Winter Weather in North Carolina, February 15 to 17, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
257 PM EST FRI FEB 15 2013

.SYNOPSIS...
A COLD FRONT WILL PUSH EAST OF THE REGION OVERNIGHT AND BRING COLDER
CANADIAN AIR TO THE AREA. AN UPPER LEVEL TROUGH WILL CROSS THE
REGION ON SATURDAY...WITH DRY HIGH PRESSURE BUILDING IN ON SUNDAY.
ANOTHER COLD FRONT WILL APPROACH THE CAROLINAS AND NORTHEAST GEORGIA
ON TUESDAY WITH DRIER WEATHER EXPECTED IN THE FRONTS WAKE.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 250 PM...LATEST RADAR COMPOSITE INDICATED A BAND OF LIGHT SHRA
SLIDING EAST ACROSS WESTERN TN...STARTING TO PUSH ACROSS THE STATE
LINE INTO GRAHAM AND SWAIN COUNTIES. COVERAGE OF THE SHRAS SHOULD
PEAK ACROSS THE TN BORDER COUNTIES BETWEEN 21Z TO 23Z. THE 4KM WRF
INDICATES THAT THE LINE WILL REMAIN INTACT ACROSS THE
MTNS...POSSIBLY PUSHING ACROSS THE FOOTHILLS AND PIEDMONT THIS
EVENING WITH FROPA. I WILL ADVERTISE LIKELY POPS ALONG THE TN
LINE...AND CHC POPS TIMED ACROSS THE I-40 FOOTHILL AND NRN PIEDMONT
CORRIDOR THIS EVENING.

TONIGHT...THE MAIN FORECAST CHALLENGE WILL CONCERN THE DURATION OF
THE PRECIPITATION ACROSS THE TN BORDER COUNTIES OVERNIGHT. MOST
GUIDANCE INDICATES THAT PRECIP SHOULD END ACROSS THE TN LINE BY
MIDNIGHT. GIVEN THE LIMITED MOISTURE AND WEAK FLOW...IT SEEMS
REASONABLE TO DROP POPS TO CHC TO SCHC...BEFORE INCREASING TOWARD SUNRISE.
HOWEVER...BEFORE THE TN BORDER PRECIP DECREASES...CAA SHOULD RESULT
IN A TRANSITION OVER TO SNOW. LIMITED MOISTURE AND LOW SLR SHOULD
SUPPORT ONLY LIGHT ACCUMULATIONS OVERNIGHT.  MIN TEMPS SHOULD RANGE
FROM SUB FREEZING ACROSS THE MTNS TO MID 30S EAST.

SATURDAY...FORECAST IS BECOMING QUITE INTERESTING WITH LATEST RUNS
OF THE GUIDANCE. NO MATTER WHAT THE GUIDANCE HOLDS...WE WILL HAVE
WARM SOIL TEMPERATURES EAST OF THE MTNS. LATEST SOIL OBS ACROSS SC
PIEDMONT RANGE IN THE MID TO UPPER 40S. HOWEVER...BRIDGES AND
OVERPASSES WILL REMAIN MUCH COOLER THAN THE SOIL. THAT BEING
SAID...THE CONSENSUS OF THE MODELS INDICATE THAT A NEUTRAL TO
NEGATIVE TILTED H5 TROF WILL PIVOT OVER THE REGION ON SAT. GFS QG H5
UPWARD VERTICAL VELOCITIES PEAK OVER 40 MB/HR ACROSS THE FA AT
18Z...WITH VALUES OVER 30 MB/HR ARRIVING FROM NRN GA AFTER 12Z. GFS
FORECAST SOUNDINGS DURING THE MORNING INDICATE THAT NEARLY SATURATED
CONDITIONS WILL DEVELOP FROM 3 FKT TO NEAR 20 KFT...WITH A DEEP
LAYER WITHIN THE IDEAL SNOW GROWTH RANGE. CYCLOGENESIS OFF THE NC
COAST ON SAT...SHOULD RESULT IN A BAND OF FRONTOGENESIS ACROSS THE
PIEDMONT DURING DAYLIGHT HOURS. IN ADDITION...850MB TO 500MB
SATURATED EPV BECOME NEGATIVE ACROSS THE PIEDMONT AND PORTIONS OF
THE FOOTHILLS DURING THE EARLY AFTERNOON. THE COMBINATION OF THE
DEEP MOISTURE...FORCING...COLD PARTIAL THICKNESSES AND SNOW GROWTH
TEMPERATURES SHOULD PLACE THE PIEDMONT UNDER A STRONG SNOW PRODUCING
ENVIRONMENT.

