Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 302341
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
741 PM EDT THU JUL 30 2015

.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO MOVE THROUGH THE AREA THIS
AFTERNOON...AND SETTLE SOUTHEAST OF THE AREA TONIGHT THROUGH FRIDAY.
THE FRONT AND ASSOCIATED DEEPER MOISTURE WILL LIKELY REMAIN CONFINED
ALONG THE SOUTHEAST COASTLINE THROUGH THE WEEKEND...WITH SLIGHTLY
COOLER TEMPERATURES AND MUCH DRIER AIR EXPECTED OVER THE FORECAST
AREA. LOW LEVEL MOISTURE WILL GRADUALLY RETURN EARLY NEXT WEEK AS
ANOTHER COLD FRONT APPROACHES FROM THE NORTH.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 740 PM EDT THURSDAY...OTHER THAN SLIGHT INCREASES TO MID
CHANCE POPS ALONG THE I85 CORRIDOR OVER THE NEXT FEW HOURS PER
LATEST CAM GUID...CURRENT FCST REMAINS ON TRACK. DID MAKE MINOR
TWEAKS TO TEMPS/DEWS AND SKY TO ACCOUNT FOR MOST RECENT SAT/OBS.

PREVIOUS DISCUSSION...

AS OF 215 PM...A VIGOROUS SHORT WAVE TROF CONTINUES TO PROGRESS ACRS
THE GREAT LAKES INTO THE NORTHEAST STATES TONIGHT...BRINGING SOME
HEIGHT FALLS ATOP THE CWFA NEAR THE BASE OF THE TROF AXIS.
HOWEVER...OVERALL FORCING IS FAIRLY WEAK THIS FAR SOUTH...AS
VORTICITY IS BEING SHEARED OUT. AT THE SFC...A COLD FRONT IS MAKING
INROADS INTO THE PIEDMONT OFF THE BLUE RIDGE. SOME METARS ARE
REPORTING A NOTABLE DROP IN DEWPTS FROM THE LWR 70S TO UPR 60S.
HOWEVER...THE DRIER AIR IS STILL BACK OVER CENTRAL KY/TN. CAPE IS
DECENT ALONG AND AHEAD OF THE FRONT...BUT DEEP CONVERGENCE MUST BE
LACKING...BECAUSE CONVECTION HAS BEEN UNIMPRESSIVE SO FAR GIVEN THE
INSTBY. I WILL KEEP A CHC POP THRU THE REST OF THE AFTN...THEN TAPER
POPS FROM NW TO SE THIS EVENING.

OVERNIGHT...DRY AIR WILL CONTINUE TO FILTER IN FROM THE NORTH...THUS
ENDING POPS. FCST SNDGS SHOW LINGERING MOISTURE UNDER A DEVELOPING
INVERSION...SO THERE WILL BE SOME LINGERING STRATOCU THRU
DAYBREAK...ESP ALONG AND SOUTHEAST OF I-85. MIN TEMPS WILL BE A
COUPLE CATEGORIES COOLER THAN IN RECENT DAYS ACRS THE NRN
ZONES...BUT STILL ABOVE NORMAL ACRS THE SOUTHERN HALF OF THE CWFA.

