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000
FXUS62 KGSP 130235
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1035 PM EDT WED JUN 12 2013

.SYNOPSIS...
HIGH PRESSURE WILL MAINTAIN WARM TEMPERATURES ACROSS THE REGION
TODAY AHEAD OF AN APPROACHING COLD FRONT...WHICH WILL CROSS THE AREA
ON THURSDAY. DRY HIGH PRESSURE WILL BUILD IN FROM THE NORTH
FRIDAY...MAKING FOR A MOSTLY DRY WEEKEND. THE NEXT COLD FRONT WILL
APPROACH THE REGION EARLY NEXT WEEK...TRIGGERING AFTERNOON SHOWERS
AND THUNDERSTORMS EACH DAY THROUGH MIDWEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1030 PM...ALL CONVECTION HAS ENDED AND DO NOT EXPECT ANY
REDEVELOPMENT OVERNIGHT. THE LATEST SYNOPTIC AND CONVECTION ALLOWING
MODELS ARE ALL PUSHING ANY CONVECTION MOVING INTO THE AREA BACK TO
15Z OR LATER. DID NOT WANT TO PUSH THINGS BACK TOO FAR WITHOUT
FURTHER ANALYSIS...SO JUST BEGAN POP SLIGHTLY LATER THAN PREVIOUS
CHANGES. DEW POINTS ARE RUNNING HIGHER THAN EVEN THE PREVIOUS
CHANGES WHICH WENT HIGHER THAN THE AFTERNOON FCST. HAVE TRIED TO
CAPTURE THESE CHANGES OVERNIGHT. WITH THE LIGHT WINDS AND
POTENTIALLY LESS CONVECTIVE DEBRIS FROM A SLOWER MCS...MTN VALLEY
AND RIVER/LAKE FOG COULD BE MORE LIKELY. OTHERWISE...ONLY MINOR
CHANGES FROM PREV FCST.

AS OF 750 PM...THE ONE AREA OF DEEP CONVECTION OVER THE FAR UPPER
SAV RIVER VALLEY HAS DISSIPATED. DESPITE WHAT THE SPC MESOANALYSIS
SUGGESTS...EXPECT THE ATMOS REMAIN CAPPED WITH A DEEP LOW LEVEL WARM
LAYER AS DEPICTED ON THE 18Z NAM AND GFS FCST SOUNDINGS. ALTHOUGH
CAPE WAS SIGNIFICANT...THE LFC WAS AROUND 10K FT. THIS IS WHAT
LIKELY LIMITED THE DEEP CONVECTION DESPITE A WEAK SHORT WAVE MOVING
OVERHEAD. GIVEN THESE TRENDS...HAVE REMOVED ALL EVENING POP EXCEPT
FOR AN AREA OF ISOLATED SHRA MOVING SOUTH ALONG THE SAV RIVER
VALLEY. EVEN THIS MAY BE OVERDONE. THE LATEST GUIDANCE HAS ALSO
SLOWED THE APPROACH OF ANY MCS ACTIVITY OVERNIGHT. THEREFORE...HAVE
BACKED OFF ON POP INCREASE ACROSS THE MTNS UNTIL NEAR DAYBREAK. MADE
SOME MINOR ADJUSTMENTS TO ALL OTHER FIELDS OVERNIGHT BASED ON
CURRENT CONDITIONS AND LATEST GUIDANCE. DID MAKE SOME SIGNIFICANT
CHANGES TO WIND FCST THU... GENERALLY INCREASING WINDS AND GUSTS IN
LINE WITH THE NAM AND GFS DEPICTION OF MIXING TAPPING THE INCREASING
LOW LEVEL FLOW AHEAD OF THE MCS OR OUTFLOW BOUNDARY DROPPING INTO
THE AREA.

AS OF 430 PM...THERE WAS A PROBLEM WITH THE PREVIOUS FORECAST. HAVE
FIXED THIS SO THE NEW DAY 7 PERIOD IS INCLUDED. CONVECTION STILL HAS
NOT DEVELOPED OVER THE CWFA DESPITE THE VERY HIGH CAPE AND UNCAPPED
ATMOS. THIS EVEN WITH A WEAK LEE TROF IN PLACE. IN FACT...THE ONLY
PRECIP IS LIGHT SHRA FROM FALLING FROM A MID CLOUD DECK OVER THE NC
AND ERN SC PIEDMONT. GIVEN THAT THE PREVIOUS THINKING IS STILL
VALID...KEPT POP AS IS BUT TRIMMED THE START TIME AND KEPT POP OVER
NC ISOLATED. OTHERWISE... MAIN UPDATES WERE FOR CURRENT CONDITIONS.

