796
FXUS62 KGSP 290619
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
219 AM EDT WED OCT 29 2025
SYNOPSIS
A COLD AIR WEDGE PATTERN OVER THE WESTERN CAROLINAS AND NORTHEAST
GEORGIA WILL KEEP TEMPERATURES CHILLY THROUGH THE DAY TODAY, ALONG
WITH PERIODS OF RAINFALL THIS AFTERNOON AND TONIGHT. TEMPERATURES
TREND WARMER IN MOST AREAS THURSDAY AND FOR THE WEEKEND, ALTHOUGH
STILL BELOW NORMAL.
NEAR TERM /THROUGH TONIGHT/
AS OF 1:45 AM EDT WEDNESDAY: THE CAD WILL REMAIN ENTRENCHED ACROSS
OUR AREA THRU MOST OF THE NEAR-TERM PERIOD. ALTHOUGH ISENTROPIC LIFT
REMAINS RATHER WEAK, WE'RE STILL SEEING SOME LIGHT DRIZZLE OVER POR-
TIONS OF THE UPSTATE AND NC MTNS. LOWS OVERNIGHT SHOULD BE NEAR NORMAL.
BOTH ISENTROPIC AND SYNOPTIC-SCALE LIFT WILL INCREASE THIS MORNING AS
AN UPPER LOW AND ASSOCIATED COLD FRONT APPROACH FROM THE WEST. UPPER
LEVEL DIVERGENCE ALSO INCREASES AS THE RIGHT ENTRANCE REGION OF AN
UPPER JET MAX MOVES OVER OUR AREA. PRECIP SHOULD START OUT AS RAIN/
DRIZZLE THEN TRANSITION TO SHOWERS AS THE DEEPER MOISTURE AND FORCING
REACH OUR FCST AREA. UNLESS THE CAD ERODES MORE QUICKLY THEN EXPECTED
(WHICH APPEARS UNLIKELY GIVEN THE PATTERN) A LACK OF SFC-BASED INSTA-
BILITY SHOULD PREVENT ANY THUNDER/LIGHTNING FROM MATERIALIZING OVER
OUR CWA. NONETHELESS, BRIEF HEAVY SHOWERS ARE EXPECTED, ESPECIALLY
ALONG AND NEAR THE BLUE RIDGE. I WOULDN'T RULE OUT SOME PONDING OF
WATER OR BANKFULL STREAM LEVELS GIVEN THE PREVIOUS DAY'S RAINFALL,
BUT THESE SHOULD BE ISOLATED IN NATURE GIVEN HOW DRY WE'VE BEEN. IN
ADDITION, GUSTY WINDS WILL CONTINUE THRU THE PERIOD ESPECIALLY OVER
THE HIGHER TERRAIN AND ALONG THE NC/TN BORDER, BUT SHOULD REMAIN
BELOW ADVISORY LEVELS. OTHERWISE, HIGHS TODAY WILL REMAIN 10 TO 20
DEG BELOW NORMAL, WITH THE COLDEST TEMPS IN THE HEART OF THE WEDGE.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
AS OF 1210 AM WED: SFC/UPPER CYCLONE TO TRACK NORTHWARD UP THE
APPALACHIANS THURSDAY. ENSUING WEST TO NORTHWEST FLOW ACROSS THE NC
MOUNTAINS WILL PROMOTE THE CAA NECESSARY TO ERODE WHAT'S LEFT OF THE
WEDGE. TIGHT GRADIENT BETWEEN THE LOW AND HIGH PRESSURE BUILDING OUT
OF THE PLAINS AND LOWER MS VALLEY WILL MAINTAIN FAIRLY WINDY AND
GUSTY CONDITIONS ACROSS THE AREA. A MOIST LAYER WILL PERSIST ON THE
UPSLOPE SIDE OF THE APPS AND LIKELY A SHALLOW CONVECTIVE LAYER
PERMITTING SOME SHOWER PRODUCTION. HENCE POPS PERSIST THRU THE DAY
ACROSS OUR MOUNTAIN ZONES AND ESPECIALLY NEAR THE TN BORDER WHERE
VALUES REMAIN IN THE LIKELY RANGE. MOISTURE IS NOT DEEP ENOUGH TO
EXPECT GOOD ICE NUCLEATION, BUT SFC TEMPS AND POSITIVE LAPSE RATES
SUGGEST SOME RIME ICING OR FREEZING DRIZZLE MAY OCCUR THRU LATE
MORNING IN VERY HIGH ELEVATIONS, MOSTLY ABOVE 5000 FT. ACROSS THE
PIEDMONT, SOME CUMULUS WILL BE SEEN BUT NOT DEEP ENOUGH FOR A
MENTIONABLE PRECIP CHANCE. EXCEPT IN HIGH ELEVATIONS AND SOME VALLEYS
NOT ORIENTED FOR NW DOWNSLOPE, TEMPS TREND WARMER, GENERALLY ON THE
ORDER OF 5-7 DEGREES, BUT A FEW SPOTS MORE THAN 10 DEGREES.
