831
FXUS62 KCHS 041441
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1041 AM EDT SAT OCT 4 2025
SYNOPSIS
STRONG HIGH PRESSURE WILL EXTEND ACROSS THE REGION THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK. A STRONG COLD FRONT WILL
LIKELY CROSS THE AREA LATER NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
LATE THIS MORNING: NO SIGNIFICANT CHANGES TO THE FORECAST
THROUGH THE REST OF TODAY. SHOWER ACTIVITY WITHIN THE NEARBY
COASTAL TROUGH HAS DIMINISHED SIGNIFICANTLY. THE HI-RES MODEL
CONSENSUS FAVORS A RELATIVE LULL IN SHOWER ACTIVITY THROUGH THE
AFTERNOON BEFORE INCREASING INTO THE EVENING. WE WILL SEE MORE
CLOUD COVER TODAY, A COMBINATION OF CUMULUS AND STRATOCUMULUS
SPREADING ONSHORE IN THE LOW-LEVELS AND MID AND HIGH LEVEL
CLOUDS SPREADING IN FROM THE SOUTHWEST ALOFT. TEMPERATURES
SHOULD STILL GET INTO THE LOW 80S IN MOST AREAS.
TODAY: ALOFT, MID-UPPER LVL RIDGING WILL HOLD IN PLACE ACROSS
MUCH OF THE EAST CONUS WHILE WEAK/EMBEDDED LOW PRESSURE MEANDERS
ACROSS THE DEEP SOUTH/NORTHERN GULF AND ACROSS THE WESTERN
ATLANTIC. AT THE SFC, HIGH PRESSURE WILL REMAIN THE DOMINANT
WEATHER FEATURE FOR MUCH OF THE MORNING, CENTERED TO THE NORTH
ACROSS THE MID-ATLANTIC AND STRETCHING SOUTH ACROSS THE
CAROLINAS INTO GEORGIA AWAY FROM THE COAST. HOWEVER, THE HIGH
LOOKS TO WEAKEN INLAND WHILE ITS CENTER SHIFTS EAST OFF THE MID-
ATLANTIC COAST, WHICH TENDS TO FAVOR COASTAL SHOWERS ASSOCIATED
WITH AN INVERTED TROUGH TO DRIFT ONSHORE DURING PEAK HEATING
HOURS. ACTIVITY COULD STRUGGLE TO MAKE SIGNIFICANT WESTWARD
PROGRESS, ENCOUNTERING DRIER AIR OVER LAND DEPICTED IN LOCAL
SOUNDINGS. HOWEVER, MOISTURE CONTENT APPEARS TO HOLD ON A BIT
LONGER ALONG COASTAL GEORGIA, WHERE NORTH-NORTHEASTLY WINDS
DRIVE MOISTURE FROM THE ATLANTIC ONSHORE. HERE, A SLIGHT CHANCE
FOR SHOWERS/THUNDERSTORMS PERSISTS LONGER DURING AFTERNOON INTO
EARLY EVENING HOURS. HIGH TEMPS SHOULD RANGE IN THE LOW-MID 80S,
WARMEST ACROSS INLAND AREAS OF SOUTHEAST GEORGIA.
TONIGHT: ALOFT, MID-UPPER LVL RIDGING BECOMES SLIGHTLY MORE
PRONOUNCED LOCALLY WHILE BECOMING CENTERED ACROSS THE MID-
ATLANTIC STATES. AT THE SFC, HIGH PRESSURE CONTINUES TO SHIFT
SLIGHTLY EASTWARD AND OFFSHORE NORTH OF THE REGION, WHILE AN
INVERTED TROUGH ATTEMPTS TO PERSIST OFF THE SOUTHEAST COAST.
LATEST GUIDANCE SUGGESTS A FEW SHOWERS AND/OR THUNDERSTORMS
COULD LINGER DURING EVENING HOURS AND PERHAPS INTO EARLY MORNING
HOURS ACROSS COASTAL GEORGIA WHILE THE TROUGH LINGERS AND WINDS
BECOME MORE DIRECTLY ONSHORE, VEERING TO THE EAST-NORTHEAST
OVERNIGHT. LOW TEMPS SHOULD BE SLIGHTLY MORE MILD THAN THE
PREVIOUS NIGHT, RANGING IN THE MID 60S INLAND TO LOW-MID 70S
NEAR THE COAST.
