-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 161418
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1018 AM EDT SUN JUN 16 2013

.SYNOPSIS...
DRY HIGH PRESSURE OVER THE CAROLINAS WILL DRIFT OFF THE CAROLINA
COAST THROUGH SUNDAY AS THE NEXT COLD FRONT CROSSES THE UPPER
MISSISSIPPI AND OHIO VALLEYS. EXPECT THIS FRONT TO BRING GOOD
COVERAGE OF RAINFALL IN THE EARLY HALF OF THE WEEK. THE FRONT WILL
THEN STALL FROM WEST TO EAST JUST SOUTH OF OUR REGION AND SLOWLY
DISSIPATE LATE IN THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 1010 AM EDT SATURDAY...DEWPOINTS HAVE SHOT UP INTO THE MID TO
UPPER 60S OVER MUCH OF THE FOOTHILLS AND PIEDMONT THIS MORNING.
WELCOME BACK...HUMIDITY. THE FFC AND EVEN OHX SOUNDINGS STILL SHOW A
SUBSIDENCE INVERSION AND I/D EXPECT DEWPOINTS TO MIX OUT A LITTLE
INTO THE AFTN...BUT I/VE STILL INCREASED THEM 3 TO 4 DEGREES ACROSS
MOST OF THE FORECAST AREA. THERE IS SOME PATCHY MID AND HIGH LEVEL
CLOUD COVER OVER THE AREA...BUT IT/S SUNNY IN MANY AREAS ATTM.
CLOUDS SHOULD GRADUALLY INCREASE THROUGH THE AFTN...HOWEVER. WITH
THE INVERSION IT SHOULD TAKE A WHILE FOR UPDRAFTS TO DEEPEN TO THE
POINT THAT CONVECTION DEVELOPS OVER THE MTNS. THIS TREND IS WELL
REPRESENTED IN THE GRIDS WITH PCPN CHANCES GRADUALLY INCREASING INTO
THE EVENING HOURS. OVER THE FOOTHILLS AND PIEDMONT SHOULD SHOULD
TAKE UNTIL AROUND DARK FOR CONVECTION TO DEVELOP. WITH MOIST
PROFILES AND WEAK LAPSE RATES ON THE 12 UTC SOUNDINGS...I/LL STILL
WITH GARDEN VARIETY CONVECTION TYPE WORDING THAT WE HAVE IN OUR
CURRENT HWO.