BY AFTERNOON, VIA THE AFOREMENTIONED CONVECTIVE LAYER AND STRONGER
MIDLEVEL FLOW MIXING DOWN, HIGH ELEVATIONS ABOVE 3500 FT PROBABLY
WILL SEE A FEW GUSTS OF 35-45 MPH, JUST SHY OF ADVISORY CRITERIA. IF
CONFIDENCE INCREASES ON SAID MIXING A WIND ADVISORY COULD BE
JUSTIFIED THERE. THE HIGH ELEVATION GUST POTENTIAL CONTINUES
OVERNIGHT BEFORE GRADIENT SLACKENS FRIDAY MORNING. GROWING SEASON
CONTINUES TO NOV 1 IN THE MOUNTAIN ZONES NOT BORDERING TN, WHERE A
FREEZE HAS NOT ALREADY OCCURRED. A SPOTTY ADVECTIVE FREEZE LOOKS TO
OCCUR IN SOME OF THE HIGHER ELEVATIONS NEAR THE ESCARPMENT FRI
MORNING; IN OTHER PARTS OF THE MOUNTAINS AREAS OF FROST COULD FORM
IF/WHERE THE WIND DOES NOT PRECLUDE SURFACE RADIATION. HENCE
FROST/FREEZE HEADLINES COULD BE ISSUED ON THURSDAY IF THESE
EXPECTATIONS HOLD.
TEMPERATURES ARE EXPECTED TO BE SIMILAR FRIDAY COMPARED TO THURSDAY,
WITH A COLDER START OFFSETTING REBOUNDING THICKNESSES. FLOW ALOFT
TURNS QUASI-ZONAL BEHIND THE DEPARTING LOW, ALLOWING AT LEAST WEAK
SFC HIGH PRESSURE TO SHIFT ACROSS THE SOUTHEAST. DECOUPLING APPEARS
LIKELY FRIDAY NIGHT AND FROST IS MORE LIKELY THEN WHERE TEMPS FALL
INTO THE LOWER-MID 30S: THE MOUNTAINS/FOOTHILLS AND SOME AREAS OF THE
UPPER PIEDMONT AS WELL. THIS WOULD BE THE LAST OPPORTUNITY FOR THE
MOUNTAINS FOR FROST/FREEZE PRODUCTS THIS FALL GIVEN THE DEFAULT
TURN-OFF DATE OF NOV 1.
