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000
FXUS62 KGSP 141749
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
149 PM EDT TUE MAY 14 2013

.SYNOPSIS...
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HIGH PRESSURE WILL PUMP WARM MOIST AIR OVER THE REGION THROUGH
WEDNESDAY..AHEAD OF A MID LEVEL DISTURBANCE THAT IS EXPECTED TO
RIPPLE OVER THE SOUTHERN APPALACHIANS ON THURSDAY. HIGH SHIFTS OFF
THE CAROLINA COAST FOR THE WEEKEND AS A COLD FRONT APPROACHES FROM
THE WEST DURING THE EARLY PART OF THE WEEK.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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AS OF EARLY AFTERNOON ACROSS THE UPSTATE AND THE NC
MOUNTAINS...FORECAST REMAINS ON TRACK THEREFORE NO CHANGES WERE MADE.

REMAINDER OF PREVIOUS DISCUSSION...

OTHERWISE...DEEP LAYER NW FLOW BETWEEN THE DEPARTING E COAST TROUGH
AXIS AND A DEVELOPING RIDGE OVER THE MS RIVER VALLEY WILL CONTINUE
THROUGH THE NEAR TERM PERIOD. MAINLY TRANSIENT MID CLOUDS ARE
EXPECTED IN THE NW FLOW. SFC HIGH PRESSURE WILL MOVE TO THE SE COAST
TODAY...TURNING LOW LEVEL FLOW MORE SOUTHWESTERLY AND INCREASING MAX
TEMPS AT LEAST A COUPLE OF CATEGORIES OVER YESTERDAY.

SLIGHTLY DEEPER MOISTURE WILL PASS NORTH OF THE FORECAST AREA LATER
TODAY THROUGH TONIGHT ALONG A WARM FRONT. HOWEVER...OUR AREA SHOULD
REMAIN DRY THROUGH THE PERIOD UNDER A BUILDING UPPER RIDGE...WITH
MIN TEMPERATURES REBOUNDING MORE THAN 10 DEGREES TONIGHT.
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&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 250 AM TUESDAY...THE AXIS OF A H5 RIDGE IS EXPECTED TO SLIDE
ACROSS THE SOUTHEAST U.S. ON WEDNESDAY. AT THE SFC...HIGH PRESSURE
CENTER OVER THE WESTERN ATLANTIC SHOULD RIDGE WEST ACROSS THE DEEP
SOUTH AS A WARM FRONT REMAINS ACROSS THE MID ATLANTIC STATES. THIS
PATTERN WILL SUPPORT WARM RETURN FLOW ACROSS THE FORECAST
AREA...ALLOWING H85 TEMPS TO REACH AROUND 18C. THE COMBINATION OF
MILD LLVL THICKNESSES...WARM MIXED LAYER TEMPERATURE PROFILES...AND
STRONG INSOLATION SHOULD SUPPORT THE WARMEST TEMPERATURES SO FAR
THIS YEAR WED AFTERNOON. I WILL FORECAST MID 80S WITHIN THE MTN
VALLEYS AND UPPER 80S EAST. FORECAST SOUNDINGS INDICATE WEAK
CONDITIONAL INSTABILITY ACROSS THE REGION DURING THE AFTERNOON...BUT
LLVL CIN LAYER SHOULD PREVENT FREE CONVECTION.

BROAD MID LEVEL RIDGING SHOULD REMAIN ACROSS THE CWA WEDNESDAY
NIGHT. TO THE WEST...H5 TROF WILL DIG ACROSS THE MID AND SOUTHERN
MISSISSIPPI RIVER VALLEY. SKY CONDITIONS WILL TRANSITION FROM NEARLY
CLEAR DURING LATE WEDS EVENING...TO GOSSAMER CIRRUS EARLY THURSDAY
MORNING...BUILDING TO 50 TO 60 PERCENT THICK CIRRUS OVER THE MTNS BY
DAYBREAK. INCREASING HIGH CLOUDS AND LINGERING MILD LLVL THICKNESSES
SHOULD FAVOR MIN TEMPS AROUND 5 DEGREES ABOVE NORMAL.

THURSDAY...SHORT RANGE MODELS AGREE THAT THE MID LEVEL TROUGH WILL
RIPPLE OVER MIDDLE TN AND NRN AL/GA BY THE LATE AFTERNOON. THE
APPROACHING TROUGH SHOULD RESULT IN INCREASING CLOUD COVER ACROSS
THE FORECAST AREA...BECOMING MOSTLY CLOUDY BY LATE AFTERNOON.
DESPITE THE FALLING MID LEVEL HEIGHTS...TEMPERATURES BELOW H5 REMAIN
VERY MILD. THE COMBINATION OF HIGH TEMPERATURES 5 DEGREES ABOVE
NORMAL AND DEWPOINTS IN THE L50S MAY ONLY YIELD CAPE VALUES 500 J/KG
OR LESS. I WILL EXPECT SCT SHRA/TSRA ACROSS THE MTNS AND I-40 WITH
ISO COVERAGE ACROSS THE PIEDMONT.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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AS OF 145 PM TUESDAY...A WEAK UPPER RIDGE IS FORECAST TO PREVAIL
FROM THE GULF OF MEX...NE THROUGH THE TN VALLEY SAT THROUGH SUN. THE
RIDGE IS THEN EXPECTED TO MOVE TO THE EAST COAST ON MON AS AN UPPER
TROUGH DEVLOPS OVER THE CENTRAL PORTION OF THE COUNTRY. AT THE
SURFACE...THE WESTERN EXTENSION OF THE WESTERN ATLANTIC SUBTROPICAL
RIDGE WILL DOMINATE THROUGH THE PERIOD. A BACKDOOR COLD FRONT EARLY
IN THE WEEKEND IS EXPECTED TO STALL SOMEWHERE OVER EASTERN NC AND
THEN MOVE NORTH AS A WARM FRONT. THEREFORE...THE FORECAST WILL
FEATURE WARM TEMPERATURES AND MAINLY DIURNAL CONVECTION FAVORING THE
MOUNTAINS. A MCS STILL CAN NOT BE COMPLETELY RULED OUT IN THE SAT
NIGHT TIMEFRAME AS AN UPPER PULSE MOVES OVER THE UPPER RIDGE.
HENCE...HAVE MAINTAINED SOME LOW CHANCE POPS OVER NORTHERN SECTIONS
SAT NIGHT. OTHERWISE...JUST SCATTERED TYPE POPS ARE FORECAST EACH
AFTERNOON AND EVENING. TEMPS ARE FORECAST TO BE ABOUT A CATEGORY
ABOVE AVERAGE EACH DAY.
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&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE
ENTIRE TAF PERIOD.  SOUTHWEST WINDS WILL DECREASE IN MAGNITUDE
DURING THE OVERNIGHT HOURS BEFORE INCREASING TO AROUND THE 10-12KT
RANGE BY LATE MORNING ON WEDNESDAY.  SKIES SHOULD REMAIN MOSTLY
CLEAR ACROSS THE REGION FOR THE REMAINDER OF THE AFTERNOON/EVENING
WITH THE ONLY EXCEPTIONS BEING SOME THIN HIGH CLOUDS ACROSS PORTIONS
OF NORTH CAROLINA.

OUTLOOK...VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH THE REST OF
THE WEEK. HOWEVER...SCATTERED AFTN AND EVENING THUNDERSTORMS WILL BE
POSSIBLE FROM THURSDAY ONWARD.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-17Z
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
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&&

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

&&

$$
SYNOPSIS...PAT
NEAR TERM...CDG/HG
SHORT TERM...NED
LONG TERM...LG
AVIATION...CDG/PM