCLT.
OUTLOOK: DRY HIGH PRESSURE AND VFR CONDITIONS MONDAY THROUGH
WEDNESDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...ARK
NEAR TERM...PM/RWH/WIMBERLEY
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...WIMBERLEY
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