762
FXUS62 KGSP 131120
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
620 AM EST WED NOV 13 2024
SYNOPSIS
DRY HIGH PRESSURE REMAINS IN PLACE TODAY WITH COOLER TEMPERATURES,
A LITTLE BELOW NORMAL. CLOUDS AND PRECIPITATION ARRIVING EARLY
TOMORROW MORNING WILL MAKE FOR A VERY DAMP AND CHILLY THURSDAY.
DRY WEATHER AND A WARMING TREND ARE EXPECTED FRIDAY THROUGH MONDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 620 AM EST WEDNESDAY...
KEY MESSAGES:
1) BELOW NORMAL HIGHS RETURN TODAY THANKS TO COLD AIR DAMMING
2) MOSTLY SUNNY SKIES THROUGH EARLY AFTERNOON WITH MOSTLY CLOUDY
SKIES BY EARLY EVENING
3) DRY CONDITIONS LINGER THROUGH EARLY THIS EVENING BEFORE A COLD
FRONT INCREASES RAIN CHANCES TONIGHT INTO DAYBREAK THURSDAY
NO MAJOR CHANGES WERE NEEDED THIS UPDATE AS THE FORECAST REMAINS ON
TRACK. OTHERWISE, SOME FOG HAS DEVELOPED ACROSS THE LITTLE TN RIVER
VALLEY BUT THIS IS EXPECTED TO REMAIN PATCHY, DISSIPATING SHORTLY
AFTER SUNRISE. MOSTLY CLEAR SKIES CONTINUE THIS MORNING OTHER THAN A
FEW BANDS OF CIRRUS TRACKING OVER WESTERN NORTH CAROLINA. TEMPS THIS
MORNING HAVE DROPPED NEAR FREEZING ACROSS THE NORTHERN NC MOUNTAINS.
SINCE THE FROST/FREEZE PROGRAM HAS OFFICIALLY ENDED FOR THE GSP CWA,
NO FROST/FREEZE PRODUCTS WERE ISSUED. TEMPS ELSEWHERE HAVE REMAINED
SLIGHTLY WARMER THAN ANTICIPATED (DESPITE GREAT RADIATIONAL COOLING
CONDITIONS OVERNIGHT) AND ARE RANGING FROM THE UPPER 30S TO LOWER
50S.
DRY SFC HIGH PRESSURE WILL CONTINUE NOSING DOWN INTO THE SOUTHERN
APPALACHIANS THROUGH THIS EVENING, ALLOWING COLD AIR DAMMING (CAD)
TO DEVELOP AND KEEPING NE'LY WINDS AROUND EAST OF THE MOUNTAINS
(WITH WINDS REMAINING E/SE'LY ACROSS THE MOUNTAINS). DRIER AIR WILL
CONTINUE FILTERING INTO THE REGION FROM NORTH TO SOUTH THROUGH THE
FIRST HALF OF THE DAY LEADING TO DEWPOINTS IN THE UPPER 20S TO MID
30S BY THIS AFTERNOON. DESPITE ABUNDANT SUNSHINE THROUGH THE EARLY
TO MID AFTERNOON, CAD WILL ALLOW BELOW NORMAL HIGHS TO RETURN NEARLY
EVERYWHERE (THE EXCEPTION BEING THE LITTLE TN VALLEY WHICH WILL SEE
HIGHS A FEW DEGREES ABOVE NORMAL). TEMPS WILL ONLY CLIMB INTO THE
MID 50S TO LOWER 60S EAST OF THE MOUNTAINS. HIGHS ACROSS THE
MOUNTAINS WILL BE SLIGHTLY COOLER, RANGING FROM THE MID 40S TO UPPER
50S. THE LITTLE TN VALLEY WILL SEE THE WARMEST TEMPS, RANGING FROM
THE LOW TO MID 60S. BREEZY WINDS WILL DEVELOP TODAY, ESPECIALLY
ACROSS THE MOUNTAIN ZONES, NORTHEAST GEORGIA, AND THE SC UPSTATE AND
MAY LINGER INTO TONIGHT AHEAD OF AN APPROACHING COLD FRONT. WINDS
ARE EXPECTED TO REMAIN WELL BELOW WIND ADVISORY CRITERIA.
