000
FXUS62 KGSP 181136
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
736 AM EDT TUE JUN 18 2013

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL MOVE EAST ACROSS THE AREA TODAY THROUGH
TONIGHT. ANOTHER UPPER LEVEL DISTURBANCE WILL CROSS THE REGION ON
WEDNESDAY...BUT WITH SOME DRYING OF THE ATMOSPHERE. HIGH PRESSURE
WILL BUILD OVER THE REGION THURSDAY THROUGH THE WEEKEND...BUT WITH
LOW LEVEL MOISTURE PERSISTING.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 350 AM EDT TUESDAY...UPPER LEVEL CYCLONIC FLOW CONTINUES TO
PROMOTE A RATHER DESTABILIZED WEATHER PATTERN ACROSS NORTHEAST
GEORGIA AND THE CAROLINAS IN THE NEAR TERM. MEANWHILE...INCREASINGLY
AMPLIFIED SHORTWAVE TROF CONTINUES ITS EASTWARD MOVEMENT ACROSS THE
MIDSOUTH REGION.  IN RESPONSE...FALLING HEIGHTS AND AMPLE SURFACE
MOISTURE HAVE ALLOWED FOR CONVECTION TO REMAIN ONGOING ACROSS
PORTIONS OF MIDDLE TENNESSEE AND NORTH CENTRAL ALABAMA.  EXPECTING
THIS CONVECTION TO CONTINUE ACROSS NORTHERN GEORGIA AND EAST
TENNESSEE EVENTUALLY MAKING IT ACROSS THE MOUNTAINS INTO THE CWFA.
INTO THE LATE MORNING HOURS AS THE UPPER IMPULSE SWINGS THROUGH.
KEPT CATEGORICAL POPS ACROSS THE MAJORITY OF THE FORECAST AREA
BEGINNING MID MORNING THROUGH TUESDAY AFTERNOON.  BEYOND
THAT...TAPERED TO LIKELY POPS ACROSS PORTIONS OF THE UPSTATE AND THE
NORTH CAROLINA PIEDMONT.  KEPT CATEGORICAL POPS ACROSS THE HIGHER
TERRAIN AS COLD FRONT WILL BE PUSHING IN AT THAT TIME.  CONVERGENCE
ALONG THE FRONT AND SOME MILD INSTABILITY WILL AT LEAST PROVIDE SOME
CHANCE FOR SOME THUNDERSTORM ORGANIZATION.  SHEAR PROFILES WILL
INCREASE ALONG THE FRONT THUS LEADING TO THE STRONGEST STORMS OF THE
DAY BEING IN THAT VICINITY.  A COMBINATION OF SHOWER AND
THUNDERSTORM ACTIVITY FROM BOTH THE EARLIER PASSING SHORTWAVE AND
THE ENCROACHING COLD FRONT...WILL LEAD TO POTENTIAL FLASH FLOODING.
FORECAST SOUNDINGS INDICATE PWAT VALUE IN EXCESS OF 1.5 INCHES IN
SOME PLACES.  THUS...ANY TRAINING THAT DEVELOPS COULD PROVIDE ENOUGH
RAINFALL IN A SHORT PERIOD OF TIME TO INITIATE FLASH FLOODING.
HOWEVER...THINK THAT IF THIS OCCURS IT WILL BE ON A MORE LOCAL SCALE
AND NOT WIDESPREAD THEREFORE OPTED AGAINST ISSUANCE OF FLASH FLOOD
WATCH.  CONDITIONS SHOULD IMPROVE SOMEWHAT BEHIND THE FRONT ON
TUESDAY EVENING AS DRIER AIR SPILLS INTO THE REGION.  TEMPERATURES
DURING THE NEAR TERM PERIOD WILL BE A FEW DEGREES BELOW NORMAL FOR
HIGHS...AND SLIGHTLY ABOVE TO NEAR NORMAL FOR LOWS.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM EDT TUESDAY...A POSITIVE TILT CLIPPER TYPE WAVE WILL
CROSS THE FORECAST AREA WED MORNING ALONG WITH THE ENTRANCE REGION
OF A WEAK UPPER JETLET. HOWEVER...A MID LEVEL DRY PUNCH WRAPPING IN
UNDER THE PASSING WAVE WILL CONSPIRE TO LIMIT SHOWER AND TSTM
COVERAGE TO SCATTERED AT BEST...MAINLY IN THE SLIGHTLY MORE UNSTABLE
EASTERN SECTIONS. THE FORECAST MODELS THEN SHOW REDEVELOPMENT BACK
OVER THE MTNS DURING THE AFTERNOON HOURS AS BOUNDARY LAYER
CONVERGENCE INCREASES AHEAD OF A WEAK COLD FRONT SETTLING SOUTHWARD
ALONG THE APPALACHIANS. WILL EXTEND SCATTERED TSTM COVERAGE SE INTO
THE PIEDMONT THROUGH EARLY WED EVENING BEFORE THE ACTIVITY
DISSIPATES.

