618
FXUS62 KCHS 091813
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
213 PM EDT THU OCT 9 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL INLAND THROUGH EARLY NEXT WEEK.
MEANWHILE, LOW PRESSURE IS EXPECTED TO DEVELOP OFF THE SOUTHEAST
COAST LATE WEEK INTO THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
THIS EVENING AND TONIGHT: SURFACE ANALYSIS SHOWS THAT THE MAIN
FRONT IS SITUATED OFFSHORE AND SOUTH OF THE AREA ACROSS NORTH
FL. THE PERSISTENT AREA OF LIGHT RAIN ALONG THE SC COAST SHOULD
CONTINUE TO SHRINK THIS AFTERNOON AND ALSO GRADUALLY SHIFT
SOUTHWARD. PRECIPITABLE WATER VALUES REMAIN HIGH, IN THE
1.5-1.9" RANGE ALONG THE COAST, BUT ANY ADDITIONAL RAINFALL
AMOUNTS THROUGH THE EVENING SHOULD BE GENERALLY A QUARTER OF AN
INCH OR LESS.
THROUGH THE OVERNIGHT, THE WEDGE OF HIGH PRESSURE WILL CONTINUE
TO BECOME ESTABLISHED ACROSS THE FORECAST AREA WHILE THE
OFFSHORE COASTAL TROUGH STARTS TO TAKE SHAPE. GUIDANCE IS IN
PRETTY GOOD AGREEMENT THAT WE WILL SEE A RELATIVE LULL IN
RAIN/SHOWER COVERAGE AS THE OFFSHORE TROUGH STARTS TO BECOME THE
MAIN FOCAL POINT. SO WHILE SHOWERS WILL LIKELY INCREASE IN
COVERAGE ACROSS THE WATERS LATE TONIGHT MOST OF THIS ACTIVITY
WILL REMAIN OFFSHORE THROUGH SUNRISE FRIDAY.
LAKE WINDS: WINDS WILL CONTINUE TO INCREASE ACROSS LAKE MOULTRIE
THROUGH THE OVERNIGHT. FREQUENT GUSTS TO 25 KNOTS ARE EXPECTED
AND A LAKE WIND ADVISORY IS IN EFFECT.
SHORT TERM /FRIDAY THROUGH SUNDAY/
A WEDGE OF HIGH PRESSURE WILL BE ANCHORED INLAND ON FRIDAY,
WHILE A COASTAL TROUGH RESIDES OFFSHORE. A MID LEVEL WAVE/TROUGH
WILL PASS OVERHEAD, EVENTUALLY HELPING TO INDUCE CYCLOGENESIS
OFF THE SOUTHEAST COAST LATER FRIDAY INTO SATURDAY. THIS PERIOD
WILL HOLD THE MOST IMPACTFUL WEATHER OF THE NEXT WEEK, BRINGING
POTENTIAL FOR GUSTY WINDS AND RAIN, IN ADDITION TO HAZARDOUS
BEACH/MARINE CONDITIONS AND COASTAL FLOODING (SEE SECTIONS
BELOW). GUIDANCE IS CONSISTENT IN KEEPING THE BULK OF RAINFALL
ASSOCIATED WITH THE COASTAL LOW OFFSHORE, BUT THERE DOES REMAIN
SOME UNCERTAINTY. REGARDLESS, HIGHEST TOTALS ARE EXPECTED TO BE
ALONG THE COAST, WHERE 0.5-1.50" ON AVERAGE IS CURRENTLY
FORECAST. AMOUNTS TAPER OFF THE FURTHER INLAND YOU GO. BREEZY
NORTHEAST TO NORTH WINDS ARE ALSO EXPECTED, ESPECIALLY ALONG THE
IMMEDIATE COAST AND BEACHES WHERE 30- 35 MPH GUSTS WILL BE
POSSIBLE. BRIDGES AND OVERPASSES COULD ALSO EXPERIENCE HIGHER
WINDS. OTHERWISE, TEMPERATURES WILL BE SEASONABLY COOL,
PARTICULARLY ON FRIDAY WHEN HIGHS TOP OUT IN THE LOWER 70S. LOWS
BOTH NIGHTS WILL BE IN THE UPPER 50S TO LOWER 60S.
