Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 042146
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
546 PM EDT SAT JUL 4 2015

.SYNOPSIS...
A BROAD UPPER LEVEL TROUGH WILL REMAIN OVER THE SOUTHEAST THROUGH
MONDAY...PROVIDING LIFT AND MAINTAINING ELEVATED RAIN AND
THUNDERSTORM CHANCES EACH DAY. SLIGHTLY DRIER CONDITIONS RETURN
TUESDAY AND WEDNESDAY...BEFORE ANOTHER FRONT PUSHES ACROSS THE
SOUTHERN APPALACHIANS BY THE END OF THE WORK WEEK. HIGH TEMPERATURES
WILL REMAIN BELOW AVERAGE OVER THE WEEKEND BEFORE CLIMBING BACK TO
NORMAL BY THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
500 PM EDT UPDATE...REGIONALLY...THE CWFA IS IN A SCCAPE MINIMA...
GENERALLY 1000 J/KG OR LESS. SCATTERED GARDEN VARIETY SHOWERS AND A
FEW STORMS WILL CONTINUE TO PERCOLATE ACRS WESTERN NC...INITIATED BY
DIFFERENTIAL HTG AND CONVERGENCE ALONG LEE/PIEDMONT TROUGH. ACTIVITY
IS EXPECTED TO WANE WITH LOSS OF HTG LATER THIS EVENING.

AS OF 215 PM EDT...NEARLY THE ENTIRE FORECAST AREA REMAINS FAIRLY
STABLE THIS AFTERNOON UNDER ABUNDANT MID CLOUDS WITH PATCHY LIGHT
SHRA FALLING INTERMITTENTLY. MOUNTAIN SHOWERS ARE STARTING TO SHOW
SOME VERTICAL DEVELOPMENT...AND A FEW BREAKS OVER THE NC FOOTHILLS
AND THE ERN FRINGE HOLD OUT SOME CHANCE FOR ISOLD TSTMS TO REDEVELOP
IN LINE WITH THE HRRR. OTHERWISE...500 MB HEIGHTS CONTINUE TO FALL
ACROSS THE MS RIVER VALLEY THIS AFTERNOON...AND HEIGHT FALLS WILL
CONTINUE EASTWARD ACROSS TN TONIGHT THROUGH SUNDAY. INTERMITTENT
SHORTWAVES WILL PIVOT EAST THROUGH THE FORECAST AREA AROUND THIS
UPPER TROUGH DURING THIS PERIOD. IN ADDITION...THE ENTRANCE REGION
OF AN UPPER JETLET WILL REMAIN PARKED JUST WEST OF THE SRN
APPALACHIANS THROUGH THE NEAR TERM...ALTHOUGH THE JETLET LOOKS A BIT
WEAKER THAN IN PREVIOUS MODEL RUNS. AT THE SURFACE...A STALLED FRONT
REMAINS DRAPED NORTH AND WEST OF THE AREA THIS AFTN...WITH A
LINGERING SFC TROUGH AXIS STRETCHED OUT WELL TO THE SOUTH IN THE
BETTER INSTABILITY. GIVEN ALL OF THESE VARIOUS FORCING
MECHANISMS...ALONG WITH CONTINUED WSW UPSLOPE INTO THE SW MTNS...AND
PRECIPITABLE WATER VALUES RUNNING 1.5 TO 1.75 INCHES OVER THE
AREA...ANTICIPATE THE PRECIPITATION COVERAGE MAKING A COMEBACK FROM
THE WEST TONIGHT THROUGH SUNDAY. OTHER THAN ANY LINGERING DIURNAL
SHRA/TSRA...A FAIRLY SHARP W TO E GRADIENT WILL BE FEATURED ON
POPS...WITH THE SW MOUNTAINS THE CLEAR FOCUS FOR ANY HIGHER END
UPSLOPE QPF. NO CHANGES ARE NEEDED AT PRESENT TO THE FFA. WILL
CONTINUE A SMALLER THAN CLIMO RANGE ON MIN/MAX TEMPS.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 205 PM SUNDAY...RISING HEIGHTS ALOFT WILL BE THE PRIMARY STORY
OF THE SHORT TERM...AS THE UPPER LOW FILLS AND SLOWLY LIFTS INTO THE
MID-ATLANTIC...AND AN UPPER RIDGE AXIS BEGINS BUILDING OVER THE
SOUTHEAST STATES. THIS WILL RESULT IN A MARKED CHANGE TO THE
THERMODYNAMIC CHARACTER OF THE AIR MASS ACROSS THE AREA...FROM
UNSEASONABLY MOIST AND RELATIVELY COOL CONDITIONS...TO MUCH MORE
SEASONAL LEVELS OF HEAT AND HUMIDITY BY TUESDAY AFTERNOON.