AS OF 230 PM...SPC MESOANAL PAGE SHOWS OVER 3000J/KG OF SBCAPE ACROSS
THE REGION WITH NO CIN. WILL CONTINUE THE IDEA PER HRRR/4KM EMC WRF
AND HI-RES WRF THAT SCT THUNDERSTORMS WILL DEVELOP OVER THE WESTERN
UPSTATE/NE GA BY LATE AFTERNOON TRIGGERED BY A MID LEVEL VORT. THE
ENTIRE AREA IS INCLUDED IN A SPC SLGT RISK AREA. THIS MAKES SENSE IN
THAT ANY STORMS THAT DEVELOP HAVE THE POTENTIAL TO PRODUCE LOCALIZED
DAMAGING WINDS PER THE 900J OF DCAPE ANALYZED BY SPC. CONVECTION IS
EXPECTED TO MOVE OUT OF THE AREA BY 00Z.

THE OVERNIGHT SHOULD BE QUIET AS A WEAK RIDGE OF HIGH PRESSURE NOSES
EASTWARD INTO THE AREA. HOWEVER...WE WILL BE KEEPING AN EYE UPSTREAM
OVER THE LOWER GREAT LAKES WHERE A CONVECTIVE COMPLEX IS EXPECTED
TO DEVELOP AND PERHAPS TRANSITION INTO A DERECHO AS IT MOVES SE
THROUGH THE OHIO VALLEY AND INTO THE APPALACHIANS. THE 4KM EMC WRF
SHOWS THIS FEATURE MAKING A RUN AT THE NC MOUNTAINS LATE
TONIGHT...THEN DISSIPATING IT AS IT HITS THE MOUNTAINS. HAVE BUMPED
SOME CHC POPS UP TO ABOUT 12Z OVER THE NC BORDER COUNTIES TO ACCOUNT
FOR THIS. CAN`T RULE OUT SOME GUSTY WINDS REACHING THE AREA THU
MORNING FROM DERECHO OUTFLOW...BUT DO NOT HAVE THAT POSSIBILITY
CODED INTO THE GRIDS. IT WILL BE A WARM AND MUGGY NIGHT WITH LOWS
NOT GETTING OUT OF THE 70S FOR MOST AREAS EAST OF THE MOUNTAINS.

ON THU...A COLD FRONT IS STILL EXPECTED TO ARRIVE AND MOVE ACROSS
THE AREA DURING THE COURSE OF THE DAY. WIND FIELDS WILL BE IMPROVING
WITH 0-6KM BULK SHEAR INCREASING TO 35-40KT AND CAPES >2500J.
HENCE...SVR STORMS ARE CERTAINLY POSSIBLE PER THE SPC DAY 2 OUTLOOK.
LOOKS LIKE THE BEST THREAT FOR SEVERE STORMS WILL BE OVER THE
PIEDMONT IN THE MID TO LATE AFTERNOON HOURS. WINDS THROUGH THE
COLUMN WILL TAKE ON A DOWNSLOPE COMPONENT ON THU SO IT IS POSSIBLE
THAT COVERAGE ESPECIALLY ACROSS THE UPSTATE PERHAPS WILL NOT BE
100%. HENCE...POPS ARE HIGHEST ACROSS THE SOUTHERN PIEDMONT AREAS.
IT WILL BE ANOTHER HOT DAY ON THU WITH A MODEL BLEND PRODUCING HIGHS
IN THE 90-95 RANGE OUTSIDE THE MOUNTAINS AND MID 80S MOUNTAIN
VALLEYS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 130 PM EDT WEDNESDAY...EXPECT QUIET AND COOLER CONDITIONS FOR
THE SHORT TERM PERIOD. CONDITIONS QUICKLY DRY OUT THURSDAY EVENING
AS A SHARP UPPER TROUGH AXIS AND ASSOCIATED SURFACE COLD FRONT PUSH
EAST OF THE AREA. HOWEVER...SCATTERED LIGHT SHOWERS MAY CONTINUE
ACROSS THE NC MTNS THROUGH LATE THURSDAY NIGHT DUE TO INCREASING NW
UPSLOPE FLOW ALONG WITH THE PASSAGE OF WEAK UPPER DPVA THERE.

