681  
FXUS62 KGSP 030552  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
152 AM EDT WED SEP 3 2025  
   
SYNOPSIS  
 
HIGH PRESSURE MOVES OFFSHORE TODAY AS A WEAK UPPER-LEVEL SYSTEM  
MOVE ACROSS THE AREA. THIS WILL BRING A ROUND OF MOUNTAIN AND  
FOOTHILL SHOWERS AND STORMS THIS AFTERNOON AND EVENING. A WEAK COLD  
FRONT APPROACHES FROM THE NORTHWEST ON THURSDAY AND MAY BRING  
ANOTHER ROUND OF SHOWERS AND STORMS TO THE AREA. TEMPERATURES REMAIN  
AT OR BELOW SEASONAL NORMALS THROUGH THURSDAY. A WARMING TREND  
RETURNS FRIDAY INTO THE WEEKEND AHEAD OF ANOTHER ADVANCING COLD  
FRONT. RAIN CHANCES RETURN THIS WEEKEND AND MAY LINGER INTO  
EARLY NEXT WEEK DEPENDING ON WHETHER THE FRONT FULLY CLEARS THE  
AREA OR STALLS ACROSS THE REGION.  
 
 
   
NEAR TERM /THROUGH TONIGHT/  
 
AS OF 135 AM EDT WEDNESDAY: AN UPPER-LEVEL IMPULSE CAN BE SEEN  
CROSSING THE TN VALLEY, PROVIDING SOME ASCENT FOR SHOWERS  
ACROSS EASTERN TN INTO THE SOUTHERN APPALACHIANS EARLY THIS  
MORNING. THIS ENERGY IS COMBINING WITH MID- LEVEL MOISTURE TO  
PRODUCE AN ALTOCUMULUS DECK THAT IS SPREADING ACROSS THE WESTERN  
HALF OF THE FORECAST AREA. IT WILL STRUGGLE TO REACH THE I-77  
CORRIDOR, BUT OVERALL, PARTLY TO MOSTLY CLOUDY SKIES IS EXPECTED  
THRU DAYBREAK. THE CLOUDS SHOULD GREATLY LIMIT THE USUAL MOUNTAIN  
VALLEY FOG.  
 
LATER THIS MORNING, THE IMPULSE WILL CROSS THE CWFA AND TAKE THE MID  
CLOUDS/ENERGY WITH IT. WE WILL ACTUALLY HAVE PRONOUNCED DEEP-LAYER  
DNVA BEHIND THE WAVE DURING THE PEAK HEATING HOURS. BUT DESPITE  
THAT, FORECAST SOUNDINGS SHOW TALL, SKINNY CAPE DEVELOPING ACROSS  
THE MOUNTAINS, AND ENOUGH LOW-LEVEL MOISTURE WILL PERSIST TO SUPPORT  
SCATTERED CONVECTION. STEERING FLOW WILL PUSH THE ACTIVITY EAST  
INTO THE NC FOOTHILLS AND NW PIEDMONT. BUT MUCH LESS INSTABILITY  
THERE SHOULD CAUSE MOST OF THE ACTIVITY TO DISSIPATE. THE 00Z HRRR  
IS RATHER AGGRESSIVE WITH CONVECTION REACHING THE I-77 CORRIDOR BY  
EARLY EVENING. THIS SEEMS TO BE AN OUTLIER, SO NO DEVIATIONS FROM  
THE NBM WERE MADE. WHATEVER DOES DEVELOP, IT IS NOT EXPECTED TO  
BE SEVERE, GIVEN LACK OF FORCING AND RELATIVELY LOW DCAPE. HIGHS  
WILL ONCE AGAIN BE SIMILAR TO THE PREVIOUS DAY, A FEW DEGREES  
BELOW NORMAL.  
 
TONIGHT, STRONG SHORTWAVE ENERGY WILL DEEPEN THE LONGWAVE TROUGH  
OVER THE MIDWEST. A COLD FRONT WILL PUSH INTO THE OH VALLEY FROM  
THE NW, WITH INCREASING SWLY FLOW AHEAD OF THE FRONT ACROSS THE  
TN VALLEY AND THE SOUTHERN APPALACHIANS. NEARLY ALL THE GUIDANCE  
HAS SOME AMOUNT OF SHOWERS DEVELOPMENT OVERNIGHT ACROSS NORTHERN  
GA/EASTERN TN THAT MAY WORK INTO OUR WESTERN ZONES BEFORE DAYBREAK  
THURSDAY. THERE IS NOT AS MUCH MID-LEVEL CLOUDINESS IN THE GUIDANCE  
AS WE'VE SEEN THE LAST COUPLE NIGHTS, BUT PERHAPS MORE LOW CLOUDS IN  
THE INCREASING SWLY WAA FLOW, MAY LIMIT MOUNTAIN VALLEY FOG AGAIN.  
LOWS WILL BE NEAR NORMAL IN THE MOUNTAINS AND SLIGHTLY BELOW NORMAL  
IN THE PIEDMONT.  
 
