251
FXUS62 KGSP 011029
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
629 AM EDT TUE JUL 1 2025
SYNOPSIS
A COLD FRONT APPROACHES THE AREA TODAY WITH A CHANCE FOR STRONGER
THUNDERSTORMS. BEHIND THE FRONT, DRIER WEATHER RETURNS FOR THE
INDEPENDENCE DAY HOLIDAY WEEKEND. TEMPERATURES REMAIN TYPICAL FOR
THE SUMMERTIME SEASON THROUGH THE BEGINNING OF NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 625 AM: LATEST WATER VAPOR IMAGERY DEPICTS A LONG WAVE TROUGH
EXTENDING FROM THE OZARKS THROUGH THE GREAT LAKES. THE AXIS OF THIS
TROUGH IS FORECAST TO EXTEND FROM THE SOUTHERN APPALACHIANS THROUGH
THE MID-ATLANTIC BY THE END OF THE PERIOD. AS SUCH, THE SYNOPTIC
PATTERN IS EXPECTED TO BECOME PROGRESSIVELY FAVORABLE FOR
DEVELOPMENT OF DEEP CONVECTION THROUGHOUT THE DAYLIGHT HOURS.
INCREASING HIGH AND MID-LEVEL CLOUDS WILL SOMEWHAT LIMIT THE HEATING
POTENTIAL TODAY...FORECAST TEMPS ARE EXPECTED TO TOP OUT RIGHT
AROUND NORMAL...BUT MOISTURE AND INSOLATION IS EXPECTED TO BE
SUFFICIENT TO ALLOW FOR DESTABILIZATION TO THE TUNE OF AROUND 2000
J/KG OF SBCAPE BY MID-AFTERNOON. SCATTERED DEEP CONVECTION IS
EXPECTED TO INITIALLY BEGIN FIRING ALONG THE BLUE RIDGE AS NORMAL
DURING EARLY AFTERNOON...ALTHOUGH THERMAL SURFACE TROUGH COULD ALSO
PROVIDE A FOCUS FOR ISOLATED PIEDMONT ACTIVITY THAT EARLY IN THE
DAY. WITH MEAN CLOUD-BEARING WINDS STEADILY INCREASING TO 10-15 KTS
THROUGH THE AFTERNOON, CONVECTION WILL MOVE OFF THE HIGH TERRAIN
INTO THE PIEDMONT AND FOOTHILLS DURING MID-TO-LATE AFTERNOON.
CONVECTIVE COVERAGE IS EXPECTED TO PEAK DURING THE LATE AFTERNOON
AND EVENING, AS ACTIVITY ASSOCIATED WITH WEAK SURFACE BOUNDARY
MOVES INTO THE SOUTHERN APPALACHIANS FROM THE TN VALLEY. POPS
ARE GENERALLY IN THE 70-80% RANGE ACROSS MUCH OF THE CWA
DURING THIS TIME. ISOLATED SEVERE STORMS WILL BE POSSIBLE THROUGHOUT
THE AFTERNOON AND EVENING...MAINLY OF THE PULSE VARIETY WITH THE
HIGH TERRAIN-INITIATING CONVECTION EARLIER IN THE AFTERNOON...AND
WITH ADDITIONAL PULSE CELLS BUT ALSO POSSIBLY CLUSTERING ALONG
OUTFLOWS LATER IN THE DAY AS THE SHEAR INCREASES TO AROUND 20 KTS.
DESPITE THE INCREASING CELL MOTION...THE POTENTIAL FOR LOCALLY
EXCESSIVE RAINFALL WILL ALSO EXIST UNDER VERY MOIST CONDITIONS...
PRECIPITABLE WATER VALUES AOA 1.75"...DEEP WARM CLOUD LAYERS OF OVER
12KFT, AND THE POTENTIAL FOR TRAINING CELLS AND/OR BACK-BUILDING
MULTICELLS. CONVECTION WILL BEGIN TO DIMINISH, BUT WITH SOME DEGREE
OF COVERAGE LIKELY PERSISTING THROUGH THE OVERNIGHT, AS TROUGH AXIS
AND ATTENDANT BOUNDARY SHIFT STEADILY EAST ACROSS THE CWA. MIN TEMPS
WILL BE A COUPLE OF DEGREES ABOVE NORMAL.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
AS OF 230 AM TUESDAY: PICKING UP WEDNESDAY, A FRONTAL BOUNDARY
SHOULD BE IN THE MIDST OF PASSING THROUGH THE CWA. ALOFT, A
WEAKENING TROUGH SLIDES OFF THE COAST BRINGING LIGHT NW FLOW AND
ADVECTING DRIER AIR INTO THE AREA. ANY LINGERING PRECIP CHANCES
QUICKLY DIMINISH THROUGH THE DAY AS THE MOISTURE SUPPLY GETS CUTOFF.
CURRENTLY, GUIDANCE DROPS POPS FROM SLIGHT CHANCE (25-35%) TO
UNMENTIONABLE (<15%) BY WEDNESDAY EVENING. FROM THERE, THE REGION
STAYS UNDER THIS REINFORCING DRY AIR AND NW WINDS INTO THURSDAY.