AN UPPER RIDGE OF H5 HIGH WILL REMAIN ANCHORED OVER THE SOUTHCENTRAL
STATES LEAVING OUR FORECAST AREA UNDER THE NW FLOW ALOFT FRI/SAT.
THIS WILL ALLOW CANADIAN SURFACE HIGH PRESSURE TO RIDGE SOUTH INTO
THE FORECAST AREA PROVIDING DRY NORTHERLY FLOW THROUGH THE PERIOD.
TEMPERATURES WILL BE AROUND 2-3 DEGREES BELOW NORMAL WITH HIGHS IN
THE LOWER TO MID 80S OVER THE PIEDMONT AND 70S IN THE HIGHER
TERRAIN.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 2PM WEDNESDAY...THE MODELS REMAIN IN FAIRLY GOOD AGREEMENT
THROUGH MOST OF THE PERIOD. AFTER A PREDOMINANTLY DRY WEEKEND...THE
RIDGE OVER THE EASTERN CONUS WILL BREAK DOWN BY THE BEGINNING OF
NEXT WEEK. A WEAK TROUGH WILL THEN SET UP OVER THE SOUTHEASTERN
CONUS AND ALLOW A MORE UNSETTLED SUMMERTIME PATTERN TO RETURN. THE
NEXT FRONTAL SYSTEM APPROACHES LATE MONDAY/EARLY TUESDAY...RESULTING
IN DIURNAL CHANCE POPS FOR THE ENTIRE CWA ON MONDAY. THE FRONT
PASSES AND STALLS OUT JUST TO THE SOUTH OF THE FORECAST AREA LATE
TUESDAY...SO CHANCE POPS CONTINUE FOR THE ENTIRE FORECAST AREA
THROUGH MIDWEEK. TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH THE
EXTENDED PERIOD.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT...CONVECTION SHOULD REMAIN NIL WITH NO RESTRICTIONS THRU THE
OVERNIGHT HOURS WITH SOME MID CLOUD SPREADING OUT UNDER THE HIGH
BASED SUBSIDENCE INVERSION. EXPECT LIGHT SWLY WINDS TO CONTINUE THRU
THE OVERNIGHT AS WELL. SWLY WINDS INCREASE IN SPEED AND BECOME GUSTY
BY NOON AS AN MCS OR OUTFLOW BOUNDARY DROPS INTO THE AREA. THE GUSTY
WINDS CONTINUE THRU THE END OF THE PERIOD. CONVECTION IS EXPECTED TO
DEVELOP BY EARLY AFTERNOON AS THE MCS OR OUTFLOW BOUNDARY MOVES INTO
THE AREA. THE CONVECTION COULD LAST THRU THE END OF THE PERIOD BUT
COULD MOVE SOUTH JUST BEFORE THE END. EITHER WAY...A PROB30 IS
WARRANTED GIVEN THE POTENTIAL.

ELSEWHERE...DEEP CONVECTION HAS BEEN MINIMAL AND IS NOT EXPECTED
THRU THE OVERNIGHT HOURS. LIGHT SWLY WIND...NWLY AT KAVL...WILL
CONTINUE THRU THE OVERNIGHT AS WELL. WSW WINDS...NWLY AT KAVL...
INCREASE IN SPEED AND BECOME GUSTY BY LATE MORNING OR EARLY
AFTERNOON AS AN MCS OR OUTFLOW BOUNDARY DROPS INTO THE AREA. THE
GUSTY WINDS WILL CONTINUE THRU THE END OF THE PERIOD. CONVECTION IS
EXPECTED TO DEVELOP OR MOVE INTO THE MTNS BY LATE MORNING AND MOVE
INTO OR DEVELOP OUTSIDE OF THE MTNS DURING THE AFTERNOON. THE
CONVECTION COULD LAST THRU THE END OF THE PERIOD BUT COULD MOVE
SOUTH JUST BEFORE THE END. EITHER WAY...A PROB30 IS WARRANTED GIVEN
THE POTENTIAL.

OUTLOOK...HIGH PRESSURE WILL BUILD IN THU NITE AND PRODUCE GENERALLY
QUIET WEATHER AND VFR CONDITIONS THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-02Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     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...VISIN
NEAR TERM...LG/RWH
SHORT TERM...JOH
LONG TERM...ARK/VISIN
AVIATION...RWH