109
FXUS62 KGSP 130001
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
801 PM EDT FRI SEP 12 2025
SYNOPSIS
DRY HIGH PRESSURE WILL PERSIST OVER THE REGION THROUGH THE WEEKEND.
A WEAK LOW PRESSURE SYSTEM MAY DEVELOP JUST OFF THE SOUTHEAST COAST
AND BRING SHOWERS TO OUR AREA BY THE MIDDLE OF NEXT WEEK.
NEAR TERM /THROUGH SATURDAY/
AS OF 753 PM FRIDAY: A FEW SHOWERS MANAGED TO DEVELOP OVER THE MTNS
EARLY THIS EVENING, AS HINTED BY A FEW OF THE CAMS. MORE ROBUST
SHOWERS WERE NOTED OVER NORTHEAST GA TO THE WEST OF RABUN COUNTY,
BUT THEY WERE DRIFTING SOUTH. THE SHOWERS SHOULD DISSIPATE IN AN
HOUR OR SO. AFTER THAT, SHOULD BE QUIET WITH THE EXCEPTION OF MORE
MTN VALLEY FOG TOWARD DAYBREAK.
OTHERWISE...HIGH PRESSURE CENTERED OVER NEW ENGLAND AND THE CANADIAN
MARITIMES WILL RIDGE DOWN THE EAST COAST THRU SATURDAY, MAINTAINING
A NET NORTHEASTERLY FLOW OVER THE CWA. THE LOW OFF THE CAROLINA
COAST MAY SPREAD SOME SHALLOW MOISTURE INLAND LATE TONIGHT OR IN THE
MORNING. THAT MAY OFFER THE POSSIBILITY OF SOME LOW ALTITUDE CLOUDS
REACHING OUR EASTERN BORDER AREA, BUT IF THAT HAPPENS IT LOOKS TO
BE SHORT-LIVED. DIURNAL CUMULUS ARE ABUNDANT THIS AFTERNOON BUT
MOSTLY CLEAR CONDITIONS ARE EXPECTED TONIGHT. SOME MOUNTAIN VALLEY
FOG IS EXPECTED TO REDEVELOP IN THE WEE HOURS OF THE MORNING. WHILE
SOME DIURNAL CU WILL POP OUT AGAIN BY MIDDAY SATURDAY, THEY LOOK
TO BE LESS ABUNDANT OWING TO SLIGHTLY DRIER MIDLEVEL AIR ADVECTING
IN. TEMPS WILL BE SIMILAR TO TODAY'S, PERHAPS TRENDING A DEGREE
OR TWO COOLER IN SOME OF THE PIEDMONT, ALBEIT SLIGHTLY WARMER IN
THE MOUNTAIN VALLEYS WHERE NE FLOW IS DOWNSLOPE.
SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/
AS OF 1:25 PM EDT FRIDAY: THE SHORT-TERM FCST PICKS UP AT 00Z ON
SUNDAY WITH A SOMEWHAT ASYMMETRICAL OMEGA BLOCKING PATTERN STILL
IN PLACE ACROSS THE CONUS. THIS PATTERN WILL KEEP DEEP UPPER TROFING
OVER THE EASTERN SEABOARD THRU MOST OF THE PERIOD. AS THE PERIOD IS
ENDING LATE MONDAY, A REX BLOCK BEGINS TO DEVELOP AS THE SOUTHERN
EXTENT OF THE UPPER TROF CUTS OFF A CLOSED LOW AND THE LOW SLIDES
WESTWARD AND UNDERNEATH THE UPPER RIDGE. AT THE SFC, BROAD HIGH
PRESSURE CENTERED WELL TO OUR NORTH WILL STILL BE COVERING MOST
OF THE EASTERN CONUS AS THE PERIOD BEGINS. OVER THE NEXT COUPLE
OF DAYS, THE CENTER OF THE HIGH WILL SLIDE SE AND MAINTAIN CONTROL
OF OUR SYNOPTIC PATTERN. TOWARDS THE END OF THE PERIOD ON MONDAY,
SOME OF THE MODEL GUIDANCE TRIES TO DEVELOP ANOTHER WEAK SFC LOW
JUST OFF THE SE COAST AND SPREAD ITS ASSOCIATED DEEPER MOISTURE
OVER THE CAROLINAS. IT REMAINS UNCLEAR IF/WHEN THIS LOW WILL MA-
TERIALIZE AND WHAT IMPACTS IT MAY HAVE ON OUR SENSIBLE WX. FOR
THE TIME BEING, WE STILL HAVE A DRY FCST THRU MONDAY EVENING WITH
HIGH TEMPERATURES JUST ABOVE CLIMATOLOGY EACH DAY.
