100
FXUS62 KCHS 082330
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
730 PM EDT WED OCT 8 2025
SYNOPSIS
A COLD FRONT WILL DROP SOUTH THROUGH THE AREA TONIGHT INTO
THURSDAY WITH INLAND HIGH PRESSURE PREVAILING INTO EARLY NEXT
WEEK. LOW PRESSURE WILL DEVELOP OFF THE SOUTHEAST U.S. COAST
THIS WEEKEND.
NEAR TERM /THROUGH THURSDAY/
THE FORECAST PHILOSOPHY THROUGH TONIGHT HAS NOT CHANGE
SIGNIFICANTLY. A SHORTWAVE EXITING OFF THE MID-ATLANTIC AND NEW
ENGLAND COASTS WILL HELP DRIVE A COLD FRONT SOUTH INTO THE AREA
TONIGHT AS HIGH PRESSURE OVER THE OHIO VALLEY/GREAT LAKES BEGINS
TO WEDGE SOUTH INTO THE SOUTHEAST STATES. THE FRONT STILL LOOKS
TO BECOME INCREASING ANAFRONTAL WITH THE BAND OF ASSOCIATED
RAINFALL OCCURRING BEHIND THE SURFACE WIND SHIFT. FORCING IS
WEAK TO MODERATE AT BEST AND MAINLY ASSOCIATED WITH A BAND OF
MID-LEVEL CHANNELED VORTICITY THAT IS FORECAST TO SWING THROUGH
LATER THIS EVENING INTO EARLY THURSDAY MORNING. THIS WILL
LIKELY RESULT IN A BAND OF SCATTERED, MOSTLY LIGHT SHOWERS
PUSHING SOUTH OVERNIGHT AS THE INLAND WEDGE DEEPENS WITH TIME.
POPS OF 30-50% LOOK REASONABLE WITH THE HIGHEST POPS OCCURRING
OVER SOUTHERN SOUTH CAROLINA WHERE FORCING LOOKS THE STRONGEST.
THE RISK FOR A TSTM OR TWO IS THERE, BUT INSTABILITY IS
MARGINAL. IT WILL TURN INCREASINGLY COOLER OVERNIGHT WITH A
DISTINCT UP TICK IN WINDS. BREEZY TO LOCALLY WINDY CONDITIONS
WILL LIKELY DEVELOP ALONG PARTS OF THE LOWER SOUTH CAROLINA
PRIOR TO DAYBREAK. LOWS TONIGHT WILL DROP INTO THE LOWER-MID 60S
EXCEPT UPPER 60S AT THE BEACHES AND FAR SOUTHERN AREAS CLOSER
TO THE ALTAMAHA RIVER.
LAKE WINDS: POST FRONTAL WINDS ARE EXPECTED TO INCREASE PRETTY
SUBSTANTIALLY OVER LAKE MOULTRIE OVERNIGHT AS HIGH PRESSURE
WEDGES SOUTH. NORTHEAST WINDS WILL INCREASE TO 15-20 KT WITH
GUSTS 25-30 KT WITH WAVES BUILDING 1-2 FT. A LAKE WIND ADVISORY
HAS BEEN ISSUED BEGINNING AT 2 AM THURSDAY.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
HIGH PRESSURE WILL WEDGE SOUTH INTO THE REGION ON THURSDAY,
FOLLOWING FRONTAL PASSAGE IN THE MORNING. DRIER AIR WILL BEGIN
TO ADVECT INTO THE AREA, BUT A FEW SHOWERS COULD LINGER THROUGH
THE DAY, MOSTLY OVER THE SOUTHEAST GEORGIA COAST. OTHERWISE,
GUSTY NORTHEAST WINDS WILL DEVELOP. HIGH TEMPERATURES WILL PEAK
IN THE LOW TO MID 70 WITH LOWS OVERNIGHT RANGING FROM THE MID
50S INLAND TO AROUND 60/LOW 60S AT THE COAST.
A MID LEVEL WAVE WILL DROP ACROSS THE SOUTHEAST FRIDAY INTO
SATURDAY, HELPING TO INDUCE CYCLOGENESIS OFF THE COAST EARLY IN
THE WEEKEND. MEANWHILE, SURFACE HIGH PRESSURE WILL REMAIN
ANCHORED INLAND. THIS SET-UP WILL FAVOR BREEZY CONDITIONS,
ESPECIALLY AT THE BEACHES WHERE GUSTS UP TO 30-35 MPH WILL BE
POSSIBLE. GUIDANCE IS CONSISTENT IN KEEPING THE BULK OF RAINFALL
ASSOCIATED WITH THE COASTAL LOW OFFSHORE, BUT ISOLATED TO
SCATTERED SHOWERS COULD STILL IMPACT LAND AREAS. RAINFALL TOTALS
ARE CURRENTLY HIGHEST IN THE 0.50- 1 INCH RANGE ALONG THE
IMMEDIATE COAST, BUT THESE TOTALS ARE DEPENDENT ON THE
LOCATION/PROXIMITY OF THE COASTAL LOW. TEMPERATURES WILL BE
BELOW NORMAL, COOLEST ON FRIDAY WITH HIGHS AGAIN PEAKING ONLY IN
THE 70-75 RANGE. LOWS FRIDAY NIGHT WILL MAINLY BE IN THE UPPER
50S TO LOWER 60S.
