858  
FXUS62 KGSP 150200  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
1000 PM EDT SUN SEP 14 2014  
   
SYNOPSIS
 
 
COOL BUT UNSETTLED WEATHER WILL CONTINUE THROUGH MONDAY NIGHT...AS A  
STATIONARY FRONT WILL REMAIN JUST TO OUR SOUTH BEFORE AN UPPER  
DISTURBANCE PASSES THROUGH. A COLD FRONT WILL THEN CROSS THE AREA IN  
ITS WAKE...WHICH AGAIN STALLS TO OUR SOUTH. THIS WILL KEEP  
TEMPERATURES A FEW DEGREES BELOW NORMAL INTO NEXT WEEKEND.  
 

 
   
NEAR TERM /THROUGH MONDAY/
 
 
AT 1000 PM EDT SUNDAY...A BROAD LOW AMPLITUDE UPPER TROUGH EXTENDED  
ACROSS THE NORTH CENTRAL PART OF THE NATION...WHILE A FLAT UPPER  
RIDGE EXTENDED FROM TX TO THE GA COAST. A WEAK IMPULSE MOVING  
THROUGH THE UPPER TROUGH WILL PASS TO THE NORTH OF NC OVERNIGHT.  
SURFACE ANALYSIS PLACED A STATIONARY FROM THE GA COAST TO THE  
NORTHERN GULF OF MEXICO. CONVECTIVE ACTIVITY WAS LOCATED ALONG THIS  
BOUNDARY.  
 
COOLER AIR NORTH OF THE FRONT EXTENDED ACROSS THE WESTERN CAROLINA  
AND NE GA. ISOLATED SHOWERS MOVING NORTHEAST ALONG INTERSTATE 85  
HAVE LARGELY ABATED THIS EVENING. WITH SOME WEAK ISENTROPIC UPGLIDE  
REMAIN OVER OUR AREA...VERY SMALL POPS WILL REMAIN IN THE FORECAST  
OVERNIGHT. MODEL GUIDANCE SUPPORTS FOG LATE TONIGHT...BUT ONLY HAD  
SIGNIFICANT REDUCTIONS IN VISIBILITY IN THE MOUNTAINS. WITH LOW  
CONFIDENCE IN DENSE FOG...NO ADVISORY WILL BE ISSUED AT THIS TIME.  
MINIMUM TEMPERATURES WILL RUN SLIGHTLY ABOVE NORMAL DUE TO CLOUDS  
AND LINGERING LOW LEVEL MOISTURE.  
 
MONDAY...H85 WINDS WILL BECOME WEST DURING THE DAYLIGHT  
HOURS...RESULTING IN DRYING ACROSS THE NC MTNS AND PIEDMONT.  
HOWEVER...MOISTURE SHOULD REMAIN PLENTIFUL ACROSS THE SC AND GA  
ZONES. THE COMBINATION OF DEEP MOISTURE AND WEAK INSTABILITY SHOULD  
IN POPS RANGING FROM U40S ACROSS THE UPPER SAVANNAH RIVER VALLEY TO  
SCHC ACROSS THE N I-77 CORRIDOR. THINNER CLOUD COVER AND WEAK  
DOWNSLOPE WINDS SHOULD ALLOW TEMPERATURES TO REBOUND TO NEAR 80  
ACROSS THE MTN VALLEYS...FOOTHILLS...AND PIEDMONT.  
 

 
   
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
 
 
AS OF 215 PM SUNDAY...THINK WE ARE ENTERING A PERIOD OF DIMINISHED  
CONFIDENCE IN THE FORECAST FOR THE EARLY TO MIDDLE PART OF THE WEEK.  
ASSUMING A REMNANT COOL POOL HAS BEEN ELIMINATED BY MONDAY EVENING  
AND SOME CONVECTION HAS DEVELOPED...IT WILL PROBABLY LINGER WELL  
INTO THE EVENING IN ADVANCE OF A SHORT WAVE. THIS WAVE WILL DRIVE A  
REINFORCING SURFACE BOUNDARY ACROSS THE REGION LATE MONDAY NIGHT OR  
EARLY TUESDAY MORNING...BUT ITS PASSAGE IS UNREMARKABLE IN THE MODEL  
GUIDANCE. THE PRECIP CHANCE HAS A DOWNWARD TREND INTO TUESDAY  
MORNING ONCE THAT BOUNDARY HAS MOVED PAST. IT IS FROM THAT POINT  
ONWARD THAT CONFIDENCE IS RELATIVELY LOW. THE GFS ONCE AGAIN BRINGS  
THE LOW LEVEL FLOW AROUND TO EASTERLY AND UPSLOPE BEHIND THE  
BOUNDARY ON TUESDAY AFTERNOON...AND DEVELOPS SOME LIGHT PRECIP  
MAINLY FROM THE BLUE RIDGE EAST. THE NAM RETAINS MUCH MORE LOW LEVEL  
MOISTURE AND DEVELOPS CONVECTION ON THE BLUE RIDGE AND MOVES IT  
EAST. THE FORECAST IS A COMPROMISE BETWEEN THE MOSGUIDE AND THE SREF  
AND WILL FEATURE A LOW END CHANCE MORE IN LINE WITH THE GFS...  
FIGURING THAT EITHER WAY THERE WILL BE SOME PRECIP OUT THERE. TEMPS  
REBOUND ANOTHER CATEGORY WARMER...BUT COULD BE TOO WARM IF TOO MUCH  
UPSLOPE CLOUDINESS DEVELOPS EARLY IN THE DAY.  
 
