710
FXUS62 KGSP 162336
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
636 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 516 PM EST MONDAY: WE'VE MANAGED TO BREAK OUT OF THE LOW
CLOUD DECK ACROSS MUCH OF THE UPSTATE, WITH GSP, GMU, SPA, AND
OTHERS ACROSS THE AREA REPORTING THE LOSS OF LOW STRATOCU OVER THE
LAST HOUR OR TWO. FARTHER NORTH AND EAST, TOWARD CHESTER, ROCK
HILL, AND CHARLOTTE...NOT SO MUCH. THERE'S BEEN SOME IMPROVEMENT,
BUT THICK CLOUDS STILL LINGER WITH SUNLIGHT PREPARING TO VANISH.
OTHERWISE...AS IS TYPICALLY THE CASE WITH REMNANT COOL POOLS AT
THIS TIME OF THE YEAR, ONCE THE SUN GOES DOWN THE LOW CLOUDS WILL
EXPAND AGAIN WITH SOME LIGHT UPSLOPE FLOW. A ZONAL FLOW ALOFT IS
EXPECTED TO STRING OUT A WEAK COLD FRONT TO THE NW OVERNIGHT. SOME
WEAK FORCING ALOFT IS EXPECTED TO SKIRT THE NC MTNS AS IT MOVES
ACROSS THE GREAT VALLEY AND THEN PAST JUST TO OUR NORTH OVERNIGHT,
AND THE GUIDANCE RESPONDS WITH SOME PRECIP CHANCES MAINLY ALONG
THE TN BORDER REGION LATE TONIGHT THAT PEAK WITH SOME LIKELY RAIN
OVER THE SMOKIES. 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. LOW LEVEL MOISTURE WILL
REMAIN PLENTIFUL EAST OF THE MOUNTAINS, SO THE BIG QUESTION IS,
DO WE DEVELOP ANY DENSE FOG LATE THIS EVENING, AND IF SO, HOW
EXTENSIVE DOES IT GET? THE SITUATION IS NOT IDEAL, WITH A LACK OF
MID/UPPER DRYING AND MOISTURE LAPSE RATES NOT EXACTLY FAVORABLE,
SO THE CURRENT THINKING IS WE WILL HAVE MORE OF THE LOW STRATUS AND
LESS OF THE DENSE FOG. 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 /00Z 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...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...AR
NEAR TERM...MPR/PM
SHORT TERM...AR
LONG TERM...AR
AVIATION...MPR
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