000 FXUS62 KGSP 061825 AFDGSP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 225 PM EDT MON JUL 6 2009 .SYNOPSIS... A WEAK COLD FRONT WILL CONTINUE TO LINGER JUST TO OUR SOUTH THROUGH TUESDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTH WEDNESDAY...AND PERSIST INTO THE WEEKEND. A COLD FRONT WILL MOVE SOUTH TOWARD THE CAROLINAS LATER IN THE WEEKEND AND COULD INCREASE THE POSSIBILITY OF SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TUESDAY/... SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED THE REMAINDER OF THE AFTERNOON MAINLY ACROSS THE NC/SC PIEDMONT AREAS. LOOKS LIKE UPPER FRONT/TROUGH AROUND 850 MB TRIGGERED THE AREA CONVECTION THAT MOVED INTO THE NC FOOTHILLS AND IS CURRENTLY BEARING DOWN ON THE NC PIEDMONT. TO THE S...WEAK SURFACE BOUNDARY THAT REMAINS ROUGHLY ALONG I-85 WILL SERVE TO FOCUS CONVECTION THERE AND SOUTHWARD DURING THE LATE AFTERNOON. ALL GUIDANCE STILL POINTS TO THE BOUNDARY SAGGIN SLOWLY SOUTHWARD INTO THE CENTRAL SC EARLY TONIGHT...SO EXPECT THAT CONVECTION WILL GENERALLY CLEAR THE FORECAST AREA TO THE S... CERTAINLY BY MIDNIGHT. 12Z GFS/NAM INDICATE THAT WEAK HIGH PRESSURE TO THE N WILL RIDGE SOUTHWARD OVERNIGHT ALONG WITH DRYER AIR. HENCE...EXPECT CLOUDS TO GRADUALLY CLEAR/SCATTER FROM N TO THE S. WITH DRYER AIRMASS IN PLACE ON TUE AND NO APPARENT FOCUSING MECHANISMS...ANY CONVECTION THAT DEVELOPS WILL HAVE TO RELY ON MECHANICAL OR DIFFERENTIAL HEATING TO GET GOING. SOME CONVERGENCE IS NOTED IN THE WIND FIELD OVER THER WESTERN UPSTATE/NE GA THU AFTERNOON ALONG WITH MODERATE CAPE VALUES WHICH MIGHT BE ENOUGH TO TRIGGER SOME WIDELY SCATTERED THUNDERSTORMS THERE...WITH DIFFERENTIAL HEATING IN THE MOUNTAINS ENOUGH THERE FOR ISOLATED CONVECTION. USED A MOS BLEND FOR MAX/MIN TEMPS WHICH PRODUCED HIGHS NEAR SEASONAL AVERAGES AND MINS SLIGHTLY BELOW AVERAGE. && .SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 200 PM MONDAY...THE SHORT RANGE EXHIBITS VERY LITTLE TO HANG YOUR HAT ON AS FAR AS FOCUSING MECHANISMS OR LARGE SCALE FORCINGS. THE H5 HEIGHT FIELD WILL BE VERY BROAD CYCLONIC WED AND BECOME MORE DIFFUSE AS THE WEEK WEARS ON. WITH THE BROAD TROF TO OUR WEST...SOME UPPER ENERGY MAY MAKE IT ACROSS THE SOUTHERN ZONES WED AND INSTIGATE A WEAK CONVERGENT SFC TROF. MODEL QPF RESPONSE IN BOTH THE GFS AND THE NAM INDICATE THIS MAY BE THE CASE AND THIS WAS ACCOUNTED FOR IN THE GRIDS BY INTRODUCING ISOL SHOWERS AND TS WED AFTERNOON. OTHER THAN THAT...THE TREND WILL BE FOR LESS AND LESS UPPER LEVEL S/W ENERGY TRAVERSING THE CWFA. THE ISOL DIURNAL CONVECTION ACROSS THE MTNS WILL BE MAINTAINED AS THE LLVLS WILL REMAIN QUITE UNSTABLE...YET WITH VERY LITTLE MOISTURE TO WORK WITH. ON FRI...A SIGNIFICANT UPPER LEVEL S/W MAY APPROACH THE MTNS...BUT AGAIN THE CROSS SECTIONS SHOW LITTLE MOISTURE TO WORK WITH AND THE COUPLED FORCING SHOULD