SHORT TERM /SUNDAY THROUGH TUESDAY/
UPPER LEVEL RIDGE HOLDS TIGHT ACROSS THE EASTERN CONUS INTO
EARLY NEXT WEEK. AT THE SURFACE, THE INVERTED TROUGH LINGERS,
BUT GRADUALLY WEAKENS, THROUGH TUESDAY. PERSISTENT LOW LEVEL
SUBTROPICAL MOISTURE ADVECTION CONTINUES IN LONG FETCH EASTERLY
WINDS, BUT WITH A CONTINUED DECREASING SIGNAL FOR ANY
SIGNIFICANT FORCING MECHANISM BEYOND COASTAL MOISTURE
CONVERGENCE. RAINFALL CHANCES AND ACCUMULATION CONTINUE TO TREND
LESSER, ESPECIALLY MONDAY, AS THE VORT ADVECTION LOOKS TO
REMAIN WELL SOUTH AND WEST OF THE AREA. LIKEWISE, THE HEAVY
RAINFALL THREAT IS DECREASING, WITH THE PROB OF GREATER THAN 1
INCH OF RAINFALL SUNDAY AND MONDAY DOWN TO 10-20% FOR THE SE GA
COAST, AND LESS THAN 10% ELSEWHERE.
TUESDAY LOOKS TO REMAIN MAINLY DRY AS THE SURFACE RIDGE AXIS
SLIDES OVERHEAD, BRINGING A MORE APPARENT RESPITE FROM THE
BREEZY NE WINDS, ESPECIALLY ALONG THE COAST. TEMPS REMAIN WITHIN
A FEW DEGREES OF NORMAL SUNDAY THROUGH TUESDAY.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
H5 HEIGHTS FALL MODESTLY WEDNESDAY AS A SHORTWAVE PASSES NORTH
OF THE AREA, THEN MORE QUICKLY THURSDAY INTO FRIDAY AS STRONGER
TROUGHING DIGS ACROSS THE MISSOURI VALLEY AND A SHORTWAVE
CROSSES THE SOUTHEAST. AT THE SURFACE, STRONG HIGH PRESSURE
BUILDING QUICKLY OVER THE NORTHEAST WILL FORCE A BACKDOOR COLD
FRONT DOWN THE EASTERN SEABOARD, LIKELY CROSSING OUR AREA VERY
EARLY THURSDAY. LIMITED LOW- TO-MID LEVEL MOISTURE WILL BE IN
PLACE AHEAD OF THIS FRONT, SO LITTLE MORE THAN A FEW COASTAL
SHOWERS ARE EXPECTED WITH THE FRONTAL PASSAGE.
GUSTY NE WINDS RETURN THURSDAY INTO FRIDAY BEHIND THE FRONT -
25TH TO 75TH PERCENTILE REFLECTING A MOST LIKELY WIND SPEED
ALONG THE COAST OF AROUND 20-30 MPH - TO END THE WORKWEEK,
WHICH, IN ADDITION TO ALREADY ELEVATED TIDE LEVELS, COULD BRING
A PERIOD OF VERY IMPACTFUL TIDAL FLOODING TO END THE WEEK. SEE
COASTAL FLOODING SECTION FOR MORE.
THE FORECAST BECOMES LESS CERTAIN AS WE MOVE INTO NEXT WEEKEND,
WITH A SPREAD OF SOLUTIONS INCLUDING THE POSSIBILITY THAT THE
FRONT LIFTS BACK NORTHWARD ACROSS THE AREA, BRINGING UNSETTLED
CONDITIONS.
AVIATION /14Z SATURDAY THROUGH WEDNESDAY/
TEMPO MVFR/IFR CIGS ARE POSSIBLE WITH LIGHT RAIN/SHOWERS,
MAINLY AT SAV OR JZI FOR THE NEXT COUPLE HOURS. OTHERWISE, VFR
CONDITIONS SHOULD RETURN AT ALL TERMINALS BY LATE MORNING, THEN
PERSIST THROUGH 12Z SUNDAY. NORTHEAST WINDS SHOULD BECOME BREEZY
AT ALL TERMINALS THIS AFTERNOON, GUSTING TO 20-25 KT THROUGH
ABOUT 23-24Z LATE DAY.
EXTENDED AVIATION FORECAST: THE RISK FOR RESTRICTIONS FROM
SHOWERS/TSTMS SUNDAY AND MONDAY IS DECREASING, THOUGH AT LEAST
BRIEF RESTRICTIONS REMAIN POSSIBLE, ESPECIALLY AT SAV.
OTHERWISE, NO SIGNIFICANT AVIATION IMPACTS EXPECTED.
