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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
250 AM EST SAT FEB 13 2016

.SYNOPSIS...
THE LEADING EDGE OF AN ARCTIC AIRMASS WILL PUSH INTO THE REGION 
TODAY AND SETTLE SOLIDLY OVER THE AREA ON SUNDAY. A LOW PRESSURE 
SYSTEM WILL APPROACH FROM THE WEST ON MONDAY...CROSS THE REGION 
MONDAY NIGHT...AND DEPART TO THE EAST ON TUESDAY. A WINTRY MIX OF 
PRECIPITATION IS LIKELY WITH THIS SYSTEM. ANOTHER FAST MOVING SYSTEM 
WILL CROSS THE SOUTHERN APPALACHIANS MID WEEK...WITH DRYING AND 
WARMING EXPECTED LATE IN THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 200 AM...A DEEP TROF CONTINUES TO DOMINATE THE EASTERN 
CONUS...WITH THE AXIS NOW SHIFTING JUST EAST OF THE CWFA TODAY. 
CONFLUENT NWLY FLOW ON THE BACK SIDE OF THE TROUGH WILL USHER IN A 
LARGE ARCTIC HIGH PRESSURE SYSTEM INTO THE REGION TODAY THRU 
TONIGHT. STRONG LLVL WINDS AND CAA IS RESULTING IN WIND ADVISORY 
CRITERIA WINDS ACROSS THE NORTHERN NC MTNS. ALSO...REGIONAL RADAR 
MOSAIC STILL SHOWING HEALTHY SNOW SHOWERS ACROSS EASTERN KY/TN. SO 
EXPECT CONTINUED LIKELY TO CATEGORICAL COVERAGE OF SNOW ALONG THE TN 
BORDER FOR THE NEXT FEW HOURS. THEN SNOW SHOULD TAPER OFF FAIRLY 
QUICKLY STARTING RIGHT BEFORE DAYBREAK THRU THE REST OF THE MORNING. 
TEMPS ARE NOT FALLING AS QUICKLY AS EXPECTED. PROBABLY DUE TO 
TURBULENT MIXING AND CLOUDS/SNOW ADDING A LITTLE HEAT. STILL...THE 
COMBINATION OF WIND AND FALLING TEMPS SHOULD RESULT IN SUB-ZERO WIND 
CHILLS FOR MUCH OF THE ELEVATIONS ABOVE 3500 FT THIS MORNING.

BY MIDDAY...SNOW SHOWERS SHOULD BE WINDING DOWN TO JUST A FEW 
FLURRIES AND LINGERING STRATUS ALONG THE TN BORDER...WHILE WINDS 
SLOWLY WEAKEN...BUT REMAIN BREEZY. TEMPS WILL ONLY HOLD STEADY OR 
RISE SLIGHTLY IN THE NORTHERN MTNS...SO WIND CHILLS WILL HOVER IN 
THE 0 TO -5 RANGE THRU THE DAY. ELSEWHERE...IT WILL BE COLD WITH 
TEMPS RANGING FROM 15 TO 30 DEGREES BELOW NORMAL...DESPITE FULL SUN 
OUTSIDE THE NW FLOW STRATUS.

