057  
FXUS62 KGSP 090110  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
910 PM EDT TUE JUL 8 2025  
   
SYNOPSIS
 
 
HOT AND HUMID CONDITIONS WILL COOL CLOSER TO NORMAL LATE  
THIS WEEK WITH NUMEROUS AFTERNOON AND EVENING SHOWERS AND  
THUNDERSTORMS. THE HEAT BUILDS AGAIN FROM LATE IN THE WEEKEND INTO  
EARLY NEXT WEEK AS AN UPPER RIDGE FORMS, BUT DAILY AFTERNOON AND  
EVENING SHOWER AND THUNDERSTORM CHANCES CONTINUE.  
 

 
   
NEAR TERM /THROUGH WEDNESDAY/
 
 
AS OF 730 PM TUESDAY: THE CONVECTION WAS WINDING DOWN ACROSS THE  
REGION, WHAT WITH A LARGE OUTFLOW BOUNDARY RUNNING OFF TO THE  
NORTHWEST FROM THE EARLIER CONVECTIVE COMPLEX OVER THE COASTAL  
PLAIN. THE AIR MASS OVER THE NORTHERN UPSTATE AND NC FOOTHILLS  
WAS RELATIVELY INHOSPITABLE WITH LOWER DEWPOINTS YIELDING ONLY  
1000 J/KG OF CAPE. NOT MUCH OF A SURPRISE THAT THE OUTFLOW WAS  
UNPRODUCTIVE. THE ONGOING CONVECTION OVER THE MTNS IS STILL EXPECTED  
TO WEAKEN AND DISSIPATE IN THE HOUR OR TWO AFTER SUNSET. TEMPS  
WERE MODULATED BY THE STORM OUTFLOWS, BUT SHOULD REVERT TO THE  
EXPECTED TREND BY THE EARLY MORNING HOURS.  
 
OTHERWISE...A BROAD BERMUDA RIDGE EXTENDED INTO THE SOUTHEAST  
STATES WITH A NORTHERN STREAM TROUGH SLIDING ACROSS THE GREAT LAKES  
REGION. THE PATTERN CHANGES TOMORROW AS THE PREVIOUSLY MENTIONED  
TROUGH SLIDES ACROSS THE OHIO VALLEY AND HELPS TO DRAW A PLUME OF  
DEEPER MOISTURE INTO THE AREA WITH PWATS SURGING TO 1.5-2" ACROSS  
THE AREA. WEAK HEIGHT FALLS OVERSPREADING THE REGION AHEAD OF THE  
TROUGH AXIS IN CONCERT WITH A VERY WARM AND MOIST AIRMASS WILL  
FOSTER A MUCH BETTER ENVIRONMENT FOR DIURNAL CONVECTION. NUMEROUS  
TO WIDESPREAD THUNDERSTORMS ARE EXPECTED ACROSS MUCH OF THE AREA,  
ESPECIALLY NORTHEAST OF THE SAVANNAH RIVER VALLEY. THIS WILL HELP  
KEEP TEMPERATURES A FEW DEGREES COOLER, BUT AT THE EXPENSE OF A  
NOTICEABLY MORE HUMID AIRMASS. AS WITH ANY SUMMER THUNDERSTORMS,  
A FEW STRONG TO ISOLATED SEVERE STORMS WITH WET MICROBURSTS CANNOT  
BE RULED OUT, BUT MEAGER LAPSE RATES AND POOR DCAPE WILL GENERALLY  
PRECLUDE A GREATER THREAT FOR ORGANIZED DAMAGING WIND. STORMS WILL  
ALSO PRODUCE VERY EFFICIENT HEAVY RAIN WITH ISOLATED POCKETS OF 1-3"  
IN SHORT AMOUNT OF TIME POSSIBLE. THIS MAY LEAD TO SEVERAL INSTANCES  
OF NUISANCE/MINOR FLOODING OF LOW-LYING AND POOR DRAINAGE AREAS,  
ESPECIALLY ALONG AND EAST OF I-77 CLOSER TO THE MAIN PLUME OF  
DEEP MOISTURE. SHOULD THIS TYPE OF RAINFALL OCCUR OVER AN URBAN  
AREA, SUCH AS THE CHARLOTTE METRO, ISOLATED FLASH FLOODING WILL  
BE POSSIBLE. GIVEN THE ISOLATED NATURE OF LOCALLY HEAVY RAINFALL  
AND UNCERTAINTY AS TO WHERE IT WOULD OCCUR, WILL HOLD OFF ON ANY  
HYDRO HEADLINES AT THIS TIME.  
 

