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"City, St"
  
000
FXUS62 KGSP 310812 CCA
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
333 AM EDT FRI OCT 31 2014

.SYNOPSIS...
MOISTURE WILL INCREASE TODAY OUT AHEAD OF AN APPROACHING COLD
FRONT. THIS FRONT...AND A STRONG MID LEVEL AREA OF LOW PRESSURE IS
FORECAST TO TRACK ACROSS THE REGION FRIDAY NIGHT INTO SATURDAY. A
STRONG SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OFFSHORE ON
SATURDAY...THEN TRACK QUICKLY NORTH BY SATURDAY NIGHT. CIRCULATION
AROUND THE COASTAL LOW WILL BRING A CANADIAN AIR MASS TO THE
REGION INTO MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM...FCST REMAINS ON TRACK WITH ONLY SOME HIGH AND MID 
CLOUDINESS APPROACHING FROM THE W. TEMP/RH TRENDS STILL LOOK GOOD. 
MIN TEMPS ALSO ON TRACK. NO CHANGES FOR THE REST OF THE OVERNIGHT 
PERIOD. THEN THINGS START TO GET INTERESTING...

THE MORNING AND EARLY AFTERNOON SHOULD BE QUIET ENOUGH...AS A 
COLLECTION OF SHORT WAVES ROTATE AROUND THE BASE OF THE DEEPENING 
UPPER TROF AND ACROSS THE FCST AREA. THE PASSAGE OF THESE WAVES 
SHOULD NOT AMOUNT TO MUCH MORE THAN AN INCREASE IN MID CLOUDS. TEMPS 
SHOULD CLIMB BACK INTO THE 60S E OF THE MTNS WITH 50S ACROSS THE NC 
MTNS. THE SITUATION WILL GO RAPIDLY DOWNHILL LATE THIS AFTERNOON 
WITH THE APPROACH AND ARRIVAL OF A DEEPENING UPPER LOW.

ALTHOUGH THE UPPER LOW IS FAIRLY SMALL...IT LOOKS WICKEDLY DYNAMIC 
AS IT DROPS DOWN ACROSS THE WESTERN CAROLINAS TONIGHT TO A POSITION 
OVER THE WRN UPSTATE AT DAYBREAK ON SATURDAY. THIS COMPACT SYSTEM 
SHOULD HAVE ALL MANNER OF LOW/MID/UPPER FORCING THAT COMES INTO PLAY 
THIS EVENING AND OVERNIGHT. YOU NAME IT...THIS SYSTEM SHOULD HAVE 
IT...IN SPADES. MOISTURE SHOULD ALSO BE FAIRLY DEEP...SO THE POP 
RAMPS UP TO CATEGORICAL OVER THE MTNS FRIDAY EVE...AND INTO THE 
LIKELY RANGE ACROSS MOST OF THE FOOTHILLS AND WRN PIEDMONT...AND 
EVENTUALLY CATEGORICAL OVER THE WRN PIEDMONT...WHERE FORCING IS 
MAXIMIZED ON THE N SIDE OF THE UPPER LOW. PRECIP WAS LIMITED TO THE 
CHC RANGE OVER THE WRN UPSTATE AND NE GEORGIA AS SOME DOWNSLOPE FLOW 
MAY INHIBIT PRECIP DEVELOPMENT. 
 
