712
FXUS62 KGSP 162334
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
734 PM EDT TUE SEP 16 2025
SYNOPSIS
LOW PRESSURE ON THE NORTH CAROLINA COAST WEAKENS AS IT DRIFTS
NORTHEAST TO BE ALONG THE VIRGINIA COAST WEDNESDAY AND THEN THE LOW
DISSIPATES ON THURSDAY. WARM AND DRY HIGH PRESSURE RETURNS FOR THE
REST OF THE WEEK WITH FRIDAY BEING THE WARMEST DAY. EXPECTING LOW
CHANCES OF SHOWER AND THUNDERSTORMS BY EARLY NEXT WEEK AS MOISTURE
SLOWLY INCREASES.
NEAR TERM /THROUGH WEDNESDAY/
AS OF 725 PM EDT TUESDAY...
KEY MESSAGES:
1) A FEW SHOWERS WILL ACROSS THE SOUTHERN NC MOUNTAINS AND THE
UPSTATE THIS EVENING.
2) QUIETER CONDITIONS WITH NEAR-NORMAL TEMPERATURES ARE EXPECTED
ON WEDNESDAY.
THE WEATHER REMAINS UNDER THE CONTROL OF AN UPPER LOW CHURNING OVER
THE CAROLINAS AND LOWER MID-ATLANTIC. AT THE SURFACE, A COASTAL
LOW IS ANALYZED NORTHEAST OF CAPE HATTERAS, DRIVING GENERALLY N
FLOW OVER THE AREA...AND SUPPORTING A BROAD SURFACE RIDGE EAST OF
THE APPALACHIANS.
TONIGHT, AS THE SURFACE LOW SLIPS NORTH INTO THE CHESAPEAKE REGION,
WINDS WILL BECOME INCREASINGLY NW, AN UPPER SHORTWAVE WILL EXIT
THE AREA, AND CONVECTION SHOULD COME TO AN END. LINGERING MOISTURE
WILL KEEP THE CLOUDS AROUND, BUT ANOTHER ROUND OF MOUNTAIN VALLEY
FOG SHOULD OCCUR NONETHELESS. LOWS WILL DROP INTO THE UPPER 50S.
WEDNESDAY, COVERAGE OF RAINFALL LOOKS MUCH LOWER THAN TODAY; THE
LACK OF ANY GOOD SYNOPTIC SUPPORT AS THE LOW MOVES NORTH WILL
MAKE INITIATION MORE DIFFICULT, EXCEPT FOR RIDGETOP SHOWERS IN
THE MOUNTAINS. HIGHS TOMORROW SHOULD BE SIMILAR TO TODAY'S.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/
AS OF 100 PM EDT TUESDAY:
KEY MESSAGES:
1) WARMING TREND CONTINUES AS DRIER CONDITIONS RETURN
2) HIGHS ~3-5 DEGREES ABOVE NORMAL.
3) PRECIP CHANCES LESS THAN 20% THROUGH THE PERIOD.
UPPER LOW OVER THE MID-ATLANTIC WILL KICK OUT AND BECOME ABSORBED
IN THE POLAR JET, AS LARGE SCALE HEIGHT FALLS OVERSPREAD EASTERN
CANADA AND THE NORTHEAST CONUS EARLY IN THE PERIOD. THE AXIS OF A
BAGGY TROUGH WILL BE LEFT BEHIND FROM THE MID-ATLANTIC INTO THE
SOUTHEAST WHICH WILL LINGER OVER THE REGION WHILE CONTINUING TO
WEAKEN. THIS PATTERN WILL TEND TO SHUNT ANY NOTEWORTHY MOISTURE
EAST AND SOUTHEAST OF OUR FORECAST AREA, AND INDEED, FORECAST
SOUNDINGS ARE RELATIVELY DRY (PWATS < 1.25") AND STABLE THROUGH THE
PERIOD. THUS, DESPITE THE FACT THAT SHORT TERM GUIDANCE GENERALLY
AGREES IN DROPPING A VORT MAX ACROSS THE AREA ON THURSDAY, PROFILES
ARE FORECAST TO BE UNSUPPORTIVE OF DEEP CONVECTION, AND POPS OF <
20% ARE CARRIED THROUGH THE PERIOD. PROGGED THICKNESS VALUES WILL
SUPPORT THE CONTINUATION OF A WARMING TREND, AND MAX TEMPS ARE
EXPECTED TO BE AROUND 3-5 DEGREES ABOVE CLIMO. A RELATIVELY DRY
AIR MASS AND GOOD RADIATIONAL COOLING CONDITIONS EACH NIGHT ARE
EXPECTED TO RESULT IN MIN TEMPS NEAR-TO-SLIGHTLY-BELOW CLIMO.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
AS OF 120 PM EDT TUESDAY:
KEY MESSAGES:
1) SLIGHTLY COOLER EARLY NEXT WEEK.