CHANCES FOR SHOWERS AND THUNDERSTORMS SUNDAY NIGHT INTO MONDAY WILL
BE HIGHEST ACROSS NORTHERN AND FAR WESTERN ZONES...AS THE UPPER LOW
MEANDERS JUST WEST OF THE APPALACHIANS. AS THE DEEPER MOISTURE LIFTS
INTO THE MID-ATLANTIC...THE HYDRO THREAT IS EXPECTED TO WANE MONDAY
AFTERNOON...WHILE THERE MAY BE AN UPTICK IN THE LOCAL SEVERE STORM
POTENTIAL...ESPECIALLY ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA...WHERE LESS CLOUD COVER IS ANTICIPATED. BY TUESDAY...A RETURN
TO A MORE TYPICAL DIURNAL DEEP CONVECTIVE CYCLE IS EXPECTED...WITH
THE POTENTIAL FOR ISOLATED STRONG-TO-SEVERE PULSE STORMS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 230 PM INDEPENDENCE DAY...THE MEDIUM RANGE BEGINS 00Z
WEDNESDAY AS A FRONTAL BOUNDARY STEERED BY AN UPPER TROUGH OVER THE
CENTRAL PLAINS/GREAT LAKES REGION CONTINUES ITS EASTWARD PROGRESSION
TOWARDS THE FORECAST AREA. H5 HEIGHTS BEGIN TO FLATTEN LATE
WEDNESDAY...AND BY THURSDAY AN ATLANTIC UPPER HIGH WITH SURFACE
REFLECTION INTRUDES INTO THE SOUTHEAST. GLOBAL MODELS DIVERGE WITH
THE HANDLING OF THIS FEATURE AND ABOVE-MENTIONED FRONT. THE GFS IS
MORE BULLISH ON THE NORTHWARD AND WESTWARD EXTENT OF THE HIGH...AND
THEREFORE ACTS TO SOMEWHAT BLOCK  THE APPROACHING FRONT AND KEEP
MAIN IMPACTS FROM A SERIES OF WEAK SURFACE LOWS/IMPULSES FARTHER TO
THE NORTH OF THE CWFA. THE ECMWF KEEPS THE HIGH PRESSURE FEATURE
FARTHER TO THE SOUTH...SO THE TRACK REMAINS A BIT FARTHER TO THE
SOUTH THAN THE GFS. THERE IS AGREEMENT THAT SOME TYPE OF IMPULSE/LOW
WILL DEVELOP OVER THE CENTRAL PLAINS FRIDAY...THOUGH MODELS AGAIN
DIVERGE ON BOTH TIMING AND STRENGTH OF THE FEATURE. WENT WITH A
BLEND OF THE FASTER/WEAKER GFS AND SLOWER/STRONGER ECMWF AS NO
PARTICULAR SOLUTION STANDS OUT AS MORE LIKELY AT THIS POINT. POPS
WERE THEREFORE ELEVATED FRIDAY NIGHT.

