762  
FXUS62 KGSP 190549  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
149 AM EDT TUE JUN 19 2018  
   
SYNOPSIS
 
 
HOT HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH THE MIDDLE OF  
THE WEEK. SCATTERED AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED  
EACH DAY, FOCUSING OVER THE MOUNTAINS. MOISTURE WILL INCREASE TOWARD  
THE END OF THE WEEK AS A WEAK FRONTAL BOUNDARY SAGS SOUTH INTO THE  
AREA.  
 

 
   
NEAR TERM /THROUGH TODAY/
 
 
AS OF 135 AM TUESDAY: A COUPLE OF SMALL, VERY LIGHT SHOWERS HAVE  
DEVELOPED NEAR THE TN/NC BORDER IN RESPONSE TO LIGHT NW UPSLOPE FLOW  
OVER THE PAST HOUR. NOT SURE THIS IS WORTH A POP MENTION IN THE  
FORECAST ATTM, BUT WILL CONTINUE TO MONITOR.  
 
OTHERWISE, OVER THE NEXT 24 HOURS...VERY LITTLE CHANGE IS EXPECTED.  
THE UPPER ANTICYCLONE CENTER WILL DRIFT A BIT TO THE SOUTH AND WE  
SHOULD SEE THE START OF THE BREAKDOWN OF THE RIDGE, BUT WITH NO REAL  
AIR MASS CHANGE THE WEATHER SHOULD BE PERSISTENT. VALLEY FOG/LOW  
STRATUS HAS BEEN SLOWER TO DEVELOP ACROSS THE NC MOUNTAINS SO FAR  
THIS MORNING, AND IT MAY CONTINUE TO STRUGGLE TO FORM AND EXPAND  
OWING TO AREAS OF UPSLOPE STRATOCU AND SLIGHTLY DRIER NEAR-SURFACE  
AIR. THUS, IT DOESN'T APPEAR IT WILL BE AS WIDESPREAD AS ON MONDAY  
MORNING.  
 
FOR THIS AFTERNOON, ONCE AGAIN THERE APPEARS TO BE NO MEANINGFUL  
MID/UPPER SUPPORT. FCST SOUNDINGS REMAIN UNCAPPED, BUT LAPSE RATES  
SHOULD REMAIN RELATIVELY POOR AND THE CAPE PROFILE IS TALL AND  
SKINNY. AS WE START TO FEEL THE WEAKENING RIDGE, THE FLOW SHOULD  
START TO INCREASE FROM THE WEST LATER IN THE DAY, SO THERE IS A  
BETTER SHOT FOR STORMS TO DEVELOP AN EASTERLY DRIFT, WHICH JUSTIFIES  
KEEPING A SLIGHT CHANCE OF PRECIP ACROSS THE AREA EAST OF THE BLUE  
RIDGE. HIGHS WILL BE WELL INTO THE 90S AGAIN, BUT THINK DEWPT STANDS  
TO MIX OUT JUST ENOUGH ONCE AGAIN TO KEEP HEAT INDEX FROM GETTING  
ABOVE ABOUT 102F, SO NO HEAT ADVY IS ANTICIPATED.  
 

 
   
SHORT TERM /TONIGHT THROUGH THURSDAY/
 
 
AS OF 145 PM MONDAY: NO SIGFNT CHANGES WERE MADE TO THE SHORT RANGE  
FCST. THE MODELS CONTINUE TO SHOW GOOD CONTINUITY WITH THE ULVL  
HIGH BREAKING DOWN AND SHIFTING SOUTH OVER THE PERIOD. THE LOWERING H5  
HEIGHTS WILL BRING A LLVL BNDRY CLOSER TO THE FA BY THU WHILE FLOW  
THRU THE COLUMN INCREASES INTO THE 15-20 KT RANGE. THIS WILL STILL  
BE A VERY WARM PATTERN AND MAXES WILL TOP OUT IN THE MID TO UPPER  
90S OVER THE NON/MTNS. SOUNDINGS SHOW SFC TD/S WILL MIX-OUT A BIT  
EACH AFTERNOON SIMILAR THE PAST FEW DAYS...OR GENERALLY LOWER BY A  
FEW DEGREES. THIS RELATIVE DRYNESS WILL BE ENUF TO OFFSET A HEAT ADV  
CONCERN...HOWEVER OVER THE SRN UPSTATE AND THE NC PIEDMONT THE HEAT  
INDEX WILL COME CLOSE TO CRITERIA OR BE MET IN ISOL LOCALES. WILL  
THUS KEEP THE HIGH HEAT MENTION IN THE HWO. CONVECTION WILL REMAIN  
DIURNALLY DRIVEN WITH NO SIGFNT TRIGGERS AND WEAK MLVL LAPSE RATES.  
EXPECT MTN-TOP CONVG TO BEGIN THE PROCESS WITH MORE SCT TSTM  
DEVELOPMENT OUTSIDE THE MTNS EACH AFTERNOON DUE TO THE INCREASING  
FLOW THRU THE COLUMN.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
 