THE LIMITS TO ACCUMULATING SNOWFALL WILL BE THE MILD SOIL
TEMPERATURES AND ABOVE FREEZING AIR TEMPERATURES. ASSUMING THAT WET
BULB WILL BRING AFTERNOON 2M TEMPS TO THE MID 30S...BELOW MOST
ENSEMBLE MEMBERS AND MOS...ACCUMS SHOULD BEGIN ACROSS THE PIEDMONT.
THE MTN AREAS ARE NOT LIMITED BY WARM SOIL OR AIR
TEMPS...THEREFORE...THE MTN AREAS SHOULD ACCUMULATE SNOW AS LONG AS
IT IS FALLING. BASED ON THE LATEST TIMING AND THINKING WITH THIS
FORECAST PACKAGE...SEVERAL INCHES OF SNOW IS POSSIBLE ACROSS THE
MTNS...WITH AROUND AN INCH ALONG THE I-85 CORRIDOR FROM KGMU TO KCLT
METRO AREA.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 230 PM FRI...THERE IS GOOD MODEL CONSENSUS THAT THE DEEP UPPER
FORCING AND MOISTURE TRAVERSING THE AREA WITH THE TROUGH AXIS LATE
SAT WILL MOVE E OF THE WRN CAROLINA PIEDMONT BY 00Z SUNDAY. THE
WINTRY EVENT WILL THEN QUICKLY TRANSITION TO A MORE TYPICAL
LINGERING NW FLOW SNOW PATTERN...WITH ADDITIONAL ONE INCH SNOW
ACCUMS ALONG THE IMMEDIATE TN BORDER THROUGH DAYBREAK SUNDAY. IN
ADDITION...THE PRESSURE GRADIENT WILL INCREASE OVER THE SRN
APPALACHIANS AS THE DEEP ERN TROUGH PULLS AWAY SAT NIGHT THROUGH SUN
MORNING. IT APPEARS THE STRONGEST 850 MB JET IN THE COLD ADVECTION
WILL BE AROUND 45 KT TOWARD 12Z SUN. SOME ADVISORY LEVEL WIND GUSTS
ALONG WITH ADVISORY WIND CHILLS IN THE STRONG COLD ADVECTION WILL BE
POSSIBLE IN THE HIGHER TERRAIN SUN MORNING. THE WINTER WEATHER
ADVISORY WILL CONTINUE INTO SUNDAY MORNING NEAR THE TN BORDER FOR
THIS REASON.