LAKE WINDS: WINDS ON LAKE MOULTRIE WILL BECOME ELEVATED EARLY
THURSDAY MORNING AND CONTINUE INTO THE WEEKEND AS A STRONG,
PINCHED GRADIENT DEVELOPS IN RESPONSE TO BUILDING HIGH PRESSURE
ACROSS THE REGION AND CYCLOGENESIS OFF THE COAST. WINDS LOOK TO
REACH LAKE WIND ADVISORY LEVEL CRITERIA (SUSTAINED 20 KT OR
FREQUENT GUSTS TO 25 KT) DURING THIS TIME AND A LAKE WIND
ADVISORY HAS BEEN ISSUED WHICH WILL BE IN EFFECT INTO SATURDAY
AFTERNOON.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
COASTAL LOW PRESSURE IS EXPECTED TO LIFT NORTH OF THE AREA SUNDAY
INTO EARLY NEXT WEEK, WHILE HIGH PRESSURE CONTINUES INLAND. THIS
WILL LEAD TO IMPROVING CONDITIONS AND LOWERING RAIN CHANCES WITH A
DRY FORECAST IN PLACE FOR MONDAY INTO MIDWEEK. TEMPERATURES WILL
RETURN TO MID-OCTOBER NORMALS.
AVIATION /00Z THURSDAY THROUGH MONDAY/
PRIOR TO THE 0Z TAFS, A LINE OF SHOWERS AND THUNDERSTORMS WAS
APPROACHING THE TERMINALS FROM THE NORTHWEST. DEEP CONVECTION IS
POSSIBLE AT EACH TERMINAL BETWEEN 0-4Z, HIGHLIGHTED WITH TEMPOS.
A BACKDOOR COLD FRONT IS TIMED TO SLIDE OVER KCHS AND KJZI
BETWEEN 9-10Z AND KSAV BY 12Z. IN THE WAKE OF THE FRONT, WINDS
WILL TURN FROM THE NORTHEAST AND STRENGTHEN TO 10-15 KTS WITH
GUSTS IN THE LOW 20S. KSAV WILL SEE A WINDOW OF MVFR CEILINGS
AROUND DAYBREAK. HOWEVER, THE DAYLIGHT HOURS WILL LIKELY FEATURE
GUSTY NORTHEAST WINDS WITH CEILINGS BELOW 4 KFT.
EXTENDED AVIATION OUTLOOK: GUSTY N TO NE WINDS WILL IMPACT
KCHS/KJZI/KSAV THURSDAY THROUGH SATURDAY. FLIGHT RESTRICTIONS ARE
POSSIBLE IN LOW CLOUDS LATE WEEK INTO THE WEEKEND AS LOW PRESSURE
DEVELOPS OFF THE SOUTHEAST COAST.
MARINE
TONIGHT: A COLD FRONT WILL BACKDOOR THROUGH THE WATERS TONIGHT
AS HIGH PRESSURE BEGINS TO WEDGE SOUTH ACROSS THE SOUTHEAST U.S.
STATES. WINDS WILL BEGIN TO SURGE REACHING 20-25 KT WITH GUSTS
TO 30 KT ACROSS THE SOUTH CAROLINA NEARSHORE WATERS AND 15-20 KT
WITH GUSTS TO 25 KT. FOR CHARLESTON HARBOR, WINDS WILL INCREASE
TO 15-20 KT WITH GUSTS 25 KT. WAVES WILL BUILD 3-5 FT SOUTH
SANTEE-EDISTO BEACH NEARSHORE WITH 3-4 FT FOR THE REMAINING
COASTAL LEGS WITH WAVES 1-2 FT IN THE CHARLESTON HARBOR. SMALL
CRAFT ADVISORIES ARE IN EFFECT.
THURSDAY THROUGH MONDAY: DETERIORATING MARINE CONDITIONS ARE
EXPECTED ON THURSDAY AS STRONG HIGH PRESSURE BUILDS INLAND
BEHIND A DEPARTING COLD FRONT. NORTHEAST WINDS WILL SURGE AND BY
MID- AFTERNOON, GUSTS TO GALE FORCE ARE EXPECTED TO BE COMMON
ACROSS ALL COASTAL WATERS OUTSIDE OF THE CHARLESTON HARBOR. THE
GALE WATCHES HAVE BEEN UPGRADED TO GALE WARNINGS, WITH A SMALL
CRAFT ADVISORY IN PLACE FOR THE CHARLESTON HARBOR. WINDS AND
SEAS WILL REMAIN ELEVATED INTO AT LEAST SATURDAY AS LOW PRESSURE
DEVELOPS OFF THE COAST. FORECAST CONDITIONS WILL SUPPORT A
CONTINUATION OF GALE WARNINGS DURING THIS PERIOD. 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 UNTIL THE END OF THE PERIOD.
