647
FXUS62 KGSP 170317
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1017 PM EST MON DEC 16 2024
SYNOPSIS
DRIER TODAY WITH RAIN CHANCES RETURNING FOR THE MOUNTAINS TONIGHT
INTO TUESDAY AHEAD OF AN APPROACHING COLD FRONT. WELL ABOVE NORMAL
TEMPERATURES RETURN TUESDAY INTO WEDNESDAY, WITH A COLD FRONT
INCREASING RAIN CHANCES AREA-WIDE WEDNESDAY AFTERNOON AND EVENING.
DRIER AND COOLER CONDITIONS ARE EXPECTED BEHIND THE FRONT THROUGH
THE WEEKEND, OUTSIDE OF NORTHWEST FLOW SNOW SHOWERS IN THE WESTERN
NORTH CAROLINA MOUNTAINS FRIDAY AFTERNOON INTO SATURDAY MORNING.
NEAR TERM /THROUGH TUESDAY/
AS OF 954 PM EST MONDAY: WIDESPREAD QUARTER-MILE VISIBILITIES ARE
IN PLACE ACROSS VIRTUALLY ALL THE NON-MOUNTAIN ZONES, AND ONLY
EXPECTED TO EXPAND OVER THE COMING HOURS. A DENSE FOG ADVISORY
IS IN PLACE FOR MOST OF THE NC PIEDMONT/FOOTHILLS, THE SC UPSTATE,
AND THE NE GEORGIA ZONES, WITH THE EXCEPTION OF RABUN COUNTY AND THE
SC MOUNTAINS. IT'LL LAST THROUGH 9 AM TOMORROW UNLESS FOG SCATTERS
OUT SOONER, WHICH SEEMS UNLIKELY BASED ON THE LAST COUPLE DAYS.
OTHERWISE, A WEAK COLD FRONT SITUATED OVER THE TENNESSEE VALLEY HAS
ALREADY SPURRED LIGHT PRECIP ALONG THE TENNESSEE BORDER, AND 15-25%
POPS ARE WARRANTED THROUGH DAYBREAK FOR THE BORDER ZONES; ELSEWHERE,
IT SHOULD REMAIN DRY. THIS SHOULD NOT POSE ANY P-TYPE ISSUE, AS
THE LOW CLOUD BLANKET WILL KEEP DIURNAL RANGES SMALL AND TEMPS ON
THE ORDER OF 10-15 DEGREES ABOVE NORMAL. THE FRONT, AS IT WERE,
SHOULD LAY OUT ACROSS THE FCST AREA ON TUESDAY WITH THE UPPER FLOW
BECOMING MORE WSW, BUT WHAT MEAGER FORCING THERE IS SHOULD MOVE
OUT TO THE EAST BY THE MIDDLE PART OF THE DAY. THAT WILL LEAVE
US WITH A RAIN CHANCE IN THE MORNING TO EARLY AFTERNOON, MAINLY
OVER THE HIGHER TERRAIN WHEN THE TAIL END OF THE VORTICITY MOVES
PAST, BUT NOT A LOT OF POTENTIAL FOR ANYTHING MORE THAN PASSING
VERY LIGHT RAIN. THE POSITION OF THE FRONT AND TRACK OF THE VORT
SUGGESTS THE AREA S/E OF I-85 WILL STAY DRY. THE TREND HAS BEEN FOR
LESS COVERAGE AND AN EARLIER DEPARTURE AS WELL, SO PRECIP PROBS ARE
CURTAILED TO THE FAR WESTERN PART BY THE END OF THE DAY. TEMPS WILL
ONCE AGAIN BE TRICKY BECAUSE OF THE TRAPPED REMNANT COOL POOL. LOW
CLOUDS AND FOG SHOULD DELAY THE WARMUP THROUGH THE LATE MORNING,
BUT IT APPEARS THAT WITH THE FRONT LAYING OUT WE WILL SEE ENOUGH
SFC WARM ADVECTION AND MIXING TO EVENTUALLY ELIMINATE THE COLD POOL
IN THE AFTERNOON, SO A NICE REBOUND ABOVE NORMAL IS STILL EXPECTED.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/
AS OF 130 PM EST MONDAY...