THE AFOREMENTIONED COLD FRONT WILL REMAIN WEST OF THE FORECAST AREA
THROUGH DAYBREAK THURSDAY BUT PRECIP CHANCES AND CLOUD COVER WILL
GRADUALLY INCREASE WELL AHEAD OF THE FRONT. CLOUD COVER WILL
INCREASE FROM WEST TO EAST LATE THIS AFTERNOON INTO EARLY THIS
EVENING BECOMING MOSTLY CLOUDY. PRECIP CHANCES LOOK TO HOLD OFF
UNTIL LATE THIS EVENING, INCREASING FROM WEST TO EAST INTO TONIGHT,
WITH THE ENTIRE FORECAST AREA LIKELY SEEING RAIN BY DAYBREAK
THURSDAY. NO FLOODING IS EXPECTED THROUGH THE NEAR TERM AS RAINFALL
AMOUNTS LOOK TO GENERALLY REMAIN BELOW HALF AN INCH TONIGHT INTO
DAYBREAK THURSDAY. MAINLY RAIN IS EXPECTED WITH THIS SYSTEM,
ALTHOUGH A FEW ISOLATED LOCATIONS IN THE NORTHERN NC MOUNTAINS WILL
SEE TEMPS DROP TO OR NEAR FREEZING TONIGHT SO SOME ISOLATED POCKETS
OF BRIEF SLEET CANNOT BE ENTIRELY RULED OUT THANKS TO DRIER AIR IN
PLACE AHEAD OF THE FRONT. THUS, ADDED SLIGHT CHANCE SLEET (24% OR
LESS) FOR LOCATIONS IN THE NORTHERN NC MOUNTAINS THAT SEE TEMPS FALL
TO OR NEAR FREEZING. NO MAJOR IMPACTS ARE EXPECTED FROM BRIEF
POCKETS OF SLEET DEVELOPING AS THE SLEET WILL NOT ACCUMULATE. CLOUD
COVER AND PRECIP WILL LIMIT RADIATIONAL COOLING TONIGHT SO LOWS
SHOULD END UP A FEW DEGREES ABOVE NORMAL.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
AS OF 200 AM WED: PLUME OF WARM UPGLIDE ASSOCIATED WITH WARM
CONVEYOR BELT OF MIDWEST LOW WILL TRAVERSE THE EASTERN TWO-THIRDS OF
THE CWA THU MORNING THROUGH ABOUT MID-AFTERNOON, ATOP ESTABLISHED
SFC WEDGE. NO REAL CHANGE FROM PREVIOUS EXPECTATIONS IN THIS
REGARD; ANY CHANCE OF SLEET MIXING WITH RAIN IN THE MOUNTAINS THU
MORNING SHOULD END BY AROUND 12Z. ONE NOTABLE CHANGE IS THAT QPF
HAS TAKEN ON A MORE CONVECTIVE LOOK THU AFTERNOON IN SOME GUIDANCE
SOURCES, WHEN PRECIP IS EXPECTED TO BE MAINLY OCCURRING OVER OUR
EASTERN ZONES. THIS IS EXEMPLIFIED BY THE 3KM NAM AND HRW-FV3
SHOWING LINEARLY ORGANIZED BANDS IN THE I-77 CORRIDOR AROUND 21Z,
ASSOCIATED WITH BETTER LAPSE RATES ABOVE THE WEDGE INVERSION THAN
WHAT HAD BEEN SHOWN ON THE PREVIOUS CYCLE, AND EFFECTIVE BULK SHEAR