LONG TERM /SATURDAY THROUGH TUESDAY/
AS OF 105 AM WED: THE GLOBAL DETERMINISTIC MODELS GENERALLY AGREE ON
A SHORTWAVE DIGGING ACROSS THE MISSISSIPPI VALLEY ON SATURDAY AND
SATURDAY NIGHT. THERE REMAINS WIDE SPREAD HOW IT EVOLVES SUNDAY INTO
EARLY NEXT WEEK. THE GFS SHOWS THE LOW ALREADY CUT OFF BY THE TIME IT
EXITS THE UPPER MIDWEST; THE GDPS IS CLOSE IN POSITION BUT NOT AS
DEEP, WHILE THE ECMWF CUTS OFF THE LOW AFTER IT PUSHES SOUTH OF THE
GULF COAST. THE 29/00Z GFS ACTIVATES A WARM FRONT DOWNSTREAM OF THE
CUTOFF LOW AND, SIMILAR TO THE 28/00Z RUN, BRINGS A BROAD AREA OF
RAIN TO THE CWA CIRCA MONDAY. THE ECMWF HASN'T HAD GREAT RUN-TO-RUN
CONSISTENCY BUT CONTINUES TO SUGGEST DRY WEATHER. THE GDPS IS FAIRLY
SIMILAR TO ITS RUN FROM 24 HOURS PRIOR, BRINGING US A BRIEF SHOT OF
CLIPPER-LIKE PRECIP. ENSEMBLE MEMBERS FROM EACH CORRESPONDING SUITE
ARE LARGELY DRY FOR OUR AREA. CONFIDENCE REMAINS LOW IN THE PATTERN
AND ANY RESULTANT PRECIP CHANCES. NBM PRODUCES A FEW SPOTS OF 15-20%
POP OVER THE MOUNTAINS HERE AND THERE SUNDAY THRU MONDAY NIGHT BUT
THAT JUST APPEARS MODEL "NOISE" AT THIS POINT. TEMPS REMAIN A FEW
DEGREES BELOW NORMAL SAT-SUN, AND SOME PATCHY FROST CAN'T BE RULED
OUT SAT NIGHT IN THE TYPICALLY COLDER SPOTS OUTSIDE THE MOUNTAINS.
WORTH NOTING THE GFS SOLUTION IS QUITE WARM ALOFT, BUT ALSO HINTS AT
CAD TAKING SHAPE. SO WHILE A SHARP GRADIENT AND CHILLY TEMPS COULD
RESULT FOR THE FOOTHILLS AND NW PIEDMONT, IF THAT SOLUTION WERE TO
VERIFY IT LOOKS LIKE WE'D SEE AN ALL-RAIN EVENT EVEN ACROSS THE
MOUNTAINS. EXCEPT WHERE THE CAD MIGHT REAR ITS HEAD, A WARMING TREND
LOOKS TO OCCUR MON-TUE, ALTHOUGH LIKEWISE TO POPS, CONFIDENCE IS LOW
IN HOW MUCH.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: A WEDGE OF COOL, MOIST AIR WILL REMAIN
IN PLACE ACROSS THE FCST AREA THRU MOST OF THE 06Z TAF PERIOD,
RESULTING IN LOW CIGS AND PERSISTENT NELY WINDS AROUND 10 KTS
AND INTERMITTENT GUSTS BETWEEN 15 AND 20 KTS AT MOST SITES.
CIGS WILL GENERALLY FAVOR MVFR LEVELS OVERNIGHT THEN DETERIO-
RATE TO IFR BY SUNRISE. CHANCES FOR -RA WILL ALSO INCREASE OVER-
NIGHT, WITH THE POTENTIAL FOR RESTRICTED VISBY INCREASING IN PRE-
CIPITATION THRU THE MORNING. CIGS ARE NOT EXPECTED TO IMPROVE
UNTIL JUST AFTER THE TAF PERIOD, WHILE THE POTENTIAL FOR HEAVIER
RAIN IS EXPECTED TO INCREASE LATER IN THE EVENING. AS SUCH, THERE
IS A BETTER CHANCE FOR LOWER VISBY LATER IN THE PERIOD. PREVAILING
SHOWERS SHOULD BE MOVING EAST OF OUR AREA BY THE END OF THE TAF
PERIOD, HOWEVER CIGS LIKELY WON'T LIFT/SCT UNTIL JUST AFTER THE
PERIOD ENDS.
OUTLOOK: CONDITIONS IMPROVE BEHIND THE FRONT EARLY THURSDAY,
ALTHOUGH GUSTY WINDS MAY LINGER THRU THE DAY, POSSIBLY CONTIN-
UING THRU FRIDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...JCW
NEAR TERM...JPT
SHORT TERM...JCW
LONG TERM...JCW
AVIATION...JPT
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