684
FXUS62 KGSP 071718
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
118 PM EDT TUE OCT 7 2025
SYNOPSIS
DRY HIGH PRESSURE MOVES OFF THE EAST COAST TONIGHT AS A COLD FRONT
APPROACHES FROM THE NORTHWEST. ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS CROSSES OUR REGION TONIGHT THROUGH WEDNESDAY WITH THE
COLD FRONT MOVING OFF THE CAROLINA COAST WEDNESDAY NIGHT. COOLER
THAN NORMAL TEMPERATURES WILL OCCUR THURSDAY AND FRIDAY BEFORE A
WARMING TREND DEVELOPS THIS WEEKEND INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH WEDNESDAY/
1) A FEW ISOLATED SHOWERS OVER THE MOUNTAINS THIS AFTERNOON.
2) A COLD FRONT MOVES INTO THE AREA OVERNIGHT AND INTO WEDNESDAY,
INCREASING SHOWER AND THUNDERSTORM CHANCES.
3) TEMPERATURES REMAIN WARM AHEAD OF THE FRONT.
AS OF 110 PM EDT TUESDAY: A GENERALLY QUIET TUESDAY EXPECTED
AHEAD OF A COLD FRONT. SYNOPTICALLY, AN UPPER LOW CHURNS ACROSS
SOUTHERN ONTARIO WITH A TROUGH DIPPING INTO THE TN/OHIO VALLEY.
OUT WEST, A RIDGE AMPLIFIES AND PUSHES THE TROUGH EASTWARD.
MEANWHILE, A BROAD UPPER HIGH SITS ACROSS THE SOUTHEAST TODAY
BEFORE HEIGHTS START TO FALL OVERNIGHT. AT THE SURFACE, THE
BERMUDA HIGH RETREATS EAST AS A FRONTAL BOUNDARY FROM THE NW
MOVES INTO THE MOUNTAINS TONIGHT. GUIDANCE SHOWS THE FRONT
WEAKENING ONCE IT REACHES THE CWA BY EARLY WEDNESDAY MORNING,
WITH THE BETTER FORCING OFF TO THE NE. CURRENTLY, FRONTOGENESIS
OCCURS AT THE TN/NC BORDER AND QUICKLY DROPS OFF AS IT MOVES
THROUGH THE NC PIEDMONT. GIVEN THE TIMING OF THE FRONT WEDNESDAY
MORNING, GUIDANCE HAS MINIMAL INSTABILITY FROM 100-300 J/KG OF
SBCAPE, WHICH IS NOT CONVINCING DUE TO THE RELATIVELY STABLE
MORNING BOUNDARY LAYER. IF THE FRONT COMES THROUGH LATER IN THE
MORNING, THERE IS A POSSIBILITY OF SOME OF THE INSTABILITY BEING
REALIZED, WHICH COULD BRING STRONG WINDS AND LOCALLY HEAVY
RAINFALL WHEREVER STORMS OCCUR. OVERALL, CONFIDENCE IS LOW ON
THE SEVERE THREAT DUE TO THESE FACTORS, BUT CANNOT RULE OUT AN
ISOLATED STRONG STORM OR TWO. CAM GUIDANCE DOES SUGGEST A FEW
SHOWERS AND THUNDERSTORMS POPPING UP EVEN BEHIND THE FRONT
WEDNESDAY EVENING, HOWEVER, THIS IS EVEN LOWER CERTAINTY. EITHER
WAY, THE HIGHER CHANCES (56-80%) FOR SHOWERS AND THUNDERSTORMS
ARE ALONG THE MOUNTAINS BEFORE SUNRISE WITH MORE
ISOLATED/SCATTERED SHOWERS EAST OF THE MOUNTAINS, ESPECIALLY IN
THE NC PIEDMONT. WILL KEEP A SLIGHT CHANCE (25-45%) FOR
WEDNESDAY AFTERNOON FOR MOST OF THE AREA. RAIN CHANCES QUICKLY
DECREASE AT THE END OF THE THIS FORECAST PERIOD AND INTO THE
OVERNIGHT HOURS WEDNESDAY. TEMPERATURES REMAIN WARM AHEAD OF THE
FRONT, WITH MID 70S AND LOW 80S EAST OF THE MOUNTAINS. EXPECT
WARM OVERNIGHT TEMPS AS THE MOISTURE LINGERS AHEAD OF THE FRONT.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/
AS OF 1225 PM EDT TUESDAY...
