Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 242342
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
642 PM EST SAT JAN 24 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD BACK INTO THE REGION ON SUNDAY...BEFORE
ANOTHER LOW PRESSURE AREA AND TRAILING UPPER LEVEL DISTURBANCE MOVE
THROUGH MONDAY AND TUESDAY. HIGH PRESSURE RETURNS DURING THE LATTER
HALF OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 630 PM EST...AN UPPER LEVEL VORTICITY LOBE MOVING INTO THE
CENTRAL APPALACHIANS FROM ERN KY IS BRINGING SHALLOW MOISTURE BACK
INTO THE MOUNTAIN CHAIN. LOW LEVEL MOISTURE IN THE NWLY UPSLOPE FLOW
DOWN THE SRN APPALACHIANS WILL LEAD TO AN INCREASE IN MOUNTAIN
CLOUDS ALONG THE SPINE THROUGH LATE EVENING AND EARLY
OVERNIGHT...AND ISOLD LIGHT SNOW SHOWERS CANNOT BE RULED OUT FOR THE
NRN NC MOUNTAINS. THESE SHOULD BE BRIEF AND SPARSE WITH LITTLE
IMPACT. WIND GUSTS COULD APPROACH 40 TO 45 MPH ALONG THE VERY
HIGHEST RIDGE TOPS OF THE NORTHERN MOUNTAINS DURING THE PERIOD OF
BEST NW FLOW WITH THE WAVE TONIGHT...BUT THIS TOO SHOULD BE OF
FAIRLY SHORT DURATION WITH THE GRADIENT DIMINISHING QUICKLY THROUGH
THE EARLY MORNING HOURS. THE ONLY OTHER CONCERN WILL BE FOR PATCHY
BLACK ICE IN LOCATIONS WHERE WET ROADS HAVE NOT BEEN ABLE TO DRY
SUFFICIENTLY. THIS COULD BE A MINOR CONCERN FROM THE NC MTNS TO
PARTS OF THE NW PIEDMONT WHERE SHOWERS LINGERED THE LONGEST TODAY.
THIS DOES NOT APPEAR TO WARRANT A SPECIAL WEATHER STATEMENT AT
PRESENT. STILL EXPECT OVERNIGHT LOWS AROUND NORMAL.

