Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 191753
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
153 PM EDT FRI SEP 19 2014

.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL LINGER ATOP THE REGION INTO
SATURDAY. COOL TEMPERATURES WILL RETURN TO NORMAL READINGS OVER THE
WEEKEND AHEAD OF A COLD FRONT WHICH IS FORECAST TO PASS THROUGH
SUNDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 150 PM...SHRA CONTINUING TO DEVELOP OVER THE NC FOOTHILLS AND
BLUE RIDGE AND REDEVELOPING SOUTH OF THERE ACROSS THE UPSTATE.
CANNOT RULE OUT A SHRA ANYWHERE THIS AFTERNOON...BUT BEST CHC WILL
BE WHERE THEY ARE NOW AND WEST. HAVE UPDATED POP TO SHOW THIS.
OTHERWISE...UPDATES MAINLY FOR CURRENT CONDITIONS.

AS OF 1045 AM...HEAVY TS/SHRA HAVE DIMINISHED...BUT LIKELY COVERAGE
REMAINS ACROSS THE LOWER PORTION OF THE UPPER SAV RIVER VALLEY.
COVERAGE ALSO INCREASING IN THE UPSLOPE FLOW OVER THE NC FOOTHILLS.
EXPECT THE COVERAGE OVER THE UPSTATE AND NE TO CONTINUE TO DIMINISH
THRU THE MORNING...BEFORE REDEVELOPING WITH AFTERNOON HEATING.
COVERAGE OVER THE NC FOOTHILLS SHUD CONTINUE TO INCREASE THRU THE
AFTERNOON AND SPREAD ACROSS THE NC MTNS. HAVE UPDATED POP TO GO WITH
SCT COVERAGE ACROSS THE WRN CWFA AND ISOLATED EAST...IN LINE WITH
LATEST TRENDS AND GUIDANCE. INSTABILITY REMAINS QUITE LOW ACROSS THE
ERN CWFA...BUT MODERATE INSTABILITY EXPECTED OVER THE WEST. SHUD BE
ENUF FORCING FROM UPSLOPE AND DIFFERENTIAL HEATING FOR TSRA OVER THE
WEST...WITH MAINLY SHRA EAST. PW VALUES ARE NOT EXCEPTIONALLY HIGH.
HOWEVER...WITH THE CONTINUED UPSLOPE FLOW...ANY CELLS THAT CAN
ANCHOR OR TRAIN NEAR THE HIGHER TERRAIN COULD LEAD TO ISOLATED
FLOODING. REST OF THE FCST APPEARS ON TRACK WITH ONLY MINOR
ADJUSTMENTS.

1030 UTC UPDATE...POPS AND QPF HAVE BEEN ADJUSTED PER RADAR
TRENDS...FAVORING THE SC SIDE OF THE UPPER SAVANNA RIVER VALLEY.

AT 300 AM EDT FRIDAY...CONVECTION IN THE CHARLOTTE AREA SHOWS LIMITED
SIGNS OF DIMINISHING EARLY THIS MORNING...AND HIGH POPS AND QPF WILL
BE CARRIED THERE EARLY TODAY.

AN UPPER TROUGH WILL DEAMPLIFY ALONG THE EAST COAST TODAY...LAVING
BEHIND AN UPPER LOW OFF THE GA COAST. A SURFACE HIGH WILL MOVE
ACROSS NEW ENGLAND TODAY...AND WILL PASS SOUTH OF NOVA SCOTIA
TONIGHT. AS THE SURFACE HIGH BUILDS DOWN THE EAST COAST..THE MODELS
SHOW SLIGHT RELATIVE DRYING EARLY TODAY...BUT ENOUGH MOISTURE WILL
REMAIN FOR PRECIPIATION WITH HEATING THIS AFTERNOON. LIGHT SURFACE
FLOW IS EXPECTED TO VEER FROM NE TO SE TODAY...IMPROVING MOIST
UPSLOPE FLOW INTO THE SOUTHERN APPALACHIANS...WHERE THE HIGHEST POPS
WILL BE CARRIED TODAY. MAXIMUM TEMPERATURES WILL RUN SLIGHTLY BELOW
NORMAL UNDER CLOUD COVER.

