814
FXUS62 KGSP 160600
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
100 AM EST MON DEC 16 2024
SYNOPSIS
CHILLY, CLOUDY, AND RAINY WEATHER CONTINUES INTO TONIGHT BEFORE
TAPERING OFF AROUND DAYBREAK MONDAY. TEMPERATURES WILL BE ON A
WARMING THROUGH THE FIRST HALF OF THE WORKWEEK, WITH RAIN CHANCES
BRIEFLY RETURNING TO THE MOUNTAINS MONDAY NIGHT AND TO ALL LOCATIONS
BY WEDNESDAY. DRIER AND COOLER CONDITIONS CAN BE EXPECTED THURSDAY
INTO THE WEEKEND.
NEAR TERM /THROUGH TODAY/
AS OF 100 AM EST MONDAY: AREA OF DRIZZLE CONTINUES TO STREAM ACROSS
THE CFWA AS THE DOME OF COLD AIR REMAINS LOCKED IN. NO MAJOR CHANGES
TO FORECAST OUTSIDE OF ADJUSTMENTS MADE BASED ON CURRENT
OBSERVATIONS AND LATEST TRENDS.
OTHERWISE, CLASSICAL COLD AIR DAMMING IS BEGINNING TO FALTER, WITH
THE SUPPORTING SURFACE HIGH NOW WELL OFF THE NEW ENGLAND COAST AS AN
OPEN WAVE EAST OF LAKE ERIE DRIVES IT EVEN FARTHER EAST. OVER THE
NEXT FEW HOURS, IT'LL BE CUT OFF ENTIRELY FROM OUR AREA...BUT WEAK
WARM ADVECTION AND ISENTROPIC UPGLIDE WILL CONTINUE OVER TOP OF THE
OLD WEDGE, PERSISTING INTO THE EARLY MORNING HOURS TOMORROW. THUS,
PRECIP CHANCES WILL SLOWLY BACK OFF OVER THE DAMMING REGION TONIGHT,
WHILE LOW CLOUDS ARE MAINTAINED. THE LAST OF THE PRECIP SHOULD MOVE
OUT OF THE NW PIEDMONT AROUND DAYBREAK. EXPECT A LOW DIURNAL RANGE
WITH TONIGHT'S TEMPS DROPPING OFF AT BEST 3-5 DEGREES FROM WHAT THEY
WERE LATE THIS AFTERNOON, AND FORTUNATELY ALL ABOVE FREEZING.
THE PROBLEM FOR MONDAY REMAINS THAT...WHILE WE NO LONGER HAVE
SUPPORT TO MAINTAIN THE WEDGE, WE ALSO LACK A MECHANISM TO REALLY
DESTROY THE REMNANT COOL POOL EAST OF THE MTNS. A FLAT UPPER RIDGE
WILL MOVE OVERHEAD AND BRING THE UPPER FLOW AROUND TO MORE WSW,
WHILE THE FLOW AT 850MB BECOMES SW. AS A RESULT, WE WON'T GET
ANY MEANINGFUL DOWNSLOPE EAST OF THE MTNS AND NO COLD ADVECTION
ALOFT. THE FLOW MIGHT NOT BE STRONG ENOUGH FOR TURBULENT MIXING
AT THE TOP OF THE INVERSION LAYER, SO WE MIGHT HAVE TO MIX OUT
THE LINGERING LOW CLOUDS FROM THE EDGES, WHICH IS A DIFFICULT
PROSPECT SO CLOSE TO THE SOLSTICE. HAVE MY DOUBTS ABOUT THE HIGH
TEMPS GETTING OUT OF THE 50S EAST OF THE MTNS, OR THE UPPER 40S
OVER THE NRN FOOTHILLS, SO WE UNDERCUT THE GUIDANCE FOR THE HIGH
TEMPS. NOTE THERE MAY BE A TIGHT GRADIENT WHERE THE CLOUDY/CLEAR
BOUNDARY SETS UP IN THE AFTERNOON, WHICH WOULD AFFECT MAINLY THE
SOUTHERN CLT METRO AREA TO THE LOWER PIEDMONT.
SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/
AS OF 130 PM EST SUNDAY...