THE NEXT IN A SERIES OF WEAK HIGH PRESSURE CENTERS BRIDGES THE MTNS  
TUESDAY NIGHT AND CONTRIBUTES TO THE FORMATION OF ANOTHER WEDGE-LET  
BY WEDNESDAY MORNING. THE EXTENT TO WHICH YOU MIGHT CALL THIS A COLD  
AIR DAMMING EVENT WILL BE DEBATABLE...AS THERE SHOULD BE NO OBVIOUS  
PARENT HIGH TO THE NORTH. HOWEVER...WE SHOULD HAVE A COOL  
NORTHEASTERLY FLOW AT LOW LEVELS E OF THE MTNS WHICH COULD RESULT IN  
SOME LIGHT PRECIP MAINLY NEAR THE BLUE RIDGE. HAVE NUDGED THE FCST  
IN THE DIRECTION OF THE SREF TO DEPICT THIS SCENARIO. TEMPS WILL  
ALSO DROP OFF TWO CATEGORIES OR MORE WITH THE NORTHEAST FLOW.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
 
 
AS OF 215 PM SUNDAY...THIS PERIOD BEGINS WED EVENING WITH AN UPPER  
TROUGH OVER THE EAST AND A RIDGE OVER THE WESTERN STATES. ANOTHER  
COLD AIR DAMMING EVENT WILL BE OCCURRING AS A 1028 MB SURFACE HIGH  
WILL BE OVER THE GREAT LAKES WED EVENING AND THEN BE OVER NEW  
ENGLAND THURS NIGHT. THIS SYSTEM WILL BRING A COOL AND STABLE AIR  
FLOW FROM CANADA AND SOME FETCH OFF THE ATLANTIC. THIS HIGH WILL  
MOVE SLOWLY EAST CROSSING NOVA SCOTIA SATURDAY MORNING WHILE STILL  
RIDGING DOWN INTO THE CAROLINAS WITH A COOL NE FLOW. THIS FLOW  
SHOULD CERTAINLY BREAK DOWN SUNDAY AND BECOME MORE SOUTHERLY SUNDAY  
NIGHT AHEAD OF THE NEXT COLD FRONT WHICH IF FORECAST TO BE CROSSING  
THE OHIO VALLEY TO START THE WEEK OF SEPTEMBER 22. THE GFS SHOWS  
WEAK INSTABILITY OF AROUND 500 J/KG IN THE PIEDMONT THURS AND FRI PM  
BEING MOSTLY ELBERTON TO GREENWOOD FRI...SO IF THERE IS ANY RAIN AT  
ALL IT WOULD BE SHOWERS OR PATCHY LIGHT RAIN UNDER THE WEDGE. TEMPS  
WILL BE THE COOLEST THURS AND FRI. TEMPS WILL BE A BIT WARMER TO  
AROUND 5 DEGREES BELOW NORMAL OVER THE WEEKEND WITH THE WEDGE  
BREAKING DOWN AND THE RESULTANT OF MORE SUNSHINE.  
 

 
   
AVIATION /02Z MONDAY THROUGH FRIDAY/
 
 
AT KCLT...GUIDANCE DOES NOT FAVOR A VSBY RESTRICTIONS...EVEN THROUGH  
NE WINDS FALL OFF CONSIDERABLY. GUIDANCE DOES FAVOR MVFR CIGS  
OVERNIGHT...WITH A RETURN TO VFR IN THE MORNING. CONVECTIVE CHANCES  
WILL INCREASE ON MONDAY AS COOL HIGH PRESSURE WEAKENS...AND WARRANT  
A MENTION IN THE TAF. LIGHT NE WINDS WILL VEER SW BY MONDAY  
AFTERNOON.  
 
ELSEWHERE...GUIDANCE FAVORS MVFR VSBY IN THE FOOTHILLS...AND LIFR IN  
AT KAVL. WITH CONFIDENCE STILL SOMEWHAT LIMITED...DESPITE LIGHT  
WINDS OVERNIGHT...ONLY IFR WILL BE CARRIED AT KAVL...AND HIGH END  
MVFR AT FOOTHILL SITES. GUIDANCE SUPPORTS MVFR CIGS OVERNIGHT...AND  
LIFR AT KAVL BY DAWN. ALTHOUGH VSBY RETURNS TO VFR MID MORNING...BUT  
CIGS ARE NOT EXPECTED TO RETURN TO VFR UNTIL MIDDAY. LIGHT NE WINDS  
WILL VEER SW BY MONDAY AFTERNOON IN THE FOOTHILLS... WHILE KAVL  
WINDS VEER FORM N TO S. CONVECTIVE CHANCES INCREASE ON  
MONDAY...WARRANTING A MENTION IN THE TAFS BY AFTERNOON.  
 
OUTLOOK...SCT SHOWERS/THUNDERSTORMS WILL CONTINUE INTO MONDAY NIGHT.  
A RETURN TO MAINLY VFR CONDITIONS IS EXPECTED TUE INTO MIDWEEK  
OUTSIDE OF RESTRICTIONS WITH DIURNAL CONVECTION.  
 
CONFIDENCE TABLE...  
 
02-08Z 08-14Z 14-20Z 20-02Z  
KCLT HIGH 81% MED 64% HIGH 92% HIGH 100%  
KGSP HIGH 90% HIGH 97% HIGH 94% HIGH 91%  
KAVL MED 77% HIGH 92% HIGH 83% HIGH 96%  
KHKY MED 74% HIGH 80% HIGH 93% HIGH 98%  
KGMU HIGH 85% HIGH 92% HIGH 95% HIGH 100%  
KAND HIGH 80% HIGH 83% HIGH 90% HIGH 91%  
 
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...DEO  
NEAR TERM...JAT/NED  
SHORT TERM...PM  
LONG TERM...DEO  
AVIATION...JAT  
 
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