AS OF 700 AM EDT...HAVE ADDED A BIT MORE MORNING FOG ACROSS THE SW
MTN VALLEYS AT DAYBREAK...OTHERWISE THE FORECAST REMAINS ON TRACK.
MODEL PROFILES CONTINUE TO SHOW SHALLOW MOISTURE TRAPPED BELOW AN
800 TO 700 MB INVERSION LAYER ACROSS THE AREA. IR SATELLITE IMAGERY
IS SHOWING THE ASSOCIATED SCATTERED STRATOCUMULUS DEVELOPING IN THIS
LAYER...AND THESE SCATTERED CLOUDS MAY LINGER THROUGH THE MUCH OF
THE DAY DESPITE SOME HEATING...WITH HIGHER CLOUDS GRADUALLY
THICKENING ALOFT FROM THE W. DEEPER MOISTURE WILL SLOWLY RETURN TO
PROFILES FROM THE SW TODAY...WITH A SERIES OF SHORTWAVES MOVING FROM
THE MID MS RIVER VALLEY TO THE BASE OF THE SRN APPALACHIANS THIS
EVENING THROUGH TONIGHT. EXPECT SCATTERED CONVECTION TO BEGIN ACROSS
THE NC MTNS THIS AFTN AS LAPSE RATES STEEPEN ALOFT...WITH ISOLD TO
SCT COVERAGE SPREADING EAST INTO THE FOOTHILLS AND PIEDMONT DURING
THE EVENING HOURS. THE FOCUS FOR CONTINUED OVERNIGHT CONVECTION WILL
THEN RETURN TO THE MTNS...ESPECIALLY SRN SECTIONS...WITH IMPROVED
FORCING FROM WEAK UPPER WAVES AND LOW LEVEL SW UPSLOPE FLOW. EXPECT
NEAR NORMAL MAX TEMPS THIS AFTN...WITH MINS 1 TO 2 CATEGORIES ABOVE
NORMAL TONIGHT IN INCREASING CLOUDS.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 230 AM EDT SUNDAY...NOT MUCH HAS CHANGED IN THE LAST 24 HOURS
WITH REGARDS TO WEATHER IN THE SHORT TERM.  BY MONDAY...UPPER LEVEL
RIDGE THAT IS CURRENTLY IN PLACE ACROSS THE SOUTHEAST WILL FLATTEN
OUT AND SURFACE HIGH PRESSURE WILL SHIFT EASTWARD OVER THE
ATLANTIC.  IN RESPONSE...SOUTHERLY FLOW WILL ADVECT IN A MARITIME
AIRMASS LEADING TO DEWPOINTS CLIMBING INTO THE THE UPPER 60S ACROSS
THE PIEDMONT AND MID 60S IN THE HIGHER TERRAIN.  THIS INCREASED
MOISTURE WILL LEAD TO INCREASING INSTABILITY AS EVIDENT IN FORECAST
SOUNDINGS.  BOTH NAM AND GFS SOUNDINGS ARE FAIRLY UNSTABLE WITH
SBCAPE VALUES NEAR 1000J/KG BY LATE MORNING MONDAY.  HOWEVER...BOTH
MODELS PLACE A SUBSTANTIAL CAPPING INVERSION IN THE LOW LEVELS
DURING THE MORNING HOURS.  THE CAP IS EXPECTED TO HOLD INTO THE
AFTERNOON HOURS WHERE BY THEN INCREASING SKY COVER SHOULD DAMPEN
OVERALL INSTABILITY ACROSS THE REGION.  WITH THAT SAID...THE AREA OF
GREATEST INSTABILITY ON MONDAY WILL LIE ACROSS NORTHEAST GEORGIA AND
THE CAROLINA PIEDMONTS.  IT WILL BE IN THIS REGION WHERE THE MORE
INTENSE UPDRAFTS WILL BE POSSIBLE...ALTHOUGH NOT EXPECTED TO REACH
SEVERE LIMITS.  ASIDE FROM THUNDERSTORM ACTIVITY...SHOWERS WILL
SPREAD ACROSS THE REGION ON MONDAY AFTERNOON LEADING LIKELY POPS
ACROSS MOST OF THE AREA.  TEMPERATURES ON MONDAY WILL BE NEAR NORMAL
FOR HIGHS AND SLIGHTLY ABOVE NORMAL FOR LOWS AS SKY COVER WILL BE
DENSE THROUGH MONDAY AND INTO TUESDAY.

