775  
FXUS62 KGSP 171038  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
638 AM EDT FRI OCT 17 2025  
   
SYNOPSIS  
 
COOLER TEMPERATURES DEVELOP FRIDAY NIGHT BEHIND A REINFORCING  
COLD FRONT. CLOUDS AND TEMPERATURES BOTH INCREASE ON SATURDAY  
BEFORE A STRONGER COLD FRONT ARRIVES SUNDAY, PRODUCING SOME RAIN  
AND POSSIBLY SOME THUNDER. DRY AND COOL CONDITIONS RETURN NEXT  
WEEK, AND LINGER THROUGH THE END OF THE PERIOD.  
 
 
   
NEAR TERM /THROUGH TONIGHT/  
 
AS OF 635 AM EDT FRIDAY: AN UPPER RIDGE AXIS ASSOCIATED WITH A  
WEAKENING OMEGA BLOCK MOVES INTO THE AREA THROUGH THE PERIOD. A  
SHORT WAVE RIDES UP THE RIDGE WEST AND NORTH OF THE AREA TONIGHT. AT  
THE SURFACE, THE CENTER OF HIGH PRESSURE MOVES ACROSS THE AREA THIS  
MORNING, SETTLING TO OUR SOUTHEAST BY AFTERNOON. DRY CONDITIONS WILL  
CONTINUE THROUGH THE PERIOD. MOUNTAIN VALLEY FOG DISSIPATES BY MID  
MORNING THEN RETURNS OVERNIGHT. SOME STRATOCU WILL LINGER ACROSS THE  
UPSTATE, NE GA, AND THE SOUTHERN NC MOUNTAINS THIS MORNING AS  
CONVERGENCE DOWNSTREAM OF THE HIGHER RIDGES ACTS ON MOISTURE TRAPPED  
UNDER A SUBSIDENCE INVERSION. THESE CLOUDS SHOULD DISSIPATE BY  
AFTERNOON AS THE FLOW WEAKENS. EXPECT CIRRUS ASSOCIATED WITH THE  
SHORT WAVE TO INCREASE ACROSS THE AREA TODAY THEN MOVE EAST  
OVERNIGHT. HIGHS WILL BE A LITTLE ABOVE NORMAL, BUT UP TO 5 DEGREES  
ABOVE NORMAL OVER THE UPPER SAVANNAH RIVER VALLEY AND THE MOUNTAINS  
WEST OF THE FRENCH BROAD. LOWS WILL BE A LITTLE ABOVE NORMAL ACROSS  
THE MOUNTAINS AND NEAR NORMAL ELSEWHERE.  
 
 
   
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/  
 
AS OF 1243 AM EDT FRIDAY: WE BEGIN THE PERIOD ON SATURDAY, WITH  
MODEST HEIGHT FALLS OVER THE CAROLINAS, AS UPPER RIDGING PREVIOUSLY  
CENTERED OVER THE EASTERN SEABOARD BEGINS RETREATING AHEAD OF A  
NEGATIVELY-TILTED Z500 TROUGH. FOR MOST/ALL OF SATURDAY, CONDITIONS  
LOOK QUIET; MOISTURE SHOULD STEADILY INCREASE AS A PREFRONTAL WAA  
REGIME DEVELOPS, PERMITTING PROFILES TO MOISTEN FROM THE BOTTOM  
UP...BUT THIS WILL DO LITTLE OTHER THAN TO INCREASE CLOUD COVER  
AND RAISE DEWPOINTS ON SATURDAY AND SATURDAY NIGHT. AS A RESULT,  
SATURDAY'S HIGHS LOOK TO LAND IN THE UPPER 70S, MAYBE EVEN THE LOW  
80S ACROSS THE SC UPSTATE AND THE I-77 CORRIDOR. LOWS SATURDAY  
NIGHT WILL BARELY FALL BELOW 60...MAYBE NOT EVEN, IF YOU'RE NEAR  
A LARGE BODY OF WATER.  
 
THE REAL ACTION - WELL, MAYBE...DON'T GET TOO EXCITED - WILL  
MATERIALIZE ON SUNDAY. AS THE TROUGH ENTERS THE CAROLINAS, IT'LL  
DRIVE AN UPPER SPEED MAX ESSENTIALLY RIGHT ACROSS GSP'S FORECAST  
AREA, WHILE AT THE LOW-LEVELS A PREFRONTAL LLJ IS DEPICTED IN MOST  
OPERATIONAL GUIDANCE. UNFORTUNATELY FOR OUR CONVECTIVE PROSPECTS,  
THAT SAME OPERATIONAL GUIDANCE IS...NOT KEEN ON GIVING US MUCH  
INSTABILITY TO WORK WITH, DEPICTING SOME 200 J/KG OR LESS SBCAPE  
DURING THE AFTERNOON SUNDAY. THE LIMITING FACTOR APPEARS TO BE  
LAPSE RATES, WHICH DON'T IMPROVE MUCH WITH THE TROUGH AND THUS  
DON'T PRODUCE AN ESPECIALLY DEEP UNSTABLE LAYER; THERE ARE INDEED  
SOME MEMBERS OF THE LATEST-AVAIBLE LREF CYCLE THAT PRODUCE AS MUCH  
AS 450 J/KG SBCAPE...BUT THESE APPEAR TO BE HIGH-END OUTLIERS, WITH  
EVEN THE 75TH PERCENTILE OF ENSEMBLE GUIDANCE DEPICTING <300 J/KG.  
THAT'S ALL TO SAY THAT SEVERE RISK LOOKS LIMITED, THOUGH NONZERO.  
IN 24 HOURS, WE'LL HAVE AN HREF RUN THAT EXTENDS OUT FAR ENOUGH  
IN TIME TO HAVE A BETTER (READ: HIGH-RES) LOOK AT WHAT TO EXPECT.  
IN THE MEANTIME...EXPECT SOME RAIN, MAYBE SOME THUNDER SUNDAY  
AFTERNOON, AND DEFINITELY A COOLING TREND LATE SUNDAY INTO SUNDAY  
NIGHT AS THE ACTUAL COLD FRONT PUSHES THROUGH AND WE GET AN AIR MASS  
CHANGE. HIGHS ON SUNDAY ARE A LITTLE TOUGH TO PIN DOWN SINCE IT'S  
NOT TOTALLY CLEAR WHERE THE FRONT WILL BE DURING PEAK HEATING...BUT  
LOWS SUNDAY NIGHT SHOULD EASILY DROP INTO THE 40S EVERYWHERE,  
WITH SOME OF THE HIGHER ELEVATIONS EVEN SEEING LOWS IN THE 30S.  
 
