432  
FXUS62 KGSP 012336  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
736 PM EDT MON SEP 1 2014  
   
SYNOPSIS
 
 
SOUTHERLY FLOW INDUCED BY A PERSISTENT BERMUDA HIGH WILL CONTINUE TO  
PROMOTE DIURNAL SHOWERS AND THUNDERSTORMS THROUGH MUCH OF THE WEEK.  
A FRONTAL PASSAGE WILL OCCUR ON TUESDAY EVENING INTO WEDNESDAY  
MORNING WITH ANOTHER FRONT PASSING THROUGH OVER THE WEEKEND LEADING  
TO ENHANCED SHOWER AND THUNDERSTORM CHANCES FOR THOSE PERIODS. HIGH  
PRESSURE WILL ONCE AGAIN REGAIN CONTROL BY EARLY NEXT WEEK BEHIND  
THE ABOVE MENTIONED FRONT RESULTING IN COOLER TEMPERATURES  
AND MORE SETTLED WEATHER.  
 

 
   
NEAR TERM /THROUGH TUESDAY/
 
 
AS OF 730 PM EDT...WILL KEEP A SLIVER OF ISOLD POP IN SRN AND SW  
SECTIONS THROUGH THIS EVENING AS CENTRAL GA ACTIVITY SLIDES EASTWARD  
TOWARD THE REGION. HOWEVER...PROFILES ARE STEADILY STABILIZING AND  
THIS ACTIVITY SHOULD NOT PERSIST OVERNIGHT. ANTICIPATE ANOTHER ROUND  
OF MORNING LOW CLOUDS AND FOG IN THE MOUNTAIN VALLEYS GIVEN LITTLE  
AIRMASS CHANGE FROM PREVIOUS MORNINGS WHERE THIS OCCURRED. MIN TEMPS  
HAVE BEEN RAISED A DEGREE OR SO IN MOST AREAS IN LINE WITH  
PERSISTENCE.  
 
MEANWHILE...THE UPPER RIDGE ACROSS THE SE WILL BE FLATTENED FURTHER  
BY THE PASSAGE OF A SHORT WAVE UP THE OH VALLEY LATE TONIGHT AND  
TUE. THE NUMERICAL MODELS ARE A BIT MORE ROBUST WITH CONVECTIVE  
PRECIP COVERAGE ARRIVING FROM THE NW WITH ANOTHER SHORTWAVE DURING  
PEAK HEATING LATE IN THE DAY...ESPECIALLY ACROSS NW NC. IMPROVED  
SURFACE BASED INSTABILITY THROUGHOUT WILL THEN ALLOW SCATTERED  
ACTIVITY TO RUN SOUTHEAST INTO THE PIEDMONT ON THE STRENGTH OF  
OUTFLOWS TUE AFTN AND EVENING. MAXES SHOULD REACHING A BIT HIGHER  
THAN IN PREVIOUS DAYS...BUT WITH HEAT INDEX VALUES STILL REMAINING  
AROUND 100 OR LESS IN THE WARMEST SE SECTIONS.  
 

 
   
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
 
 
AS OF 2 PM MONDAY...SHORT RANGE MODELS INDICATE THAT A  
WEAKENING MID LEVEL SHORT WAVE WILL RIPPLE OVER THE REGION TUESDAY  
NIGHT. THE COMBINATION OF THE PASSAGE OF MID LEVEL DISTURBANCE AND  
LINGERING WEAK INSTABILITY SHOULD SUPPORT ISO TO SCT SHRA/TSRA INTO  
WEDNESDAY MORNING. LOW TEMPERATURES ARE FORECAST TO RANGE FROM THE  
MID 60S WITHIN THE MTN VALLEYS TO THE LOW 70S EAST OF THE MTNS. ON  
WEDNESDAY...MID LEVEL HEIGHTS ARE FORECAST TO SLOW RISE ACROSS THE  
REGION...SOURCED FROM A RIDGE CENTERED OVER THE DEEP SOUTH. MODELS  
INDICATE THAT REMNANT VORTICITY MAY LINGER ACROSS THE WESTERN  
CAROLINAS THROUGH THE DAYLIGHT HOURS WEDNESDAY. FORECAST SOUNDING  
SHOW WEAK TO MODERATE CAPE DEVELOPING BY MID AFTERNOON...WITH LITTLE  
TO NO LLVL SHEAR. THE ENVIRONMENT SHOULD FAVOR SCT TO NUM CONVECTION  
ACROSS THE RIDGES DURING THE AFTERNOON AND EVENING...WITH SCT  
CONVECTION EAST. A BLEND OF FAVORED MOS SUPPORTS HIGHS FROM THE MID  
80S WITHIN THE MTN VALLEYS TO LOW 90S EAST OF I-85.  
 