KEY MESSAGES:
1) TRENDING DRIER TUESDAY EVENING INTO WEDNESDAY MORNING WITH RAIN
HOLDING OFF UNTIL LATE WEDNESDAY AFTERNOON/EVENING
2) WELL ABOVE NORMAL TEMPERATURES LINGER THROUGH WEDNESDAY NIGHT
3) DRIER AND COOLER ON THURSDAY WITH THE SUNSHINE RETURNING
A COLD FRONT WILL APPROACH OUT OF THE WEST TUESDAY EVENING INTO
WEDNESDAY AFTERNOON BEFORE TRACKING ACROSS THE FORECAST AREA
WEDNESDAY EVENING INTO WEDNESDAY NIGHT. THE 12Z CAMS DEPICT MOSTLY
DRY CONDITIONS TUESDAY NIGHT INTO EARLY WEDNESDAY AFTERNOON, SO WENT
WITH LOWER POPS THAN THE PREVIOUS FORECAST HAD. CAMS SHOW THE BEST
TIMING FOR WILL BE LATE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT
AHEAD OF AND ALONG THE FRONTAL BOUNDARY. HAVE THE HIGHEST POPS
CONFINED TO THE WESTERN NORTH CAROLINA MOUNTAINS WITH LOWER POPS
ELSEWHERE FOR NOW BASED ON THE LATEST CAM AND GLOBAL MODEL GUIDANCE
TRENDS. ALL LIQUID PRECIP IS EXPECTED WITH TEMPS TRENDING WELL ABOVE
NORMAL THROUGH WEDNESDAY NIGHT. LOWS TUESDAY NIGHT WILL END UP ~20
DEGREES ABOVE NORMAL THANKS TO INCREASING CLOUD COVER. HIGHS ON
WEDNESDAY WILL REMAIN WELL ABOVE NORMAL (~15 DEGREES) THANKS TO
STRONG SW'LY FLOW AHEAD OF THE FRONT. BREEZY SW WINDS CAN BE
EXPECTED AHEAD OF THE FRONT AREA-WIDE ON WEDNESDAY. WINDS WILL
GRADUALLY TURN NW BEHIND THE FRONT, WITH GUSTS LINGERING ACROSS THE
MOUNTAINS THROUGH WEDNESDAY NIGHT BEFORE TAPERING OFF AROUND
DAYBREAK THURSDAY. LOWS WEDNESDAY NIGHT WILL BE COOLER, BUT STILL
~10-12 DEGREES ABOVE NORMAL.
DRIER CONDITIONS ARE EXPECTED BEHIND THE FRONT BY EARLY THURSDAY
MORNING THANKS TO SFC HIGH PRESSURE BUILDING IN FROM THE WEST. HIGHS
ON THURSDAY WILL BE NOTICEABLY COOLER BEHIND THE FRONT, DESPITE THE
RETURN OF SUNSHINE, BUT WILL STILL END UP ~3-6 DEGREES ABOVE NORMAL.
LOWS THURSDAY NIGHT WILL DROP INTO THE 30S IN MOST AREAS BUT TEMPS
WILL STILL END UP ~5-8 DEGREES ABOVE NORMAL THANKS TO PARTLY CLOUDY
SKIES.
LONG TERM /FRIDAY THROUGH MONDAY/
AS OF 200 PM EST MONDAY...
KEY MESSAGES:
1) COOLING TREND CONTINUES INTO THE WEEKEND, WITH WELL BELOW NORMAL
TEMPERATURES RETURNING ON SATURDAY
2) DRY THROUGH THE LONG TERM OUTSIDE OF NW FLOW SNOW SHOWERS IN THE
WESTERN NC MOUNTAINS FRIDAY INTO EARLY SATURDAY
2 GUSTY WINDS MAY DEVELOP FRIDAY INTO SATURDAY, ESPECIALLY ACROSS
THE MOUNTAINS
A MOSTLY DRY COLD FRONT WILL TRACK ACROSS THE WESTERN CAROLINAS AND
NORTHEAST GEORGIA ON FRIDAY, ALLOWING GUSTY NW WINDS TO DEVELOP
ACROSS THE MOUNTAINS. GUSTY WINDS WILL LINGER THROUGH FRIDAY NIGHT
BEFORE GRADUALLY TAPERING OFF SATURDAY. THE LATEST GLOBAL MODEL
GUIDANCE AGREE THAT THERE WILL BE ENOUGH MOISTURE BEHIND THE FRONT
FOR NW FLOW SNOW SHOWERS TO DEVELOP FRIDAY AFTERNOON INTO EARLY
SATURDAY MORNING ALONG THE NC/TN BORDER. THE NBM DID END UP WITH
SOME VERY LIGHT SNOWFALL ACCUMS (A FEW TENTHS OF AN INCH) THIS
FORECAST CYCLE. THE LREF 90TH PERCENTILE ACCUMULATED SNOWFALL ONLY
SHOWS UP TO AN INCH ALONG THE TN BORDER FRIDAY INTO EARLY SATURDAY
SO NOT ANTICIPATING A MAJOR NW FLOW SNOW EVENT. DRY CONDITIONS ARE
EXPECTED ELSEWHERE THANKS TO SFC HIGH PRESSURE BUILDING INTO THE
REGION BEHIND THE FRONT AND LINGERING THROUGH THE REST OF THE
FORECAST PERIOD. WE WILL HAVE ONE MORE DAY OF ABOVE NORMAL TEMPS ON
FRIDAY AHEAD OF THE FRONT BEFORE WELL BELOW NORMAL TEMPS RETURN
BEHIND THE FRONT THIS WEEKEND INTO EARLY NEXT WEEK.
