Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 200730
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
230 AM EST THU NOV 20 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION FROM THE NORTHWEST TODAY THROUGH
TONIGHT. HIGH PRESSURE WILL BUILD OVER TO THE NORTH BEHIND THE COLD
FRONT ON FRIDAY AND MOVE OFF THE EASTERN SEABOARD THROUGH SATURDAY.
ABUNDANT MOISTURE WILL RETURN ON SUNDAY AHEAD OF A LOW PRESSURE
SYSTEM LIFTING FROM TEXAS TO THE GREAT LAKES. THE WEATHER MAY REMAIN
UNSETTLED EARLY NEXT WEEK AS ANOTHER COLD FRONT APPROACHES FROM THE
WEST...BUT WITH LESS MOISTURE.

&&

.NEAR TERM /THROUGH TONIGHT/...
AT 245 AM EST THURSDAY...A DEAMPLIFYING MEAN UPPER TROUGH WAS OVER
EASTERN NORTH AMERICA EARLY THIS MORNING...WITH A BELT OF CHANNELED
VORTICITY STRETCHING FROM THE PLAINS TO THE CAROLINAS. A SURFACE
COLD FRONT WAS LOCATED FROM THE EASTERN GREAT LAKES TO THE TN RIVER
VALLEY. MOISTURE ASSOCIATED WITH THIS BOUNDARY WAS MOVING INTO THE
NC MOUNTAINS. ALTHOUGH 850 MB FLOW WHERE THE MOISTURE IS LOCATED IS
STOUT AND WESTERLY...THE KMRX RADAR WAS SHOWING NO PRECIPITATION IN
THE MOUNTAINS.

WITH ONLY A BRIEF...SHALLOW MOIST LAYER ALONG THE TN BORDER...SNOW
SHOWERS WILL NO BE CARRIED THERE THIS MORNING. THE MODELS SHOW
MOISTURE ALONG THE COLD FRONT DIMINISHING TODAY. THE FRONT IS
EXPECTED TO CROSS THE MOUNTAINS AROUND DAYBREAK...THE FOOTHILLS BY
MIDDAY...AND THE PIEDMONT THIS AFTERNOON. VEERING WINDS WILL PRODUCE
A DOWNSLOPE FLOW...LIMITING LOW LEVEL CLOUD COVER IN THE LEE OF THE
MOUNTAINS. WITH RISING HEIGHTS ALOFT RESULTING FORM THE
DEAMPLIFICATION OF THE UPPER RIDGE...AND WARMING DOWNSLOPE
FLOW...HIGH TEMPERATURES SHOULD RUN AROUND 7 DEGREES BELOW NORMAL.

MODEL TIME HEIGHTS INDICATE LOW LEVEL DRYING THIS EVENING...WITH
SOME MID TO HIGH CLOUDS ARRIVING TOWARD DAWN ON FRIDAY. MINIMUM
TEMPERATURES WILL RUN AROUND 9 DEGREE BELOW NORMAL...AS LIGHT
DOWNSLOPE FLOW OFFSETS COLD ADVECTION BEHIND THE FRONT.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
AS OF 215 AM EST THURSDAY...HEIGHTS WILL RISE OVER THE SOUTHEAST FRI
INTO SAT AS A VIGOROUS SOUTHERN STREAM SYSTEM MOVES FROM THE FOUR
CORNERS REGION INTO TX. MEANWHILE...SFC HIGH PRESSURE CENTERED OVER
THE UPPER OH VALLEY ON FRI WILL MOVE OFF THE OUTER BANKS ON SAT.
MODEL TIME HEIGHTS SHOW PLENTY OF HIGH LEVEL MOISTURE WHICH APPEARS
TO BE ASSOCIATED WITH A JET STREAK STRETCHING OVER THE RIDGE TO OUR
NORTH THROUGH THE SHORT RANGE. THIS WILL LEAD TO CIRRUS WHICH SHOULD
KEEP A LID ON MAX TEMPS...WITH HIGHS MAINLY 5 TO 10 DEGREES BELOW
CLIMO FRI AND SAT AFTERNOONS. CONDITIONS SHOULD REMAIN DRY...WITH
ANY MOIST SOUTHERLY RETURN FLOW GENERALLY S OR SW OF THE AREA
THROUGH LATE DAY ON SAT.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 AM EST THURSDAY...THE SRN PLAINS/TX LOW PRESSURE SYSTEM
WILL QUICKLY ACQUIRE A NEGATIVE TILT SAT NIGHT AND MOVE RAPIDLY TO
THE GREAT LAKES THROUGH SUNDAY. THE SWIFTLY MOVING WARM CONVEYOR
BELT OF DEEP MOISTURE OUT AHEAD OF THIS SYSTEM WILL CROSS THE REGION
ON SUNDAY. IN SITU CAD FROM THE OFFSHORE HIGH PRESSURE CENTER MAY
LINGER THROUGH AT LEAST SUNDAY MORNING...AS THE WEDGE FRONT MAKES
INROADS INTO OUR FORECAST AREA FROM THE S. VERY BRIEF...TRANSIENT
POCKETS OF LIGHT FREEZING RAIN ARE MARGINALLY POSSIBLE IN NRN MTN
LOCATIONS AT ONSET SUNDAY MORNING...BUT MOST MOUNTAIN LOCATIONS WILL
HAVE TEMPERATURES IN THE MID AND UPPER 30S AROUND DAYBREAK. BOUNDARY
LAYER FLOW SHOULD BE QUITE BACKED BY MIDDAY SUNDAY AS A FEW HUNDRED
J/KG OF SFC BASED CAPE TRANSITS THE PIEDMONT SE OF THE WEDGE FRONT
DURING THE AFTN. ANY FURTHER INSTABILITY WILL BE A FRIGHTENING
PROPOSITION AS THE GFS FEATURES SOME 70+ KT OF SFC TO 3 KM BULK
SHEAR CIRCA 18Z. HOWEVER...IT APPEARS THAT THE BEST SHEAR ARRIVES
AHEAD OF THE STRONGEST INSTABILITY TO LIMIT THE SEVERE THREAT
SOMEWHAT FOR SUNDAY AFTERNOON. DESPITE THE FAST MOVEMENT OF THE
SYSTEM...RAINFALL TOTALS OF 0.5 INCHES NW TO 1.5 INCHES SE ARE
POSSIBLE SUNDAY. THIS SHOULD NOT LEAD TO ANY HYDRO ISSUES GIVEN THE
DRY ANTECEDENT CONDITIONS.