 
   
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/
 
 
AS OF NOON TUE: CYCLONIC FLOW CONTINUES OVER THE EASTERN US THROUGH  
THE SHORT TERM PERIOD AS DEEP SHORTWAVE MOVES ACROSS ONTARIO/QUEBEC.  
SUFFICIENT SHEAR AND FORCING IS EXPECTED TO ALLOW DIURNALLY  
INITIATED CONVECTION TO CONTINUE THROUGH WEDNESDAY EVENING, SO  
POPS DIMINISH ONLY SLOWLY AT THAT TIME. MODEL CONSENSUS SUGGESTS  
AN EMBEDDED, MORE COMPACT SHORTWAVE WILL MOVE ACROSS THE MID-MS  
VALLEY THURSDAY AND BE INVOF THE SOUTHERN APPALACHIANS FRIDAY.  
THIS FEATURE MAY BE ENHANCED BY DIURNAL CONVECTION UPSTREAM OF OUR  
AREA, AND ACCORDINGLY THERE IS SPREAD AMONG MODELS AS TO WHERE  
IT WILL BE LOCATED FRIDAY. REGARDLESS THE UPPER PATTERN SHOULD  
BE MORE FAVORABLE FOR DIURNAL CONVECTION THAN WHAT WE TYPICALLY  
SEE THIS TIME OF YEAR. FOLLOWING MULTIPLE DAYS OF SW FLOW AHEAD  
OF THE TROUGH AXIS, PWATS WILL BE ABOVE NORMAL (+1.2 TO +1.5 SD),  
GENERALLY A BIT HIGHER THU COMPARED TO FRI AS THE MAIN TROUGH AXIS  
SHIFTS EAST A BIT. ALTOGETHER THIS RESULTS IN POPS IN THE LIKELY  
TO CATEGORICAL RANGE EACH DAY, ONCE AGAIN BEING HIGHER THURSDAY.  
 
0-6KM SHEAR IS SHOWN TO INCREASE AHEAD OF THE COMPACT SHORTWAVE,  
PERHAPS EXCEEDING 30 KT THURSDAY OR THURSDAY NIGHT. THERE APPEARS  
THE POSSIBILITY OF AN ORGANIZED BAND OF CONVECTION DEVELOPING WITH  
THE WAVE LATE THURSDAY IN OUR WESTERN CWA, WHICH MIGHT RESULT IN  
A DAMAGING WIND THREAT MORE WIDESPREAD THAN FROM TYPICAL SUMMER  
PULSE STORMS; THAT SAID, MOIST PROFILES THAT DAY MAY LIMIT COLD POOL  
FORMATION AND MITIGATE THAT THREAT TO SOME DEGREE. DESPITE THE DEEP  
LAYER SHEAR, FLOW WILL BE UNIDIRECTIONAL AND CORFIDI VECTORS SHORT,  
SO TRAINING OR BACKBUILDING MAY OCCUR. COMBINED WITH THE PWATS,  
AN ABOVE-AVERAGE THREAT OF LOCALIZED TORRENTIAL RAINFALL AND FLASH  
FLOODING WILL PERSIST.  
 
MAX TEMPS WILL BE NEAR NORMAL AND HEAT INDEX WILL REMAIN BELOW  
ADVISORY CRITERIA.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
 