SHORT WAVE RIDGING WILL DEVELOP OVER THE AREA SUNDAY AHEAD OF A
STRONG CLIPPER SYSTEM MOVING INTO THE MID MISSISSIPPI VALLEY. LOW
LEVEL FLOW WILL BECOME SLY AHEAD OF THE ASSOCIATED SFC LOW. AFTER
CLEARING SKIES ACROSS THE MTNS DURING THE MORNING AS LOW LEVEL
MOISTURE DEPARTS...CLOUDS MOVE BACK IN IN THE DEVELOPING WAA
PATTERN. ISOLATED SHRA MAY ALSO DEVELOP ACROSS THE MTNS VERY LATE IN
THE DAY AS DEEP MOISTURE INCREASES...BUT NO SIGNIFICANT QPF IS
EXPECTED. CLOUDS WILL INCREASE LATE IN THE DAY OUTSIDE OF THE
MTNS...BUT MOSTLY SUNNY SKIES WILL PREVAIL FOR THE BULK OF THE DAY.
HIGHS WILL BE A FEW DEGREES ABOVE NORMAL ACROSS THE CWFA.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM SATURDAY...THE POTENT CLIPPER SYSTEM WILL CROSS THE
CWFA SUNDAY NIGHT THRU MONDAY MORNING PER LATEST CONSENSUS. GUIDANCE
CONTINUES TO BE IN GOOD AGREEMENT ON THE TIMING. BEST Q-VECTOR
CONVERGENCE LOOKS TO BE AROUND 00-06Z MON...SHIFTING EAST BY 12Z.
STEEP LOW-MID LVL LAPSE RATES AND DECENT MOISTURE SHUD RESULT IN
GOOD COVERAGE OF PRECIP ACRS THE HIGH TERRAIN OVERNIGHT...WITH SOME
ACTIVITY BEING ABLE TO DEVELOP EAST OF THE MTNS. WITH MID LVL
THICKNESSES CRASHING...COUPLED WITH WEAK SBCAPE (UP TO 150
J/KG)...MAY SEE CONVECTIVE SNOW SHWRS ACRS THE MTNS. IN THE LWR
ELEVATIONS...ALL INDICATIONS ARE THAT THE SFC-BASED WARM LAYER WILL
PROBABLY JUST BE TOO WARM. IF THE BEST FORCING IS ABLE TO OCCUR
DURING THE WEE MORNING HOURS...CANNOT RULE OUT SPOTTY SNOW SHWRS
ACRS NE GA AND THE WRN UPSTATE. BASED ON CURRENT TIMING...IT LOOKS
LIKE THE NC FOOTHILLS AND PIEDMONT HAVE A BETTER SHOT AT SEEING A FEW
FLAKES...BUT EVEN THERE...NOT EXPECTING ANY WIDESPREAD ACCUMS. EVEN
IN THE MTNS...ACCUMS MAY STRUGGLE TO REACH ADVISORY CRITERIA...AS
LLVL FLOW WILL BE OUT OF THE WEST-SOUTHWEST OVERNIGHT. FOR TEMPS...I
WENT CLOSE TO THE MOS CONSENSUS...MAINLY IN THE UPR 20S TO MID 30S
MTNS AND UPR 30S-40 PIEDMONT.

AS THE MID LVL LOW PASSES TO THE EAST MONDAY MORNING...LLVL FLOW
WILL VEER TO NWLY...BUT NEVER GETS ALL THAT STRONG. SO ONLY LIGHT
ADDITIONAL NW FLOW SNOW ACCUMS ARE EXPECTED ALONG THE TN LINE DURING
THE DAY. EAST OF THE MTNS...FCST SNDGS SHOW LINGERING LLVL MOISTURE
WITHIN WEAK NW FLOW...BUT FORCING SHUD WANE FOR ANY PRECIP. TEMPS
WILL WARM INTO THE MID 30S TO LWR 40S IN THE MTNS...AND UPR 40S TO
LWR 50S ACRS THE PIEDMONT.