PEAKING ABOVE 40 KT. THIS CONVECTION STILL ALMOST CERTAINLY WILL
BE ELEVATED, AND WE'RE TALKING ABOUT MUCAPE ON THE ORDER OF 100
J/KG AT MOST. HENCE SEVERE THREAT REMAINS MINIMAL, BUT AT LEAST
BRIEF HEAVY RAIN APPEARS MORE PLAUSIBLE THAN IT ONCE HAD DURING THIS
EVENT. THAT SAID, TOTAL QPF REMAINS MOSTLY IN THE 0.75" TO 1" RANGE,
POSSIBLY UP TO 1.5" IN A FEW SPOTS ALONG THE SOUTH-FACING BLUE RIDGE
ESCARPMENT, BUT THE LIKELIHOOD OF FLOODING STILL LOOKS SMALL. FCST
TEMPS THU HAVEN'T CHANGED MUCH FROM PREVIOUS FCST AND STILL WILL
REFLECT THE RELATIVELY STRONG CAD, BEING KEPT IN THE UPPER 40S IN
MUCH OF THE PIEDMONT, PERHAPS BREAKING 50 IN THE LOWER MOUNTAIN
VALLEYS NEAR THE TN BORDER AND ALONG OUR SOUTHEASTERN FRINGE.
COLD FRONT STILL TIMED TO CROSS THE AREA THU EVENING; THIS SHOULD
BEGIN CAD EROSION ALTHOUGH THAT MAY NOT COMPLETE UNTIL INSOLATION
OCCURS FRIDAY MORNING. SOME MODEL SOURCES DEPICT CLOUD COVER ONLY
SLOWLY RETREATING FROM NW TO SE ACROSS THE FOOTHILLS/PIEDMONT
OVERNIGHT. NW WINDS BEHIND THE FRONT STILL SHOULD PRODUCE UPSLOPE
CLOUDS AND PRECIP CHANCES NEAR THE TN BORDER THU NIGHT, BUT TEMPS
WILL BE TOO WARM FOR WINTRY PRECIP. HEIGHT GRADIENT WILL TIGHTEN AS
UPPER LOW CROSSES THE APPALACHIANS JUST TO OUR NORTH; THE HIGHEST
ELEVATIONS COULD SEE WIND GUSTS AROUND 45 MPH EARLY FRI MORNING,
SO FLIRTING WITH ADVISORY CRITERIA, BUT LOWER MOUNTAIN ELEVATIONS
LOOK UNLIKELY TO SEE GUSTS RISE MUCH ABOVE 30 MPH. AS SFC HIGH
BUILDS IN FROM THE WEST, WINDS RELAX FRI SUCH THAT POPS WILL TAPER
OFF, BUT ENOUGH MOISTURE IS SHOWN ON THE UPSLOPE SIDE TO EXPECT
SOME CLOUDS TO LINGER THERE UNTIL EARLY SATURDAY. UPPER RIDGE AXIS
WILL MIGRATE TOWARD THE AREA THRU EARLY SAT. MAX TEMPS FRI WILL BE
A SHADE ABOVE NORMAL WITH ABUNDANT SUNSHINE AND, FOR THE PIEDMONT,
DOWNSLOPE FLOW.
LONG TERM /SATURDAY THROUGH TUESDAY/
AS OF 245 AM WED: SFC/UPPER RIDGE STILL TO DOMINATE OUR PATTERN OVER
THE WEEKEND. MAX TEMPS WILL TREND WARMER AND SEVERAL DEGREES ABOVE
NORMAL BY SAT, WITH MINS REMAINING NEAR TO SLIGHTLY ABOVE NORMAL.