KEY MESSAGES:
1) BREEZY CONDITIONS OUTSIDE THE MOUNTAINS THURSDAY THROUGH FRIDAY
2) COOL TEMPERATURES...ABOUT FIVE DEGREES BELOW NORMAL
3) PATCHY FROST POSSIBLE IN SHELTERED LOCATIONS ACROSS THE NORTHERN
MOUNTAINS OF NC THURSDAY NIGHT
THE COLD FRONT SHOULD MAKE ITS WAY SOUTHWARD ACROSS THE REGION
WEDNESDAY NIGHT AND SHOULD BE CLEAR OF THE FCST AREA BY DAYBREAK
THURSDAY. A SMALL PRECIP PROB WILL BE RETAINED OVER THE SRN ZONES,
BUT THAT WILL BE GRADUALLY TAPERING OFF AFTER MIDNIGHT. OTHERWISE,
THE REST OF THE WORK WEEK SHOULD HAVE FAIR AND DRY BUT COOL WEATHER,
IN SPITE OF A SHORT WAVE MOVING PAST TO OUR SOUTHWEST AND FORCING
THE DEVELOPMENT OF A BAGGY UPPER LOW OVER THE SOUTHEAST LATE
THURSDAY AND INTO FRIDAY. THIS FEATURE MOVES SLOWLY ENOUGH AND
DOESN'T REALLY DEVELOP A SFC REFLECTION UNTIL AFTER SUNSET ON
FRIDAY. AS A RESULT, OUR WEATHER WILL BE CONTROLLED MORE BY AN
UPPER RIDGE IN THE NRN STREAM THAT SUPPORTS A SPRAWLING PARENT
SFC HIGH MOVING ACROSS THE GREAT LAKES AND NORTHEAST THROUGH THE
BULK OF THE SHORT TERM. WE EFFECTIVELY END UP WITH ANOTHER DRY
COLD AIR DAMMING WEDGE UNDER A FORMIDABLE SUBSIDENCE INVERSION
BOTH DAYS. THE PRESSURE GRADIENT AND BOUNDARY LAYER FLOW UNDER
THE INVERSION SHOULD PROVIDE FOR BREEZY CONDITIONS THROUGH THE
PERIOD OUTSIDE THE MTNS, THOUGH NOWHERE NEAR STRONG ENOUGH TO
CAUSE PROBLEMS. THE MOUNTAINS MAY BE ABOVE THE INVERSION WHERE THE
WINDS ARE NOT QUITE AS STRONG. TEMPS WILL BE AROUND FIVE DEGREES
BELOW NORMAL, SO, COOL BUT NOT ESPECIALLY NOTEWORTHY. THE ONE MINOR
COMPLICATION MIGHT BE THE LOW TEMPS THURSDAY NIGHT ACROSS THE MTNS,
WITH THE NORTHERN MOUNTAINS AND ELEVATIONS ABOVE 5K FEET DROPPING
DOWN INTO THE MIDDLE 30S. IF THE WIND COULD TAPER OFF ENOUGH, IT
WOULD BE COOL ENOUGH FOR SOME PATCHY FROST, SO WE WILL BE WATCHING
THAT GOING FORWARD.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
AS OF 1242 PM EDT TUESDAY...HEADING INTO THE WEEKEND, WE WILL BE
WATCHING FOR POSSIBLE WEAK CYCLOGENESIS OFF THE SOUTHEAST COAST
FRIDAY NIGHT INTO SATURDAY AS THE AFOREMENTIONED WEAK UPPER LOW
INTERACTS WITH THE OLD STALLED FRONTAL BOUNDARY TO OUR SOUTH. ALL
THE OPERATIONAL MODEL SOLUTIONS HAVE THIS DEVELOPMENT BY SATURDAY