THE COASTAL LOW WILL BEGIN LIFTING NORTH OF THE AREA SATURDAY
NIGHT INTO SUNDAY. THERE IS SOME DIFFERENCE IN THE SPEED OF
EXIT, BUT OVERALL CONDITIONS WILL BE ON AN IMPROVING TREND.
WINDS SHOULD TURN MORE OUT OF THE NORTHWEST AND REMAIN A BIT
GUSTY INTO THE AFTERNOON AS THE PRESSURE GRADIENT REMAINS FAIRLY
TIGHT. ISOLATED TO SCATTERED SHOWERS COULD STILL WRAP AROUND ON
THE BACKSIDE OF THE LOW, IMPACTING MAINLY COLLETON COUNTY
NORTHWARD INCLUDING THE CHARLESTON TRI-COUNTY. ANY SHOWERS WILL
REMAIN FAIRLY LIGHT. TEMPERATURES SUNDAY SHOULD PEAK IN THE
75-80 RANGE.
LAKE WINDS: WINDS ON LAKE MOULTRIE WILL REMAIN ELEVATED INTO
THE WEEKEND AS A STRONG, PINCHED GRADIENT DOMINATES IN RESPONSE
TO BUILDING HIGH PRESSURE ACROSS THE REGION AND CYCLOGENESIS OFF
THE COAST. A LAKE ADVISORY IS IN EFFECT FOR LAKE MOULTRIE
THROUGH SATURDAY AFTERNOON FOR NE WIND GUSTS 25 TO 30 KNOTS AND
WAVES 2 TO 3 FT.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
THE FORECAST AREA WILL BECOME POSITIONED BETWEEN A MID LEVEL
RIDGE OVER THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY AND
A MID LEVEL LOW EXITING OFF THE MID-ATLANTIC COAST DURING THE
EARLY TO MIDDLE OF NEXT WEEK. THE SURFACE WILL FEATURE HIGH
PRESSURE GRADUALLY EXPANDING ACROSS THE REGION AS LOW PRESSURE
DEPARTS. NO NOTABLE WEATHER CONCERNS WITH A DRY FORECAST IN
PLACE. TEMPERATURES SHOULD BE WITHIN A FEW DEGREES OF NORMAL.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
THE 18Z TAF PERIOD BEGINS WITH VFR CONDITIONS AT KCHS, BUT KJZI
(IFR) AND KSAV (MVFR), ARE EXPERIENCING LOW CEILINGS AND EVEN
SOME LIGHT RAINFALL. THE COVERAGE OF RAIN SHOULD CONTINUE TO
DIMINISH THROUGH THE AFTERNOON AND THE BULK OF THE OVERNIGHT
SHOULD REMAIN MOSTLY DRY AS WELL. VFR CONDITIONS ARE EXPECTED TO
MOSTLY PREVAIL THROUGH THE OVERNIGHT, BEFORE LOWER CEILINGS AND
INCREASED RAIN COVERAGE BECOMES A CONCERN FOR THE LATTER PART
OF THE TAF PERIOD. RAIN AND CEILINGS SHOULD START TO SHIFT
ONSHORE AS EARLY AS MID TO LATE MORNING AND PERSIST THROUGH THE
END OF THE TAF PERIOD.
EXTENDED AVIATION OUTLOOK: GUSTY N TO NE WINDS WILL IMPACT
KCHS/KJZI/KSAV THROUGH SATURDAY. FLIGHT RESTRICTIONS ARE
POSSIBLE IN LOW CLOUDS LATE WEEK INTO THE WEEKEND AS LOW
PRESSURE DEVELOPS OFF THE SOUTHEAST COAST.
