Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 141938
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
238 PM EST SUN FEB 14 2016

.SYNOPSIS...
COLD ARCTIC HIGH PRESSURE WILL REMAIN RIDGED ACROSS THE CAROLINAS
INTO MONDAY. MEANWHILE...A MOIST STORM SYSTEM WILL CROSS FROM THE
WEST TONIGHT THROUGH TUESDAY. A FAST MOVING UPPER LEVEL SYSTEM WILL
REACH THE MOUNTAINS LATE TUESDAY...BEFORE DRY AND MILDER HIGH
PRESSURE RETURNS AND REMAINS THROUGH THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
AT 230 PM SUNDAY...AN UPPER LEVEL TROUGH WILL AMPLIFY OVER THE MS
RIVER VALLEY TONIGHT AND MONDAY. WEAK CHANNELED VORTICITY WILL CROSS
GA AND THE CAROLINA FROM THE GULF STETS TONIGHT. ON MONDAY A STRING
VORT LOBE WILL ROUND THE BASED OF THE TROUGH OVER THE LOWER MS RIVER
VALLEY.

A SURFACE RIDGE NOW OVER NY WILL DRIFT OFF THE NE COAST TONIGHT...
BUT WITH PRESSURE WILL REMAIN BANKED UP AGAINST THE BLUE RIDGE
THROUGH MONDAY...ALBEIT WITH SOME WEAKENING LATE IN THE DAY. THE
MODEL SHOW ISENTROPIC UPGLIDE FROM THE SW OVER THIS RIDGE...BUT
HAVE LEANED TOWARD A LOW LEVEL DRY SLOT OVER NE GA AND UPSTATE SC
INITIALLY...WITH MOIST LOW LEVEL UPGLIDE MAINLY OVER NC. MODEL
SOUNDINGS ARE LESS SUPPORTIVE OF ICE NUCLEATION OVER THE SOUTHERN
PORTIONS OF THE FORECAST AREA...AND SNOW AND SLEET ARE LOOKING LESS
LIKELY S OF INTERSTATE 85...WHERE FREEZING RAIN IS FAVORED. THE
MODELS ARE ALSO MORE AGGRESSIVE IN MOVING THE FREEZING RAIN NORTH INTO
NC ON MONDAY...FOLLOWED BY LIQUID RAIN MOVING NORTH OUT OF SC. BY
MONDAY AFTERNOON...FREEZING RAIN WOULD BE CONFINED TO A FEW PLACES
ON THE BLUE RIDGE AND PARTS OF THE NORTHERN NC FOOTHILLS. WINTER
WEATHER PRODUCTS HAVE BEEN ADJSUTED TO REFLECT CHANGES TO THE
FORECAST.

MINIMUM TEMPERATURES WILL RUN AROUND EIGHT DEGREES BELOW NORMAL
TONIGHT... AND MAXIMUM TEMPERATUES AROUND 20 DEGREES BELWO NORMAL ON
MONDAY.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 230 PM EST SUNDAY...THE SHORT TERM BEGINS RIGHT IN THE MIDDLE
OF THE EVENT AT 00Z TUESDAY. GUIDANCE HAS FINALLY COME INTO BETTER
AGREEMENT ON THE PATH OF THE SURFACE LOW AND ALL CONTINUE TO SHIFT
TOWARD THE SPINE OF THE APPALACHIANS...GOOD THING SINCE THIS WAS
WHAT WE COMPROMISED WITH YESTERDAY. STILL SOME DIFFERENCES AS
THE NAM IS A BIT STRONGER AND STUBBORNLY HOLDS ONTO A SURFACE
COLD LAYER WHILE OTHER MODELS ARE SLIGHTLY WARMER. OVERNIGHT
MONDAY NIGHT...SHARP DIGGING UPPER TROUGH WILL PUSH ACROSS THE
APPALACHIANS AS ANOTHER SHORTWAVE DIVES DOWN THE BACKSIDE OF THE
LONGWAVE ROUGH INTO THE CENTRAL MISSISSIPPI VALLEY.  THE SURFACE LOW
WILL PUSH ACROSS NORTHERN GEORGIA AND INTO THE SOUTHERN MOUNTAINS
OVERNIGHT AND AS IT DOES SO...PRECIPITATION WILL INCREASE ACROSS
THE AREA. GOING INTO THE PERIOD WE HAVE QUITE A BIT OF DRYING ALOFT
BUT THE COLUMN WILL RE-SATURATE AT THIS POINT...HOWEVER INCREASING
WAA AHEAD OF THE DIGGING UPPER TROUGH WILL PERPETUATE THE WARM
NOSE...AND SURFACE TEMPERATURES SHOULD BE ABOVE FREEZING FOR ALL BUT
THE EXTREME NORTHERN TIER...SO BASICALLY ALL RAIN EVERYWHERE BUT
UP NORTH. FOR THE EASTERN SLOPES OF THE BLUE RIDGE WHERE SURFACE
TEMPERATURES ARE BELOW FREEZING /WARM NOSE ALOFT WILL SHOULD KEEP
THE HIGHER PEAKS ALONG THE SPINE OF THE APPALACHIANS ABOVE FREEZING/
COULD SEE SOME LINGERING LIGHT FREEZING RAIN...BUT BY MIDNIGHT OR
SO MONDAY NIGHT THE ENTIRE FORECAST AREA SHOULD BE ALL RAIN.

