347
FXUS62 KGSP 302348
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
748 PM EDT MON JUN 30 2025
SYNOPSIS
A TYPICAL SUMMER PATTERN CONTINUES WITH SEASONABLE TEMPERATURES
AND CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS. A COLD
FRONT APPROACHES THE AREA TUESDAY WITH A CHANCE FOR STRONGER
THUNDERSTORMS. BEHIND THE FRONT, DRIER WEATHER RETURNS FOR THE
INDEPENDENCE DAY HOLIDAY WEEKEND.
NEAR TERM /THROUGH TUESDAY/
AS OF 550 PM: CONVECTION HAS TRENDED MORE ISOLATED OVER THE PAST
HR OR TWO OVERALL, ALTHOUGH NEW CU GROWTH IS SEEN IN THE LOWER
PIEDMONT AND IN PARTS OF THE SW NC MOUNTAINS, SO COVERAGE STILL
LOOKS TO INCREASE IN THOSE AREAS FOR A TIME, BUT STILL NO BETTER
THAN "SCATTERED." NOT COMFORTABLE REMOVING POPS FROM ANY PART OF
THE CWA JUST YET, ALTHOUGH DID REVISE VALUES TO BE A BIT LOWER
IN THE OTHER PARTS OF THE CWA AND TO REFLECT LATEST EXPECTED
TRENDS IN THE EVENING. WEAKLY ORGANIZED BANDS OF CONVECTION IN
TN/KY APPEAR TO BE ASSOCIATED WITH SLIGHT CONVERGENCE AHEAD OF
THE APPROACHING UPPER TROUGH. THINKING THAT CONVERGENCE WILL
PROGRESS EASTWARD SLOWLY ENOUGH NOT TO BE A FACTOR IN INITIATION
THIS EVENING. UNSTABLE AIR MASS, LIGHT BULK SHEAR, MODERATE DCAPE,
AND VERY HIGH PW VALUES. ANY STORM THAT CAN GET TALL ENOUGH HAS
THE POTENTIAL FOR A DAMAGING DOWNBURST, ALTHOUGH THAT IS LOOKING
INCREASINGLY UNLIKELY. ISOLATED FLOODING IS POSSIBLE WHERE STORMS
TRAIN OR ARE ANCHORED TO TERRAIN. COVERAGE WILL DIMINISH AROUND
MIDNIGHT OR SO. THERE MAY BE MORE IN THE WAY OF CLOUDS OVERNIGHT
AHEAD OF THE APPROACHING FRONT BUT STILL EXPECT MOUNTAIN VALLEY
FOG WITH PATCHY FOG ELSEWHERE. LOWS NEAR NORMAL MOUNTAINS AND A
FEW DEGREES ABOVE NORMAL ELSEWHERE.
THE STAGNANT PATTERN FINALLY BEGINS BREAKING DOWN TUESDAY AND A
WEAK UPPER TROUGH AND SURFACE COLD FRONT MOVE INTO THE AREA FROM
THE WEST. THIS WILL KEEP HIGH PW VALUES ACROSS THE AREA AND BRING
AN UPTICK IN BULK SHEAR. THE INCREASED CLOUDS AND LOWER THICKNESS
VALUES WILL HELP PUT HIGHS A LITTLE BELOW NORMAL FOR THE MOUNTAINS
AND NEAR NORMAL ELSEWHERE. THIS WILL KEEP INSTABILITY SLIGHTLY
LOWER, BUT STILL REACHING AT LEAST THE MODERATE RANGE. DEEPER
MOISTURE IS EXPECTED AS WELL LIMITING DCAPE AND SFC DELTA THETA-E
VALUES. BUT GIVEN THE INCREASED FORCING, OVERALL SEVERE THUNDERSTORM
POTENTIAL IS HIGHER AS SOME WEAK ORGANIZATION MAY DEVELOP. ISOLATED
FLOOD THREAT REMAINS AS WELL AS STORM COVERAGE SHOULD BE HIGHER
DESPITE FASTER CELL MOVEMENT.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
AS OF 100 PM MONDAY: AN UPPER TROUGH AXIS WILL CROSS THE SPINE
OF THE APPALACHIANS TUESDAY NIGHT AND SET UP ROUGHLY ALONG THE
EAST COAST WEDNESDAY THRU THURSDAY AS THE UPPER FLOW PATTERN
AMPLIFIES. THIS SHOULD PUSH A COLD FRONT THRU THE FORECAST AREA ON
WEDNESDAY. SCATTERED DIURNAL CONVECTION IS EXPECTED, WITH BETTER
COVERAGE TO OUR SOUTHEAST. TEMPS WILL BE NEAR CLIMO. THE FRONT
PUSHES FURTHER SOUTHEAST OF THE AREA THURSDAY, RESULTING IN DRIER