HAVE LITTLE IMPACT AS FAR AS INCREASING TS/SHRA ACTIVITY BEYOND ISOL. WEAK FLOW FROM THE SFC TO H5 WILL PERSIST WED THROUGH FRI AND THIS WILL NOT ALLOW MUCH IF ANY GOM NOR ATL MOISTURE TO THE CWFA. SO...CLOUD COVER WILL BE SCT AT BEST WITH MAINLY FAIR WX CU OUTSIDE THE MTNS. THIS WILL KEEP THE MAJORITY OF THE FORECAST AREA DRY AND MAX TEMPS SHOULD HAVE NO PROBLEM REACHING A FEW DEGREES ABOVE NORMAL BY THU/FRI. THIS SCENARIO WILL ALSO ALLOW FOR DRYING SURFACE CONDITIONS AND A DECREASE IN REGIONAL WATER TABLES...THUS A LOW END DROUGHT COND MAY BE REINTRODUCED TO THE AREA. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 215 PM MONDAY...SURFACE HIGH PRESSURE WILL BE BREAKING DOWN SATURDAY OVER THE MID ATLANTIC AS THE NEXT WEAK COLD FRONT MOVES SOUTH FROM THE OHIO RIVER VALLEY. ALTHOUGH THE GFS AND ECMWF ARE NOT WORLDS APART ON THEIR SOLUTIONS...THE EC IS THE PREFERRED MODEL IN THE END PERIODS OF THE MEDIUM RANGE. THE GFS AND EC HAVE SIMILAR POSITIONS OF THE TROUGH AND FRONT UNTIL MONDAY WHEN IT BECOMES CLEAR THAT THE EC HOLDS THE FRONT TO THE NORTH LONGER AND THE GFS BUILDS A HIGH TO THE NORTHEAST AND PUSHES THE FRONT SOUTH OF OUR AREA BY MONDAY NIGHT. PREFER TO STICK CLOSER TO THE EC AND HPC PROJECTIONS. DID NOT RAISE POPS TOO HIGH...BUT HAVE THE SLIGHTLY HIGHER POPS ON MONDAY AND WE CONFORM WELL WITH AT LEAST TWO OF OUR NEIGHBORS. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... AT KCLT...WEAK FRONTAL BOUNDARY HAS PUSHED JUST SOUTH OF THE AIRFIELD. AREA OF SHOWERS/THUNDERSTORMS TO THE NW...VICINITY KHKY IS MOVING SE AND EXPECT IT WILL MOVE ACROSS THE AIRFIELD BETWEEN 1830-22Z. HENCE...TEMPO FOR TSRA/MVFR CONDITIONS. CAN'T RULE OUT BRIEF IFR IF A THUNDERSTORM CORE MOVES OVER. EXPECT THAT THUNDERSTORM THREAT SHOULD BE S/SE OF AIRFIELD BY 22Z WITH IMPROVING CONDITIONS TO VFR. MOST GUID POINTS TOWARD MVFR VSBY CIRCA SUNRISE ON TUE DUE TO FOG. WINDS SHOULD FAVOR THE NE THROUGH THE FORECAST PERIOD...AND COULD BE GUSTY NEAR THUNDERSTORMS THIS AFTERNOON. ELSEWHERE...CLUSTER OF THUNDERSTORMS TO MOVE ACROSS KHKY BY 22Z WITH TEMPO IFR CONDITIONS. BOUNDARY JUST S OF I-85 WILL TRIGGER MORE CONVECTION BY 20Z SO MENTION OF CB AT ALL SC AIRFIELDS. KAVL WILL PROBABLY MISS OUT OF ANY THUDNERSTORM ACTIVITY THIS AFTERNOON. SCATTERD TO NUMEROUS THUNDERSTORMS ACROSS THE SC PIEDMONT LATE THIS AFTERNOON WILL PUSH S OF ALL AIRFIELDS BY 00Z. GUID POINTS TOWARD IFR FOG AT KAVL AND MVFR FOG ELSEWHERE CIRCA SUNRISE TUE. OTEHRWISE...VFR. OUTLOOK...CONVECTION SHOULD BE MORE ISOLATED...AND LIMITED TO THE MOUNTAINS TUESDAY THROUGH THURSDAY. CHANCES FOR DIURNAL CONVECTION WILL EXPAND TO THE PIEDMONT BY THE END OF THE WEEK. MVFR/IFR FOG CONDITIONS CIRCA SUNRISE AT KAVL EACH DAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...DEO NEAR TERM...LG SHORT TERM...SBK LONG TERM...DEO AVIATION...LG