MODELS CONTINUE TO SHOW TWO UPPER LOWS, ONE OVER THE SW CONUS AND THE
OTHER NORTH OF THE GREAT LAKES, SUPPRESSING THE RIDGE TO SOME EXTENT
BY MONDAY; A PIVOTING FRONTAL BOUNDARY WILL EXIST BETWEEN THEM. IT
NOW LOOKS LIKE THAT FRONT WILL REMAIN NORTH OF THE CWA AND MONDAY
LOOKS MORE LIKELY TO BE DRY THAN IT DID ON YESTERDAY MORNING'S
FORECAST. HOWEVER, THE SOUTHERN LOW WILL OPEN UP INTO A SHORTWAVE
AND INDUCE CYCLOGENESIS IN THE LEE OF THE ROCKIES, WITH THE INCIPIENT
SYSTEM TRACKING GENERALLY INTO THE MIDWEST. AFTER THE DRY WEEKEND,
OUR NEXT POSSIBILITY OF PRECIP CURRENTLY LOOKS TO BE WITH THE LATTER
COLD FRONT REACHING OUR WESTERN ZONES TUESDAY. DESPITE THE
SUPPRESSION OF THE RIDGE, TEMPS WILL REMAIN SEVERAL DEGREES ABOVE
NORMAL EARLY NEXT WEEK, GENERALLY WITHIN A CATEGORY EITHER SIDE OF 70
IN THE PIEDMONT AND VALLEYS. THERE PRESENTLY APPEARS NO WINTRY WX
THREAT WITH THE TUE POPS.
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: DRY AND VFR THROUGH LATE THIS EVENING ACROSS
THE TERMINALS THANKS TO DRY HIGH PRESSURE BUILDING INTO THE REGION.
A COLD FRONT APPROACHING OUT OF THE WEST INCREASES CLOUD COVER AND
RAIN CHANCES TONIGHT INTO THURSDAY. CLOUD COVER WILL REMAIN VFR
THROUGH LATE THIS EVENING BUT WILL GRADUALLY THICKEN THIS AFTERNOON,
BECOMING OVC BY EARLY THIS EVENING. RAIN CHANCES SHOULD START TO
INCREASE AFTER ROUGHLY 04Z-05Z THURSDAY FROM WEST TO EAST, WITH RAIN
EXPECTED ACROSS ALL TERMINALS BY 08Z-12Z. RAIN WILL LINGER OVER THE
TERMINALS THROUGH THE END OF THE 12Z TAF PERIOD. HAVE PROB30S ACROSS
ALL TERMINALS TO ACCOUNT FOR RA, LOWERING CIGS, AND VSBYS. HAVE
PREVAILING RA AT KCLT AND KAVL AFTER THE PROB30S END AS THE KCLT TAF
GOES OUT 30 HOURS AND KAVL WILL SEE THE ONSET OF RAIN FIRST. CIGS
WILL GRADUALLY LOWER FROM WEST TO EAST AFTER ROUGHLY 04Z-05Z
THURSDAY, DROPPING TO IFR TO MVFR LEVELS BY 12Z THURSDAY. SOME
TERMINALS MAY EVEN SEE CIGS DROP TO LIFR LEVELS BUT CONFIDENCE WAS
TOO LOW TO MENTION AT THIS TIME DUE TO THIS BEING TOWARDS THE END
OF THE TAF FORECAST PERIOD. WINDS WILL REMAIN SE'LY AT KAVL AND
NE'LY AT THE REST OF THE TERMINALS THROUGH THE ENTIRE TAF PERIOD.
LOW-END GUSTS SHOULD DEVELOP THIS MORNING ACROSS THE SC UPSTATE
TERMINALS. GUSTS SHOULD LINGER THROUGH AT LEAST THE AFTERNOON/EARLY
EVENING HOURS. GUSTS MAY EVEN LINGER THROUGH TONIGHT ACROSS THE SC
UPSTATE TERMINALS BUT CONFIDENCE REMAINS TOO LOW KEEP THE GUST
MENTION THAT LONG.
OUTLOOK: HIGH PRESSURE BRINGS DRY AND VFR CONDITIONS BACK FRIDAY
INTO EARLY NEXT WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...AR
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...AR
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