 
   
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/  
 
AS OF 1159 PM TUESDAY: GUIDANCE IS IN GOOD AGREEMENT THAT BROAD  
TROUGHING WILL ENCOMPASS MUST OF THE CONUS EAST OF THE ROCKIES AS A  
PARENT CLOSED UPPER LOW SPINS JUST NORTH OF THE GREAT LAKES OVER  
SOUTHERN ONTARIO. SEVERAL SHORTWAVE TROUGHS WILL DIVE ACROSS THE  
GREAT PLAINS AND INTO THE MIDWEST/OHIO VALLEY WITH THE LEAD TROUGH  
SLIDING ACROSS THE OHIO VALLEY ON THURSDAY. THIS WILL DRAG AN  
ATTENDANT SURFACE COLD FRONT INTO WESTERN KENTUCKY AND SOUTHERN  
OHIO. THE WESTERN CAROLINAS AND NORTHEAST GEORGIA WILL REMAIN ON THE  
SOUTHERN FLANK OF THE UPPER TROUGH WITH THE STRONGEST FORCING FOR  
ASCENT DISPLACED WELL NORTH OF THE AREA TOWARDS THE CENTRAL  
APPALACHIANS AND MID-ATLANTIC. H5 HEIGHTS WILL BE RATHER HIGH IN THE  
578-580 DAM RANGE WITH HEIGHT TENDENCIES NEUTRAL AT BEST. AS SUCH,  
THE 00Z SUITE OF CAM GUIDANCE IS IN GOOD AGREEMENT THAT A BAND OF  
MORE ORGANIZED PRE-FRONTAL CONVECTION WILL PROPAGATE ACROSS EASTERN  
KENTUCKY INTO WESTERN VIRGINIA AND PORTIONS OF WEST VIRGINIA. A  
BROKEN BAND OF SCATTERED CONVECTION WILL BE POSSIBLE ACROSS EAST  
TENNESSEE WITH SOME OF THIS ACTIVITY MAKING A RUN AT THE MOUNTAINS  
LATE THURSDAY AFTERNOON INTO THE EARLY EVENING HOURS. HERE,  
PARAMETER SPACE WILL BE CHARACTERIZED BY 30-40KTS OF DEEP-LAYER  
VERTICAL WIND SHEAR AND MODEST INSTABILITY WITH AROUND 2000 J/KG OF  
SURFACE-BASED INSTABILITY. A COUPLE STRONG STORMS WITH LOCALLY GUSTY  
WINDS WILL BE POSSIBLE AND AN ISOLATED SEVERE STORM CANNOT BE  
COMPLETELY DISCOUNTED. HOWEVER, A DEARTH OF FORCING WILL GENERALLY  
PRECLUDE GREATER COVERAGE AND SEVERITY WITH CONVECTION STRUGGLING TO  
MAKE IT EAST OF THE MOUNTAINS. BY FRIDAY, THE LEAD SHORTWAVE TROUGH  
WILL QUICKLY PULL AWAY FROM THE AREA AS IT LIFTS INTO NEW ENGLAND  
WITH BROAD ZONAL FLOW BECOMING ESTABLISHED IN THE BASE OF THE MEAN  
TROUGH ACROSS MUCH OF THE REGION. THIS WILL IN TURN STALL THE COLD  
FRONT NORTHWEST OF THE AREA, WHICH COMBINED WITH RISING HEIGHTS WILL  
SUPPORT A NOTABLE WARMING TREND. AFTERNOON HIGHS ARE FORECAST TO BE  
ABOVE AVERAGE FOR THE FIRST TIME IN QUITE A WHILE WITH UPPER 80S TO  
NEAR 90 COMMON EAST OF THE MOUNTAINS.  
 