2) SMALL CHANCES FOR MAINLY MOUNTAIN SHOWERS OR A STORM MOST
AFTERNOONS, BUT OTHERWISE REMAINING DRY.
WEAK UPPER TROUGH CENTERED OVER THE REGION AT THE START OF THE
PERIOD WILL CONTINUE TO WEAKEN OVER THE WEEKEND, BECOMING DISPLACED
BY WEAK RIDGING EARLY IN THE NEW WEEK. MEANWHILE 1030-ISH MB SURFACE
HIGH PRESSURE BUILDING INTO THE NORTHEAST CONUS WILL RESULT IN AN
INVERTED SURFACE RIDGE DEVELOPING DOWN THE EASTERN SEABOARD SATURDAY
THROUGH SUNDAY, WITH EFFECTIVE WEAK BACKDOOR COLD FRONT FORECAST TO
PUSH INTO OUR CWA LATE SATURDAY/EARLY SUNDAY. THIS WILL ACT TO SHAVE
A FEW DEGREES OFF OF TEMPERATURES FOR SUNDAY/MONDAY, BRINGING THEM
MORE IN LINE WITH SEASONAL NORMALS...IF NOT SLIGHTLY COOLER THAN
NORMAL. OTHERWISE, THE AIR MASS IS EXPECTED TO REMAIN RELATIVELY DRY
AND STABLE THROUGH THE PERIOD, AND POPS ARE LIMITED TO (AT MOST) 20%
CHANCES FOR DIURNAL SHOWERS OR A STORM ACROSS THE MOUNTAINS EACH
AFTERNOON. TEMPERATURES ARE FORECAST TO REBOUND TO ABOVE-NORMAL
CONDITIONS BY TUESDAY, WHEN GLOBAL MODELS ARE IN GOOD AGREEMENT IN
DEPICTING SIGNIFICANT WEAKENING OF THE INVERTED RIDGE...AS SURFACE
HIGH PRESSURE PROGRESSES RATHER QUICKLY OFF THE NEW ENGLAND COAST.
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: A COUPLE AREAS OF SHOWERS AT TIME OF 00Z
TAF ISSUANCE ARE LARGELY STAYING WEST OF THE TAF SITES. ALTHOUGH
SOME OF THE SHOWERS MAY DRIFT SOUTH NEAR KAND, WARRANTING A VCSH
FOR A COUPLE HOURS THIS EVENING. OTHERWISE, PLENTY OF MID CLOUDS
WILL LINGER INTO THE NIGHT, BUT SHOULD SCATTER OUT ENOUGH TO ALLOW
PLENTY OF MOUNTAIN VALLEY FOG TO DEVELOP OVERNIGHT. CONDITIONS
LOOK GOOD FOR FOG AT KAVL, SO WILL ADD A TEMPO FOR SOME 1/2SM
VSBY DURING THE HOURS NEAR SUNRISE. THE REST OF THE SITES LOOK
TO STAY VFR OVERNIGHT. ON WEDNESDAY, A LITTLE DRIER AIR WILL WORK
IN FROM THE NW AND SHOULD LIMIT DIURNAL CONVECTION TO JUST A FEW
ISOLATED SHOWERS. THUS, NO SHOWER OR TSTM MENTION FOR WEDNESDAY
IN ANY OF THE TAF SITES. WINDS SHOULD BE LIGHT, TOGGLING TO A SW
OR WSW DIRECTION EAST OF THE MOUNTAINS, WHILE REMAINING NNW AT KAVL.
OUTLOOK: DRY CONDITIONS EXPECTED THROUGH SATURDAY. SOME MOUNTAIN
VALLEY FOG WILL REMAIN POSSIBLE EACH MORNING WHEREVER CLOUDS DO
NOT INHIBIT NOCTURNAL RADIATION.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...JDL
NEAR TERM...ARK/MPR
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...ARK
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