000
FXUS62 KGSP 171752
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
152 PM EDT MON JUN 17 2013

.SYNOPSIS...
WEAK UPPER LEVEL DISTURBANCES WILL CROSS THE AREA FROM THE WEST
THROUGH MID WEEK AS A ZONE OF RELATIVELY ABUNDANT MOISTURE LAYS
DRAPED ACROSS THE AREA. SLIGHTLY DRIER HIGH PRESSURE WILL BUILD INTO
THE REGION THROUGH FRIDAY...WITH WARMER BERMUDA HIGH PRESSURE
DOMINATING THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
130 PM UPDATE...CONV ACTIVITY IS BEGINNING TO FILL IN ACROSS THE WRN
ZONES AND INTO THE NC FHILLS. THE CURRENT POPS HAVE THIS SCENARIO
WELL IN HAND AND WILL ANTICIPATE CONTINUED DEVELOPMENT TO THE EAST
THROUGH THE NEXT UPDATE...MAINLY ACROSS THE NC ZONES. SOME CELLS
ARE BECOMING RELATIVELY DEEP AND PRODUCING PEA HAIL. WITH WEAK UPPER
ENERGY AND MODEST SBCAPE...DONT EXPECT MUCH MORE THAN A FEW SPS/S
OVER THE NEXT COUPLE OF HRS. MAX TEMPS LOOK GOOD AND HR/LY TRENDS IN
THE OTHER SENSIBLE WX HAVE REQUIRED ONLY MINOR TWEAKS.

1030 AM UPDATE...MANY UPDATES NEEDED TO THE GRIDS DUE TO SERVICE
BACKUP THIS MORNING. THE MAIN ISSUE OVER THE NEXT COUPLE HRS WILL BE
THE DEVELOPMENT OF CONVECTION INTO THE WRN ZONES. THE 88D IS SHOWING
GOOD RESPONSE AND SOME DEEP CELLS TO THE H5 S/W AND IS FILLING ATTM
ACROSS THE NRN GA AND SE/RN TN. POPS HAVE BEEN ADJ UP WEST AND
LOWERED EAST AND SE WHERE SBCIN IS HOLDING STRONG. THE HIRES MODELS
INDICATE THE UPSTATE AND PIEDMONT WILL BE ONE OF THE LAST AREAS TO
SEE SHRA/TSTM DEVELOPMENT AND THIS MAKES SENSE AMOUNT OF DNVA TO
OVERCOME IN THESE AREAS. SKY AND TEMPS/TDS WERE ALSO ADJUSTED PER
THE ADVANCEMENT OF ACTIVITY IN FROM THE WEST. MAX TEMPS WERE BUMPED
UP A LITTLE EAST USING THE LLVL THICKNESS SCHEME WHERE LESS CLOUD
COVER EARLY SHOULD ENABLE BETTER OVERALL HEATING.

AS OF 430 AM EDT MONDAY...SCATTERED SHOWER ACTIVITY CONTINUES ACROSS
PORTIONS OF THE NORTH AND SOUTH CAROLINA PIEDMONTS.  EXPECTING THIS
ACTIVITY TO CONTINUE MOVING EASTWARD THROUGHOUT THE MORNING.
ELSEWHERE...MORE SHOWERS WILL BE MOVING IN FROM THE WEST AND
INCREASING IN COVERAGE LATER IN THE MORNING.  THEREFORE...UPDATED
NEAR TERM POPS TO REFLECT RECENT RADAR TRENDS AND ADJUSTED
TEMPERATURES ACCORDING TO RECENT OBSERVATIONS.  OTHERWISE...NO OTHER
CHANGES WERE MADE.

PREVIOUS DISCUSSION...