FRIDAY...AS AN UPPER TROF DIGS ACRS THE APPALACHIANS...DRY HIGH PRES
WILL CONTINUE TO BUILD IN FROM THE NORTHWEST. GUIDANCE IN GOOD
AGREEMENT ON DEEPER MOISTURE BEING SHUNTED SOUTH OF THE CWFA ACRS
THE GULF STATES AND MIDLANDS. SO EXPECT A DRY DAY ON TAP.
THICKNESSES DO NOT FALL MUCH BEHIND THE FRONT...BUT DEWPTS SHUD DROP
INTO THE 50S TO LWR 60S ACRS THE ENTIRE AREA DURING THE AFTN. SO IT
SHUD FEEL MUCH LESS MUGGY. HIGHS WILL STILL BE A CATEGORY OR TWO
ABOVE NORMAL...EXCEPT NEAR NORMAL IN THE HIGH ELEVATIONS.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 230 PM EDT THURSDAY...THE WEATHER FOR THE WEEKEND LOOKS ABOUT
AS QUIET AND UNINTERESTING AS IT GETS FOR MID-SUMMER ACROSS THE
WESTERN CAROLINAS AND NORTHEAST GEORGIA. TEMPERATURES SHOULD BE
SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD...BUT THE MAIN STORY WILL
BE THE RELATIVELY DRY AIR MASS. IN THE WAKE OF THE COLD FRONT
PASSAGE...THE HIGH PRESSURE AIR MASS TO THE N AND NW WILL BE SLOW TO
MODIFY THRU THE WEEKEND. A BLEND OF THE MODELS SUGGESTS DEWPOINTS
DROPPING INTO THE 55 TO 60 RANGE SATURDAY AND SUNDAY...WHICH WILL
DROP THE AFTERNOON RH DOWN NEAR 30 PCT. THAT COMBINED WITH SOME
RELATIVELY WARM AIR AT MID LEVELS WILL ALL BUT ELIMINATE MOST OF THE
POTENTIAL FOR POSITIVE BUOYANCY...WHICH MEANS A VERY LOW POTENTIAL
FOR DEEP MOIST CONVECTION. ALTHO THE REMNANT COLD FRONT BOUNDARY
WILL BE CLOSE...IT SHOULD BE TO THE SOUTH OF THE FCST AREA.
THUS...EXPECT ONLY AN ISOLATED SHOWER OVER THE BALSAMS SATURDAY
AFTERNOON...OTHERWISE THE ENTIRE AREA SHOULD BE DRY THROUGH MIDDAY
SUNDAY. WILL ALLOW FOR SOME MODIFICATION BY SUNDAY AFTERNOON...SO A
SLIGHT CHANCE POP WILL BE INCLUDED MAINLY OVER THE MTNS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM EDT THURSDAY...THE MEDIUM RANGE BEGINS MONDAY WITH
SLIGHT HEIGHT RISES IN THE UPPER TROUGH HOVERING OVER THE EASTERN
SEABOARD. MONDAY AND TUESDAY ARE MARKED BY CONTINUED AIRMASS DRYING
AND LOW LEVEL Q-VECTOR DIVERGENCE...WITH BOTH MAJOR GLOBAL MODELS
SHOWING ONLY MINIMAL QPF RESPONSE OVER THE FORECAST AREA. MODEL
AGREEMENT WANES SIGNIFICANTLY AFTER TUESDAY...AS A FRONTAL BOUNDARY
SWINGS OUT OF THE MIDWEST. THE GFS PASSES THE FRONT THROUGH THE AREA
ON WEDNESDAY...WHILE THE ECMWF HANGS UP THE BOUNDARY OVER THE OHIO
RIVER VALLEY. QPF RESPONSE IS ONLY SLIGHT IN THE GFS DUE TO LACK OF
DEEP LAYER MOISTURE AND LESS THAN IMPRESSIVE INSTABILITY...SO KEPT
POPS TO SLIGHT CHANCE OR LOWER WITH BEST CHANCES OVER THE HIGHER
TERRAIN. THE UPPER TROUGH WILL CONTINUE TO HANG OVER THE EASTERN
CONUS THROUGH THE END OF THE PERIOD...AND THE TROUGH AXIS FINALLY
APPROACHES AND FORCES ANOTHER MORE SUBSTANTIAL FRONT THROUGH THE
AREA LATE THURSDAY OR FRIDAY. EXACT TIMING OF THE FRONT WILL NEED TO
BE HASHED OUT AS MODELS HOPEFULLY COME INTO BETTER AGREEMENT LATER
IN THE PERIOD...THOUGH QPF RESPONSE IS AGAIN NOT PARTICULARLY
IMPRESSIVE DUE TO LACK OF INSTABILITY. MAX TEMPS WILL START JUST
ABOVE CLIMO...AND RISE A DEGREE OR TWO BY THE END OF THE PERIOD.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR THROUGH THE PERIOD DESPITE WEAK COLD FROPA THIS
EVENING.  INITIALIZED TAF WITH VCSH AS LATEST CONVECTIVE ALLOWING
GUIDANCE FAVORS DEVELOPMENT ALONG/SOUTH OF THE I85 CORRIDOR THROUGH
03Z-04Z.  CONFIDENCE IS LOW DUE TO THE POOR VERIFICATION OF THE
GUIDANCE OVER THE LAST 6 HOURS...THUS OPTED NOT TO INCLUDE TEMPO.
OTHERWISE...THE FRONT WILL SLIDE THROUGH OVERNIGHT WITH 5-10KT WINDS
SOLIDLY OUT OF THE NNW THROUGH THE REMAINDER OF THE PERIOD WITH SOME
MINOR GUSTING POSSIBLE AROUND DAYBREAK...HOWEVER NOT IN TAF.  SKIES
WILL SCT AFTER ANY POSSIBLE CONVECTION TONIGHT LEADING TO FEW LOW
STRATUS UNDER HIGH LEVEL CIRRUS BY MORNING.  SOUNDINGS ARE RATHER
DRY ALOFT ON FRIDAY THUS REMOVAL OF ANY HIGH CLOUDS SEEMED WARRANTED
THEREFORE THE REMAINDER OF THE TAF BEYOND 18Z FEATURES ONLY LOW VFR
FEW CU.

ELSEWHERE...VFR AND THUS SIMILAR TO THAT OF KCLT ABOVE WITH A WEAK
COLD FROPA OCCURRING THIS EVENING.  ALL SITES ASIDE FOR KAVL FEATURE
LOW CONFIDENCE VCTS AS THE ATMOSPHERE IS MOST STABLE OVER THE
MOUNTAINS.  OTHERWISE...REMOVED ALL WX MENTION FROM ALL SITES AROUND
THE 03Z-04Z TIMEFRAME LEADING TO PREVAILING 06-10KTS NNW WINDS BY
MORNING ALONG WITH FEW LOW VFR STRATUS AND HIGH LEVEL CIRRUS.
EVENTUALLY EXPECTING THE MID/UPPER LEVELS TO DRY LEADING TO ONLY LOW
LEVEL FEW VFR CU BY MIDDAY AT THE SC SITES WITH SKC AT THE NC SITES.

OUTLOOK...EXPECTING GENERALLY DRY AND QUIET WEATHER THROUGH THE
WEEKEND WITH A GRADUAL INCREASE IN CHANCES FOR SHOWERS/THUNDERSTORMS
AND RESTRICTIONS FOR THE START OF THE NEW WORK WEEK.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
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...LEV
NEAR TERM...ARK/CDG
SHORT TERM...PM
LONG TERM...LEV
AVIATION...CDG



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