MEANWHILE...SURFACE LOW LOCATED OVER SOUTHERN ONTARIO AND THE
NORTHEAST UNITED STATES WILL SPREAD A COLD FRONT ACROSS THE OHIO AND
TENNESSEE VALLEYS.  THIS FRONT WILL BEGIN TO PUSH INTO WESTERN NORTH
CAROLINA ON TUESDAY AFTERNOON CAUSING AN INCREASE IN SHOWER
ACTIVITY.  SOLID LIKELY POPS OVERSPREAD THE ENTIRE CWA ON TUESDAY
AFTERNOON DUE TO CONVERGENCE ALONG THE BOUNDARY AS IT MOVES
THROUGH.  INSTABILITY SHOULD BE FAIRLY LIMITED ON TUESDAY AS
CONTINUED SKY COVER LEADS TO MINIMAL HEATING AND DAYTIME HIGH
TEMPERATURES STRUGGLING TO TOP 80 IN MOST AREAS.  THEREFORE...
CONSIDERING LOW INSTABILITY COMBINED WITH MINIMAL BULK SHEAR...THE
SEVERE WEATHER THREAT LOOKS TO BE RATHER LOW AT THIS TIME THUS
LEADING TO MORE OF A GENERAL THUNDERSTORM OUTLOOK.  LATEST MODEL
GUIDANCE CONTINUES TO THE SLOW PROGRESSION OF THE FRONT INTO THE
MIDLANDS/LOW COUNTRY BY WEDNESDAY MORNING...WHICH IS A CHANGE FROM
PREVIOUS MODEL RUNS WHICH WANTED TO STALL THE FRONT ACROSS THE
UPSTATE INTO WEDNESDAY.  LOWERED POPS TO CHANCE LEVELS ACROSS THE
ENTIRE AREA AS SOME POST FRONTAL STRATIFORM PRECIPITATION COULD
LINGER ON WEDNESDAY.  ALTHOUGH THE FRONT SHOULD BE LOCATED TO THE
SOUTH...TEMPERATURES AND DEWPOINTS WONT SUFFER MUCH AS HIGHS ON
WEDNESDAY WILL BE AROUND 80 AND DEWPOINTS REMAIN IN THE MID TO UPPER
60S.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 245 AM EDT SUNDAY...ASIDE FROM HIGH TEMPERATURES...THE
EXTENDED PERIOD LOOKS RATHER NORMAL FOR THIS TIME OF YEAR.  HIGH
PRESSURE WILL BUILD IN ACROSS THE APPALACHIANS ON THURSDAY MORNING
AND IMMEDIATELY BEING PUSHING EASTWARD...EVENTUALLY SETTING UP
OFFSHORE BY THURSDAY EVENING.  IN RESPONSE...RETURNING SOUTHERLY
FLOW WILL USHER IN A GRADUAL WARMING TREND.  KEPT LOW END CHANCE
POPS IN THE FORECAST FOR THURSDAY THROUGH SATURDAY EVENING...MAINLY
DUE TO DAYTIME HEATING INDUCED CONVECTION.  HIGH TEMPERATURES
THROUGH THE PERIOD WILL START OFF BELOW NORMAL AND INCREASE TO NEAR
NORMAL LEVELS...LOWS SHOULD BE AT OR ABOVE NORMAL.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
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AT KCLT...MAINLY SCATTERED STRATOCUMULUS WILL PERSIST ACROSS THE
AREA TODAY WITH MOISTURE TRAPPED JUST BELOW AN 800 TO 700 MB
INVERSION. MEANWHILE...HIGHER LEVEL CLOUDS WILL INCREASE AND THICKEN
AHEAD OF WEAK SHORTWAVES MOVING EAST FROM THE MS RIVER VALLEY. WILL
KEEP THE KCLT FORECAST DRY THROUGH TONIGHT. ISOLD TSTMS COULD MOVE
EAST OFF THE MTNS LATE IN THE DAY AND POSSIBLY APPROACH THE PIEDMONT
THIS EVENING...BUT CONFIDENCE IS TOO LOW TO MENTION THIS IN THE TAF.
WINDS WILL REMAIN SOLIDLY S TO SW AT 10 KT OR LESS THROUGH THE
PERIOD. RETURNING BL MOISTURE IN THE SRLY FLOW MAY GENERATE SOME LOW
CLOUDS...SO WILL HINT AT THIS WITH A SCATTERED LAYER TOWARD DAYBREAK
MONDAY.

ELSEWHERE...EXPECT THICKENING CIRRUS ABOVE SCT TO BKN STRATOCUMULUS
TRAPPED BENEATH THE 800 TO 700 MB INVERSION LAYER ACROSS THE REGION.
SCT CONVECTION WILL START ACROSS THE NC MTNS THIS AFTERNOON AS
MOISTURE INCREASES AND WEAK UPPER TRIGGERING ARRIVES FROM THE WEST
AS THE CAP WEAKENS...ESPECIALLY OVER THE MTNS. THE CONVECTION MAY
MOVE OFF THE MTNS THROUGH THE EVENING HOURS TO APPROACH THE FOOTHILL
TAF SITES...BUT CONFIDENCE IS ONLY HIGH ENOUGH FOR A VCTS AND PROB30
FOR THUNDER KAVL LATE THIS AFTN/EVENING. EXPECT S TO SW SFC WINDS
LESS THAN 10 KT. SOME BL MOISTURE SHOULD RETURN OVERNIGHT...WITH A
STRATUS LAYER POSSIBLE TOWARD DAYBREAK MONDAY.

OUTLOOK...THE CHANCES FOR SHRA/TSTMS AND ASSOCIATED FLIGHT
RESTRICTIONS WILL INCREASE MON THROUGH TUE WITH THE ARRIVAL OF A
FRONT. CONDITIONS WILL REMAIN UNSETTLED THROUGH MUCH OF THE WEEK.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-14Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  81%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     MED   75%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  92%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
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
-- End Changed Discussion --

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...HG/MCAVOY
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...HG