AS OF 250 AM EDT MONDAY...CURRENT RADAR TRENDS INDICATE A LARGE
SHIELD OF STRATIFORM PRECIPITATION LOCATED ACROSS NORTHEAST GEORGIA
AND THE WESTERN UPSTATE REGION OF SOUTH CAROLINA.  OTHERWISE...BROAD
CYCLONIC FLOW WILL PROMOTE CONTINUED SHOWER AND THUNDERSTORM
ACTIVITY THROUGH THE PERIOD.  SHORT RANGE MODEL GUIDANCE INDICATES A
SERIES OF MID-UPPER LEVEL VORTICITY MAXIMA PASSING THROUGH THE
REGION OVER THE NEXT 18-24 HOURS.  IN RESPONSE...A MILDLY UNSTABLE
AIRMASS AT THE SURFACE WILL PROVIDE ENOUGH LOW LEVEL LIFTING
POTENTIAL FOR SCATTERED SHOWER AND THUNDERSTORM DEVELOPMENT MONDAY
MORNING. SOUNDINGS INDICATE SBCAPE VALUES GENERALLY RANGING FROM
500-1000 J/KG WITH THE HIGHEST VALUES LYING ACROSS WESTERN NORTH
CAROLINA DUE TO CURRENT SHOWER ACTIVITY WORKING OVER THE ATMOSPHERE
ACROSS THE UPSTATE AND NORTHEAST GEORGIA.  BY LATE MORNING TO EARLY
AFTERNOON...EXPECTING SKY COVER TO INCREASE AS THE COLUMN MOISTENS
THEREBY DECREASING SURFACE HEATING.  WITH THAT...MOST IF NOT ALL
ISOLATED THUNDERSTORM DEVELOPMENT WILL CEASE LEADING TO MORE OF A
STRATIFORM PRECIPITATION REGIME WITH EMBEDDED CLUSTERS OF HEAVIER
RAINFALL.  SHOWER ACTIVITY WILL DECREASE FROM NORTH TO SOUTH AS
UPPER LEVEL IMPULSES EXIT THE REGION ON MONDAY EVENING.  THE
OVERNIGHT HOURS OF TUESDAY MORNING SHOULD REMAIN MOSTLY DRY AS MODEL
GUIDANCE INDICATES A LULL IN THE SHOWER ACTIVITY.  TEMPERATURES
THROUGH THIS PERIOD WILL REMAIN A FEW DEGREES BELOW NORMAL FOR
HIGHS...AND SLIGHTLY ABOVE NORMAL FOR LOWS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AT 315 AM EDT MON...A CLIPPER WAVE MOVING SE THROUGH THE MIDWEST ON
TUE WILL SHARPEN UP AN ERN TROUGH AXIS OVER THE APPALACHIANS TUE
NIGHT THROUGH WED. THE NUMERICAL MODELS ALL FEATURE WEAK SFC WAVES
AHEAD OF THE UPPER CLIPPER MOVING EAST ALONG THE LINGERING WEAK
BOUNDARY IN PLACE OVER THE FORECAST AREA. IN ADDITION...THE
STRONGEST RIGHT ENTRANCE REGION UPPER JET DIVERGENCE WILL CROSS THE
FORECAST AREA MAINLY TUE NIGHT INTO WED. THESE VARIOUS FORCING
MECHANISMS WILL COINCIDE WITH A ZONE OF RELATIVELY DEEP MOISTURE
ORIENTED W TO E ACROSS THE AREA TUE THROUGH MUCH OF WED. THIS WILL
REQUIRE SOLID CHC TO LOW END LIKELY POPS THROUGHOUT. THERE IS VERY
LIMITED SHEAR IN THE MODEL PROFILES TUE THROUGH WED...AND SFC BASED
INSTABILITY MAY ALSO BE LIMITED DESPITE THE HIGH DEWPOINTS BECAUSE
OF CLOUD COVER. LOCALLY HEAVY RAINFALL WILL BE THE PRIMARY THREAT.
WILL CONTINUE TO FEATURE A SMALLER THAN CLIMO DIURNAL RANGE OF WARM
MIN TEMPS AND COOLER THAN NORMAL MAX TEMPS TUE THROUGH WED NIGHT
GIVEN THE CLOUD COVER AND PRECIP CHANCES.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 110 PM EDT MONDAY...HEIGHTS WILL SLOWLY BUILD FROM THE WEST
FROM THURSDAY NIGHT INTO THE WEEKEND AS THE CENTER OF THE UPPER
RIDGE SHIFTS EAST FROM TEXAS TO SOMEWHERE OVER THE SE
STATES...DEPENDING ON WHICH MODEL YOU REFERENCE. A LIGHT EASTERLY
LOW LEVEL FLOW FRIDAY AND SATURDAY WILL SHIFT TO LIGHT SOUTHWEST BY
LATE SUNDAY INTO MONDAY. LIGHT WIND ALL THE WAY UP TO AROUND 500MB
WITH AROUND 10 KTS AT 500MB AND GENERALLY LESS DOWN TO THE SURFACE
FROM DAY 5 THROUGH NEW DAY 7. SURFACE HIGH PRESSURE CENTERED NEAR
NEW JERSEY THURSDAY NIGHT WILL RIDGE DOWN THROUGH THE CAROLINAS WITH
THE COOLER THAN NORMAL TEMPERATURES. THE CENTER OF THIS HIGH WILL
DRIFT TO NEAR BERMUDA LATE IN THE WEEKEND AND EARLY NEXT WEEK
PROVIDING A CHANGE IN AIRMASS COMBINED WITH INCREASING INFLUENCE OF
THE UPPER RIDGE BUILDING FROM THE WEST. CAPE VALUES ON FRIDAY AND
SATURDAY WILL BE A LITTLE HIGHER OVER THE MTNS...1000 TO 1600 ON THE
GFS FRIDAY. CAPE VALUES DROP OFF VERY LOW SUNDAY AND MONDAY. VARYING
LEVELS OF LOW LEVEL MOISTURE THROUGHOUT THE MEDIUM RANGE WILL SERVE
FOR THE PRODUCTION OF PM SHOWERS AND T-STORMS. TEMPERATURES A BIT
WARMER AT END OF THE WEEKEND AND START OF NEXT WEEK.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT KCLT...TIMING OF CONVECTION WILL BE TRICKY THIS AFTERNOON AS
UPPER S/W PATTERN IS WEAKLY DEFINED AND NO GOOD AREAS OF LLVL CONVG
EXIST. NONETHELESS...WILL COUNT OF INCREASING COVERAGE SHRA/TSTM
ACROSS THE PIEDMONT AFT 19Z AND DEEPER CELLULAR ACTIVITY WITHIN THE
TAF ZONE AND POSSIBLY PREDOMINATE FOR A COUPLE HRS THROUGH 23Z/00Z.
MOISTURE REMAINS HIGH OVERNIGHT...BUT NOT ENOUGH TO MENTION PRECIP
OR CONVECTION. WITH STAGNANT AIRMASS IN PLACE...WILL EXPECT A COUPLE
HRS OF MVFR CIGS/VSBY AROUND DAYBREAK WITH LIFTING CONDS AFT
13Z/14Z.