THE BIGGER CONCERN MONDAY NIGHT WILL BE QPF TOTALS WHERE A QUICK
INCH...POSSIBLY SLIGHTLY MORE...OF RAIN WILL BE POSSIBLE ACROSS
MOST OF THE AREA. FOR SOUTHERN ZONES THIS SHOULD BE FINE BUT THE
GROUND IS STILL SATURATED AND WITH THE VERY COLD TEMPERATURES WE
HAVE BEEN SEEING...RAIN WILL BE SLOW TO INFILTRATE SO COULD SEE
SOME RAPID RUNOFF ESPECIALLY ACROSS THE HIGHER ELEVATIONS. WILL
NEED TO WATCH HYDRO CONCERNS CLOSELY OVERNIGHT...BUT PRECIPITATION
MOVES OUT VERY QUICKLY AFTER DAYBREAK ON TUESDAY AND IS PRETTY MUCH
ALL GONE BY MIDDAY WITH THE EXCEPTION OF WRAPAROUND PRECIP IN THE
MOUNTAINS AND ACROSS THE NORTHERN TIER. ADDITIONALLY...THERE IS
THE INDICATION OF SOME SMALL AMOUNTS OF SBCAPE AS THE TROUGH AXIS
PUSHES THROUGH...AND THOUGH THUNDER IS NOT INCLUDED IN THE GRIDS
AT THIS TIME...IT IS POSSIBLE THAT SOME ISOLATED RUMBLES MIGHT BE
HEARD. TEMPERATURES ON TUESDAY WILL ACTUALLY BE FAIRLY PLEASANT
AND PRETTY CLOSE TO SEASONAL NORMALS FOR MOST OF THE AREA...AND
SIMILAR ON WEDNESDAY EXCEPT FOR PERHAPS IN THE NORTHERN MOUNTAINS.

THE AFOREMENTIONED SECONDARY SHORTWAVE WRAPS UP SOMEWHERE OVER THE
MID-MISSISSIPPI VALLEY ON TUESDAY. GFS IS FARTHER NORTH...A TAD
FASTER...AND MUCH STRONGER WITH THE SYNOPTIC PATTERN BUT ECMWF
KEEPS IT AN OPEN WAVE WITH A WEAKER SURFACE LOW. PRECIPITATION
SHOULD PUSH BACK INTO THE MOUNTAINS TUESDAY EVENING STARTING AS
SNOW AT THE HIGHER ELEVATIONS THAT WILL HAVE COOLED DOWN AGAIN
BELOW FREEZING BEHIND THE EARLIER SYSTEM BUT SOME LIGHT RAIN
AT LOWER ELEVATIONS. SHOULD CHANGE OVER TO ALL SNOW OVERNIGHT
WITH THE POTENTIAL FOR AN INCH OR SO OF SNOW ACROSS THE NORTHERN
MOUNTAINS. WILL REVISIT THIS IN SUBSEQUENT FORECASTS.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 2 PM SUNDAY...I WILL USE A BLEND OF THE 12Z GFS AND 0Z EMCWF
FOR THE EXTENDED PERIOD...12Z THURSDAY THROUGH SUNDAY. THE PERIOD
BEGINS WITH THE CENTER OF A H5 590 DM HIGH CENTERED OVER THE GULF OF
MEXICO...WITH A LONGWAVE RIDGE BUILDING OVER THE SOUTHERN
APPALACHIANS THURSDAY THROUGH FRIDAY. THURSDAY AND FRIDAY WILL
REMAIN DRY AND TRENDING WARMER. HIGHS TEMPERATURES ON THURSDAY ARE
FORECAST TO RANGE FROM 50 DEGREES WITHIN THE MTN VALLEYS TO THE MID
50S ACROSS THE UPPER SAVANNAH RIVER VALLEY. ON FRIDAY...TEMPERATURES
SHOULD RISE 2 TO 3 DEGREES ABOVE NORMAL...GENERALLY AROUND 60 EAST
OF I-85.