KEY MESSAGES:
1) RAIN WILL BE CONFINED TO THE WESTERN NORTH CAROLINA MOUNTAINS
MONDAY NIGHT INTO TUESDAY MORNING, WITH COLD AIR DAMMING ERODING BY
TUESDAY AFTERNOON
2) MUCH WARMER AND WELL ABOVE NORMAL TEMPERATURES EXPECTED THROUGH
THE SHORT TERM
3) RAIN CHANCES RETURN AREA-WIDE WEDNESDAY INTO WEDNESDAY NIGHT
A COLD FRONT WILL TRACK OUT OF THE WEST MONDAY NIGHT BEFORE PUSHING
INTO THE WESTERN NORTH CAROLINA MOUNTAINS BY DAYBREAK TUESDAY. CLOUD
COVER IN PLACE AHEAD OF THE FRONT WILL LIMIT RADIATIONAL COOLING,
LEADING TO LOWS ~15-20 DEGREES ABOVE NORMAL MONDAY NIGHT. THE FRONT
LOOKS TO PETER OUT WHILE PUSHING EAST SO RAIN CHANCES WILL BE
CONFINED TO THE NORTH CAROLINA MOUNTAINS MONDAY NIGHT INTO TUESDAY.
WITH THE FRONT EXPECTED TO FALL APART OVER THE MOUNTAINS, WINDS WILL
TOGGLE NW ACROSS THE MOUNTAINS BUT WILL REMAIN SW EAST OF THE
MOUNTAINS. THIS NW DOWNSLOPE FLOW WILL GRADUALLY ERODE THE WEDGE BY
TUESDAY AFTERNOON, LEADING TO MUCH WARMER HIGHS (~15 DEGREES ABOVE
NORMAL). TEMPS WILL CLIMB INTO THE MID TO UPPER 60S EAST OF THE
MOUNTAINS AND IN THE MOUNTAIN VALLEYS ON TUESDAY, WITH TEMPS ACROSS
THE HIGHER ELEVATIONS RANGING FROM THE LOWER TO UPPER 50S.
RAIN CHANCES RETURN FOR THE ENTIRE FORECAST AREA THE REST OF THE
SHORT TERM FORECAST PERIOD AS ANOTHER MORE POTENT COLD FRONT
APPROACHES OUT OF THE WEST TUESDAY NIGHT INTO WEDNESDAY, TRACKING
ACROSS THE FORECAST AREA WEDNESDAY EVENING. HAVE THE HIGHEST POPS
PAINTED ACROSS THE MOUNTAINS AND THE NORTHERN NC FOOTHILLS/PIEDMONT
PER THE LATEST GLOBAL MODEL GUIDANCE. TEMPERATURES WILL ONCE AGAIN
END UP WELL ABOVE NORMAL TUESDAY NIGHT (~20 DEGREES) THANKS TO
INCREASING CLOUD COVER. STRONG SW'LY FLOW AHEAD OF THE FRONT WILL
LEAD TO ANOTHER VERY WARM AFTERNOON ON WEDNESDAY, WITH HIGHS ENDING
UP A DEGREE OR TWO WARMER THAN TUESDAY. RAIN CHANCES WILL GRADUALLY
TAPER OFF WEDNESDAY NIGHT BEHIND THE FRONT. LOWS WEDNESDAY NIGHT
WILL BE NOTICEABLY COOLER THANKS TO CAA FILTERING INTO THE REGION
AND GRADUALLY DECREASING CLOUD COVER. HOWEVER, TEMPS WILL STILL END
UP ~10-12 DEGREES ABOVE NORMAL.
LONG TERM /THURSDAY THROUGH SUNDAY/
AS OF 200 PM EST SUNDAY...