ELSEWHERE...THE BETTER CONV ACTIVITY WILL BE ACROSS THE NC AREAS
THIS AFTERNOON WHERE POCKETS OF DPVA CROSS A DEEPLY MOIST ATMOS. A
LINE OF CONV SHOULD REACH KHKY IN THE NEXT HOUR OR SO...SO
PREDOMINATE TSTMS ARE GIVEN FOR THE FIRST FEW HRS. THERE ISNT ENOUGH
CONFIDENCE TO ADD ANYTHING BUT A TEMPO TSTM OR VCTS...ESP OUTSIDE
THE HIGHER TERRAIN THROUGH 00Z/01Z. KEPT DIURNAL VCSH ACROSS THE NC
TAF SITES WITH INCREASING LIFT. ALL SITES SHOULD SEE EITHER A VSBY
OR CIG MFVR RESTRICTION AROUND DAYBREAK...WITH KAVL LIKELY SEEING
IFR VSBY AFT 10Z FOR A FEW HRS.

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

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  86%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  95%     HIGH  80%     HIGH  96%
KHKY       HIGH 100%     HIGH 100%     HIGH  95%     HIGH  85%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  96%
KAND       HIGH 100%     HIGH 100%     HIGH  87%     HIGH  88%

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/SBK
SHORT TERM...HG
LONG TERM...HG
AVIATION...SBK