ON THURSDAY...SFC HIGH PRESSURE WILL BECOME CENTERED ACROSS THE MID  
ATLANTIC STATES...RESULTING IN WEAK SOUTHEAST LLVL FLOW. H5 HEIGHTS  
ACROSS THE FORECAST AREA WILL LIKELY RISE ABOVE 590 DM. FORECAST  
SOUNDINGS INDICATE A WEAK SUBSIDENCE INVERSION DEVELOPING DURING THE  
AFTERNOON AROUND H6. AFTERNOON CAPES WILL LIKELY RANGE FROM FROM  
1500-2000 J/KG ACROSS THE REGION. CIN VALUES MAY ERODE DURING THE  
HEAT OF THE AFTERNOON. THE NAM LIMITS CONVECTION TO THE HIGH TERRAIN  
AS THE GFS APPEARS MUCH WETTER ACROSS THE FOOTHILLS AND PIEDMONT. I  
WILL TAKE A COMPROMISE OF BOTH SOLUTIONS...FORECASTING 40 TO 50 POPS  
ACROSS THE MTNS TO 30 TO 40 POPS ACROSS THE FOOTHILLS AND PIEDMONT.  
I WILL FORECAST HIGH TEMPERATURES 2 TO 3 DEGREES ABOVE NORMAL...BUT  
SLIGHTLY COOLER THAN WED DUE TO GREATER COVERAGE OF CONVECTION.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
 
 
AS OF 230 PM EDT MONDAY...AN UPPER RIDGE WILL WEAKEN OVER THE REGION  
THU NIGHT INTO SAT AS THE CENTER OF H5 HIGH RETROGRADES TOWARD THE  
WESTERN CONUS WHILE A NORTHERN STREAM UPPER TROUGH DIGS INTO THE  
GREAT LAKES REGION. THE TROUGH IS EXPECTED TO PROGRESS EASTWARD TO  
THE MID ATLANTIC STATES THRU SUN AND OFF THE EASTERN SEABOARD BY  
MONDAY.  
 
AT THE SURFACE...A BERMUDA HIGH PRESSURE WILL REMAIN IN PLACE THRU  
FRI NIGHT RESULTING IN PERSISTENT MOIST S/SE FLOW AND SLIGHTLY ABOVE  
NORMAL TEMPS. DESPITE THE UPPER RIDGING...MOIST PROFILE AND MODERATE  
DIURNAL BUOYANCY SHOULD OVERCOME THE WEAKLY CAPPED ALOFT LEADING TO  
LOW END TO SOLID CHANCE POPS FOR DIURNALLY DRIVEN CONVECTION. SAT  
AND SUN...MODELS HAVE COME INTO BETTER AGREEMENT WITH THE TIMING OF  
THE FROPA LATE SAT INTO EARLY SUN. THE MAIN CONCERN DURING THIS  
PERIOD WILL BE HEAVY RAINFALL DUE TO THE COMBINATION OF SLOW PASSAGE  
OF THE FRONT...MOIST PROFILE AND GOOD BUOYANCY. BOTH THE GFS AND  
ECMWF DEPICT HEALTHY QPF RESPONSE OVER THE MTNS SAT AND OVER MUCH OF  
THE CWA ON SUN. THEREFORE...HAVE UPDATED POPS TO INCREASE TO AROUND  
30-50 ON SAT AND 40-60 ON SUN. MONDAY...DRIER AND COOLER CONDITIONS  
EXPECTED AS THE FRONT STAYS SOUTH OF THE AREA AND A WEDGE OF SURFACE  
HIGH BUILDS IN FROM THE NE. TEMPERATURES WILL REMAIN SLIGHTLY ABOVE  
NORMAL THU INTO SUN AND COOLS DOWN BY 5-10 DEGREES BY MON.  
 