KEY MESSAGES:
1) DRIER CONDITIONS EXPECTED THROUGH THE LONG TERM
2) COOLING TREND STARTS THURSDAY WITH BELOW NORMAL TEMPERATURES
RETURNING BY THE WEEKEND
3) PERIODIC NW FLOW SNOW SHOWERS ARE POSSIBLE ALONG THE NC/TN BORDER
FRIDAY INTO SATURDAY
SFC HIGH PRESSURE BUILDS INTO THE WESTERN CAROLINAS AND NORTHEAST
GEORGIA THURSDAY INTO FRIDAY BEFORE A MOSTLY DRY COLD FRONT TRACKS
ACROSS THE REGION LATE FRIDAY. THERE COULD BE ENOUGH MOISTURE
ALONG/BEHIND THE FRONT TO ALLOW FOR SOME LIGHT AND PERIODIC NW FLOW
SNOW SHOWERS TO DEVELOP FRIDAY EVENING INTO SATURDAY MORNING.
HOWEVER, CONFIDENCE ON WHETHER THERE WILL BE ENOUGH MOISTURE REMAINS
LOW AT THIS TIME. DID NOT END UP WITH ANY SNOW ACCUMS ALONG THE
NC/TN BORDER THIS FORECAST CYCLE. DRY SFC HIGH PRESSURE RETURNS
BEHIND THE DEPARTING FRONT SATURDAY INTO SUNDAY. TEMPS WILL DEPICT A
COOLING TREND THROUGH THE LONG TERM FORECAST PERIOD, WITH BELOW
NORMAL TEMPS RETURNING BY THE WEEKEND.
AVIATION /06Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: WIDESPREAD RESTRICTIONS ASSOCIATED WITH A
COLD AIR WEDGE IN PLACE WILL CONTINUE THROUGH THE OVERNIGHT PERIOD
AS IFR/LIFR CLOUD DECK REMAINS LOCKED IN ACROSS THE AREA. CONDITIONS
WILL ONLY WORSEN BEFORE IMPROVING AS ALL TERMINALS WILL EXPERIENCE
LIFR CIGS THROUGH AT LEAST DAYBREAK. ONGOING LIGHT -RA/DZ IS LIKELY
TO STICK AROUND THROUGH DAYBREAK BEFORE COVERAGE DWINDLES AROUND
MID-MORNING. KEPT A VCSH MENTION THROUGH THIS TIME FRAME, BUT
INCLUDED A TEMPO FOR -RA AT ALL SITES OVER THE NEXT FEW HOURS AS
SHOWER COVERAGE HAS EXPANDED ACROSS MOST OF THE TERMINALS. PATCHY
DENSE FOG ALSO CAN'T BE RULED OUT, MAINLY ACROSS THE MOUNTAINS
AND FOOTHILLS, BUT MOST LOCATIONS WILL RIDE WITH IFR/MVFR VSBY
RESTRICTIONS BEFORE THE FOG BURNS OFF AFTER DAYBREAK. WITHOUT A
REAL MECHANISM TO ERODE THE DOME OF COLD AIR, THE LOW CLOUD DECK
WILL TAKE TIME TO SCATTER WITH IFR/MVFR CIGS REMAINING IN PLACE
THROUGH EARLY AFTERNOON BEFORE PEAK HEATING TAKES OVER AND LIFTS
CIGS TO MVFR AND EVEN VFR IN SOME SPOTS, BUT THIS WOULD LIKELY
HAPPEN AT KCLT/KAVL/KAND AS THESE SITES ARE ON THE EDGE OF THE
WEDGE. ALL OTHER SITES LIKELY RETAIN AN MVFR RESTRICTION THROUGH
THE DAYTIME PERIOD. LIGHT NORTHEASTERLY WINDS CONTINUE TO FILTER IN
THROUGH THE MORNING, WHILE VEERING TO A SOUTHWESTERLY COMPONENT BY
THE AFTERNOON. GUIDANCE IS KEEN ON RESTRICTIONS RETURNING TONIGHT
AS IFR/LIFR CIGS RETURN, WITH MVFR/IFR VSBYS AS WELL. INTRODUCED
THIS IN THE 06Z TAF UPDATE AS LOW-LEVEL MOISTURE LINGERS AND THE
WEDGE WON'T COMPLETELY SCOUR OUT THROUGH THE FORECAST PERIOD.
OUTLOOK: RESTRICTIONS MAY CONTINUE THROUGH TONIGHT, BUT SHOULD
CLEAR OUT MID-MORNING TUESDAY. 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...CAC/MPR/PM
SHORT TERM...AR
LONG TERM...AR
AVIATION...CAC
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page