HEIGHTS WILL RISE SLOWLY THROUGH THE DAY ON SUNDAY...WITH THE PRES
GRADIENT GRADUALLY RELAXING DURING THE AFTERNOON. NW DOWNSLOPE FLOW
AND BETTER INSOLATION WILL ALLOW FOOTHILL/PIEDMONT TEMPS TO WARM
BACK THROUGH THE 40S DESPITE THE COLD THICKNESSES. A SHALLOW RIDGE
WILL THEN BUILD ACROSS OVER THE AREA SUN NIGHT THROUGH MON...BUT
WITH A WARM FRONT AND SHALLOW MOISTURE BRUSHING THE NW CWA SUN NIGHT
UNDER THE RIDGE AXIS. WILL ADVERTISE A BIT MORE CLOUDS IN NW
SECTIONS...BUT NO POPS WITH THIS FEATURE. SW FLOW WILL IMPROVE ON
MONDAY AS THE WARM FRONT LIFTS WELL N OF THE AREA.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 215 PM FRIDAY...THERE ARE TWO SYSTEMS TO DEAL WITH IN THE
MEDIUM RANGE. THE FIRST ONE IS EXPECTED TO MOVE THROUGH TUESDAY...
WHILE THE SECOND ONE SHOULD AFFECT THE REGION LATE IN THE WEEK.
AS FOR THE FIRST SYSTEM...THE MODELS ARE IN FAIRLY GOOD AGREEMENT
AND HAVE SHOWN DECENT RUN-TO-RUN CONSISTENCY...WHICH INCREASES
CONFIDENCE. THE GFS HAS INCHED THE START TIME BACK EVEN MORE TOWARD
DAYBREAK TUESDAY AS MOISTURE RETURN AND UPGLIDE ARE DELAYED... BUT
THE ECMWF TIMING LOOKS THE SAME AS PREVIOUS RUNS. SO...PRECIP
CHANCES WILL BE RAMPED UP STARTING IN THE MID TO LATE EVENING WITH A
CHANCE SPREADING ACROSS THE WHOLE FCST AREA BY 12Z TUESDAY AND SOME
LIKELY BROUGHT INTO THE FAR W. FCST SOUNDINGS OVER THE HIGHER
TERRAIN STILL SHOW THE POSSIBILITY OF SNOW ABOVE ABOUT 4K FEET OWING
TO WET BULB EFFECTS...BUT THIS SHOULD CHANGE OVER AROUND DAYBREAK
AFTER MAYBE DROPPING A WET INCH. THE BEST MID/UPPER/QG FORCING STILL
LOOKS LIKE IT WILL MISS TO THE NORTH...ALTHO WE GET A QUICK SHOT OF
SOME DECENT DPVA. THE MODELS ALSO HAVE A 40-50 KT LOW LEVEL JET
MOVING ACROSS THE REGION ON TUESDAY MORNING...BUT THE DIRECTION IS
MORE SW THAN S COMPARED TO RECENT EVENTS...WHICH WILL NOT BE QUITE
AS FAVORABLE FOR UPSLOPE PRECIP ENHANCEMENT. FOR THIS REASON...WILL
ONLY BRING THE MTNS INTO THE LIKELY CATEGORY FOR NOW...AND AROUND 50
PCT E OF THE MTNS AS PRECIP BECOMES MORE SHOWERY IN THE AFTERNOON
WITH THE FRONT. THIS MIGHT ULTIMATELY BE BUMPED UP AS CONFIDENCE
INCREASES. PRECIP CHANCES SHOULD TAPER OFF AROUND SUNSET WITH THE
GUIDANCE BEING ESSENTIALLY DRY AFTER 00Z...WITH THE EXCEPTION OF
SOME SMALL POTENTIAL FOR NW FLOW SNOW. TEMPS WERE KEPT NEAR A
GUIDANCE BLEND.

UPPER LEVEL RIDGING WILL BUILD IN TUESDAY NIGHT AND WEDNESDAY...
WHICH WILL SUPPORT DRY HIGH PRESSURE MOVING THROUGH...THUS THE MID
WEEK SHOULD BE QUIET.