TONIGHT...THE CENTER OF ARCTIC HIGH PRESSURE WILL SETTLE OVER THE 
CENTRAL APPALACHIANS...WHILE A WEAK ALBERTA CLIPPER DIVES INTO THE 
PLAINS STATES. THE UPPER FLOW WILL FLATTEN OUT SOMEWHAT AS THE 
CLIPPER SYSTEM APPROACHES...ALLOWING SOME MID AND HIGH CLOUDS TO 
START STREAMING ATOP THE AREA LATE. STILL...IT LOOKS LIKE A DECENT 
RADIATIONAL COOLING NIGHT...WITH SOME OF THE COLDEST TEMPS OF THE 
WINTER EXPECTED BY DAYBREAK SUNDAY. LOWS WILL BE GENERALLY 20-25 
DEGREES BELOW NORMAL. EVEN THOUGH WINDS WILL BE SUBSTANTIALLY WEAKER 
IN THE NORTHERN MTNS...THE COLDER TEMPS WILL RESULT IN DANGEROUS 
WIND CHILLS CONTINUING THRU THE NIGHT.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
AS OF 245 AM EST SATURDAY...CONSIDERABLE UNCERTAINTY PERSISTS WITH 
THE WINTRY WEATHER FORECAST FOR SUNDAY NIGHT THROUGH TUE. ONE 
QUESTION CENTERS AROUND HOW QUICKLY THE COLD AND DRY ARCTIC AIRMASS 
PRESENT AT ONSET SUNDAY NIGHT WILL RETREAT/MODIFY THROUGH THE 
PERIOD. UNCERTAINTY ALSO ARISES OVER THE SURFACE LOW TRACK 
FORECASTS...WITH THE GFS/ECMWF CAMP STARTING OFF THE SURFACE LOW 
WEST OF THE MOUNTAINS AND TRACKING IT THROUGH THE CENTRAL/SOUTHERN 
APPALACHIANS...WHILE THE NAM/GEM CAMP DEPICT MORE OF A REDEVELOPING 
PIEDMONT LOW TO THE SOUTHEAST. THESE DIFFERENCES WILL NEED TO BE 
RESOLVED BEFORE ENOUGH CONFIDENCE EXISTS TO POST A WINTER STORM 
WATCH.

FOR THE SPECIFICS...A NORTHERN STREAM SYSTEM MOVING ACROSS THE UPPER 
MIDWEST ON SUNDAY WILL EXTEND A WARM FRONTAL FEATURE ACROSS THE 
SOUTHERN APPALACHIANS THROUGH THE DAY...WITH ASSOCIATED UPGLIDE 
MOISTURE ARRIVING AT MID LEVELS. LOWER LEVELS...HOWEVER...REMAIN 
MOSTLY DRY THROUGH LATE DAY. MEANWHILE...1034 MB SURFACE HIGH 
PRESSURE WILL MOVE EAST THROUGH THE MID ATLANTIC REGION SUNDAY AND 
OFFSHORE SUNDAY NIGHT. THE LOW LEVEL THICKNESS TROUGH REMAINING 
ACROSS THE WESTERN CAROLINAS WILL BE COLD AND DRY AND FAVORABLE FOR 
HYBRID COLD AIR DAMMING AS THE PRECIPITATION STARTS AHEAD OF AN 
APPROACHING SOUTHERN STREAM WAVE. THE MODELS HAVE TRENDED LESS 
AMPLIFIED AND MORE PROGRESSIVE WITH THIS SOUTHERN WAVE WHICH 
SHARPENS UP OVER THE MS RIVER VALLEY ON MONDAY. A CONSENSUS OF THE 
VARYING MODEL PROFILES PROMOTES A SLOW WARMUP WITH GRADUAL CAD 
EROSION LATE MONDAY INTO MONDAY NIGHT. THE FASTER SOLUTIONS NOW 
BRING A MID DRY SLOT IN QUICKLY BEHIND THE WAVE LATE MONDAY NIGHT 
THROUGH TUESDAY MORNING...WITH HEAVIEST PRECIPITATION SHUTTING OFF 
MORE QUICKLY.