AVIATION /03Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: HEADING INTO ANOTHER DREARY NIGHT, WITH
LIFR RESTRICTIONS EXPECTED ACROSS A BROAD SWATH OF THE TERMINAL
FORECAST AREA AFTER MIDNIGHT. LOCATIONS ACROSS THE UPSTATE THAT
MANAGED TO SCATTER OUT LOW CEILINGS THIS AFTERNOON SHOULD START
DETERIORATING AGAIN IN SHORT ORDER; IN THE FOOTHILLS AND ALONG
THE I-77 CORRIDOR, MEANWHILE, MOST SITES NEVER SCATTERED OUT TO
BEGIN WITH AND ARE STARTING OUT THE NIGHT SOCKED INTO MVFR OR EVEN
IFR CEILINGS. MODELS ARE HAMMERING THE PIEDMONT AND FOOTHILLS, IN
PARTICULAR, WITH DENSE FOG OVERNIGHT, AND ALTHOUGH IT'S QUESTIONABLE
WHETHER WE'LL MAKE IT TO THE WIDESPREAD 1/2 TO 1/4 MILE VISIBILITY
FORECAST BY SOME MORE AGGRESSIVE GUIDANCE SOURCES, IT'S LIKELY TO
BE A SOUPY NIGHT EAST OF THE MOUNTAINS, WITH RAPID DETERIORATION
EXPECTED AFTER MIDNIGHT. THE MOUNTAINS WILL BE THE EXCEPTION;
ABSENT MUCH OF A COLD POOL, KAVL IS ONLY EXPECTED TO MAKE IT DOWN
TO MVFR, WITH MAYBE SOME PERIODS OF IFR CEILINGS THROUGH DAYBREAK.
A COLD FRONT WILL APPROACH FROM THE WEST IN THE MORNING, RESULTING
IN SOME LOW-END RAIN CHANCES AT KAVL, BUT WILL FALL APART ON
APPROACH...SO THERE WON'T BE MUCH OF AN AIR MASS CHANGE NOR ANY
DISCERNIBLE MECHANISM TO BREAK UP THE COLD POOL, AND IMPROVEMENT
WILL BE SLOW TOMORROW...WITH AT LEAST MVFR LIKELY TO PERSIST WELL
INTO THE AFTERNOON AT MOST NON-MOUNTAIN SITES.
OUTLOOK: AN UNSETTLED PATTERN CONTINUES THROUGH THE REST OF THE
WEEK AS MULTIPLE STORM SYSTEMS PUSH INTO REGION LIKELY LEADING TO
PERIODS OF ASSOCIATED RESTRICTIONS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...DENSE FOG ADVISORY UNTIL 9 AM EST TUESDAY FOR GAZ017-018-026-
028-029.
NC...DENSE FOG ADVISORY UNTIL 9 AM EST TUESDAY FOR NCZ035>037-056-
057-068>072-502-504-506-508-510.
SC...DENSE FOG ADVISORY UNTIL 9 AM EST TUESDAY FOR SCZ008>014-019-
104>109.
SYNOPSIS...AR
NEAR TERM...MPR/PM
SHORT TERM...AR
LONG TERM...AR
AVIATION...MPR
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