MARINE
THROUGH TONIGHT: NORTHEAST FLOW WILL CONTINUE TO STRENGTHEN
ACROSS THE LOCAL WATERS. WIDESPREAD GUSTS INTO THE 35-40 KNOT
RANGE ARE EXPECTED AND GALE WARNINGS ARE IN EFFECT THROUGH THE
PERIOD. IN CHARLESTON HARBOR, WIND SHOULD REMAIN JUST BELOW GALE
WARNING CRITERIA, WITH SUSTAINED WINDS 15-25 KNOTS AND GUSTS TO
AROUND 30 KNOTS. SEAS WILL CONTINUE TO TREND UPWARD IN RESPONSE
TO THE STRONG NORTHEAST FLOW WITH 9-10 FT SEAS STARTING TO GET
WITHIN 20 NM OF SHORE.
FRIDAY THROUGH TUESDAY: HAZARDOUS MARINE CONDITIONS WILL BE
ONGOING AT THE START OF THE PERIOD, WITH GALE WARNINGS IN PLACE
FOR ALL COASTAL WATERS OUTSIDE OF THE CHARLESTON HARBOR FOR
FREQUENT GUSTS TO 35 KT. A FEW GUSTS TO NEAR GALE FORCE WILL BE
POSSIBLE IN THE HARBOR, BUT FOR THE MOST PART CONDITIONS SHOULD
STAY JUST SHY SO A SMALL CRAFT ADVISORY PERSISTS. SEAS ARE
EXPECTED TO PEAK IN THE 7-11 FOOT RANGE. THESE ELEVATED WINDS
AND SEAS WILL CONTINUE THROUGH MUCH OF SATURDAY AS LOW PRESSURE
DEVELOPS OFF THE SOUTHEAST COAST. THE LOW IS EXPECTED TO LIFT
NORTH OF THE AREA LATER SATURDAY INTO EARLY NEXT WEEK, LEADING
TO IMPROVING CONDITIONS, HOWEVER WINDS AND SEAS WILL TAKE TIME
TO SUBSIDE, SO GALE WATCHES/WARNINGS ARE EXPECTED TO BE REPLACED
BY SMALL CRAFT ADVISORIES. THE ADVISORIES COULD PERSIST INTO
MONDAY.
RIP CURRENTS: STRONG NORTHEAST WINDS AND BUILDING SEAS WILL
LEAD TO AN ENHANCED RISK OF RIP CURRENTS LATE WEEK THROUGH THE
WEEKEND. A HIGH RISK OF RIP CURRENTS IS FORECAST AT ALL AREA
BEACHES FOR BOTH THROUGH SATURDAY.
HIGH SURF: LARGE BREAKING WAVES OF 5+ FEET ARE EXPECTED AT ALL
AREA BEACHES THROUGH SATURDAY AS STRONG HIGH PRESSURE BUILDS
INLAND AND LOW PRESSURE DEVELOPS OFFSHORE. A HIGH SURF ADVISORY
IS IN EFFECT FOR THE ENTIRE COASTLINE. THIS IN ADDITION TO VERY
HIGH TIDE CYCLES WILL LIKELY LEAD TO SOME EROSION AT AREA
BEACHES.
TIDES/COASTAL FLOODING
UPCOMING EVENING HIGH TIDE (10:30 PM): TIDAL DEPARTURES CONTINUE
TO INCREASE AS STRONG NORTHEAST FLOW TAKES HOLD. THERE IS
POTENTIAL FOR MINOR COASTAL FLOODING AT CHARLESTON AS THE
ASTRONOMICAL HIGH TIDE IS 5.89 FT MLLW. HIGH TIDE COULD PEAK IN
THE 7.0-7.2 FT RANGE, BUT SOME UNCERTAINTY REMAINS REGARDING HOW
TIDE DEPARTURES TREND IN THE NEXT FEW HOURS. WE WILL HOLD OFF ON
ISSUING ANY COASTAL FLOOD ADVISORY FOR NOW, BUT ONE COULD BE
NEEDED LATER ON THIS AFTERNOON OR EVENING. COASTAL FLOODING DOES
NOT LOOK TO BE AN ISSUE AT FORT PULASKI.
