100  
FXUS62 KGSP 190658  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
258 AM EDT SAT APR 19 2014  
   
SYNOPSIS
 
 
A MOIST LOW PRESSURE SYSTEM WILL MOVE SLOWLY ACROSS SOUTHERN GEORGIA  
TODAY...AND CONTINUE TRACKING EAST OFF THE SOUTH CAROLINA COAST  
TONIGHT THROUGH SUNDAY. HIGH PRESSURE WILL BRIEFLY BUILD IN  
MONDAY...BEFORE A COLD FRONT PUSHES ACROSS THE REGION ON TUESDAY. A  
BROAD AND DRY AREA OF HIGH PRESSURE WILL THEN BUILD IN FROM THE  
NORTH WEDNESDAY AND LINGER THROUGH THE END OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 250 AM EDT...SATELLITE IMAGERY SHOWED AN UPPER LEVEL CLOSED  
LOW MOVING EWD ACROSS SW GA AND THE FL PANHANDLE VERY EARLY THIS  
MORNING. IN ADDITION...WATER VAPOR IMAGERY IS SHOWING DRY SLOTTING  
WRAPPING IN FROM THE SW WHICH WILL CURTAIL POPS AND QPF IN SW  
SECTIONS THROUGH DAYBREAK. THE SFC LOW UNDER THE CLOSED UPPER SYSTEM  
WILL MOVE EWD ALONG THE GA/FL BORDER TODAY AND THEN OFF THE COAST BY  
THIS EVENING...WITH A CORRESPONDING GRADUAL DECREASE IN PRECIPITABLE  
WATER VALUES IN AREA PROFILES FROM THE EARLY MORNING MAX VALUES.  
ALTHOUGH UPPER LEVEL DIVERGENCE WILL GRADUALLY WEAKEN TODAY...DEEP  
LAYER QG FORCING WILL CROSS THE FORECAST AREA BETWEEN 12Z AND 18Z  
BEFORE DIMINISHING FROM THE W. IN ADDITION...AN AXIS OF STRONG  
FRONTOGENESIS WILL CONTINUE THROUGH THE HEART OF THE FORECAST AREA  
THIS MORNING BEFORE WEAKENING THIS AFTERNOON AND DIMINISHING TONIGHT  
AS THE LOW PRESSURE SYSTEM MOVES AWAY OFFSHORE. THIS FRONTOGENESIS  
MAX MAY PIVOT ACROSS PIEDMONT SECTIONS TO PRODUCE THE HEAVIEST  
RAINFALL GOING FORWARD ACROSS THE CHARLOTTE METRO AREA. SERIOUS  
CONSIDERATION HAS BEEN GIVEN TO A FLOOD WATCH ACROSS THE CLT METRO  
AREA...BUT GIVEN THE WEAK RAINFALL RATES THUS FAR...AND THE FFG AND  
HEADWATER GUIDANCE VALUES...IT APPEARS THAT ANY HYDRO PROBLEMS  
SHOULD BE FAIRLY ISOLATED. WILL CONTINUE THE HWO MENTION FOR HEAVY  
RAINFALL...BUT ADDRESS ANY HYDRO PROBLEMS AS THEY ARISE WITH SHORTER  
FUSE PRODUCTS.  
 
IN ADDITION TO THE RAINFALL...THE TIGHTENING PRES GRADIENT WILL  
CAUSE NE WINDS TO PICK UP...WITH GUSTS WELL INTO THE 20S AND  
POSSIBLY ABOVE 30 MPH AT TIMES THIS AFTN ACROSS THE PIEDMONT. SFC  
CAD REMAINING IN PLACE THROUGH TONIGHT WILL KEEP THE DIURNAL TEMP  
RANGE FAIRLY SMALL. PRECIPITATION SHOULD GRADUALLY END FROM THE WEST  
TONIGHT AS THE MOISTURE AND FORCING DIMINISH.  
 