OVERALL...SOUTHWESTERLY FLOW DRIVEN BY THE BERMUDA HIGH WILL LEND
ITSELF TO MORE OF A GULF FETCH...KEEPING DEEP LAYER MOISTURE
ABUNDANT THROUGH MOST OF THE PERIOD. A LACK OF GOOD UPPER FORCING
COMBINED WITH SOMEWHAT UNIMPRESSIVE INSTABILITY FOR MID-SUMMER WILL
LEND ITSELF TO MAINLY DIURNAL POPS NEAR CLIMO FOR MOST OF THE
PERIOD...THOUGH THE PREVIOUSLY MENTIONED LOW/FRONTAL BOUNDARY WILL
ENHANCE THE DIURNAL POPS LATER IN THE WEEK. BOTH MAX AND MIN TEMPS
WILL REMAIN NEAR TO JUST ABOVE CLIMO THROUGH THE ENTIRE MEDIUM
RANGE.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
AT KCLT...VFR CLOUDS AND LIGHT SHRA HAVE KEPT THE PIEDMONT FAIRLY
STABLE THIS AFTERNOON...WITH MAINLY INTERMITTENT -SHRA EXPECTED
THROUGH LATE AFTERNOON. THE COVERAGE OF PRECIPITATION SHOULD SHIFT
BACK TOWARD THE MOUNTAINS TONIGHT INTO SUNDAY AS THE UPPER TROUGH
SHARPENS UP WEST OF THE MTN CHAIN. WILL ONCE AGAIN HINT AT FEW TO
SCT LOW STRATUS BUT NONE OF THE MODEL PROFILES OR MOS HAVE ANY CIG
RESTRICTIONS TOWARD DAYBREAK SUNDAY. EXPECT OCNL SW GUSTS TO
CONTINUE UNTIL EARLY EVENING...WITH STEADIER SW FLOW LESS THAN 10 KT
THEREAFTER.

ELSEWHERE...SHOWER COVERAGE WILL STEADILY INCREASE IN THE MTNS AS
HEIGHTS FALL TO THE WEST OF THE APPALACHIANS...BUT COVERAGE REMAINS
MORE UNCERTAIN OVER THE FOOTHILLS WHERE PROFILES ARE FAIRLY STABLE.
ANTICIPATE VFR CONDITIONS INITIALLY...WITH TEMPO MVFR UNDER ANY SHRA
AT KAVL. LOWER CIG RESTRICTIONS WILL BE POSSIBLE ONCE AGAIN TOWARD
DAYBREAK...BUT MORE CERTAIN AT KAVL WHERE MORE QPF IS EXPECTED. WILL
JUST HINT AT MVFR CIGS OVERNIGHT AT THE FOOTHILL SITES. SW WINDS
WILL GUST AT THE UPSTATE TAF SITES THROUGH LATE AFTN BEFORE SETTLING
DOWN TO STEADY SW LESS THAN 10 KT FOR THE REMAINDER OF THE PERIOD.
ANOTHER ROUND OF SHOWERS MAY MOVE UP THE MTNS/FOOTHILLS SUNDAY
MORNING...WITH MAINLY VCSH AT THE FOOTHILL SITES...AND MORE SOLID
SHRA WITH VCTS AT KAVL AFTER 15Z SUNDAY.

OUTLOOK...PRECIPITATION COVERAGE WILL REMAIN FAIRLY HIGH INTO SUNDAY
NIGHT BEFORE THE PATTERN GRADUALLY TRANSITIONS TO MORE DIURNAL
TIMING AND COVERAGE MONDAY THROUGH THURSDAY. WITH CONTINUED MOISTURE
IN THE AREA...RESTRICTIONS WILL BE POSSIBLE UNDER ANY HEAVIER
SHOWERS AND ALSO AROUND DAYBREAK.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH  92%     HIGH 100%
KAVL       HIGH  85%     HIGH  85%     MED   61%     HIGH  85%
KHKY       HIGH 100%     HIGH 100%     HIGH  85%     HIGH  85%
KGMU       HIGH 100%     HIGH 100%     HIGH  92%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH  84%     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...FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR GAZ010-017-018-
     026-028-029.
NC...FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR NCZ048-051-052-
     058-059-062-063.
SC...FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR SCZ001-004.

&&

$$
SYNOPSIS...LEV
NEAR TERM...CSH/HG
SHORT TERM...JDL/WIMBERLEY
LONG TERM...LEV
AVIATION...HG


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