 
   
AVIATION /00Z TUESDAY THROUGH SATURDAY/
 
 
AT KCLT...ANY LINGERING LATE DAY SHOWER ACTIVITY CONTINUES TO  
DIMINISH AROUND ISSUANCE TIME THIS EVENING...AND NO FURTHER  
TRIGGERING IS EXPECTED IN THE PIEDMONT THROUGH TONIGHT. JUST HIGH  
DEBRIS CLOUDS WILL PERSIST BUT THIN THROUGH THE NIGHT WITH THE  
CHANCES OF ANY LOWER RESTRICTIONS TOWARD DAYBREAK QUITE LIMITED IN  
THE LATEST SOUNDINGS AND MOS FORECASTS. A SCATTERED CUMULUS FIELD  
WILL BUILD THROUGH THE DAY WITH HEATING ON TUE AS WINDS INCREASE  
FROM THE SW...BUT REMAIN LESS THAN 10 KT THROUGHOUT. SHORTWAVES  
MOVING INTO WESTERN NC FROM THE NW LATE DAY COULD ALLOW TSRA TO MAKE  
A RUN TOWARD THE PIEDMONT AGAIN...AND PROB30 FOR TSRA AFTER 21Z  
APPEARS WARRANTED.  
 
ELSEWHERE...ANY LATE DAY TSRA STEERING E FROM CENTRAL GA AT ISSUANCE  
TIME SHOULD REMAIN S OF THE SC TAF SITES THROUGH EVENING AS IT  
GRADUALLY DIMINISHES. EXPECT MAINLY THIN DEBRIS CLOUDS  
OVERNIGHT...EXCEPT FOR ANOTHER ROUND OF LOW CLOUDS AND RESTRICTIONS  
AT KAVL AND ACROSS THE MTN VALLEYS. WILL GO AHEAD AND FEATURE LIFR  
CONDITIONS WITH THIS PACKAGE GIVEN THE MOS CONSENSUS AND  
OBSERVATIONS THIS MORNING. BRIEF MVFR FOG WILL BE POSSIBLE AT KHKY  
AS WELL...AND PERHAPS KAND BUT VERY BRIEF THERE. EXPECT CUMULUS TO  
BUILD WITH HEATING AND FLOW TO REMAIN SW...EXCEPT NW AT  
KAVL...THROUGH TUE. PROB30 FOR TSRA APPEARS WARRANTED AT ALL  
LOCATIONS LATE DAY...BUT WITH THE BEST CHANCES FROM KAVL TO KHKY  
AFTER 20Z.  
 
OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH THE REST OF  
THE WEEK...BUT RESTRICTIONS ARE LIKELY EARLY EACH MORNING IN THE  
MOUNTAIN VALLEYS DUE TO LOW CLOUDS AND FOG. DIURNALLY DRIVEN  
SHRA/TSRA ARE EXPECTED EACH AFTERNOON AND EARLY EVENING...WITH THE  
MOST COVERAGE OVER THE MOUNTAINS.  
 
CONFIDENCE TABLE...  
 
23-05Z 05-11Z 11-17Z 17-23Z  
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAVL HIGH 100% MED 69% MED 79% HIGH 100%  
KHKY HIGH 100% HIGH 100% HIGH 91% HIGH 100%  
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAND HIGH 100% HIGH 100% HIGH 91% 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: (MUST BE LOWER CASE)  
 
WWW.WEATHER.GOV/GSP/AVIATION_TABLES  
 

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

 
 

 
SYNOPSIS...JOH  
NEAR TERM...HG  
SHORT TERM...NED  
LONG TERM...JOH  
AVIATION...HG  
 
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