MEANWHILE, A RIDGE BEGINS TO AMPLIFY OVER THE CENTRAL CONUS AND BY
THURSDAY NIGHT, PROGRESSES EASTWARD. SLOW HEIGHT RISES THROUGH THE
END OF THE PERIOD AS THIS HIGH PRESSURE EXPANDS. POPS REMAIN LESS
THAN 15% ON THURSDAY, KEEPING THE SHORT TERM PERIOD RELATIVELY DRY.
CNA'T RULE OUT A STRAY SHOWER OVER THE MOUNTAINS GIVEN THE TYPICAL
DAYTIME HEATING, BUT IT WILL BE DIFFICULT TO INITIATE WITH THE DRIER
AIR. AS FOR TEMPERATURES, WEDNESDAY WILL BE THE COOLEST DAY AS
WARMING REBOUNDS DUE TO THE BUILDING HIGH PRESSURE BY THURSDAY.
LONG TERM /FRIDAY THROUGH MONDAY/
AS OF 220 AM TUESDAY: BY THE INDEPENDENCE DAY HOLIDAY, GUIDANCE IS
KEEPING THE WEATHER LOOKING FAVORABLE FOR ACTIVITIES INVOLVING
FIREWORKS. LONG RANGE GUIDANCE HAS THE AREA UNDER MOSTLY HIGH
PRESSURE BY FRIDAY AND INTO THE MAJORITY OF THE WEEKEND. POPS REMAIN
LOW AND IN THE SLIGHT CHANCE RANGE (15-35%), WITH THE HIGHER CHANCES
OVER THE MOUNTAINS. LIGHT WINDS AND TEMPERATURES CLOSE TO NORMAL
THROUGH AT LEAST MONDAY. NOW, THERE IS SOME DISAGREEMENT WITH MODEL
RUNS ABOUT AN AREA OF LOW PRESSURE OVER THE GULF, BUT HOW THE HIGH
PRESSURE AMPLIFIES, SHOULD BE ENOUGH TO KEEP ANYTHING FROM REACHING
THE CWA AT THIS TIME. EITHER WAY, POPS START TO INCREASE TOWARD THE
END OF THE PERIOD WITH MORE TYPICAL SUMMERTIME SHOWERS AND
THUNDERSTORMS. TEMPERATURES THROUGH THE PERIOD LOOK TO REMAIN STEADY
AROUND CLIMO AND SHUNTS AWAY ANY CHANCE FOR EXCESSIVE HEAT.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: THE PRIMARY IMMEDIATE CONCERN IS LIFR STRATUS
AT KAVL AND IFR STRATUS AT KCLT. THERE ALSO REMAINS SOME POTENTIAL
FOR IFR RESTRICTIONS AT KHKY. CONDITIONS SHOULD RETURN TO VFR AT
ALL SITES NO LATER THAN 14Z. OTHERWISE, CONVECTION IS EXPECTED TO
DEVELOP ACROSS THE MOUNTAINS BY EARLY AFTERNOON...WITH SOME ISOLATED
ACTIVITY POSSIBLE IN OTHER AREAS DURING THAT TIME. CONVECTION
WILL MOVE OFF THE HIGH TERRAIN INTO THE PIEDMONT/FOOTHILLS FROM
MID-AFTERNOON INTO THE EVENING. ADDITIONAL CONVECTION WILL MOVE OVER
THE AREA DURING THE EVENING IN ADVANCE OF A COLD FRONT. PROB30S
FOR TSRA ARE WARRANTED AT ALL SITES THIS AFTERNOON...WITH A
TRANSITION TO CATEGORICAL -SHRA AND VCTS AND TEMPO TSRA THIS
EVENING. SW WINDS OF 5-10 KTS ARE EXPECTED THROUGH MUCH OF THE
PERIOD. CAN'T RULE OUT SOME GUSTS OF 15-20 KTS ACROSS THE PIEDMONT
DURING THE AFTERNOON. THE POTENTIAL FOR SHOWERS, AND PERHAPS A TS
OR TWO WILL LINGER INTO AT LEAST THE EARLY PART OF THE OVERNIGHT
AT KCLT. CIGS ARE EXPECTED TO FILL IN AFTER MIDNIGHT TONIGHT,
WITH MVFR GENERALLY EXPECTED. IFR CONDITIONS ARE POSSIBLE, BUT
CONFIDENCE IS LOW-TO-MODERATE AT THIS TIME.
OUTLOOK: SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED AGAIN WEDNESDAY AFTERNOON/EVENING. DRIER AIR MOVING IN
THURSDAY IS EXPECTED TO INHIBIT DIURNAL CONVECTION INTO THE WEEKEND,
WITH AT MOST ISOLATED ACTIVITY EXPECTED EACH DAY. FOG AND/OR LOW
STRATUS POSSIBLE EACH MORNING IN THE USUAL MOUNTAIN VALLEYS, AS
WELL AS NEAR LAKES AND RIVERS, AND WHERE SIGNIFICANT RAIN FELL
THE DAY BEFORE.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...CP
NEAR TERM...JDL
SHORT TERM...CP
LONG TERM...CP
AVIATION...JDL
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