Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 241638
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1238 PM EDT THU JUL 24 2014

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS MORNING AND
SHOULD MOVE ACROSS THE CAROLINAS AND NORTH GEORGIA THIS AFTERNOON
AND EVENING. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR FRIDAY
AND THE WEEKEND. ANOTHER FRONT IS EXPECTED TO PASS ON MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AT 1230 PM...SEE NO NEED TO CHANGE MUCH IN THE VERY NEAR TERM. SBCIN
OVER THE PIEDMONT IS GONE AND CAPES ARE AROUND 2500J SO WE ARE
BEGINNING TO SEE MORE CONVECTIVE DEVELOPMENT...SO SCT-NUMEROUS
SHOWERS/THUNDERSTORMS SHOULD OCCUR BEFORE 00Z. SFC-6KM BULK SHEAR
GENERALLY IN THE 25-30KT RANGE...SO A FEW SEVERE STROMS ARE IN THE
OFFING. ADJUSTED MOST FIELDS WITH LATEST CONSSHORT RUN.

AS OF 1020 AM...14Z SFC MAP INDICATES THAT THE COLD FRONT IS STILL
WEST OF THE NC MOUNTAINS FROM FAR SW VA THROUGH EASTERN TN. AS USUAL
THE FRONTAL PASSAGE WILL BECOME MUDDLED AS IT MOVES ACROSS THE
MOUNTAINS. LOOKS LIKE THE LEE TROUGH WILL BECOME A PLAYER THIS
AFTERNOON WITH ITS LOW LEVEL CONVERGENCE TRIGGERING STORMS. THE
ACTUAL FRONT MAY NOT MAKE IT THROUGH THE AREA UNTIL THIS EVENING. IN
ANY EVENT...CURRENT SPC MESO-ANAL SHOWS PLENTY OF CAPE POOLING
ACROSS THE PIEDMONT ALREADY LATE THIS MORNING WITH SBCAPE VALUES
ALREADY OVER 2000J. CURRENT SBCIN SHOULD DISSIPATE AS BOUNDARY LAYER
CONTINUES TO WARM. HENCE...SCT-NUMEROUS THUNDERSTORMS STILL LOOK
GOOD FOR THE AFTERNOON. SPC HAS UPGRADED OUR EASTERN AREAS TO A
SLIGHT RISK. CAN`T ARGUE WITH IN THAT THERE IS A DCAPE GRADIENT IN
THAT REGION AND 0-6KM SHEAR HAS INCREASED TO 20-30KTS. HENCE...A FEW
SEVERE STORMS ARE LIKELY. ADJUSTED MOST FIELDS BASED ON LATEST
CONSSHORT RUN AND TRENDS. THAT YIELDED MAX TEMPS A COUPLE DEGREES
LOWER AS CLOUD COVER SLOWING THE TEMP RISE.

PREVIOUS DISCUSSION:
AS OF 330 AM...RECENT REGIONAL RADAR INDICATED THAT THE CONVECTION
ACROSS EASTERN TN HAS DECREASED TO ISO SHOWERS...WITH A SECONDARY
PATCH OF SHOWERS ACROSS THE SOUTHERN I-77 CORRIDOR. W/V SHOWED THE
MID LEVEL TROF AXIS WAS LOCATED ACROSS EASTERN KY/TN...SWEEPING
EAST. AT 330 AM...W/V AND RAP INDICATED THAT SEVERAL S/W EXISTED EAST
OF THE TROF AXIS...WITH STRONGER S/W ACROSS THE WESTERN OHIO RIVER
VALLEY. I ANTICIPATE THAT WIDELY SCT TO SCT SHRA WILL DRIFT OR
DEVELOP ACROSS NC MTNS EARLY THIS MORNING. BY MID DAY...THE MID
LEVEL TROF IS EXPECTED TO RIPPLE OVER THE SOUTHERN APPALACHIAN
REGION. BY 17Z...FORECAST SOUNDINGS INDICATE THAT CAPES WILL RANGE
BETWEEN 1000-1500 J/KG ACROSS THE REGION. AS WEAK MID LEVEL FORCING
REACHES THE MTNS AND FOOTHILLS EARLY THIS AFTERNOON...CONVECTION
SHOULD DEVELOP ACROSS THE EAST FACING SLOPES AND FOOTHILLS. FORECAST
SOUNDINGS INDICATE THAT THE STEERING FLOW WILL PUSH CELLS NW TO SE
ACROSS THE WESTERN CAROLINAS AND NE GEORGIA. SHEAR MAY REMAIN WEAK
THROUGH THIS AFTERNOON...BUT POSSIBLY ENOUGH TO ORGANIZE CONVECTION
INTO A BAND. ONCE DEVELOPED...THE BAND SHOULD SLIDE
QUICKLY EAST...REACHING THE CLT AREA BY LATE AFTERNOON. THESE STORMS
MAY RESULT IN STRONG TO SEVERE TSRA WIND GUSTS ACROSS PORTIONS OF
THE OF THE FORECAST AREA. IN ADDITION...DCAPE ACROSS THE EASTERN
PIEDMONT MAY RANGE FROM 500-1000 J/KG. WE WILL HIGHLIGHT IN THE HWO
THE POTENTIAL FOR DAMAGING WIND GUSTS ASSOCIATED WITH THE FORECAST
THUNDERSTORM BAND. HIGH TEMPERATURES MAY RANGE FROM 80 WITHIN THE
MTN VALLEYS NEAR 90 EAST OF I-85.