LONG TERM /MONDAY THROUGH FRIDAY/
AS OF 1:15 PM EDT FRIDAY: THE EXTENDED FORECAST PICKS UP AT 00Z
ON TUESDAY WITH PERSISTENT OMEGA BLOCKING CENTERED TO OUR WEST
TRANSITIONING INTO MORE OF A REX-TYPE BLOCKING PATTERN. THIS WILL
RESULT IN A CLOSED UPPER LOW DEVELOPING OVER THE SOUTHEAST WHILE
UPPER RIDGING MAINTAINS ITSELF NORTH OF THE UPPER LOW. BY MID-WEEK,
MOST OF THE LONG-RANGE GUIDANCE HAS THIS PATTERN BREAKING DOWN AS
THE UPPER LOW OPENS BACK UP TO THE NLY FLOW ALOFT AND IS ABSORBED
BY THE UPPER RIDGE. BY THE END OF THE PERIOD LATE NEXT WEEK, UPPER
TROFING APPEARS TO AMPLIFY AGAIN TO OUR NORTH AND/OR NORTHWEST.
AT THE SFC, VERY BROAD HIGH PRESSURE WILL STILL BE CENTERED WELL
TO OUR NORTH AND COVERING MOST OF THE EASTERN CONUS AS THE PERIOD
BEGINS. ON TUESDAY, THE HIGH WILL CONTINUE TO SHIFT EASTWARD AND
BEGIN TO MOVE OFF THE NEW ENGLAND COAST. AT THE SAME TIME, ANOTHER
WEAK LOW TRIES TO DEVELOP JUST OFF THE SOUTHEAST COAST AND SPREAD
DEEPER MOISTURE INLAND OVER OUR AREA. IT REMAINS UNCLEAR IF THIS
LOW WILL ACTUALLY MATERIALIZE, AND WHETHER OR NOT IT BRINGS ANY
ASSOCIATED PRECIP AS FAR WEST AS OUR CWA. AS SUCH, WE MAINTAIN A
SLIGHT CHANCE FOR PRECIP ON TUES AND WED ACROSS MOST OF OUR FCST
AREA. ON THURS AND FRI, WE CARRY A DIURNALLY-DRIVEN SLIGHT TO SOLID
CHANCE POP OVER THE HIGHER TERRAIN. TEMPERATURES HAVE TRENDED COOLER
FOR TUES AND WED WITH VALUES A FEW DEGREES BELOW CLIMATOLOGY. THEY
WARM DURING THE LATER HALF OF THE WEEK WITH VALUES JUST ABOVE CLIMO
BY FRI.
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: PERSISTENCE IS A GOOD FORECAST. WILL GO
FOR THE FOG/LOW STRATUS IN THE PRE-DAWN TO DAYBREAK AT KAVL ONCE
AGAIN AS THE SETUP APPEARS FAVORABLE ONCE AGAIN. OTHERWISE...VFR
AT ALL OTHER TERMINALS. THE GUIDANCE KEEPS ANY LOW CLOUD DECK TO
THE EAST OF THE FCST AREA. WIND SHOULD STAY MOSTLY LIGHT FROM THE
NE. EXPECT A FEW MORE HIGH-BASED CU SATURDAY AFTERNOON.
OUTLOOK: DRY AND MOSTLY VFR THROUGH EARLY NEXT WEEK, OUTSIDE OF THE
POTENTIAL FOR MOUNTAIN VALLEY FOG AND/OR LOW STRATUS EACH MORNING.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...JPT
NEAR TERM...PM/WIMBERLEY
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...PM
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