374  
FXUS62 KGSP 181841  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
241 PM EDT THU JUL 18 2019  
   
SYNOPSIS
 
 
SUMMERTIME HEAT AND HUMIDITY WILL CONTINUE INTO THE UPCOMING  
WEEKEND. THERE IS A GOOD CHANCE OF AFTERNOON AND EVENING SHOWERS AND  
THUNDERSTORMS THROUGH THE PERIOD AS WELL. A COLD FRONT WILL PROVIDE  
RELIEF FROM THE HEAT AND HUMIDITY EARLY NEXT WEEK. HOWEVER, CHANCES  
FOR SHOWERS AND STORMS WILL CONTINUE.  
 

 
   
NEAR TERM /THROUGH FRIDAY/
 
 
AS OF 235 PM: MESO-ANALYSIS SHOWS AT LEAST MODERATE CAPE ACROSS THE  
AREA WITH VERY HIGH DCAPE VALUES OUTSIDE OF THE MOUNTAINS. AS STORMS  
DEVELOP OVER THE HIGHER TERRAIN AND MOVE SOUTHEAST ACROSS THE AREA  
THIS AFTERNOON, STRONG TO A FEW SEVERE STORMS ARE LIKELY TO DEVELOP  
WITH WET MICROBURSTS BEING THE MAIN THREAT. VERY GUSTY WINDS COULD  
DEVELOP FROM ANY STORM TODAY. EXCESSIVE RAINFALL THREAT IS LOW AS  
THE STORMS ARE MOVING QUITE WELL, BUT CAN'T RULE OUT AN ISOLATED  
FLOOD THREAT IF CELLS TRAIN OVER THE SAME AREA.  
 
A WEAK UPPER TROUGH/WEAKNESS IN THE SUBTROPICAL RIDGE WILL REMAIN IN  
PLACE ACROSS THE AREA THROUGH FRIDAY. WEAK SHORT WAVE ENERGY WILL  
CROSS THE AREA IN THIS WEAKNESS. UPPER JET DYNAMICS WILL ALSO BE  
FAVORABLE FOR SOME UPPER DIVERGENCE THROUGH FRIDAY AS WELL. AT THE  
SURFACE, A LEE TROUGH ALSO REMAINS IN PLACE THROUGH THE PERIOD. BEST  
OVERALL COVERAGE OF CONVECTION WILL BE THIS AFTERNOON WITH COPIOUS  
LOW LEVEL MOISTURE AND MODERATE OR BETTER INSTABILITY. THE GUIDANCE  
DIFFERS ON THE COVERAGE FRIDAY AFTERNOON. THEY AGREE ON GOOD  
COVERAGE OVER THE MOUNTAINS, BUT DON'T AGREE ELSEWHERE. SOME SHOW  
GOOD COVERAGE OVER NE GA AND THE WESTER UPSTATE DIMINISHING TO THE  
NORTHEAST. OTHERS SHOW ONLY LOW END SCATTERED OR ISOLATED COVERAGE  
OUTSIDE OF THE MOUNTAINS. HAVE GONE WITH A MODEL BLEND WHICH FAVORS  
THE MOUNTAINS, NE GA, AND THE WESTERN UPSTATE, BUT KEEPS AT LEAST  
LOW END SCATTERED OVER THE REST OF THE AREA. STRONG TO SEVERE STORMS  
LOOK TO BE LESS LIKELY FRIDAY AS FORECAST DCAPE IS LOWER, BUT AT  
LEAST MODERATE INSTABILITY DEVELOPS WITH SOME MID LEVEL DRY AIR, SO  
ISOLATED WET MICROBURSTS CAN'T BE RULED OUT. HIGHS SHOULD BE IN THE  
MID 90S ONCE AGAIN WITH HEAT INDEX VALUES 100 OR BETTER ACROSS MUCH  
OF THE AREA.  
 