MONDAY NIGHT AND TUESDAY...ANOTHER SHORTWAVE WILL DIVE SOUTHEAST
ACRS THE OHIO VALLEY...AND REINFORCE NWLY FLOW ATOP THE CWFA. IN
FACT...THE 12Z NAM AND GFS AGREE ON BETTER OVERALL NW FLOW SETUP
ACRS THE SOUTHERN APPALACHIANS...ESPECIALLY AROUND MIDDAY TUESDAY.
ON THE PLAN VIEW...THE 925-850 MB FLOW ALSO SEEMS TO COME OFF THE
GREAT LAKES TO THE NC MTNS. SO MAY SEE DIURNALLY-ENHANCED CONVECTIVE
SNOW SHWRS DEVELOPING ACRS ERN KY/TN...THEN INTO THE NC
MTNS...PRODUCING A QUICK 1-2" OF SNOW. I WILL PLAN TO ADD A MENTION
OF SNOW ACCUM IN THE HWO ALONG THE TN BORDER FOR TUESDAY.
OTHERWISE...EXPECT GENERALLY MOSTLY CLEAR SKIES AND BELOW NORMAL
TEMPS ACRS THE REGION.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM SAT...THE PERSISTENT DEEP TROUGH OVER THE ERN SEABOARD
WILL FINALLY MOVE OFF THE EAST COAST WEDNESDAY ALLOWING A SHORT RIDGE
AND HIGH PRESSURE TO BUILD ACROSS THE CWFA. COLD ADVECTION AND MOIST
NW FLOW WILL CONTINUE TUE NIGHT INTO WED...WITH POPS ACCORDINGLY
CONTINUED NEAR THE TENN BORDER. DRY AND SETTLED WEATHER RETURN
BRIEFLY BEFORE THE NEXT CLIPPER MOVES IN LATE THURSDAY. THE CLIPPER
WILL HAVE ABSORBED A WEAK WAVE IN THE SRN STREAM AND IS PROGGED TO
PUSH A WEAK COLD FRONT INTO THE DEEP SOUTH AND CAROLINAS THU NIGHT.
CHC POPS FOR THE UPSLOPE AREAS OF THE MTNS WILL BE ADVERTISED...IN
ADDITION TO SCHC POPS IN THE PIEDMONT AFFORDED BY THE PRESENCE OF
SOME LLVL FORCING. HIGH PRESSURE RETURNS IN THE WAKE OF THE FRONT AS
THE UPPER FLOW BECOMES MORE ZONAL. REGARDING FURTHER EVOLUTION...THE
24/12Z RUNS OF THE GFS AND EC DIVERGE BY THE WEEKEND. EC BRINGS
ANOTHER CLIPPER INTO THE CENTRAL APPALACHIANS BY SATURDAY NIGHT WITH
AN ERN TROUGH DEVELOPING AFTERWARD. GFS IS A BIT MORE ACTIVE WITH THE
SRN STREAM DURING THE SAME PERIOD...SHOWING RETURN FLOW OVER THE HIGH
WHICH DEVELOPS INTO A WEDGE. BOTH MODELS KEEP US DRY THRU SATURDAY
HOWEVER. TEMPS WILL REMAIN IN A SEASONABLE RANGE THRU THE FCST
PERIOD...STARTING OFF A COUPLE DEGREES BELOW NORMALS...BUT WARMING
WED-THU PRIOR TO THE FROPA AND A SUBSEQUENT RETURN OF READINGS A BIT
BELOW NORMAL.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AT KCLT...ANTICIPATE WINDS TO REMAIN JUST N OF W THROUGH MUCH OF THE
NIGHTTIME HOURS...BEFORE TURNING SW AROUND DAYBREAK AND THEN BACKING
TO SRLY THROUGH SUNDAY. LITTLE MORE THAN INCREASING HIGH CLOUDS IS
EXPECTED AHEAD OF THE NEXT APPROACHING CLIPPER THROUGH SUNDAY AFTN.

ELSEWHERE...NW FLOW MOISTURE PEAKING AROUND 06Z TONIGHT COULD
PRODUCE SOME MVFR TO LOWER VFR CLOUDS NEAR THE SPINE OF THE SRN
APPALACHIANS...BUT THESE LOWER CLOUDS ARE NOT EXPECTED TO REACH THE
AIRFIELD AT KAVL. OTHERWISE...ANTICIPATE MAINLY GRADUALLY INCREASING
HIGHER LEVEL CLOUDS THROUGH SUNDAY AHEAD OF THE NEXT APPROACHING
CLIPPER SYSTEM. FLOW WILL STEADILY BACK FROM WSW TO SW TO SRLY
THROUGH SUNDAY...EXCEPT NW AT KAVL EARLY BECOMING SRLY SUDDENLY
AROUND MIDDAY SUNDAY.

OUTLOOK...A SERIES OF CLIPPER SYSTEMS WILL BRING SNOW CHANCES MAINLY
TO THE MOUNTAINS EARLY IN THE WEEK. ANY RESTRICTIONS AND SNOW
SHOWERS WOULD BE POSSIBLE AT KAVL...WITH MAINLY VFR CONDITIONS
LIKELY ELSEWHERE.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
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...CSH
NEAR TERM...HG/RWH
SHORT TERM...ARK
LONG TERM...WIMBERLEY
AVIATION...HG/RWH



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