STRONG NE WINDS RESULTING FROM HIGH PRESSURE INLAND AND
DEVELOPING LOW PRESSURE OFFSHORE WILL ALLOW TIDAL DEPARTURES TO
INCREASE THROUGH THE NEXT SEVERAL HIGH TIDE CYCLES. ASTRONOMICAL
TIDE VALUES ARE ALREADY ELEVATED OWING TO THE RECENT FULL MOON
AND PERIGEE, WHICH COMBINED WITH INCREASING DEPARTURES WILL
RESULT IN COASTAL FLOODING WITH EACH HIGH TIDE CYCLE INTO THE
WEEKEND.
CHARLESTON HARBOR TIDE GAGE: THE LATE MORNING HIGH TIDE CYCLES
FRIDAY AND SATURDAY HAVE THE POTENTIAL TO HIT MAJOR COASTAL
FLOODING THRESHOLDS (>8 FT MLLW). A COASTAL FLOOD WARNING IS IN
EFFECT FOR CHARLESTON AND COASTAL COLLETON COUNTIES FOR THE
FRIDAY MORNING HIGH TIDE CYCLE WHEN LEVELS COULD PEAK IN THE
8.4-8.6 FT MLLW RANGE. THESE VALUES WOULD RANK IN THE TOP 10
NON-TROPICAL TIDES ON RECORD. A COASTAL FLOOD ADVISORY IS IN
EFFECT FOR TIDAL BERKELEY COUNTY. FLOODING CAN OCCUR SEVERAL
HOURS BEFORE AND AFTER THE TIDE PEAKS. IT'S WORTH NOTING
CONFIDENCE IS NOT QUITE AS HIGH IN REACHING MAJOR ON SATURDAY AS
PURE ASTRONOMICAL VALUES START TO COME DOWN. WHILE THE MORNING
TIDES ARE DOMINANT, MINOR COASTAL FLOODING WILL BE POSSIBLE WITH
THE EVENING HIGH TIDES. THE THREAT FOR COASTAL FLOODING SHOULD
DECREASE EARLY NEXT WEEK.
FORT PULASKI TIDE GAGE: THE LATE MORNING HIGH TIDE CYCLES
THROUGH SATURDAY HAVE THE POTENTIAL TO REACH MODERATE COASTAL
FLOODING (10 TO 10.5 FT MLLW). THE FORECAST FOR THE FRIDAY
MORNING HIGH TIDE OF 10.3-10.5 FT MLLW WOULD RANK IN THE TOP 10
NON-TROPICAL TIDES ON RECORD. ADDITIONAL COASTAL FLOOD
ADVISORIES ARE EXPECTED. MINOR COASTAL FLOODING WILL BE POSSIBLE
WITH THE SUNDAY EARLY AFTERNOON TIDE CYCLE, THEN THE THREAT FOR
COASTAL FLOODING SHOULD DECREASE.
CHS WATCHES/WARNINGS/ADVISORIES
GA...HIGH RISK FOR RIP CURRENTS THROUGH FRIDAY EVENING FOR GAZ117-119-
139-141.
HIGH SURF ADVISORY UNTIL 8 AM EDT SUNDAY FOR GAZ117-119-139-
141.
SC...HIGH RISK FOR RIP CURRENTS THROUGH FRIDAY EVENING FOR SCZ048>051.
HIGH SURF ADVISORY UNTIL 8 AM EDT SUNDAY FOR SCZ048>051.
LAKE WIND ADVISORY UNTIL 2 PM EDT SATURDAY FOR SCZ045.
COASTAL FLOOD WARNING FROM 9 AM TO 3 PM EDT FRIDAY FOR SCZ049-
050.
COASTAL FLOOD ADVISORY FROM 9 AM TO 3 PM EDT FRIDAY FOR SCZ052.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR AMZ330.
GALE WARNING UNTIL 11 PM EDT SATURDAY FOR AMZ350-352.
GALE WARNING UNTIL 8 PM EDT SATURDAY FOR AMZ354.
GALE WARNING UNTIL 2 AM EDT SUNDAY FOR AMZ374.
NEAR TERM...BSH
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...BSH/ETM
MARINE...BSH/ETM
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