 
   
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/
 
 
AS OF 1215 PM THURSDAY: THE CWFA IS PROGGED TO LINGER WITHIN THE  
WESTERN PERIPHERY OF BERMUDA HIPRES THIS WEEKEND, MAINTAINING OUR  
VERY WARM AND HUMID AIRMASS. SATURDAY REMAINS FORECAST TO BE THE  
MOST OPPRESSIVE DAY WITH PIEDMONT APPARENT TEMPERATURES IN THE LOWER  
100S BEFORE WE BEGIN TO DIAL BACK THE BORDERINE HEAT ADVISORY  
THRESHOLDS ON SUNDAY. THE COVERAGE OF DIURNALLY ENHANCED DEEP  
CONVECTION IS EXPECTED TO BECOME NUMEROUS ACROSS THE MOUNTAINS EACH  
DAY WHERE TERRAIN EFFECTS AND THE PROXIMITY TO DEVELOPING UPPER  
RIDGE WEAKNESS WILL AID IN COVERAGE. NEARER THE SUPPRESSIVE EFFECTS  
OF THE UPPER RIDGE, ONLY ISOLATED TSTM COVERAGE IS EXPECTED IN THE  
EASTERN CWFA.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
 
 
AS OF 1230 PM THURSDAY: THE PATTERN ACRS THE CONUS WILL CONTINUE TO  
AMPLIFY AS THE WORK WEEK GETS UNDERWAY, FEATURING A DEVELOPING L/W  
TROUGH IN THE EAST. A BAND OF DEEPER MOISTURE AND BROAD FORCING IS  
PROGGED TO PUSH SOUTH INTO THE CWFA AIDING IN THE DEVELOPMENT OF  
NUMEROUS SHOWERS AND STORMS MONDAY INTO TUESDAY. WITH FALLING UPPER  
HEIGHTS AND CONSIDERABLE CLOUDS AND PCPN, MAXIMUM TEMPERATURES WILL  
DIP TO BELOW CLIMO LEVELS BY TUESDAY. FOR THE LATTER HALF OF THE  
PERIOD, ATYPICAL LATE JULY CONDITIONS ARE ON TAP AS UPPER TROUGH  
AXIS SETTLES ATOP THE REGION. EXPECT IMPINGEMENT OF SOME  
CONTINENTAL AIR AND DEEP MOISTURE WILL BE DISPLACED SOUTH AND EAST  
OF THE REGION MAINTAINING BELOW NORMAL TEMPERATURE AND HUMIDITY  
LEVELS.  
 

 
   
AVIATION /19Z THURSDAY THROUGH TUESDAY/
 
 
AT KCLT AND ELSEWHERE: ALL SITES SHOULD REMAIN PREDOMINANTLY VFR  
THROUGH THE PERIOD. CONVECTION ALREADY GOING THIS AFTERNOON ACROSS  
THE WESTERN PORTIONS OF THE FORECAST AREA. HAVE STARTED WITH VCTS  
AND TEMPO FOR THOSE SITES AND START AT 19Z FOR KCLT. CONVECTION  
SHOULD END BY EARLY EVENING BUT SHOWERS MAY LINGER NEAR KCLT AT  
LITTLE LONGER. ANOTHER ROUND OF MTN VALLEY FOG IS LIKELY TONIGHT,  
BUT JUST HOW MUCH CONDITIONS DETERIORATE AT KAVL TOMORROW MORNING  
WILL DEPEND LARGELY UPON HOW MUCH RAIN THE SITE RECEIVES THIS  
AFTERNOON. HAVE GONE WITH MVFR FOR NOW, BUT CONDITIONS COULD GO  
EITHER WAY. ONLY PATCHY FOG ELSEWHERE. CONVECTION SHOULD START EARLY  
AGAIN FRIDAY, BUT WITH LOWER CHANCES OUTSIDE OF THE MOUNTAINS THAN  
TODAY. DID GO WITH PROB30 FOR KCLT THOUGH. SOUTHWEST TO WEST WINDS  
TODAY BECOME N TO NW OVERNIGHT THEN W TO NW FOR FRIDAY.  
 
OUTLOOK: TYPICAL, SCATTERED DIURNAL CONVECTION IS EXPECTED THROUGH  
THE WEEKEND, ESPECIALLY OVER THE MOUNTAINS. PATCHY MOUNTAIN VALLEY  
FOG AND LOW CIGS REMAIN POSSIBLE DURING THE OVERNIGHT AND EARLY  
MORNING HOURS. A TRANSITION TO A MORE ACTIVE PATTERN MAY OCCUR  
BEGINNING MONDAY.  
 
CONFIDENCE TABLE...  
 
18-24Z 00-06Z 06-12Z 12-18Z  
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAVL HIGH 100% HIGH 100% HIGH 91% HIGH 95%  
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...CSH  
NEAR TERM...RWH  
SHORT TERM...CSH  
LONG TERM...CSH  
AVIATION...RWH  
 
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