A LEAD WAVE WILL COME OVER THE TOP OF THE UPPER RIDGE AXIS MOVING IN
FROM THE WEST ON THURSDAY MORNING. MOISTURE AND ISENTROPIC UPGLIDE
AT LOW LEVELS MAY START TO SPREAD UP FROM THE SOUTH ON THURSDAY
AFTERNOON AS THE UPPER RIDGE AXIS CROSSES OVERHEAD WITH THE GFS
INDICATING THE ACTIVATION OF A WARM-FRONTAL TYPE FEATURE. PRECIP
CHANCES RAMP UP INTO THE CHANCE RANGE FROM THE SW DURING THE DAY AND
THEN PERSIST OVERNIGHT WITH THE WARM FRONT MOVING THROUGH. ON
FRIDAY...WE SHOULD BE IN A WARM SECTOR OF SORTS FOR PART OF THE
DAY...WITH THE COLD FRONT CROSSING THE REGION LATE IN THE DAY.
PRECIP WAS KEPT IN THE CHANCE RANGE. UNCERTAINTY IS TOO GREAT TO
SPECULATE ABOUT SEVERE WEATHER POTENTIAL.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WITH SW WINDS WILL CONTINUE
ACROSS THE TERMINALS THROUGH THE REST OF TODAY. FROPA SHOULD OCCUR
OVER KAVL BY 23Z....REACHING KAND...KGMU...KGSP...KHKY BY 2Z...AND
KCLT BY 4Z...RESULTING IN NNW WINDS. IT IS ALSO POSSIBLE A THIN BAND
OF SHRA COULD DEVELOP ALONG AND AHEAD OF THE FRONT...BUT IMPACTS
WILL BE MINIMAL. INTERESTING WEATHER DEVELOPS DURING THE DAYLIGHT
HOURS SAT. A NEUTRAL TO NEGATIVE TILTED H5 TROUGH WILL PIVOT OVER
THE REGION...RESULTING IN DEEP FORCING ACROSS THE REGION. AT THE
SAME TIME...CYCLOGENESIS SHOULD OCCUR OFF THE NC COAST. THE RESULT
SHOULD BE BKN TO OVC SKY...NORTH TO NORTHEAST WINDS...AND WIDESPREAD
PRECIP. THE PRECIP SHOULD FAVOR SNOW ACROSS THE REGION. IN
ADDITION...KCLT SHOULD END THE TAF PERIOD WITH MVFR CEILINGS.

OUTLOOK...MOISTURE AND SOME RESTRICTIONS WILL REMAIN ALONG THE TN
BORDER THROUGH EARLY SUNDAY. ELSEWHERE...CONDITIONS WILL GENERALLY
REMAIN DRY WITH VFR CONDITIONS. HIGH PRESSURE BUILDS OVER THE REGION
EARLY NEXT WEEK.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-20Z
KCLT       HIGH 100%     HIGH 100%     HIGH  91%     MED   77%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%
KAVL       HIGH 100%     HIGH 100%     HIGH  96%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH  97%     HIGH  95%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH  93%     HIGH  91%

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

&&

.FIRE WEATHER...
DRY AND BREEZY TO WINDY CONDITIONS ARE EXPECTED ON SUNDAY.
HOWEVER...THE LOWEST RH VALUES WILL BE MID TO LATE AFTERNOON...WHILE
THE WINDIEST CONDITIONS SHOULD BE IN THE MORNING THROUGH EARLY
AFTERNOON. IN ADDITION...WE WILL HAVE TO WAIT AND SEE HOW MUCH
PRECIPITATION FALLS OVER THE NEXT 24 TO 36 HOURS IN ORDER TO ASSESS
FUEL MOISTURE CONTENT AND ASSOCIATED FIRE DANGER FOR LATE THIS
WEEKEND.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM EST SATURDAY FOR
     NCZ053-065-501-503-505-507-509.
     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
     SUNDAY FOR NCZ033-048>052-058.
SC...NONE.

&&

SYNOPSIS...JPT
NEAR TERM...NED
SHORT TERM...HG
LONG TERM...PM
AVIATION...NED
FIRE WEATHER...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
347 PM EST FRI FEB 15 2013

NCZ033-048>052-058-162100-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-GRAHAM-
347 PM EST FRI FEB 15 2013

...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO NOON
EST SUNDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE TENNESSEE BORDER
COUNTIES OF THE WESTERN NORTH CAROLINA MOUNTAINS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS SHOULD RELAY SNOW ACCUMULATION REPORTS TO THE NATIONAL
WEATHER SERVICE.