ON SATURDAY...A WEAK FRONT WILL LIKELY BECOME STATIONARY ACROSS THE
WESTERN CAROLINAS AND NE GA. THE FRONT MAY START TO LIFT SLOWLY
NORTH AS A WARM FRONT AS LOW PRESSURE DEVELOPS ACROSS THE GREAT
PLAINS. WEAK WAA SHOULD KEEP MIN TEMPS SAT MORNING ABOVE FREEZING
ACROSS THE FORECAST AREA. HIGH TEMPERATURES APPEAR MILD...WITH LOW
TO MID 60S EAST OF THE MTNS AND UPPER 50S EAST. I WILL CARRY CHC TO
SCHC POPS ACROSS THE WESTERN MOUNTAINS FOR LIGHT RAIN SHOWERS. ON
SUNDAY...GUIDANCE INDICATES THAT THE LOW CENTER WILL TRACK EAST
ACROSS THE MID MISSISSIPPI VALLEY...CARRIED BY ZONAL FLOW. WAA WILL
INCREASE AS THE LOW CENTER APPROACHES THE SOUTHERN APPALACHIANS.
HIGH TEMPERATURES ARE FORECAST TO WARM TO NEAR 60 AT KAVL AND
RANGING FROM THE MID TO UPPER 60S EAST. MOIST SOUTHWEST FLOW...WEAK
INSTABILITY...AND PASSAGE OF MID LEVEL FORCING SHOULD YIELD CHC TO
SCHC POPS FOR SHRA ACROSS THE MTNS AND FOOTHILLS SUNDAY AFTERNOON.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AT KCLT....CLOUD HEIGHTS ARE EXPECTED FALL TO LOW VFR EARLY IN THE
FORECAST AHEAD OF AN APPROACHING SYSTEM. BY DAWN MONDAY GUIDANCE
SUPPORTS AN MVFR CIG. SNOW COULD REACH THE FIELD AS EARLY AS THIS
EVENING. THE SNOW WOULD CHANGE OVER TO SLEET AND THEN FREEZING RAIN
BY DAWN. VSBY RESTRICTIONS APPEAR TO BE WORSE OVERNIGHT...BUT AT THIS
TIME LIMITED CONFIDENCE SUPPORTS NOW LOWER THAN MVFR. VFR WOULD
RETURN AFTER DAWN. WINDS ARE EXPECTED TO VEER SE THIS AFTERNOON...
BACKING TO THE NE AFTER MIDNIGHT...WITH ONLY LIMITED GUST POTENTIAL.

ELSEWHERE...CIGS ARE EXPECTED TO FALL TO LOW VFR THIS AFTERNOON AS
LOW LEVEL MOISTURE INCREASES. CIGS FALL TO MVFR BY DAWN...EXCEPT IFR
AT KAND. SNOW COULD REACH KAVL AS EARLY AS LATE AFTERNOON...KHKY BY
EVENING...AND SC SITES LATE THIS EVENING. SC SITES WOULD SEE A
CHANGEOVER TO SLEET AND THEN FREEZING RAIN BY DAWN...WITH NC SITES
FOLLOWING ON MONDAY MORNING. VSBY RESTRICTIONS ASSOCIATED WITH
PRECIPITATION APPEAR TO MAXIMIZE OVERNIGHT...WITH IFR IN NC...AND
MVFR IN SC...ALTHOUGH CONFIDENCE IS LIMITED AT THIS POINT. VFR WOULD
RETURN AFTER DAWN IN SC...AND BY MIDDAY IN NC.

OUTLOOK...A STRONG LOW PRESSURE SYSTEM WILL CROSS THRU MONDAY
NIGHT...BRINGING CLOUDS AND PRECIP. PRECIP IS EXPECTED TO START OUT
AS SNOW OR WINTRY MIX...THEN GRADUALLY TRANSITION TO ALL RAIN AT THE
TAF SITES BY MONDAY EVENING. DRY AIR WILL RETURN DURING THE DAY ON
TUESDAY...EXCEPT AT KAVL...WHERE SOME LIGHT SNOW MAY RETURN TUESDAY
NIGHT BEFORE ENDING WEDNESDAY MORNING.

CONFIDENCE TABLE...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       HIGH 100%     HIGH  93%     LOW   35%     HIGH 100%
KGSP       HIGH 100%     HIGH  93%     LOW   44%     HIGH 100%
KAVL       HIGH 100%     MED   66%     LOW   50%     HIGH  80%
KHKY       HIGH 100%     MED   73%     LOW   49%     MED   76%
KGMU       HIGH 100%     HIGH  93%     LOW   44%     HIGH 100%
KAND       HIGH 100%     HIGH  98%     HIGH  81%     MED   78%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 PM EST
     MONDAY FOR GAZ010-017.
     FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST
     MONDAY FOR GAZ018-026-028-029.
NC...WINTER STORM WARNING FROM 6 PM THIS EVENING TO MIDNIGHT EST
     MONDAY NIGHT FOR NCZ033-035-049-050-501>506.
     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 PM EST
     MONDAY FOR NCZ036-037-048-051>053-056>059-062>065-068>072-
     507>510.
     FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST
     MONDAY FOR NCZ082.
SC...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 PM EST
     MONDAY FOR SCZ001>003.
     FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST
     MONDAY FOR SCZ004>010.

&&

$$
SYNOPSIS...SBK
NEAR TERM...JAT
SHORT TERM...TDP
LONG TERM...NED
AVIATION...JAT


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