738  
FXUS62 KGSP 302059  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
459 PM EDT THU JUN 30 2016  
   
SYNOPSIS
 
 
AN UPPER TROUGH WILL PUSH A COLD FRONT THROUGH THE REGION TODAY AND  
TOMORROW. THE FRONT WILL STALL JUST TO THE SOUTH OF THE AREA BY  
SATURDAY, BUT THEN WILL LIFT SLOWLY BACK NORTH LATE IN THE WEEKEND  
INTO THE BEGINNING OF NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH FRIDAY/
 
 
AS OF 445 PM EDT...WATER VAPOR IMAGERY INDICATES A SUBTLE  
IMPULSE SHIFTING ACROSS THE TENNESSEE VALLEY AND UPPER GULF COAST  
STATES. THIS FEATURE WILL PROVIDE A SOURCE OF SLIGHTLY ENHANCED LIFT  
AS IT ENCROACHES ON OUR AREA, WHERE SBCAPE VALUES ARE ANALYZED AT  
1500-2500 J/KG, AND DCAPE 800-1200 J/KG. DAMAGING WINDS AND LARGE  
HAIL ARE THE PRIMARY CONCERNS WITH THE STORMS THAT DEVELOP IN THIS  
ENVIRONMENT, ALTHOUGH TORRENTIAL RAIN AND FREQUENT LIGHTNING WILL  
BE NOTED. MESO MODELS DEPICT EVOLUTION SIMILAR TO THAT YESTERDAY  
EVENING, WHEN OUTFLOWS CONTINUED TO INITIATE NEW CONVECTION UNTIL  
A COUPLE HOURS AFTER SUNSET. SO OUR REVISED POPS WILL REFLECT A  
PEAK AROUND THAT TIME, AND THE FACT THAT THE MODELS ARE DEPICTING  
BEST COVERAGE OVER THE ERN HALF OF THE CWFA.  
 
WE WILL CONTINUE THE ACTIVITY INTO THE NIGHT TIME HOURS, SOMEWHAT  
SIMILAR TO WEDNESDAY NIGHT, BEFORE ACTIVITY WANES WITH PASSAGE OF  
THE UPPER AIR FEATURE AND OVERTURNING OF ATMOSPHERE.  
 
FOG AND STRATUS ARE EXPECTED TO DEVELOP OVERNIGHT WHERE HEAVY RAIN  
FALLS THIS AFTN/EVENING.  
 
FOR FRIDAY WE HAVE GONE WITH WARMER TEMPERATURES, PER GUIDE,  
AND LIMITED OUR THUNDERSTORM CHANCES TO A NARROW WINDOW IN THE  
AFTERNOON, AND ESPECIALLY ALONG THE LESS SIDE TROUGH.  
 

 
   
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/
 
 
AS OF 230 PM EDT THURSDAY: UPPER TROUGH AXIS AND SURFACE COLD FRONT  
WILL BE PUSHING EAST OF THE AREA AS WE START THE SHORT TERM. THE  
FRONTAL BOUNDARY WILL STALL TO OUR SOUTH ON SATURDAY AS THE CANADIAN  
UPPER LOW LIFTS NORTHEAST AND A SHORTWAVE PUSHES OFF THE CENTRAL  
ROCKIES INTO THE CENTRAL PLAINS. THE SURFACE SYSTEM ASSOCIATED WITH  
THE PLAINS SHORTWAVE WILL STRETCH ACROSS THE OHIO/TENNESSEE VALLEYS,  
MERGING WITH THE STALLED SOUTHEAST FRONT, AND PROVIDING FOCUS FOR  
CONVECTION TO PICK BACK UP AGAIN THROUGH THE SHORT TERM AS FLOW  
ALOFT TRANSITIONS TO ZONAL. THE BOUNDARY WILL SLIDE SLOWLY BACK  
NORTH AS THE PLAINS SHORTWAVE PUSHES EAST, WITH MODEST INSTABILITY -  
800-1200 J/KG SBCAPE - RETURNING TO THE AREA SATURDAY. SHOULD SEE A  
DIURNAL TREND THROUGH SATURDAY NIGHT, BUT WITH THE PLANS SHORTWAVE  
MOVING INTO THE MID-MISSISSIPPI VALLEY ON SUNDAY, SHOULD SEE AN  
ENHANCEMENT TO THE DIURNAL POPS FOR SUNDAY AFTERNOON, WITH LIKELY  
POPS OVER THE MOUNTAINS AND HEALTHY CHANCE ELSEWHERE. HIGH TEMPS  
THROUGH THE SHORT TERM SHOULD BE A COUPLE OF DEGREES ABOVE SEASONAL  
NORMALS, WITH A LARGER DEPARTURE FOR OVERNIGHT LOWS WHERE THE  
INCREASING MOISTURE WILL NOT ALLOW FOR MUCH OF A COOL-DOWN OVERNIGHT.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
 