MORNING, JUST NOT ALL OF THEM TRACK THE LOW CLOSE ENOUGH TO BE OF
MUCH CONCERN. ONLY THE 06Z OPERATIONAL RUN OF THE GFS HAS THE LOW
NEAR THE COAST TO THE EXTENT THAT THE WESTERN EDGE OF THE PRECIP
SHIELD IMPACTS THE AREA EAST OF I-77, BUT THERE ISN'T A GREAT DEAL
OF SUPPORT IN THE GFS ENSEMBLE. THE 12Z RUN IS COMING IN WITH A MORE
EASTERLY TRACK OF THIS LOW. THE MODEL BLEND KEEPS THE EASTERN PART
OF THE FCST AREA DRY AGAIN FOR THIS MODEL CYCLE, AND THAT IS STILL
A GOOD CALL BASED ON THE GFS TREND. WITH THAT OUT OF THE WAY, THE
WEATHER LOOKS DRY FOR THE REST OF THE PERIOD WITH A MEAN UPPER RIDGE
AXIS STAYING TO OUR WEST SUPPORTING SFC HIGH PRESSURE. IT MIGHT
REMAIN A LITTLE BREEZY, BUT NOT OUT OF THE ORDINARY. TEMPS WOULD
UNDERGO A GRADUAL WARMING TREND BACK TO NORMAL THROUGH THE WEEKEND.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: A MIX OF MVFR AND VFR THIS AFTERNOON AS LOWER
CLOUDS FILTER INTO THE AREA AHEAD OF A COLD FRONT. THIS SHOULD BE
THE CASE FOR CIGS/VSBY THROUGH AT LEAST MIDNIGHT. A FRONT
APPROACHING FROM THE NW IS EXPECTED TO CROSS INTO THE MOUNTAINS AND
EVENTUALLY THE REMAINDER TERMINAL SITES WEDNESDAY MORNING/ EARLY
AFTERNOON. AT THIS TIME, VSBY RESTRICTIONS FOR BR/FG ARE ANTICIPATED
AT KAVL/KHKY, WHICH NOW HAVE A TEMPO FOR THE PRE-DAWN HOURS 09Z-13Z.
THERE SHOULD ALSO BE SHRA OR -RA WITH THIS FRONT, BUT COVERAGE IS
LIMITED. FOR THE REMAINDER SITES, PROB30 FOR SHRA SHOULD SUFFICE.
WINDS AHEAD OF THE FRONT ARE S/SW AND SHOULD TURN NW/N BETWEEN 16Z-
18Z. THOUGH TSRA IS POSSIBLE, CONFIDENCE ISN'T HIGH ENOUGH TO PUT
INTO THE TAFS AT THIS TIME. AFTER THE FRONT PASSES, EXPECT
RESTRICTIONS TO IMPROVE INTO THE VFR CATEGORY. A FEW LOW END GUSTS
ARE POSSIBLE AT KCLT FOR WEDNESDAY AFTERNOON SO A G15KT IS CURRENTLY
IN THE FORECAST.
OUTLOOK: A COLD FRONT INCREASES RAIN CHANCES AND RESTRICTIONS,
THROUGH WEDNESDAY NIGHT BEFORE DRIER CONDITIONS RETURN FOR THE
REMAINDER OF THE WEEK/WEEKEND. MORNING LOW STRATUS/FOG IN THE
MOUNTAIN VALLEYS EACH DAY, BUT CHANCES DECREASE AFTER THE FRONT.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...CP
SHORT TERM...PM
LONG TERM...PM
AVIATION...CP
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