THIS EVENING...CONVECTION WILL PROPAGATE EAST...EXITING THE CWA
EARLY THIS EVENING. OVERNIGHT...CONDITIONS WILL DRY WITH CLOUD COVER
DECREASING FROM WEST TO EAST. LOW TEMPERATURES MAY RANGE 2-3 DEGREES
COOLER THAN THIS MORNING.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...THE SHORT RANGE IS SHAPING UP TO BE
RELATIVELY QUIET. THE FRONT SHOULD BE DRIVEN FAR ENOUGH S TO NOT
AFFECT THE REGION ON FRIDAY. THE UPPER TROF OVER THE EAST SHOULD
PULL OUT OR FILL A BIT ON FRIDAY INTO SATURDAY WITH WEAK SURFACE
HIGH PRESSURE MOVING OVER THE REGION. THE MODELS CONTINUE TO
ALTERNATELY DEPICT ISOLATED/WIDELY SCATTERED SHOWER DEVELOPMENT
DURING HEATING ON FRIDAY AND SATURDAY...BUT THE SITUATION DOES NOT
APPEAR TO HAVE A WHOLE LOT GOING FOR IT AS MOISTURE SHOULD BE MUCH
LESS THAN THE LAST WEEK. A FEW SHORT WAVES WILL MOVE ACROSS THE
REGION BUT THE MODELS DO NOT RESPOND TO ANY GREAT DEGREE. AT THIS
POINT...WOULD PREFER TO REMAIN OPTIMISTIC FOR THE FIRST PART OF THE
WEEKEND AND HAVE KEPT THE FCST DRY. ANY BRIEF DROP IN TEMPS ON
FRIDAY WILL BE WIPED OUT FOR SATURDAY AS THE AIR MASS MODIFIES BACK
TO NORMAL. TOWARD THE END OF THE PERIOD...THERE IS SOME POTENTIAL
FOR AN MCS OR REMNANTS TO APPROACH FROM THE W OR NW...SO A SMALL POP
WAS INTRODUCED ON THE TN BORDER.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 330 AM THURSDAY...THE MEDIUM RANGE HAS PERHAPS A BIT MORE
UNCERTAINTY THROWN IN FOR SUNDAY AND MONDAY. THE RETURN MOISTURE
DOES NOT APPEAR TO BE AS GREAT ON SUNDAY AND ANY UPPER SUPPORT FOR
CONVECTION SHOULD MOVE PAST TO THE NORTH...TO THE POINT WHERE THE
GFS/ECMWF BOTH FAIL TO DEVELOP MUCH IN THE WAY OF PRECIP. AT THE
SAME TIME...THE MODELS CONTINUE TO SUGGEST SOME SORT OF MCS
ACTIVITY...BUT KEEP IT MOVING ACROSS THE OH VALLEY/CENTRAL
APPALACHIANS. THERE IS THE POTENTIAL FOR A BOUNDARY TO MOVE DOWN
FROM THAT ACTIVITY WHICH COULD TRIGGER SOME STORMS. WILL NOT MAKE
ANY CHANGES TO THE PRECIP PROBS FOR SUNDAY...BUT KEEP IN MIND THE
TREND IS FOR LESS ACTIVITY ON THAT DAY. THE MODELS CONTINUE TO
DEEPEN THE UPPER TROF OVER THE EAST AGAIN ON MONDAY WITH STRONGER
WAVES DRIVING ANOTHER SURFACE COLD FRONT SE ACROSS THE REGION...MOST
LIKELY ON MONDAY. IN SPITE OF THIS BOUNDARY BEING MORE SIGNIFICANT
IN TERMS OF AIR MASS CHANGE...THE MODEL RESPONSE IS UNDERWHELMING IN
TERMS OF PRECIP. AGAIN...WILL NOT MAKE ANY CHANGES...BUT A DOWNWARD
TREND MIGHT BE STARTED LATER TODAY. STILL LOOKS BELOW NORMAL FOR THE
MIDDLE OF NEXT WEEK AS A SURFACE HIGH OF CONTINENTAL ORIGIN DROPS
DOWN FROM CANADA/NRN PLAINS. HAVE NUDGED TEMPS/DEWPTS DOWN A BIT
MORE FOR TUESDAY NIGHT INTO WEDNESDAY.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT...THE PRIMARY FORECAST CHALLENGE WILL BE THE TIMING OF
AFTERNOON TSRA. THE 4KM WRF AND 6Z NAM12 INDICATES THAT CONVECTION
WILL DEVELOP ACROSS THE NC FOOTHILLS BETWEEN 18Z-19Z...FORMING A
BAND. STEERING FLOW AND COLD POOL GENERATION SHOULD RESULT IN THE
BAND TO MOVE BRISKLY EAST DURING THE AFTERNOON...LIKELY PASSING
ACROSS THE CLT METRO AREA BETWEEN 20Z TO 22Z. I WILL HIGHLIGHT THE
TSRA POTENTIAL WITH A TEMPO GROUP FROM 21Z TO 24Z. ALTHOUGH FROPA
SHOULD OCCUR BETWEEN 18Z-0Z...LIGHT NORTH WINDS ARE NOT FORECAST TO
DEVELOP UNTIL THIS EVENING. THE COMBINATION OF LIGHT NORTH
WINDS...LINGERING MID LEVEL CLOUD COVER...AND 2-3 DEGREE DEWPOINT
DEPRESSIONS SHOULD FAVOR VFR CONDITIONS TONIGHT.