CONDITIONS. ONLY VERY ISOLATED SHOWERS OR STORMS EXPECTED, MAINLY IN
THE MOUNTAINS, AS HEIGHTS RISE ALOFT AND LIMIT INSTABILITY. TEMPS
THURSDAY WILL BE A CATEGORY OR SO WARMER WITH LESS CLOUD COVER
THAN WEDNESDAY. LOWS WILL BE NEAR CLIMO.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
AS OF 130 PM MONDAY: RELATIVE DRY WEATHER IS EXPECTED FOR THE
FOURTH OF JULY HOLIDAY WEEKEND (DRY FOR EARLY JULY). AN UPPER
RIDGE WILL SLOWLY BUILD IN FROM THE MIDWEST TO THE OHIO VALLEY
AND INTO THE MID-ATLANTIC. THIS WILL HELP SUPPRESS CONVECTION AND
KEEP MID-LEVEL LAPSE RATES WEAK. AN AXIS OF SFC HIGH PRESSURE WILL
EXTEND FROM THE MID-ATLANTIC WEST TO THE MID-MS VALLEY, WHILE A
FRONT STALLS OUT OVER FL AND THE GULF. BELOW-CLIMO POPS IS IN THE
FORECAST FOR FRIDAY AND SATURDAY. POPS TREND TOWARD CLIMO SUNDAY,
BUT THE LATEST GUIDANCE HAS TRENDED DRIER. THIS IS DUE TO THE
UNCERTAINTY ON A TROPICAL LOW DEVELOPMENT ALONG THE STALLED FRONT
IN THE EASTERN GULF. THE 12Z GFS HAS COME IN MORE IN LINE WITH THE
ECMWF ON KEEPING ANY DISTURBANCE SHUNTED SOUTH. REGARDLESS OF WHAT
HAPPENS IN THE GULF, POPS SHOULD BEGIN TO RAMP UP TO MORE TYPICAL
MID-SUMMER LEVELS, AS A NORTHERN STREAM TROUGH BEGINS TO DIG INTO
THE UPPER MIDWEST AND THE UPPER RIDGE SHIFTS EAST. TEMPS WILL BE
CLOSE TO OR SLIGHTLY ABOVE NORMAL THRU THE PERIOD.
AVIATION /00Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: SOME WELL DEVELOPED CUMULUS ARE STILL
SEEN ON SATELLITE AT ISSUANCE TIME WHICH IS WORTHY OF LOW VFR
MENTION IN TAFS FOR THE FIRST COUPLE OF HOURS. MATCHED WITH LIGHT
PRECIP RETURNS WITHIN 10-20 MI, INCLUDED VCSH AT KCLT. CAN'T
ABSOLUTELY RULE OUT DEVELOPMENT AT THE OTHER SITES IN THE FIRST
HR OR TWO BUT CHANCE TOO SMALL TO MENTION. OTHERWISE, LIGHT SW
WINDS WITH DISSIPATING CU BY LATE EVENING AND JUST FEW-SCT HIGH
ALTITUDE CLOUDS OVERNIGHT. RADIATION FOG/STRATUS LIKELY IN THE
MOUNTAIN VALLEYS WITH A FLEETING CHANCE AT KAVL NEAR DAYBREAK,
HENCE TEMPO. CONFIDENCE REMAINS LOW. WINDS PICK UP STILL FROM THE
SW LATE MORNING WITH DIURNAL CU DEVELOPING IN SIMILAR FASHION TO
MONDAY. APPROACHING COLD FRONT HOWEVER WILL PROVIDE BETTER OVERALL
FORCING. THINKING THAT DIURNAL SHRA/TSRA CHANCES WILL DEVELOP
SIMILARLY TO THE PAST COUPLE OF DAYS, BUT WITH CHANCE LINGERING
A BIT LATER INTO THE EVENING BASED ON TIMING OF FRONT. MULTIPLE
ROUNDS ARE POSSIBLE. VCTS FOR SLIGHTLY EARLIER START POSSIBLE AT
KAVL AND VCSH CONTINUES TO 06Z AT KCLT ON THE BACK END. OTHERWISE
PROB30 FOR PEAK COVERAGE/IMPACT PERIOD.
OUTLOOK: CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
AGAIN WEDNESDAY. DRIER AIR MOVING IN THURSDAY MAY HELP INHIBIT
CONVECTION INTO THE WEEKEND. FOG AND/OR LOW STRATUS POSSIBLE
EACH MORNING IN THE USUAL MOUNTAIN VALLEYS AS WELL AS NEAR LAKES
AND RIVERS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...ARK/CP
NEAR TERM...RWH/WIMBERLEY
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...WIMBERLEY
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