Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 011541
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1141 AM 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 LEADING TO SLIGHTLY
COOLER TEMPERATURES AND MORE SETTLED WEATHER.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1130 AM...IN A RELATIVE LULL IN CONVECTIVE ACTIVITY THAT
SHOULD END DURING THE EARLY AFTERNOON AS CONVECTION DEVELOPS OVER
THE RIDGETOPS. SO...AFTER A BRIEF LOWERING OF POP...THE CHANCES
SHOULD GO UP ACROSS PARTS OF THE MTNS BASED ON OUTPUT OF THE
CONVECTION ALLOWING MODELS. THE CONSENSUS GENERALLY FAVORS THE
SMOKIES AND BALSAMS...AND DOWNPLAYS THE CHANCES OVER THE NC
PIEDMONT. SKY COVER ALSO NEEDS TO BE ADJUSTED TO TAKE INTO ACCT THE
THICKER AREA OF HIGH CLOUDS E OF THE MTNS. NO OTHER BIG CHANGES.

REMAINDER OF PREVIOUS DISCUSSION...

AS OF 305 AM...UPPER RIDGE AND SFC BERMUDA HIGH WILL REMAIN IN PLACE
TODAY AND TONIGHT. HOWEVER...A SHORT WAVE WILL BRUSH BY THE MTNS
TODAY. THIS MAY BE JUST ENUF FORCING TO ACT ON THE DEVELOPING
INSTABILITY AND DIFFERENTIAL HEATING TO PRODUCE LOW END SCT
CONVECTION ACROSS MOST OF THE NC MTNS...THE FRENCH BROAD VALLEY
BEING THE MAIN EXCEPTION WHERE ISOLATED COVERAGE EXPECTED. OUTSIDE
OF THE NC MTNS...ATMOS WILL REMAIN CAPPED MOST OF THE DAY WITH ONLY
WEAK INSTABILITY DEVELOPING LATE IN THE AFTERNOON WITH RELATIVELY
HIGH LFC LEVELS. THERE WILL BE LITTLE IN THE WAY OF FORCING AS LEE
TROF SETS UP EAST OF THE CWFA. HAVE LOW END ISOLATED CONVECTION OVER
THIS AREA. IN FACT...THERE MAY NOT BE ANY CONVECTION AT ALL ALONG
AND SOUTH OF THE I-85 CORRIDOR...BUT WILL MAINTAIN CONSISTENCY WITH
THE LOW END ISOLATED POP. HIGHS WILL AGAIN WELL ABOVE NORMAL.

CONVECTION WILL DISSIPATE THRU THE EVENING...BUT COULD LINGER A
LITTLE LONGER ALONG THE TN BORDER BEFORE DISSIPATING OVERNIGHT. LOWS
WILL ALSO AGAIN BE ABOVE NORMAL.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 305 AM EDT SUNDAY...NOT A LOT OF CHANGE REGARDING THE SHORT
TERM FORECAST PERIOD WHICH INITIALIZES TUESDAY MORNING AMIDST BROAD
SUBTROPICAL DEEP LAYER RIDGING.  AMPLIFYING UPPER TROF PUSHING
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY WILL BE MOVING EAST WITH
AN ASSOCIATED COLD FRONT DRAPED ALONG OR JUST NORTH OF THE OHIO
RIVER VALLEY.  CONTINUED SOUTHERLY FLOW OVER THE SOUTHEAST AHEAD OF
APPROACHING FRONTAL BOUNDARY WILL WARRANT NEAR CLIMO POPS FOR MUCH
OF THE REGION ON A DIURNAL TREND.  ABOVE MENTIONED RIDING WILL
PROVIDE SOME INHIBITION TO CONVECTION ON TUESDAY...ESPECIALLY ACROSS
THE EAST.  WEAK LEE TROF PRESENT ACROSS CENTRAL NC/SC COULD BE A
FOCUS FOR CONVECTION PROVIDING ENOUGH LOW LEVEL CONVERGENCE TO
SUPPORT INITIATION DESPITE ABOVE MENTIONED CAP.  LAPSE RATES ACROSS
THE REGION WILL BE RATHER STEEP LATER IN THE DAY AS TEMPS SURGE TO
ABOVE NORMAL LEVELS...THEREFORE MODERATE INSTABILITY COULD ALLOW FOR
ENHANCED/STRONG CONVECTION ACROSS THE WESTERN MOST ZONES WHERE
UPDRAFTS WILL BE LESS INHIBITED.  OTHERWISE...EXPECTING GENERAL
SHOWERS AND THUNDERSTORMS ON TUESDAY AFTERNOON/EVENING AHEAD OF
APPROACHING FRONT.