 
AS OF 300 PM EDT THURSDAY: ZONAL FLOW WILL CONTINUE ACROSS THE  
OHIO/TENNESSEE VALLEYS AS A SUBTROPICAL RIDGE OVER THE WESTERN  
ATLANTIC CONTINUES TO BUILD WEST TOWARD FL AS THE SHORTWAVE  
CONTINUES TO WORK ITS WAY EAST UP THE OHIO VALLEY. SEVERAL  
DIFFERENCES CONTINUE IN MODELS' HANDLING OF THIS SHORTWAVE WITH THE  
GFS A LITTLE MORE ROBUST ESPECIALLY WITH THE ASSOCIATED SURFACE LOW.  
SHOULD SEE A FAIRLY SIGNIFICANT INCREASE IN CONVECTION FOR  
INDEPENDENCE DAY. ALONG WITH THE DECENT INSTABILITY (SBCAPES BETWEEN  
1000-2000 J/KG), WE HAVE SOME MINIMAL LOW-LEVEL SHEAR AS WELL WHICH  
MAY HELP TO ORGANIZE CONVECTION. OVERALL AND UNFORTUNATELY, IT LOOKS  
LIKE A PRETTY WET AND OCCASIONALLY STORMY DAY/EVENING, SO RESIDENTS  
OF THE WESTERN CAROLINAS AND NORTHEAST GEORGIA MAY WANT TO BE  
PREPARED FOR IMPACTS TO INDEPENDENCE DAY FESTIVITIES.  
 
THE WAVE PUSHES EAST ON TUESDAY, WITH THE ECMWF KEEPING AN OPEN WAVE  
AND PUSHING IT OFFSHORE EARLY IN THE DAY, BUT THE STRONGER GFS  
CLOSING IT OFF AND NOT PUSHING IT THROUGH FOR ANOTHER 24 HOURS.  
QUITE A BIT OF UNCERTAINTY HERE OBVIOUSLY BUT SINCE THE ECMWF KEEPS  
A TRAILING FRONT ACROSS OUR AREA ANYWAY, BOTH HAVE SIMILAR SENSIBLE  
WEATHER IMPACTS WITH ENHANCED DIURNAL CONVECTION CONTINUING THROUGH  
MID-WEEK. AS WOULD BE TYPICAL WITH ENHANCED SUMMERTIME CONVECTION,  
HEAVY RAIN AND AT LEAST ISOLATED SEVERE STORMS WILL BE POSSIBLE.  
 
THE SUBTROPICAL RIDGE CONTINUES TO BUILD WESTWARD, WITH INTERMITTENT  
SHORTWAVES RIDING ALONG THE NORTHERN EDGE OF THE RIDGE. DIFFERENCES  
BETWEEN THE OPERATIONAL GUIDANCE INCREASE THROUGH THE MIDDLE OF NEXT  
WEEK SO HAVE TRENDED CLOSE TO CLIMO ON POPS, BUT WITH A SLIGHT  
INCREASING TREND FOR TEMPERATURES, RISING INTO THE MID-90S, AS  
THICKNESSES INCREASE.  
 

 
   
AVIATION /21Z THURSDAY THROUGH TUESDAY/
 
 
AT KCLT AND THE SC SITES: JUDGING BY THE VARIOUS CAM MODELS WE  
HAVE RETAINED THUNDERSTORM CHANCES INTO THE CLT AIRFIELD DURING THE  
EVENING. THIS IS TRYING TO FOLLOW LARGE SCALE FEATURES/DEVELOPMENT,  
AND SMALL SCALE INTERACTIONS. SINCE CEILINGS ARE NEAR MVFR LEVELS,  
IT IS POSSIBLE THAT TENDENCY OF BOUNCING IN AND OUT WILL CONTINUE  
THROUGH THE EVENING. WE WOULD EXPECT GREATER RESTRICTIONS TO  
CEILINGS AND VISIBILITES WITH STORMS NEAR THE AIRFIELD. WE HAVE  
MENTIONED SOME VARIABLE GUSTY WINDS TO TAKE INTO ACCOUNT CURRENT  
ACTIVE SITUATION.  
 
ANY STRATUS AND FOG SHOULD LIFT TO LOW VFR CEILINGS FRIDAY MORNING.  
 
FOR THE REMAINDER OF OUR TAF SITES, THE BIGGEST DIFFERENCE IS  
IN THE TIMING OF CONVECTION, ARRIVAL AND/OR DEVELOPMENT. WE HAVE  
FOLLOWED CONTINUITY WITH LOWER CEILINGS AT SITES WHICH WERE NOT  
YET MIXED. OTHERWISE WOULD EXPECT POTENTIAL THUNDERSTORMS WITH  
REDUCED CEILINGS AND VISIBILITIES ACROSS THE BOARD.  
 
OUTLOOK: DIURNAL CONVECTION EXPECTED FRIDAY AFTERNOON AND SATURDAY.  
ANOTHER SERIES OF FRONTS, AND POTENTIAL WEAK LOW PRESSURE SYSTEMS  
RIDING ALONG THE FRONTS, APPEARS ON TAP FOR SUNDAY THROUGH TUESDAY.  
THIS PERIOD MAY OFFER AN ENHANCED THUNDERSTORMS POSSIBILITIES.  
 
CONFIDENCE TABLE...  
 
21-03Z 03-09Z 09-15Z 15-18Z  
KCLT HIGH 100% HIGH 98% MED 74% HIGH 100%  
KGSP HIGH 100% HIGH 96% MED 69% HIGH 100%  
KAVL HIGH 98% HIGH 91% MED 76% HIGH 100%  
KHKY HIGH 100% HIGH 98% HIGH 93% HIGH 100%  
KGMU HIGH 100% HIGH 96% HIGH 84% HIGH 100%  
KAND HIGH 100% HIGH 95% MED 73% HIGH 87%  
 
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING  
WITH THE SCHEDULE 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...TDP  
NEAR TERM...TS/WIMBERLEY  
SHORT TERM...TDP  
LONG TERM...TDP  
AVIATION...TS/WIMBERLEY  
 
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