ELSEWHERE...ALL TERMINALS WILL LIKELY SEE CONVECTION EITHER OVER THE
TERMINAL OR VICINITY THROUGH 0Z. I WILL HIGHLIGHT THE CONVECTIVE
PERIOD WITH VCTS OR TEMPO GROUPS...GENERALLY BETWEEN 19Z-22Z. AHEAD
OF THE COLD FRONT FLOW WILL REMAIN FROM THE SOUTHWEST BETWEEN
5-10KTS. WINDS WILL VEER FROM THE NORTH THIS EVENING. KAVL COULD SEE
NNW WINDS DEVELOP THIS MORNING...REMAINING THROUGH THE REST OF THE
12Z PACKAGE. NAM CONDENSATION PRESSURE DEFICITS AND MOS INDICATES
THAT KAVL COULD SEE IFR CEILINGS DURING THE PRE DAWN HOURS FRI.

OUTLOOK...FRI AND SAT SHOULD BE QUIET AND VFR...EXCEPT FOR THE MTN
VALLEYS WHERE EARLY MORNING FOG MAY OCCUR. THUNDERSTORMS WILL RETURN
TO THE FORECAST FOR SUNDAY AFTERNOON THROUGH MON AS ANOTHER COLD
FRONT APPROACHES AND THEN MOVES THROUGH THE AREA ON MON.

CONFIDENCE TABLE...

            16-22Z        22-04Z        04-10Z        10-16Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     MED   72%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  89%
KAVL       HIGH 100%     HIGH  96%     MED   70%     HIGH  83%
KHKY       HIGH 100%     HIGH 100%     HIGH  88%     MED   63%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  89%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   72%

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...PM
NEAR TERM...LG
SHORT TERM...PM
LONG TERM...PM
AVIATION...NED






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