NCZ053-065-501-503-505-507-509-162100-
BUNCOMBE-HENDERSON-CALDWELL MOUNTAINS-BURKE MOUNTAINS-
MCDOWELL MOUNTAINS-RUTHERFORD MOUNTAINS-POLK MOUNTAINS-
347 PM EST FRI FEB 15 2013

...WINTER WEATHER ADVISORY IN EFFECT FROM 6 AM TO 6 PM EST
SATURDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE CENTRAL AND EASTERN
MOUNTAINS OF WESTERN NORTH CAROLINA...NEAR THE BLUE RIDGE.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS SHOULD RELAY SNOW ACCUMULATION REPORTS TO THE NATIONAL
WEATHER SERVICE.

NCZ059-062>064-162100-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
347 PM EST FRI FEB 15 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE EXTREME SOUTHERN
MOUNTAINS OF WESTERN NORTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

A COLD FRONT WILL CROSS THE REGION TONIGHT...BRINGING A COLD
CANADIAN AIRMASS TO THE AREA. A PASSING UPPER LEVEL DISTURBANCE ON
SATURDAY WILL PRODUCE NUMEROUS SNOW SHOWERS ACROSS THE
MOUNTAINS...WITH LIGHT ACCUMULATIONS LIKELY. THE COMBINATION OF
ACCUMULATING SNOW SHOWERS AND TEMPERATURES IN THE 20S COULD
PRODUCE SLIPPERY ROADS SATURDAY THROUGH SATURDAY NIGHT. IF THE
SNOW SHOWER INTENSITY IS EXPECTED TO TREND UP SLIGHTLY...A WINTER
WEATHER ADVISORY COULD BE NEEDED ON SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ASKED TO RELAY ANY SNOW REPORTS TO THE NATIONAL
WEATHER SERVICE.

GAZ010-017-018-026-028-029-NCZ035>037-056-057-068>072-082-502-504-
506-508-510-SCZ001>014-019-162100-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-ALEXANDER-IREDELL-
DAVIE-CATAWBA-ROWAN-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-
UNION NC-GREATER CALDWELL-GREATER BURKE-EASTERN MCDOWELL-
GREATER RUTHERFORD-EASTERN POLK-OCONEE MOUNTAINS-PICKENS MOUNTAINS-
GREENVILLE MOUNTAINS-GREATER OCONEE-GREATER PICKENS-
GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-ANDERSON-ABBEVILLE-
LAURENS-UNION SC-CHESTER-GREENWOOD-
347 PM EST FRI FEB 15 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

A COLD FRONT WILL CROSS THE WESTERN CAROLINAS AND NORTHEAST
GEORGIA TONIGHT...USHERING IN A COLD CANADIAN AIRMASS. A PASSING
UPPER LEVEL DISTURBANCE WILL PRODUCE SCATTERED TO NUMEROUS RAIN
SHOWERS ON SATURDAY...GRADUALLY CHANGING OVER TO ALL SNOW SHOWERS
THROUGH THE DAY. LIGHT SNOW ACCUMULATIONS WILL BE POSSIBLE ON
SATURDAY JUST ABOUT ANYWHERE ACROSS NORTHEAST GEORGIA...THE
UPSTATE OF SOUTH CAROLINA...AND THE FOOTHILLS AND PIEDMONT OF
WESTERN NORTH CAROLINA. THE BEST CHANCE OF LIGHT ACCUMULATING
SNOWFALL CURRENTLY APPEARS TO BE ALONG THE INTERSTATE 85 CORRIDOR
FROM SPARTANBURG TO CHARLOTTE...AND ALSO THE EASTERN PIEDMONT EAST
OF INTERSTATE 77. IF CONFIDENCE INCREASES IN ACCUMULATING SNOWFALL
FOR SATURDAY...A WINTER WEATHER ADVISORY WILL BE NEEDED.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ASKED TO RELAY ANY SNOW REPORTS TO THE NATIONAL
WEATHER SERVICE.

GERAPETRITIS