 
   
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
 
 
AS OF 230 AM SATURDAY...THE STACKED LOW PRES SYSTEM WILL CONTINUE TO  
SLOWLY DRIFT EAST AWAY FROM THE CAROLINA COASTS ON SUNDAY...WITH  
WRAP-AROUND CLOUD COVER AND DECENT NELY LLVL FLOW LINGERING ATOP THE  
CWFA. IT DOES LOOK LIKE POPS SHUD PRETTY MUCH BE OVER ACRS THE AREA  
BY DAYBREAK SUNDAY...BUT A SLGT CHC DOES LINGER IN THE SE ZONES THRU  
MIDDAY. WITH THE COOL NE FLOW AND LINGERING CLOUDS...I UNDERCUT MOS  
TEMPS...ESP IN THE EAST.  
 
SUNDAY NIGHT THRU MONDAY...SHORTWAVE RIDGING RIPPLES ACRS THE AREA  
BEHIND THE DEPARTING LOW. TEMPS REBOUND TO NEAR NORMAL READINGS  
UNDER MOSTLY CLEAR SKIES.  
 
MONDAY NIGHT...THE NEXT SHORTWAVE TROF APPROACHES FROM THE WEST.  
HEIGHT FALLS ALOFT AND LLVL MOISTURE ARRIVING WITHIN INCREASING WLY  
FLOW MAY SUPPORT A FEW SHWRS ALONG THE NC/TN BORDER OVERNIGHT. BUT  
OTHERWISE...JUST AN INCREASE IN CLOUDS AND TEMPS A COUPLE CATEGORIES  
ABOVE NORMAL.  
 

 
   
LONG TERM /TUESDAY THROUGH FRIDAY/
 
 
AS OF 245 AM SATURDAY...MODELS STILL IN GOOD AGREEMENT ON TIMING A  
COLD FROPA ACRS THE CWFA ON TUESDAY. THE FRONT WILL BE RELATIVELY  
WEAKLY FORCED. BUT THERE SHUD BE ENUF Q-VECTOR CONVERGENCE COUPLED  
WITH LLVL FRONTAL CONVERGENCE AND MOISTURE TO SUPPORT AT LEAST  
SCATTERED SHWRS WITH THE FRONT. THE TIMING LOOKS GOOD FOR ABOUT  
MAXIMUM DAYTIME HEATING INSTBY...WITH THE GFS MOST BULLISH WITH UP  
TO 1000 J/KG OF SBCAPE BY 18Z TUESDAY. HOWEVER...I THINK THE  
DOWNSLOPE W/NW LLVL FLOW WILL LIMIT COVERAGE AND OVERALL INSTBY. THE  
GFS HODOGRAPHS ALSO DON/T SHOW MUCH SHEAR FOR ORGANIZED  
CONVECTION...WITH UNIDIRECTIONAL W/NW FLOW ONLY INCREASING TO ABOUT  
30 KTS IN THE MID LVLS. TEMPS WILL BE ABOVE NORMAL...UPR 70S TO LWR  
80S EAST OF THE MTNS...ASSUMING FRONT PUSHES THRU LATE AFTN/EVE.  
 
TUESDAY NIGHT THRU END OF THE WEEK...UPR FLOW CONTINUES TO BE QUITE  
PROGRESSIVE...WITH ANOTHER UPR RIDGE BUILDING IN FOR WEDNESDAY AND  
THURSDAY...FOLLOWED BY ANOTHER LATITUDINAL TROF APPROACHING THE AREA  
FRIDAY. TEMPS REMAIN NEAR OR SLIGHTLY ABOVE NORMAL...WITH THE SFC  
HIGH PRES CENTER TRANSLATING EAST ACRS THE GREAT LAKES. A COLD FRONT  
WILL PUSH INTO THE OHIO VALLEY FRIDAY...WITH SLGT CHC TO LOW-END CHC  
POPS CREEPING BACK IN BY FRIDAY EVENING.  
 