AN INTENSE UPPER LEVEL JET WILL REMAIN STRETCHED ALONG THE
APPALACHIAN MOUNTAIN CHAIN MONDAY THROUGH TUESDAY AS A DEEP TROUGH
AXIS PERSISTS OVER THE CENTRAL CONUS. HOWEVER...THE DRY SLOT
WRAPPING INTO THE REGION WILL LIMIT DEEP MOISTURE SOMEWHAT. MAINLY
SCATTERED SHOWERS SHOULD RESULT AS A FRONTAL BOUNDARY APPROACHES
FROM THE WEST ON MONDAY...WITH LESS COVERAGE ON TUESDAY AS THE
BOUNDARY SLIPS GRADUALLY EAST. THE UPPER TROUGH AXIS WILL FINALLY
MOVE EAST ACROSS THE FORECAST AREA ON WEDNESDAY...ACCOMPANIED BY
DEEP LAYER Q VECTOR CONVERGENCE. A REINFORCING COLD FRONT WILL CROSS
THE REGION ON WED AS WELL...BUT WITH GENERALLY SPARSE MOISTURE UNDER
THE PASSING UPPER TROUGH.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AT KCLT...VFR. BROKEN CIRRUS WILL MOVE OFF TO THE EAST...WHILE LOW
CIGS UPSTREAM ACCOMPANYING A COLD FRONT WILL REMAIN MAINLY CONFINED
TO THE MOUNTAINS...WITH JUST SCATTERED LOW CLOUDS SURVIVING
DOWNSLOPE FLOW INTO THE PIEDMONT THURSDAY AFTERNOON. SW WINDS WILL
BECOME GUSTY DURING THE DAY. WINDS VEER WNW WITH FRONTAL PASSAGE
THURSDAY EVENING.

ELSEWHERE...VFR. LOW CLOUDS ALONG AN APPROACHING COLD FRONT ARE
EXPECTED TO FORM A CIG TO THE W OF KAVL BEFORE DAWN...BUT ONLY
SCATTERED LOW CLOUDS ARE EXPECTED TO REACH TAF SITES...BEOFRE DAWN
AT KAVL...AND DURING THE DAY IN THE FOOTHILLS. SW WINDS WILL VEER NW
AT KAVL BEFORE DAWN. SW WINDS WILL PERSIST THROUGH THE DAY AT
FOOTHILLS SITES. GUSTS CAN BE EXPECTED AT ALL SITES DURING THE DAY.
WINDS VEER WNW AT KHKY BY THIS EVENING AS THE FRONT MOVES THROUGH.

OUTLOOK...DRY HIGH PRESSURE BUILDS IN ACRS THE REGION FOR FRIDAY AND
SATURDAY. CLOUDS AND PRECIPITATION RETURN TO THE AREA ON SUNDAY WITH
ANOTHER FRONT...AND ASSOCIATED RESTRICTIONS ARE POSSIBLE. BRIEF
DRYING FOLLOWS THE FRONT ON MONDAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
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

&&

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

&&

$$
SYNOPSIS...HG
NEAR TERM...JAT
SHORT TERM...HG
LONG TERM...HG
AVIATION...JAT


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