 
   
LONG TERM /MONDAY THROUGH THURSDAY/  
 
AS OF 1254 AM EDT FRIDAY: THE UPPER PATTERN WILL REMAIN PROGRESSIVE  
THROUGH THE LONG TERM PERIOD NEXT WEEK...BUT THIS WON'T REALLY  
MEAN MUCH IN TERMS OF GETTING ANY MUCH-NEEDED RAIN. ON MONDAY,  
A BROAD ~1023MB SURFACE HIGH WILL SETTLE INTO THE SOUTHEAST  
BENEATH LOW-AMPLITUDE UPPER RIDGING. DURING THIS TIME, AN  
UPPER LOW WILL BE GAINING SOME TRACTION OVER THE NORTHERN GREAT  
PLAINS, AND THIS FEATURE WILL DIP INTO THE OHIO VALLEY BY LATE  
TUESDAY OR EARLY WEDNESDAY (ENSEMBLES DON'T QUITE HAVE THEIR  
HEADS AROUND THIS ONE YET, SO TIMING REMAINS A QUESTION MARK).  
AN ATTENDANT COLD FRONT WILL SLIDE THROUGH THE WESTERN CAROLINAS  
BY EARLY WEDNESDAY MORNING, BUT IF OUR RAIN/THUNDER PROSPECTS  
DIDN'T LOOK GOOD WITH THE WEEKEND FRONT, THEY REALLY DON'T LOOK  
GOOD WITH THIS LATE-PERIOD SYSTEM...WITH LONG-RANGE ENSEMBLES IN  
VERY POOR AGREEMENT ON WHETHER WE'LL EVEN GET ANY RAIN WITH THIS  
SYSTEM, OR WHETHER WE'LL STAY DRY AND JUST SEE FURTHER COOLING.  
FOR NOW, THE NBM ISN'T DEPICTING ANY MORE THAN A FEW HUNDREDTHS  
OF AN INCH OF RAIN ALONG THE NC-TN BORDER. IT LOOKS MORE LIKELY  
WE'LL JUST SEE AN INFLUX OF COOLER AIR AS THE NEXT SURFACE HIGH  
BUILDS IN...WHICH SHOULD KEEP HIGHS IN THE 60S OR LOW 70S AND LOWS  
IN THE 40S THROUGH THE END OF D7.  
 
 
   
AVIATION /12Z FRIDAY THROUGH TUESDAY/  
 
AT KCLT AND ELSEWHERE: VFR STRATOCU MAY BRIEFLY GO BKN AT THE SC  
SITES THIS MORNING BEFORE DISSIPATING BY AFTERNOON. FEW OR SCT  
ELSEWHERE. MOUNTAIN VALLEY FOG SHOULD STAY AWAY FROM KAVL THIS  
MORNING BUT A BRIEF RESTRICTION CAN'T BE RULED OUT. EXPECT CIRRUS TO  
SPREAD IN THROUGH THE DAY THEN MOVE EAST OVERNIGHT. THIS WILL KEEP  
THE POTENTIAL FOR MOUNTAIN VALLEY FOG IN PLAY. AGAIN, GIVEN RECENT  
TRENDS, WILL KEEP OUT OF KAVL FOR NOW. LIGHT N TO NE WIND BECOMES S  
TO SW FOR THE AFTERNOON, THEN LIGHT AND VARIABLE OVERNIGHT.  
 
OUTLOOK: VFR CONDITIONS CONTINUE SATURDAY, EXCEPT FOR THE POTENTIAL  
FOR MOUNTAIN VALLEY FOG AND/OR LOW STRATUS IN THE MORNING. A COLD  
FRONT MAY BRING SHOWERS AND ASSOCIATED RESTRICTIONS SUNDAY ALONG  
WITH BREEZY CONDITIONS. DRY CONDITIONS RETURN ON MONDAY. A DRY COLD  
FRONT MAY BRING BREEZY CONDITIONS AGAIN ON TUESDAY.  
 
 
   
GSP WATCHES/WARNINGS/ADVISORIES  
 
GA...NONE.  
NC...NONE.  
SC...NONE.  
 
 
 
 
 
SYNOPSIS...MPR  
NEAR TERM...RWH  
SHORT TERM...MPR  
LONG TERM...MPR  
AVIATION...RWH  
CLICK HERE TO GO TO PREVIOUS BULLETINS.
The Nexlab SC Page
The Nexlab NC Page
The Nexlab GA Page
Main Text Page