EXPECTING A NOCTURNAL FROPA OVERNIGHT INTO WEDNESDAY MORNING WITH
THE MORE ENHANCED UPPER LEVEL SUPPORT PASSING BY TO NORTH.
THUS...POPS WILL ACTUALLY TAPER WITH DIURNAL COOLING THROUGH THE
NIGHT WITH ONLY LOW END CHANCE LEVEL POPS RESIDING ACROSS THE HIGH
TERRAIN.  MODELS CONTINUE TO INDICATE THE FRONT SLOWING AND BECOMING
NEARLY STATIONARY THROUGH THE REMAINDER OF THE DAY ON WEDNESDAY AS
THE UPPER FLOW FLATTENS AND PARENT SURFACE TROF EJECTS TO THE
NORTHEAST.  THIS WILL BEGIN A RATHER NOCTURNALLY INDUCED UNSETTLED
WEATHER PERIOD ACROSS NORTHEAST GA AND THE WESTERN CAROLINAS.  DUE
TO THE SLOWER/STALLED PROGRESSION OF THE FRONT...EXPECTING ANY
SURFACE COOLING/DRYING TO BE MINIMAL.  HOWEVER...THE MID AND UPPER
LEVELS WILL EXPERIENCE MODERATE DRYING WHICH WILL ACTUALLY ALLOW FOR
RATHER STEEP LAPSE RATES WEDNESDAY AFTERNOON.  AS THE UPPER RIDGE
SLOWLY RETROGRADES WEST AND THE SURFACE HIGH WEAKENS...THE
ATMOSPHERE WILL LIKELY BE FREE FOR CONVECTION AMIDST PROFILES
SUPPORTING NEARLY 1500J/KG SBCAPE.  THUS...POPS WILL RAMP UP INTO
THE AFTERNOON TO LOW END LIKELY LEVELS OVER THE MORE CLIMO FAVORED
REGIONS OF THE UPPER FRENCH BROAD WHILE SOLID CHANCE POPS RESIDE
SOUTH OF INTERSTATE 40 WHERE FRONTAL BOUNDARY REMAINS.  WILL
CONTINUE TO EVALUATE STRONG/SEVERE THUNDERSTORM POTENTIAL ON
WEDNESDAY AS PROFILES WOULD SUPPORT DOWNBURST/HAIL THREATS.
TEMPERATURES THROUGH THE SHORT TERM PERIOD WILL REMAIN NEAR OR JUST
ABOVE NORMAL.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 330 AM EDT MONDAY...THE EXTENDED RANGE FORECAST PERIOD
INITIALIZES THURSDAY MORNING WITH DIFFUSE QUASI STATIONARY MOISTURE
AXIS FROM OLD FRONTAL BOUNDARY REMAINING OVER THE REGION.
MEANWHILE...UPPER RIDGE WILL REBUILD SOMEWHAT ACROSS THE SOUTHEAST
WITH REINFORCING SURFACE HIGH PRESSURE SLIDING EAST AND OUT TO SEA
OVER THE MID ATLANTIC.  THIS PATTERN WILL PERSIST THROUGH WEEKS END
WITH DIURNALLY INDUCED INSTABILITY WORKING TO OVERCOME CAPPING EACH
DAY WARRANTING AT LEAST CHANCE LEVEL POPS FOR THE AFTERNOON HOURS.
GLOBAL MODELS REMAIN IN CONSENSUS ON ANOTHER RATHER ROBUST FROPA
OVER THE WEEKEND WITH SOME DISCONTINUITY REGARDING TIMING AND
INTENSITY.  THE GFS SOLUTIONS ARE A FEW HOURS FASTER THAN THAT OF
THE ECWMF...NEVERTHELESS BOTH INDICATE FRONTAL PASSAGE LATE SATURDAY
EVENING INTO SUNDAY.  AS THE FRONT APPROACHES...ABOVE MENTIONED
SUBSIDENCE WILL WEAKEN AS UPPER HEIGHTS AND SURFACE PRESSURES FALL.
THEREFORE FAIRLY HEALTHY POPS ARE FORECAST OVER THE WEEKEND WITH MID
LEVEL CHANCE POPS FEATURED ACROSS THE LOWER TERRAIN WHILE NEAR
LIKELY LEVEL POPS ARE MENTIONED ACROSS THE NORTHERN
MOUNTAINS/FOOTHILLS.  HIGH PRESSURE LOOKS TO BUILD IN BEHIND THE
FRONT FOR THE START OF THE NEW WORK WEEK LEADING TO DECREASING
PRECIPITATION CHANCES AS DRIER AIR ADVECTS IN.  TEMPERATURES THROUGH
THE MAJORITY OF THE EXTENDED RANGE WILL BE ABOVE NORMAL WITH SLIGHT
COOLING FORECAST BEHIND THE LATE WEEKEND FROPA FOR THE NEW WEEK.