IT IS PROBABLY A GOOD THING THAT IT IS NOT JANUARY...OR ELSE IT 
MIGHT BE REALLY INTERESTING. NEVERTHELESS... THE DISTRIBUTION OF 
PARTIAL THICKNESS ACCOMPANYING THE UPPER LOW WILL BE DECIDEDLY 
WINTER-LIKE. STRONG COLD ADVECTION FRIDAY EVENING SHOULD ALLOW 
PRECIP TO CHANGE OVER FROM RAIN TO SNOW FROM RIDGETOPS DOWN TO THE 
VALLEYS ACROSS THE NC MTNS BY THE EARLY MORNING HOURS. EAST OF THE 
MTNS...THE LATEST GFS SUGGESTS A SLIGHT UPWARD TREND IN TEMP AND 
DEWPT BY DAYBREAK SATURDAY PERHAPS BECAUSE THE OPERATIONAL MODEL WAS 
WETTER...WHICH WAS GENERALLY FOLLOWED. THAT SHOULD BUMP THE SFC WET 
BULB TEMPS UP A BIT MORE...MEANING LESS OF A CHANCE OF SEEING ANY 
SNOW E OF THE FOOTHILLS THRU 12Z SATURDAY. OF NOTE IS THE 21Z 
SREF...WHICH AT THIS TIME WAS THE MOST RECENT...THAT SHOWS PTYPE 
OVERWHELMINGLY IN FAVOR OF RAIN. THAT BEING SAID...WILL GIVE A NOD 
TO THE COOLER NAM BUFKIT PROFILES THAT SUGGEST A POSSIBILITY OF A 
WET SNOWSHOWER AROUND DAYBREAK OVER THE NC FOOTHILLS AND WRN 
PIEDMONT...BUT THIS MIGHT NOT YET MAKE THE CUT AND APPEAR IN THE 
FCST. SNOW STILL LOOKS LIKE A GOOD BET OVER THE MTNS MAINLY NEAR THE 
TN BORDER...WITH UPWARDS OF 2-4 INCHES POSSIBLE BY SUNRISE. SOME OF 
THE SNOW MAY WRAP AROUND INTO THE UPPER SAVANNAH RIVER BASIN AND NE 
GEORGIA AROUND SUNRISE. HOWEVER...THOSE LOCATIONS HAVE THE LOWEST 
PROBABILITY OF ANY PRECIP REACHING THE GROUND...AT THE LOW END OF 
THE CHC RANGE. AN ADVISORY WILL NOT BE ISSUED YET FOR THE REST OF 
THE SRN MOUNTAINS OF NC AND NE GEORGIA...INSTEAD WILL TAKE A LOOK AT 
THE MORNING MODEL RUNS FOR MORE GUIDANCE AND CONFIDENCE. NO
CHANGES TO THE ADVISORY/WARNING CONFIGURATION AT THIS TIME.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 320 AM EDT FRIDAY...THE LATEST 00Z SHORT RANGE MODELS CONTINUE 
TO INDICATE THAT AN ANOMALOUS UPPER LOW JUST SOUTH OF OUR CWA 12Z 
SAT WILL MOVE OFF THE SE COAST BETWEEN 21Z SAT AND 00Z SUN WITH AN 
UNSEASONABLY COLD AIRMASS FILTERING IN BEHIND THE LOW IN ITS WAKE. 
MODELS HAVE TRENDED A BIT WETTER...ESPECIALLY EAST OF THE MTNS ON 
EARLY SAT AS BETTER DEFORMATION ZONE OVER THE NORTHERN PERIPHERY OF 
THE UPPER LOW SETS UP OVER THE WESTERN CAROLINAS PIEDMONT. 
HOWEVER...LATEST MODEL TEMPS OUT SIDE OF THE MTNS APPEAR A BIT 
WARMER THAN THE PREVIOUS MODEL RUNS. HENCE...HAVE UPDATED WX GRIDS 
TO HIGHLIGHT MORE OF LIQUID PRECIP OVER THE PIEDMONT. STILL WITH 
COLDER TEMPS OVER THE MTNS...EXPECT HEAVY SNOW ACCUMS TO OCCUR 
THROUGH EARLY SUN MAINLY ALONG THE TN BORDER. TOTAL SNOWFALL FROM 
THIS EVENT WILL RANGE FROM 8" OVER THE NORTHERN NC MTNS TO 12" OVER 
THE SMOKIES. ELSEWHERE OVER THE NC MTNS WILL SEE BETWEEN 1 AND 2 
INCHES OF SNOW. HENCE...WILL CONTINUE TO HIGHLIGHT A WINTER STORM 
WARNING OVER THE TN BORDER COUNTIES AND A WINTER WEATHER ADVISORY 
OVER BUNCOMBE...NORTHERN HALF OF JACKSON...AND GRAHAM COUNTIES.  

STRONG NW WINDS OF 20-40 MPH WILL DEVELOP ON SAT IN LIGHT OF 
TIGHTENING SURFACE PRESSURE GRADIENT BETWEEN A DEVELOPING SURFACE 
LOW OFF THE SE COAST AND STRONG HIGH PRESSURE TO OUR WEST. 
AS THE UPPER LOW MOVES OFF TO THE EAST...POPS TAPER OFF FROM WEST TO 
EAST THROUGH SAT EVENING. TEMPERATURES ON SAT WILL REMAIN WELL BELOW 
NORMAL (AROUND 15-20 BELOW NORMAL). SUN LOOKS MOSTLY DRY AS THE 
CANADIAN HIGH SETTLES OVER THE REGION. NW SNOW OVER THE NC MTNS WILL 
TAPER OFF BY EARLY SUN AS DRY AIRMASS MOVES IN. TEMPS ON SUN WILL BE 
AROUND 5-10 DEGREES WARMER THAN SAT.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 250 AM EDT FRIDAY...LATEST GLOBAL MODELS CONTINUE TO AGREE
THAT AN UPPER RIDGE AXIS IS FORECAST TO CROSS THE FORECAST AREA ON
MONDAY AND OFF TO THE EAST COAST BY TUE. SWLY FLOW ALOFT WILL THEN
SET UP BY TUE NIGHT AS A POSITIVELY TILED UPPER TROUGH APPROACHES
FROM THE CENTRAL CONUS. THIS UPPER TROUGH WILL CROSS THE REGION ON
THU FOLLOWED BY NWLY FLOW THU NIGHT.