SURFACE WINDS WILL BACK TO NE THIS EVENING AS A SURFACE LOW DEVELOPS
OFF THE FL COAST...AND THE MODEL SHOW ADDITIONAL DRYING EAST OF THE
MOUNTAINS TONIGHT. POPS WILL BE ALLOWED TO FALL OFF THIS EVENING
WITH THE LOSS OF HEATING. MINIMUM TEMPERATURES WILL BE NEAR NORMAL.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 130 PM EDT FRIDAY...THE PRIMARY HIGHLIGHT OF THE SHORT TERM
FORECAST PERIOD WILL BE A COLD FRONTAL PASSAGE SUNDAY NIGHT INTO
EARLY MONDAY AFTERNOON.  THE FORECAST WILL INITIALIZE DRY SATURDAY
EVENING WITH THE UPPER PATTERN FEATURING A RATHER PROGRESSIVE
POSITIVELY TILTED TROF EJECTING OUT OF THE UPPER MIDWEST.  AT THE
SURFACE...AN ASSOCIATED COLD FRONT WILL STRETCH ALONG THE PARENT
SURFACE TROF FROM LAKE MICHIGAN SOUTHWEST INTO CENTRAL
MISSOURI/NEBRASKA.  MEANWHILE ACROSS THE SOUTHEAST...MODELS CONTINUE
TO INDICATE A WEAK SURFACE DISTURBANCE OFF THE CAROLINA COASTLINE
WHILE SURFACE HIGH PRESSURE CENTERED OVER THE NORTHEAST BEGINS
RETREATING OUT TO SEA.  IN RESPONSE...SOUTHERLY WAA REGIME WILL
RESUME ON SUNDAY AHEAD OF THE ABOVE MENTIONED TROF/FRONT COMPLEX.
THAT SAID...MODELS REMAIN RATHER UNIMPRESSIVE REGARDING THE
MAGNITUDE OF MOISTURE FLUX INTO NORTHEAST GA AND THE WESTERN
CAROLINAS ON SUNDAY BEFORE THE FRONT SWEEPS IN.  SURFACE DEWPOINTS
WILL STRUGGLE TO TOP THE 60 DEGREE MARK LEADING TO MINIMAL MOISTURE
AVAILABILITY FOR BOTH PREFRONTAL CONVECTION IN THE QUASI WARM
SECTOR...AND ALSO FOR FRONTAL CONVECTION DURING THE NOCTURNAL
FROPA.  AS A RESULT...SOUNDINGS REMAIN SOMEWHAT STABLE DUE TO BOTH
LACK OF LOW LEVEL MOISTURE AND WARM MID LEVEL TEMPERATURES
EFFECTIVELY KEEPING CONVECTION AT BAY.  ALL THAT SAID...SHEAR WILL
BE INCREASING AS THE UPPER JET DYNAMICS AND ASSOCIATED VORTICITY
MAXIMA PASS THROUGH THE OHIO VALLEY THEREFORE A ROGUE STRONG/SEVERE
THUNDERSTORM CANNOT BE RULED OUT AT THIS TIME...ESPECIALLY NORTH OF
I40 WHERE BETTER DYNAMICS ARE IN PLAY.