&&

.AVIATION /16Z MONDAY THROUGH FRIDAY/...
AT KCLT...BKN CIRRUS WILL REMAIN OVER THE AREA THRU THE MORNING WITH
SCT HIGH BASED CU DEVELOPING FOR THE AFTERNOON. THE CU WILL BECOME
BKN FOR LATE AFTERNOON INTO EARLY EVENING WHEN IT SCATTERS OUT. DO
NOT EXPECT ANY VSBY RESTRICTIONS THRU THE PERIOD. LIGHT SW WIND THIS
MORNING BECOMES WSW FOR THE AFTERNOON. LIGHT SLY WIND EXPECTED
DURING THE EVENING AND OVERNIGHT. BEST CHC OF CONVECTION WILL BE
ACROSS THE MTNS.

ELSEWHERE...OUTSIDE OF THE MTNS WILL SEE SIMILAR CONDITIONS AS KCLT.
KAVL WILL SEE VLIFR THRU 13Z...LIFR BECOMING LOW VFR BY 14Z. THERE
WILL ALSO BE SOME SHRA AROUND THIS MORNING. NWLY WIND PICKS UP THIS
MORNING BECOMING SLY THIS AFTERNOON...THEN CALM OVERNIGHT. SHUD BE
ANOTHER NITE WITH AT LEAST IFR AND LIKELY VLIFR BEFORE DAYBREAK.
KAVL HAS THE BEST CHC OF SEEING ANY AFTERNOON/EVENING CONVECTION.
HOWEVER...CHC STILL TOO LOW TO INCLUDE IN THE TAF ATTM.

OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE
WEEK...BUT RESTRICTIONS ARE POSSIBLE EARLY EACH MORNING DUE TO LOW
CLOUDS AND FOG...PRIMARILY IN THE MOUNTAIN VALLEYS. DIURNALLY DRIVEN
SHRA/TSRA ARE EXPECTED EACH AFTERNOON WITH THE MOST COVERAGE OVER
THE MOUNTAINS.

CONFIDENCE TABLE...

            15-21Z        21-03Z        03-09Z        09-15Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH  84%     MED   70%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%

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...CDG
NEAR TERM...PM/RWH
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...RWH






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