 
AS OF 220 PM EDT MONDAY: THE EXTENDED FCST PICKS UP AT 00Z ON FRIDAY  
WITH BROAD UPPER TROFING MOVING OFF THE NEW ENGLAND COAST AND WEAK  
UPPER RIDGING OVER THE SOUTHEAST. TO THE WEST, A CLOSED UPPER LOW IS  
MOVING EAST OVER THE CENTRAL PLAINS. AS WE MOVE INTO THE WEEKEND,  
THE MODEL GUIDANCE HAS THE UPPER LOW OPEN UP AND LIFT NORTHWARD AND  
TOWARDS THE GREAT LAKES AS UPPER RIDGING BUILDS TO OUR EAST OFFSHORE.  
BY EARLY SUNDAY, AS THE UPPER LOW LIFTS NORTHWARD, IT DEAMPLIFIES  
AND GETS ABSORBED INTO THE MEAN NORTHERLY FLOW. FOR THE REST OF THE  
PERIOD, WE WILL REMAIN UNDER RELATIVELY FLAT UPPER RIDGING AS  
ANOTHER UPPER TROF BEGINS TO DIG DOWN OVER EASTERN CANADA AND NEW  
ENGLAND. AT THE SFC, A RATHER COMPLEX PATTERN WILL BE IN PLACE TO  
BEGIN THE PERIOD. HIGH PRESSURE TO OUR NORTH WILL BE SITUATED  
BETWEEN LOW PRESSURE WELL TO OUR NE AND NW. THRU THE DAY ON FRIDAY,  
THE EASTERN LOW WILL MOVE WELL OFFSHORE WHILE THE LOW TO OUR WEST  
DEEPENS AND TRACKS NE TOWARDS THE GREAT LAKES. AT THE SAME TIME, THE  
HIGH BEGINS TO MOVE OFFSHORE AND WE LOSE ITS INFLUENCE ON THE SFC  
PATTERN. ON SAT, THE LOW LIFTS FARTHER NE AND BRINGS A COLD FRONT TO  
OUR DOORSTEP. THE GUIDANCE HAS THE FRONT MOVING THRU THE FCST AREA  
BY EARLY SUNDAY WITH SLY FLOW RE-ESTABLISHING ITSELF ACROSS THE  
REGION THE FRONT'S WAKE. AS FOR THE SENSIBLE FCST, BOTH FRIDAY AND  
SAT WILL HAVE THE BEST CHANCES FOR WIDESPREAD CONVECTION WITH AMPLE  
INSTABILITY AND DEEP MOISTURE OVER THE AREA. POPS DECREASE TO AROUND  
CLIMATOLOGY FOR SUNDAY AND MONDAY AND WE RETURN TO A MORE TYPICAL  
SUMMER-TIME PATTERN. AS FOR TEMPS, FRIDAY AND SATURDAY WILL SEE  
VALUES NEAR NORMAL IF NOT A FEW DEGREES ABOVE, AND SUNDAY AND MONDAY  
WILL SEE VALUES A FEW DEGREES WARMER THAN FRI AND SAT.  
 

 
   
AVIATION /06Z TUESDAY THROUGH SATURDAY/
 
 
AT KCLT AND ELSEWHERE: VFR CONDITIONS ARE EXPECTED THROUGH THE  
PERIOD. WINDS AND THE POTENTIAL FOR AFTERNOON/EVENING CONVECTION ARE  
THEREFORE THE PRIMARY CONCERN. MOST SITES WILL SEE WINDS BECOME  
LIGHT NW BY MID/LATE MORNING. FOOTHILLS SITES ARE EXPECTED TO SEE A  
RETURN OF LIGHT SW WINDS DURING THE AFTERNOON. THIS MAY ALSO OCCUR  
AT KCLT, BUT CONFIDENCE IS LOWER, AND WINDS ARE THEREFORE MAINTAINED  
FROM THE NW THERE. AS FAR AS CONVECTION, CONDITIONS WILL BE SLIGHTLY  
MORE FAVORABLE THIS AFTERNOON, WITH THE BEST CHANCES ONCE AGAIN  
BEING OVER THE HIGH TERRAIN. A PROB30 FOR TSRA IS CARRIED AT KAVL  
FROM 18-22Z. WHILE THERE IS A SLIGHT CHANCE FOR CONVECTION TO IMPACT  
THE OTHER TERMINALS, CONFIDENCE IS TOO LOW TO INCLUDE A TAF MENTION  
ATTM.  
 
OUTLOOK: TYPICAL SUMMERTIME PATTERN WILL CONTINUE THROUGH AT LEAST  
MID-WEEK, WITH DIURNALLY-DRIVEN SHOWERS AND THUNDERSTORMS FAVORING  
THE HIGH TERRAIN, AND SOME MORNING FOG POSSIBLE IN THE MOUNTAIN  
VALLEYS AND OVER LAKES EACH DAY. CHANCES FOR CONVECTION LOOK GREATER  
LATE IN THE WEEK AS UPPER RIDGE BEGINS TO BREAK DOWN.  
 
CONFIDENCE TABLE...  
 
05-11Z 11-17Z 17-23Z 23-00Z  
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
 
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING  
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY  
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS  
ARE AVAILABLE AT THE FOLLOWING LINK:  
 
WWW.WEATHER.GOV/GSP/AVIATION  
 

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

 
 

 
SYNOPSIS...JPT  
NEAR TERM...JDL/PM  
SHORT TERM...SBK  
LONG TERM...JPT  
AVIATION...JDL  
 
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