 
   
LONG TERM /SATURDAY THROUGH TUESDAY/  
 
AS OF 1225 AM WEDNESDAY: HEADING INTO THE WEEKEND, THE CLOSED UPPER  
LOW IS GENERALLY EXPECTED TO MEANDER EAST ACROSS ONTARIO WITH TWO  
MORE IN A SERIES OF SHORTWAVE TROUGHS DIVING THROUGH THE NORTHERN  
PLAINS AND INTO THE MIDWEST AND OHIO VALLEY. ONCE AGAIN, THE  
MAJORITY OF ASSOCIATED UPPER FORCING WILL REMAIN DISPLACED WELL  
NORTH OF THE AREA, HOWEVER A LARGE SPRAWLING SURFACE HIGH SPILLING  
INTO THE GREAT PLAINS WILL FINALLY PUSH THE STALLED COLD FRONT INTO  
THE AREA. FORECAST CONFIDENCE QUICKLY WANES AT THIS POINT AS  
GUIDANCE RAPIDLY DIVERGES WITH REGARDS TO THE EVOLUTION OF THE  
SURFACE AND UPPER PATTERNS. SEVERAL MEMBERS OF GUIDANCE PUSH THE  
FRONT THROUGH THE AREA ON SATURDAY WITH DRY CONDITIONS TO CLOSE THE  
WEEKEND INTO EARLY NEXT WEEK. ON THE OTHER HAND, OTHER PIECES OF  
GUIDANCE STALL THE FRONT ACROSS OR IN THE VICINITY OF THE AREA WITH  
MULTIPLE DAYS OF ACTIVE WEATHER ALONG THE BOUNDARY CONTINUING INTO  
THE START OF NEXT WEEK. THE ONE AGREEMENT AMONGST GUIDANCE, HOWEVER,  
IS FOR THE AFOREMENTIONED SURFACE HIGH TO TRANSLATE INTO NEW ENGLAND  
WITH A CAD SURFACE PRESSURE PATTERN DEVELOPING EARLY NEXT WEEK.  
ANOTHER WARM DAY IS EXPECTED AHEAD OF THE FRONT ON SATURDAY BEFORE  
THE PRESENCE OF PRECIP AND/OR THE DEVELOPMENT OF CAD BRINGS  
TEMPERATURES BACK DOWN TO BELOW SEASONAL AVERAGES.  
 
 
   
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/  
 
AT KCLT: VFR CONDITIONS EXPECTED THRU THE PERIOD, EXCEPT FOR  
POSSIBLE IFR STRATUS AROUND DAYBREAK AT KAVL, BUT CONFIDENCE  
REMAINS LOW DUE TO PERSISTENT MID CLOUDS. THE MID CLOUDS WILL LIKELY  
SPREAD ACROSS ALL THE TAF SITES THRU EARLY MORNING, THEN THIN OUT,  
LEAVING A LOWER-VFR CU FIELD BY MIDDAY. SCATTERED CONVECTION IS  
EXPECTED TO DEVELOP ACROSS THE MOUNTAINS AND DRIFT EAST INTO THE  
NC PIEDMONT. WILL KEEP PROB30 FOR TSRA FOR KAVL AND KHKY, BUT  
CONFIDENCE REMAINS TOO LOW FOR ANY MENTION AT KCLT. THE LATEST  
HRRR MODEL SHOWS SOME SHOWERS REACHING KCLT EARLY IN THE EVENING,  
SO SOME SHRA MENTION MAY BE NEEDED IN A LATER FCST, IF TRENDS  
HOLD. THE UPSTATE SITES WILL LIKELY REMAIN DRY TODAY. LESS MID  
CLOUDS EXPECTED TONIGHT, BUT SOME STRATOCU MAY LINGER. WINDS  
WILL BE LIGHT, TOGGLING TO SW IN THE 16-18Z TIME FRAME EAST OF  
THE MOUNTAINS.  
 
OUTLOOK: AT LEAST SCT AFTN/EVENING CONVECTION WILL BE POSSIBLE  
ACROSS THE HIGHER TERRAIN ON THURSDAY WITH CHANCES DIMINISHING  
AGAIN ON FRIDAY. NOCTURNAL FOG AND/OR LOW STRATUS WILL ALSO BE  
POSSIBLE OVERNIGHT AND INTO THE MORNING, ESPECIALLY IN THE FAVORED  
MTN VALLEYS.  
 
 
   
GSP WATCHES/WARNINGS/ADVISORIES  
 
GA...NONE.  
NC...NONE.  
SC...NONE.  
 
 
 
 
 
SYNOPSIS...TW  
NEAR TERM...ARK  
SHORT TERM...TW  
LONG TERM...TW  
AVIATION...ARK  
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