MARINE
TODAY AND TONIGHT: HIGH PRESSURE WILL REMAIN CENTERED NORTH OF
THE REGION, MAINTAINING A PERSISTENT NORTHEAST FLOW, THEN
EVENTUALLY MORE EASTERLY FLOW WITHIN A TIGHT PRESSURE GRADIENT
BETWEEN HIGH PRESSURE INLAND AND AN INVERTED TROUGH OFF THE
COAST. THE SETUP WILL KEEP ELEVATED WINDS AND SEAS THROUGH THE
DAY AND INTO THE NIGHT, MAINLY FOR ALL WATERS OUTSIDE THE
CHARLESTON HARBOR WHERE SMALL CRAFT ADVISORIES REMAIN IN EFFECT.
HOWEVER, BOTH WINDS/SEAS COULD LOWER JUST BELOW SMALL CRAFT
ADVISORY LEVEL CONDITIONS ACROSS NEARSHORE WATERS OFF THE
CHARLESTON COUNTY COAST, BUT GIVEN THE RISK FOR 6 FT SEAS TO
LINGER NEAR 15-20 NM LATER THIS AFTERNOON AND TONIGHT A SMALL
CRAFT ADVISORY WILL CONTINUE FOR THE PERIOD. IN GENERAL,
NORTHEAST WINDS SHOULD PEAK IN THE 20-25 KT, HIGHEST ACROSS
GEORGIA WATERS, WHILE SEAS RANGE BETWEEN 4-6 FT NEARSHORE AND
6-8 FT ACROSS OUTER GEORGIA WATERS.
SUNDAY THROUGH THE MIDDLE OF NEXT WEEK: VERY LONG FETCH
EASTERLY WINDS WILL BRING PERSISTENT MEDIUM PERIOD SWELL ACROSS
THE WATERS, WITH SOME UNDERLYING, BUT MUCH SMALLER, LONGER
PERIOD SWELL THROUGH EARLY WEEK AS WELL. THE SWELL WILL PEAK
SUNDAY NIGHT INTO MONDAY WITH WAVE HEIGHTS REACHING 6-9 FT
OFFSHORE, BEFORE ONLY GRADUALLY SUBSIDING THROUGH MIDWEEK, WHEN
BREEZY NE WINDS WILL BEGIN TO EASE AS WELL.
RIP CURRENTS: A HIGH RISK OF RIP CURRENTS WILL CONTINUE THROUGH
SUNDAY IN PRIMARILY MEDIUM PERIOD E TO NE SWELLS.
TIDES/COASTAL FLOODING
TIDAL DEPARTURES REMAIN QUITE HIGH AS WE MOVE TOWARDS THE EARLY
EVENING HIGH TIDE CYCLE. THE CURRENT FORECAST TAKES CHARLESTON
HARBOR TO 7.4 FT MLLW AND A COASTAL FLOOD ADVISORY HAS BEEN
ISSUED. FOR FORT PULASKI, THERE IS A CHANCE WE APPROACH 9.5 FT
MLLW AND THE ADVISORY WILL NEED TO BE EXPANDED. WILL CONTINUE TO
MONITOR OBSERVATIONS AND ADJUST ACCORDINGLY.
HEADING INTO THIS WEEKEND AND EARLY NEXT WEEK, ASTRONOMICAL
TIDES WILL INCREASE DUE TO THE UPCOMING FULL MOON (OCT 7) AND
PERIGEE (OCT 8). THIS IN COMBINATION WITH THE ANTICIPATION OF
CONTINUED NORTHEASTERLY FLOW WILL CAUSE THE POSSIBILITY OF
COASTAL FLOODING TO BECOME MORE LIKELY ALONG THE ENTIRE
COASTLINE, INCLUDING BOTH DOWNTOWN CHARLESTON AND FORT PULASKI.
SALTWATER INUNDATION COULD THEN OCCUR DURING BOTH THE MORNING
AND EVENING HIGH TIDE CYCLES DURING THIS TIME. ALTHOUGH THERE IS
CONSIDERABLE UNCERTAINTY THIS FAR OUT, PERSISTENT FAVORABLE
WINDS HAVE THE POTENTIAL TO PRODUCE UP TO MAJOR COASTAL FLOODING
BY THE LATTER PART OF NEXT WEEK.
CHS WATCHES/WARNINGS/ADVISORIES
GA...HIGH RISK FOR RIP CURRENTS UNTIL 8 PM EDT THIS EVENING FOR GAZ117-
119-139-141.
SC...HIGH RISK FOR RIP CURRENTS UNTIL 8 PM EDT THIS EVENING FOR
SCZ048>051.
COASTAL FLOOD ADVISORY FROM 5 PM THIS AFTERNOON TO 9 PM EDT
THIS EVENING FOR SCZ049-050.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT TUESDAY FOR AMZ350-352-354.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR AMZ374.
NEAR TERM...BSH/DPB
SHORT TERM...CEB
LONG TERM...CEB
AVIATION...CEB/DPB
MARINE...CEB/DPB
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