 
   
AVIATION /07Z SATURDAY THROUGH WEDNESDAY/
 
 
AT KCLT...IFR TO MVFR LEVEL CLOUDS HAVE FILLED IN AROUND THE KCLT  
AIRFIELD...BUT GUIDANCE INSISTS ON KCLT REMAINING AN ISLAND OF  
MAINLY MVFR TO VFR CIGS. STILL THINK THAT MOISTURE AND RAINFALL WILL  
EVENTUALLY OVERCOME THE BOUNDARY LAYER TO PRODUCE AT LEAST TEMPO IFR  
CONDITIONS AFTER 08Z. ANTICIPATE MAINLY MVFR CIGS THROUGH THE DAY  
WITH PERIODS OF MODERATE RAINFALL AS THE FRONTOGENESIS MAX PIVOTS  
OVERHEAD. ADDITIONAL TEMPO IFR CIGS WILL LIKELY BE NEEDED IN LATER  
ISSUANCES. THE TIGHTENING PRES GRADIENT SHOULD EASILY PRODUCE GUSTS  
INTO THE 20S THROUGH MOST OF THE TAF PERIOD.  
 
AT KAVL AND KHKY...THE WESTERN NC TAF SITES WILL BE THE FARTHEST  
FROM THE DEEPER MOISTURE WITH THE SE LOW...AND THE LEAST LIKELY TO  
EXPERIENCE ANY EXTENDED PERIODS OF IFR CIGS. IFR CIGS ARE  
POSSIBLE...BUT FOLLOWING A MOS CONSENSUS OF MAINLY MVFR TO LOWERING  
VFR SEEMS REASONABLE. BRIEF N TO NE WIND GUSTS ARE LIKELY AS  
WELL...BUT WITH LESS MAGNITUDE THAN TAF LOCATIONS FARTHER SE.  
 
AT THE UPSTATE TAF SITES...IFR CIGS SHOULD CERTAINLY MAKE A RUN AT  
THE AIRFIELDS THROUGHOUT THE MORNING HOURS IN LIGHT TO MODERATE  
RAINFALL. THE MOST PRUDENT COURSE WILL BE TO TEMPO IFR CIGS IN AFTER  
08Z...SOONER AT KGSP...AND THEN FEATURE MAINLY MVFR CIGS THROUGH THE  
COURSE OF THE DAY. NE FLOW WILL STEADILY INCREASE AS THE PRES  
GRADIENT TIGHTENS...AND GUSTS TO BETTER THAN 25 KT WILL BE LIKELY  
TODAY THROUGH THIS EVENING. RAIN SHOULD TAPER OFF FROM THE WEST LATE  
IN THE PERIOD.  
 
OUTLOOK...CEILING RESTRICTIONS MAY WELL LINGER INTO SUNDAY MORNING  
BEFORE MOISTURE PULLS AWAY WITH THE SLOWLY DEPARTING OFFSHORE LOW  
PRESSURE SYSTEM. DRY HIGH PRES WILL THEN DEVELOP THROUGH  
MONDAY...WITH A FAIRLY WET FRONTAL SYSTEM EXPECTED ON TUE.  
 
CONFIDENCE TABLE...  
 
07-13Z 13-19Z 19-01Z 01-07Z  
KCLT HIGH 95% HIGH 98% HIGH 82% HIGH 85%  
KGSP HIGH 83% HIGH 96% HIGH 90% HIGH 80%  
KAVL HIGH 95% HIGH 86% MED 69% HIGH 84%  
KHKY HIGH 96% MED 78% MED 66% HIGH 97%  
KGMU MED 79% HIGH 90% HIGH 81% HIGH 81%  
KAND HIGH 86% HIGH 92% HIGH 95% HIGH 87%  
 
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: (MUST BE LOWER CASE)  
 
WWW.WEATHER.GOV/GSP/AVIATION_TABLES  
 

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

 
 

 
SYNOPSIS...ARK  
NEAR TERM...HG  
SHORT TERM...ARK  
LONG TERM...ARK  
AVIATION...HG  
 
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