 
AS OF 1245 PM TUE: AXIS OF THE CANADIAN TROUGH WILL BE EAST OF THE  
AREA FRIDAY NIGHT AND 500MB HEIGHTS SLOWLY RISE THRU THE WEEKEND.  
THAT RESULTS IN A GRADUAL WARMING TREND, WITH DAILY MAX TEMPS  
A FEW DEGREES ABOVE NORMAL FOR SUNDAY AND MONDAY. HEAT INDEX  
ACCORDINGLY WILL RISE CLOSER TO, BUT NOT QUITE REACHING, HEAT  
ADVISORY CRITERIA IN PARTS OF OUR PIEDMONT SOUTHEAST OF I-85. WITH  
RESPECT TO CONVECTION, WHILE WE MAY LOSE THE ENHANCING EFFECT  
OF THE TROUGH, ENSEMBLE CAPE AND CIN DON'T CHANGE MUCH SAT-MON  
AFTERNOONS COMPARED TO FRIDAY. FURTHERMORE MOST DETERMINISTIC RUNS  
AND ENSEMBLE MEMBERS DEPICT ANOTHER TROUGH IN THE MIDWEST CIRCA  
SUNDAY, SUGGESTING A FRONT WILL APPROACH THE CWA FROM THE WEST  
BY MONDAY. THERE IS HOWEVER SPREAD AS TO THE ADVANCEMENT OF ANY  
FRONT EAST OF THE APPALACHIANS BETWEEN THE GEFS AND EC ENSEMBLE,  
KEEPING CONFIDENCE LOW. FOR NOW, IT SEEMS REASONABLE TO EXPECT ONLY  
A SMALL DECLINE IN DAILY POPS FOR THIS PERIOD, STILL WARRANTING  
LIKELY VALUES FOR THE MOUNTAINS EACH AFTERNOON AND A SOLID CHANCE  
(30-45%) FOR THE PIEDMONT.  
 

 
   
AVIATION /01Z WEDNESDAY THROUGH SUNDAY/
 
 
AT KCLT AND ELSEWHERE: DEALING WITH A FEW THUNDERSTORMS RIGHT  
AROUND KAVL AT ISSUANCE TIME, SO WE WILL HANG ONTO A TEMPO FOR TSRA  
THERE. OTHERWISE, THE OUTFLOW BOUNDARY HAS PASSED NW ACROSS KCLT SO  
THEY SHOULD BE QUIET, AND THE UPSTATE/FOOTHILLS TERMINALS ARE NOT  
UNSTABLE ENOUGH TO SUPPORT NEW STORM DEVELOPMENT. THUS, EXPECT A  
QUIET VFR NIGHT WITH ONLY SOME DEBRIS CLOUDS. WILL PLAN TO ADD SOME  
MVFR FOG RESTRICTIONS BACK IN AT KAVL IN THE PRE-DAWN HOURS ONCE  
THE ONGOING STORMS DISSIPATE. THAT BRINGS US TO WEDNESDAY, WHICH  
LOOKS QUITE A BIT MORE ACTIVE THAN TODAY, WHAT WITH MORE HUMIDITY  
RETURNING AND A MORE FAVORABLE UPPER LEVEL ENVIRONMENT FOR STORM  
DEVELOPMENT. DAYTIME HEATING SHOULD PUSH THE BUOYANCY UP HIGH ENOUGH  
TO ALLOW FOR NUMEROUS STORMS MAINLY IN THE AFTERNOON AND EVENING,  
THOUGH THE MODELS INDICATE A LATER THAN USUAL DEVELOPMENT TIME. FOR  
THAT REASON, WE WILL GO WITH A STRATEGY THAT EMPLOYS A PROB30 FIRST  
IN THE MID/LATE AFTERNOON AND A TEMPO IN THE EARLY EVENING. THERE  
WILL BE SOME POTENTIAL FOR STRONG THUNDERSTORM OUTFLOWS, SO EXPECT  
VARIABLE FLIGHT CONDITIONS AND STRONG GUSTS NEAR STORMS.  
 
OUTLOOK: TYPICAL SUMMERTIME WEATHER IS EXPECTED INTO THE  
WEEKEND, WITH SCATTERED TO NUMEROUS THUNDERSTORMS MAINLY IN THE  
AFTERNOON/EVENING AND FOG AND/OR LOW STRATUS POSSIBLE EACH MORNING.  
 

 
   
GSP WATCHES/WARNINGS/ADVISORIES
 
 
GA...NONE.  
NC...NONE.  
SC...NONE.  
 

 
 

 
 
SYNOPSIS...DEO  
NEAR TERM...PM/TW  
SHORT TERM...WIMBERLEY  
LONG TERM...WIMBERLEY  
AVIATION...PM  
 
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