UPGLIDE MOISTURE SHOULD GET STARTED IN EARNEST ACROSS THE FORECAST 
AREA BEFORE DAYBREAK MONDAY. STILL ANTICIPATE NEARLY ALL SNOW AT 
ONSET WITH THE 850 MB ZERO DEGREE ISOTHERM ALONG THE SOUTHERN 
PERIPHERY OF THE FORECAST AREA. HOWEVER...THE WARM NOSE ALOFT SHOULD 
STEADILY EXPAND AND MOVE NORTHWARD THROUGH THE DAY TO PERMIT A 
TRANSITION TO SLEET AND THEN FREEZING RAIN THROUGHOUT MOST AREAS BY 
MONDAY EVENING. THE MID LEVEL DRYING AND ASSOCIATED REMOVAL OF ICE 
NUCLEI MAY KEEP ANY OVERNIGHT PRECIPITATION RAIN OR FREEZING 
RAIN/FREEZING DRIZZLE IN ANY LINGERING COLDER MOUNTAINS POCKETS. 
THEN...NORTHWEST UPSLOPE MOISTURE ON TUESDAY MORNING WILL DIMINISH 
THROUGH TUESDAY AFTERNOON...WITH A BRIEF LULL IN PRECIPITATION 
LIKELY. ALL TOLD...AT LEAST ADVISORY SNOW OR ICE ACCUMS LOOK QUITE 
POSSIBLE FOR A SIGNIFICANT CHUNK OF THE FORECAST AREA...WITH MAINLY 
THE NORTHERN MOUNTAINS AT RISK OF WINTER STORM SNOW/ICE AT THIS 
POINT. WINTER STORM WATCHES COULD BE NEEDED FOR MONDAY AS EARLY AS 
THIS AFTERNOON.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
AS OF 245 AM EST SATURDAY...THE NEXT UPSTREAM SHORTWAVE ROUNDING THE 
BROAD EASTERN TROUGH WILL CROSS THE SOUTHERN APPALACHIANS TUESDAY 
NIGHT. A RESURGENCE OF UPSLOPE MOISTURE WILL ACCOMPANY THE WAVE AS 
COLDER TEMPERATURES BRIEFLY RETURN...AND SOME SCATTERED SNOW SHOWER 
ACTIVITY COULD BREAK CONTAINMENT EAST OF THE MOUNTAINS IN THE EARLY 
MORNING HOURS WED. BEHIND THE DEPARTING THE WAVE...HEIGHTS WILL 
BUILD IN FROM THE WEST LATER WEDNESDAY THROUGH THURSDAY. TIMING 
DIFFERENCES EXIST ON THE NEXT UPSTREAM WAVE LATE WEEK IN THE 
PROGRESSIVE FLOW PATTEN...AND NO PRECIPITATION WILL BE ADVERTISED 
THROUGH FRIDAY. THE MAIN FEATURE OF THE FORECAST WED THROUGH FRI 
WILL BE DRYING AND WARMING CONDITIONS WITH MAX TEMPERATURES FINALLY 
CLIMBING ABOVE CLIMATOLOGY BY FRIDAY.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE EAST OF THE MTNS...VFR...WITH GENERALLY SKC OR 
FEW250 FOR MOST OF THE PERIOD. WINDS WILL REMAIN OUT OF THE 
NW...WITH SOME LOW-END GUSTS EXPECTED AS MIXING DEEPENS LATE MORNING 
THRU THE MIDAFTERNOON.

AT KAVL...NORTH-NORTHWEST WINDS WILL REMAIN ACROSS THE TERMINAL 
THROUGH THE TAF PERIOD AS HIGH PRESSURE APPROACHES FROM THE 
NORTHWEST. WIND GUSTS HAVE BEEN INTERMITTENT THRU THE EVENING...BUT 
ARE EXPECTED TO BE MORE FREQUENT BY 9Z...AND CONTINUE THRU THE 
AFTERNOON. A TEMPO FOR THE GUSTS AND FOR POTENTIAL MVFR CIG FROM THE 
TN BORDER WILL BE KEPT THRU 9Z. SKIES SHOULD CLEAR OUT BY 14Z...AS THE 
LLVL MOISTURE TAPERS OFF. 

OUTLOOK...AN ARCTIC AIR MASS WILL BUILD IN ACROSS THE REGION OVER THE 
WEEKEND. A SIGNIFICANT WINTER WEATHER SYSTEM IS POSSIBLE EARLY NEXT 
WEEK.

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  85%     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 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...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR 
     NCZ033-048>052.
     WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR NCZ033-049-050.
     WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR NCZ048-051-052-
     058-059.
SC...NONE.

&&

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

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