UPPER HEIGHTS WILL THEN INCREASE IN EARNEST WED NIGHT THROUGH THU
NIGHT. ALTHOUGH MID AND UPPER LEVELS DRY OUT DURING THIS
PERIOD...THE SFC TO 850 MB LAYER WILL REMAIN MOIST AND A SE UPSLOPE
FLOW WILL DEVELOP TO KEEP SOME CLOUDS IN THE PICTURE. WILL FEATURE
MORE OF A DIURNAL SCT MTN TO ISOLD PIEDMONT TSTM PATTERN FOR THU
AFTN AND EVENING...WITH MAX TEMPS REMAINING BELOW CLIMATOLOGY.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 330 AM EDT TUESDAY...A DOMINANT RIDGE WILL GRADUALLY SET UP
OVER THE SOUTHEAST THROUGH THE MEDIUM RANGE PERIOD. BOUNDARY LAYER
MOISTURE WILL PERSIST FRI THROUGH MON AS BERMUDA HIGH PRESSURE
PUSHES ATLANTIC AND GULF MOISTURE INTO THE REGION ON PERSISTENT SE
TO SW LOW LEVEL FLOW. A PATTERN OF MAINLY DIURNAL CONVECTION WILL BE
ADVERTISED...WITH THE BEST CHANCE POPS OVER THE MOUNTAINS EACH
AFTERNOON AND EVENING. EXPECT A WARMING TREND UNDER THE HIGH
PRESSURE...WITH MAX TEMPS RECOVERING TO AROUND OR SLIGHTLY ABOVE
NORMAL SUNDAY AND MONDAY.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AT KCLT...SOLID IFR CIGS HAVE PREVAILED AT CHARLOTTE THROUGH THE
EVENING...HOWEVER STILL EXPECTING AN IMPROVEMENT TO MVFR LEVELS A
FEW HOURS AFTER SUNRISE.  SCATTERED CONVECTION CONTINUES ACROSS
PORTIONS OF EAST TENNESSEE AND NORTHEAST GEORGIA ASSOCIATED WITH AN
ADVANCING SHORT WAVE TROF.  AS UPPER LEVEL SHORT WAVE TROF
APPROACHES...AMPLE MOISTURE IN THE BOUNDARY LAYER WILL PROMPT A
REORGANIZATION OF OVC MVFR CIGS AND SCATTERED SHOWER DEVELOPMENT.
PRECIPITATION COVERAGE WILL CONTINUE TO INCREASE THROUGH THE LATE
MORNING HOURS ACROSS THE REGION THUS ADDED -SHRA BY AROUND 15Z.
CIGS WILL INCREASE TO VFR LEVELS LATE TOMORROW MORNING AS THE
ATMOSPHERE HEATS.  FURTHERMORE...INCREASING INSTABILITY THROUGH THE
COLUMN...AND CONVERGENCE ALONG A PASSING FRONTAL BOUNDARY WILL ALLOW
FOR SOME THUNDERSTORM DEVELOPMENT TOMORROW AFTERNOON.  WITH
THAT...INCLUDED A TEMPO FROM 20-24Z FOR MVFR VISB WITH TSRA.  THE
FRONT WILL LIKELY NOT REACH KCLT UNTIL AROUND THE 02Z TIMEFRAME
SHIFTING WINDS TO A NORTHERLY COMPONENT.  WINDS ALONG AND JUST AHEAD
OF THE FRONT COULD BE GUSTY WITH READINGS IN THE 20KT RANGE NOT
BEING OUT OF THE QUESTION.

ELSEWHERE...CIGS WILL RAISE SLIGHTLY ON TUESDAY MORNING BUT SHOULD
REMAIN AT MVFR LEVELS.  CIGS WILL FINALLY REBOUND TO VFR CONDITIONS
LATE MORNING AS THE BOUNDARY LAYER WARMS.  BY MID TO LATE
MORNING...UPPER LEVEL SHORTWAVE WILL MOVE IN...AND INSTABILITY WILL
HAVE INCREASED SOMEWHAT ALLOWING FOR SOME THUNDERSTORM ACTIVITY TO
DEVELOP.  THE WINDOW FOR THUNDERSTORMS LOOKS TO BE A LITTLE NARROWER
FOR THE SOUTH CAROLINA SITES..THUS HANDLED THEM WITH TEMPO GROUPS.
FOR KAVL AND KHKY...DECIDED TO PREVAIL TSRA AS MODEL GUIDANCE
INDICATES INSTABILITY SHOULD REMAIN HIGHER LATER INTO THE DAY AS THE
FRONT APPROACHES.  NEAR THE END OF THE PERIOD...THE FRONT WILL MOVE
THROUGH WESTERN NORTH CAROLINA BY AROUND 01Z...AND CONTINUE PUSHING
TO THE SOUTHEAST REACHING THE SOUTH CAROLINA SITES BY AROUND 03-04Z
WEDNESDAY.  WINDS ALONG AND JUST AHEAD OF THE FRONT COULD BE GUSTY
WITH READINGS IN THE 20KT RANGE NOT BEING OUT OF THE QUESTION.

OUTLOOK...CONDITIONS WILL IMPROVE SOMEWHAT TUE NIGHT AS DRIER AIR
FILLS IN BEHIND A COLD FRONT.  A MODERATELY UNSTABLE ATMOSPHERE
COMBINED WITH EASTERLY FLOW MAY LEAD TO SHOWER AND THUNDERSTORM
DEVELOPMENT MIDWEEK...CAUSING SPOTTY RESTRICTIONS.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-11Z
KCLT       HIGH  89%     HIGH  98%     HIGH  93%     HIGH  90%
KGSP       HIGH  91%     HIGH  98%     HIGH  95%     HIGH  98%
KAVL       HIGH  95%     HIGH  92%     HIGH  92%     HIGH  91%
KHKY       MED   79%     HIGH  97%     HIGH  92%     HIGH  98%
KGMU       HIGH  90%     HIGH  98%     HIGH  93%     HIGH  94%
KAND       HIGH  83%     HIGH  90%     HIGH  96%     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...HG
NEAR TERM...CDG
SHORT TERM...HG
LONG TERM...HG
AVIATION...CDG