CONVECTION WILL ERODE WITH HEATING LOSS AS THE FRONT SPILLS INTO THE
HIGH TERRAIN SUNDAY NIGHT...EVENTUALLY SLIDING INTO THE SOUTHERN NC
PIEDMONT...NORTHEAST GA...AND SC UPSTATE BY LATE MORNING TO EARLY
AFTERNOON MONDAY BEFORE ANY HEATING CAN SUBSTANTIALLY DESTABILIZE
THE ATMOSPHERE.  THUS...NO ROBUST CONVECTION IS EXPECTED MONDAY
ALONG THE BOUNDARY AS IT SLIDES SOUTH THROUGH THE CWFA.  HIGH
PRESSURE WILL ADVECT INTO THE REGION QUICKLY BEHIND THE FRONT LIKELY
LEADING TO THE FIRST ROUND OF FALL LIKE WEATHER THROUGH THE
PERIOD.   THEREFORE THE FORECAST WILL FEATURE CHANCE LEVEL POPS
ACROSS THE HIGH TERRAIN ON SUNDAY EVENING WITH ONLY SLIGHT CHANCE
POPS HIGHLIGHTED OVERNIGHT ACROSS NORTHEAST GA AND THE NC/SC
PIEDMONT.  SLIGHT CHANCE POPS WILL ONCE AGAIN BE FEATURED EARLY ON
MONDAY ALONG AND SOUTH OF THE I85 CORRIDOR ASSOCIATED WITH THE
PASSING BOUNDARY WITH A DRY FORECAST PREVAILING ELSEWHERE.
TEMPERATURES WILL REMAIN AT OR ABOVE NORMAL LEVELS FOR SUNDAY AHEAD
OF THE FRONT BEFORE COOLING ON MONDAY TO BELOW NORMAL.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 240 AM FRI...ONCE THE MINIMAL INSTABILITY FADES SUNDAY EVENING
OVER THE NC MTNS...THERE IS NO RETURN OF INSTABILITY FOR THE WESTERN
CAROLINAS AND NE GA WITH THE LATE NIGHT PASSAGE OF THE COLD FRONT.
WE HAVE LOW SLIGHT CHANCE POPS ON MONDAY IN THE FORM OF ONLY
SHOWERS. DRY AND COOLER HIGH PRESSURE WILL PREVAIL MONDAY NIGHT
THROUGH AT LEAST WED NIGHT. THE COMBINATION OF A DEVELOPING COASTAL
LOW NEAR THE FLORIDA AND GEORGIA COAST AND THE 1035MB HIGH OVER NEW
ENGLAND ON THURSDAY WILL CREATE A STRONG EASTERLY LOW LEVEL FLOW OFF
THE ATLANTIC LATE THURSDAY AND THURS NIGHT. MODELS SHOW A BATCH OF
MOISTURE MOVING IN FROM THE EAST BUT SINCE THAT IS THE END OF THE
CURRENT FORECAST CYCLE IT IS BEST TO LEAVE POPS QUIT LOW UNTIL THE
GET CLOSER TO THAT TIME FRAME. AFTER THE FRONT PASSES EXPECT TEMPS 5
TO 7 DEGREES BELOW NORMAL THROUGH MID WEEK.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...SCT LOW VFR WITH BKN MID TO HIGH CLOUDS WILL CONTINUE INTO
EARLY EVENING. BULK OF CONVECTION SHUD REMAIN WEST OF THE AIRFIELD.
OVERNIGHT...LOW LEVEL MOISTURE AND E TO SE FLOW RETURN...BRINGING
MVFR CLOUDS BACK INTO THE AREA. EVEN WORST CASE GUIDANCE SUGGESTS
LITTLE CHC OF IFR OVERNIGHT. SCATTER CLOUDS BY LATE MORNING AS DRIER
AIR AND NELY FLOW BUILD IN. SELY WINDS THIS AFTERNOON BECOME ENE
THIS EVENING THEN NELY OVERNIGHT AND REMAIN THERE SAT MORN.

ELSEWHERE...SHUD BE VFR...ALTHOUGH LOW VFR CIGS WILL DEVELOP FROM
TIME TO TIME...THIS AFTERNOON. COULD BE SOME MVFR RESTRICTIONS IN
THE SHRA DEVELOPING ACROSS THE AREA THIS AFTERNOON. CANNOT RULE OUT
A TSRA...BUT CHC IS LOW. INCLUDED VCSH FOR NOW WHERE SHRA MORE
LIKELY. OVERNIGHT...LOW LEVEL MOISTURE AND E TO SE FLOW RETURN...
BRINGING MVFR CLOUDS BACK INTO THE AREA. EVEN WORST CASE GUIDANCE
SUGGESTS ONLY A LOW CHC OF IFR OVERNIGHT...EXCEPT AT KAVL WHERE LIFR
DEVELOPS AND VLIFR POSSIBLE. RESTRICTIONS SHUD LIFT TO LOW VFR BY
NOON AND COULD EVEN SCATTER OUT BEFORE LIFTING AS DRIER AIR AND NELY
FLOW BUILD IN. S TO SE WINDS THIS AFTERNOON BECOME ENE THIS EVENING
THEN NELY OVERNIGHT AND REMAIN THERE SAT MORN. KAVL THE EXCEPTION
WHERE WINDS REMAIN S TO SE THROUGHOUT.

OUTLOOK...CONDITIONS SHUD REMAIN DRY FOR THE LATTER PART OF THE
WEEKEND. A COLD FRONT MAY BRING INCREASING CHANCES FOR SHOWERS/TSTMS
EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     MED   76%     HIGH  90%
KGSP       HIGH 100%     HIGH 100%     MED   77%     HIGH  85%
KAVL       HIGH  86%     HIGH  94%     HIGH  80%     HIGH  82%
KHKY       HIGH 100%     HIGH 100%     MED   70%     HIGH  88%
KGMU       HIGH  99%     HIGH 100%     MED   77%     HIGH  86%
KAND       HIGH 100%     HIGH 100%     MED   68%     HIGH  86%

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/RWH
SHORT TERM...CDG
LONG TERM...DEO
AVIATION...RWH





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