AT THE SURFACE...A DRY HIGH PRESSURE CENTERED OVER THE SE STATES MON 
WILL GRADUALLY SHIFT OFFSHORE THROUGH WED AS A WEAK COLD FRONT 
APPROACHES FROM THE WEST. THE FRONT WILL CROSS THE REGION AROUND WED 
NIGHT AND OFF TO OUR EAST BY FRI MORNING. MODELS INDICATE THAT THE 
FRONT WILL DRY OUT AS IT REACHES THE MTNS. HENCE...HAVE CARRIED 
SLIGHT TO LOW END CHANCE POP MAINLY ALONG THE TN BORDER DURING THE 
FROPA. OTHERWISE...CONDITIONS LOOK DRY THROUGHOUT THE MEDIUM RANGE 
PERIOD. TEMPERATURES WILL QUICKLY WARM UP TO NEAR CLIMO BY TUE.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
AT KCLT...EXPECT VFR CONDITIONS TO CONTINUE THROUGH THE 
PERIOD...ALTHO THE SITUATION WILL BE GOING DOWNHILL AT THE END OF 
THE FCST PERIOD. UNTIL THEN...MAINLY HIGH CLOUDS THROUGH THE EARLY 
TO MID MORNING WITH A LIGHT NE WIND...FOLLOWED BY THICKENING MOSTLY 
ALTOCU CEILINGS. BY MID/LATE AFTERNOON...THE WIND SHOULD BE LIGHT 
AND VARIABLE AND MAY CHANGE BETWEEN NW AND SW OFTEN. AT THAT TIME... 
A LOW CLOUD CEILING SHOULD MOVE IN FROM THE NW AHEAD OF THE 
APPROACHING LOW...BUT STILL VFR. THE LATEST MODEL GUIDANCE IS IN 
GOOD AGREEMENT WITH DEVELOPING LIGHT PRECIP INTO THE CLT METRO AREA 
AROUND SUNSET. A CONSENSUS OF THE GUIDANCE SUGGESTS A PREVAILING 
LIGHT RAIN...BUT WITH STILL A VFR CATEGORY VISIBILITY...AFTER 02Z. 
WIND AT THAT TIME SHOULD SETTLE INTO A N COMPONENT. NO ISSUES WITH 
PRECIP TYPE UNTIL AFTER 06Z SATURDAY.

ELSEWHERE...VFR THROUGH THE DAYLIGHT HOURS FRIDAY. LIGHT AND 
VARIABLE WINDS AND INCREASING MID/HIGH CLOUDS EXPECTED THROUGH MID 
MORNING. LOW VFR AND MID CLOUDS INCREASE THRU THE DAY FRI WITH LOW 
VFR CIGS EXPECTED BY AFTERNOON AT KAVL. WINDS TURN WSW FRI AFTERNOON 
AHEAD OF THE APPROACHING COLD FRONT. HOWEVER...WINDS REMAIN NLY AT 
KAVL. KAVL ALSO HAS THE BEST CHC OF SEEING ANY SHRA BY LATE IN THE 
AFTERNOON...WHICH WAS INCLUDED AS A VCSH AT THIS TIME. THE STEADIER 
RAIN SHOULD MOVE INTO THE MTNS BY SUNSET. HAVE INCLUDED THE RAIN 
PREVAILING AFTER 02Z AT KAVL...AT WHICH TIME THE CEILING SHOULD DROP 
TO MVFR. PRELIMINARY INDICATION IS THAT PRECIP COULD CHANGE OVER TO 
SNOW SHOWERS AT KAVL AS EARLY AS 05Z.  A SIMILAR PROGRESSION IS 
NOTED AT KHKY...BUT PRECIP WAS KEPT LIQUID. OTHER TAF SITES ONLY 
HAVE A VCSH AFTER 02Z OR 03Z...OWING TO LOW CONFIDENCE. 
 
OUTLOOK...LIGHT PRECIP WILL DEVELOP ACROSS THE ENTIRE AREA LATE 
FRIDAY NIGHT. SOME RESTRICTIONS ARE POSSIBLE...ESPECIALLY IN THE 
MOUNTAINS WHERE EVEN SOME SNOW SHOWERS ARE EXPECTED LATE FRIDAY 
NIGHT AND SATURDAY. VFR BEYOND SUNDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER STORM WARNING FROM 8 PM THIS EVENING TO 8 PM EDT 
     SATURDAY FOR NCZ033-048>052.
     WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT 
     SATURDAY FOR NCZ053-058-059.
SC...NONE.

&&

$$
SYNOPSIS...JOH
NEAR TERM...PM
SHORT TERM...JOH
LONG TERM...JOH
AVIATION...PM




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Page last modified: January 20, 2010

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