RIP CURRENTS: STRONG NORTHEAST WINDS AND BUILDING SEAS WILL
LEAD TO AN ENHANCED RISK OF RIP CURRENTS LATE WEEK INTO THE
WEEKEND. A HIGH RISK OF RIP CURRENTS IS FORECAST AT ALL AREA
BEACHES FOR BOTH THURSDAY AND FRIDAY, WITH THE THREAT PERSISTING
INTO AT LEAST SATURDAY AS A COASTAL LOW DEVELOPS OFFSHORE.
HIGH SURF: LARGE BREAKING WAVES OF 5+ FEET ARE EXPECTED AT ALL
AREA BEACHES BEGINNING THURSDAY AFTERNOON AND CONTINUING INTO
SATURDAY AS STRONG HIGH PRESSURE BUILDS INLAND AND LOW PRESSURE
DEVELOPS OFFSHORE. A HIGH SURF ADVISORY HAS BEEN ISSUED.
TIDES/COASTAL FLOODING
THIS EVENING'S ASTRONOMICAL HIGH TIDE IS EXPECTED TO PEAK AT
JUST OVER 6 FEET MLLW IN THE CHARLESTON HARBOR, AND WITH TIDAL
DEPARTURES EXPECTED TO BE BELOW 1 FOOT NO NOTABLE COASTAL
FLOODING IMPACTS ARE EXPECTED THIS EVENING ACROSS COASTAL
CHARLESTON AND COLLETON COUNTIES. AT FORT PULASKI, ASTRO HIGH
TIDE IS JUST OVER 8 FEET, WITH DEPARTURES EXPECTED TO REMAIN
WELL BELOW 1.5 FEET, RESULTING IN NO COASTAL FLOODING EXPECTED
FOR THIS EVENING FROM COASTAL BEAUFORT DOWN TO COASTAL MCINTOSH
COUNTIES.
THE FOLLOWING DISCUSSION IS FOR COASTAL CHARLESTON AND COLLETON
COUNTIES, ALONG WITH TIDAL BERKELEY COUNTY AS THEIR IMPACTS ARE
TIED TO THE CHARLESTON HARBOR TIDE GAGE, FOR THE REMAINDER OF
OUR SOUTHEAST COAST PLEASE SEE THE NEXT DISCUSSION. MAJOR
COASTAL FLOODING IS POSSIBLE THURSDAY MORNING AS KING TIDES
CONTINUE, WITH ASTRO TIDES OF 7.06 FT MLLW, WHICH BY ITSELF IS
ALREADY ABOVE MINOR FLOOD STAGE, TIDAL DEPARTURES OF 1 FOOT ARE
EXPECTED WHICH WILL BRING THE TIDE FORECAST OVER 8 FEET MLLW,
WITH THE CURRENT FORECAST AT 8.1 FT MLLW. AT THESE LEVELS,
WIDESPREAD AND HIGHLY IMPACTFUL COASTAL FLOODING OCCURS IN
DOWNTOWN CHARLESTON WITH NUMEROUS ROADS FLOODED AND IMPASSABLE
AND WATER ENTERING SOME STRUCTURES. IMPACTS ALSO INCLUDE EROSION
AT AREA BEACHES, WITH LIMITED TO NO ACCESS TO DOCKS, PIERS, AND
SOME ISLANDS. MAJOR FLOOD STAGE AT THE CHARLESTON HARBOR
RESULTS IN MINOR COASTAL FLOODING IN TIDAL BERKELEY COUNTY.
WHILE MODERATE COASTAL FLOODING IS AGAIN EXPECTED LATE THURSDAY
EVENING AS DEPARTURES RISE THROUGHOUT THE DAY AS STRONG
NORTHEASTERLY WINDS DEVELOP, WE ARE MOST CONCERNED FOR LATE
FRIDAY MORNING'S HIGH TIDE AS STRONG NORTHEAST WINDS CONTINUE
AND ASTRO TIDE FALLING TO JUST BELOW 7 FT MLLW, WHICH MAY AGAIN
RESULT IN MAJOR COASTAL FLOODING. THIS IS WHEN THE HIGHEST TIDE
IS EXPECTED AS DEPARTURES RISE TO NEAR 1.5 FT, WHICH SHOULD
BRING THE TIDE GAGE UP TO NEAR 8.5 FT MLLW. WHILE CONFIDENCE IS
HIGH IN MAJOR FLOOD STAGE BEING REACHED, MINOR FLUCTUATIONS IN
WIND DIRECTION AND WIND SPEED AROUND HIGH TIDE WILL ULTIMATELY
DETERMINE JUST HOW HIGH ABOVE 8 FEET WE GO, WITH NORTHEAST WINDS
RESULTING IN HIGHER READINGS ABOVE 8.5 FT MLLW AND MORE
NORTHERLY WINDS KEEPING US CLOSER TO 8.0 FT MLLW. IF WE WERE TO
REACH 8.5 FT MLLW, MODERATE COASTAL FLOODING IS EXPECTED IN
TIDAL BERKELEY COUNTY. FOR LATE FRIDAY EVENING THE ASTRO TIDE
DROPS TO 5.6 FT MLLW RESULTING MINOR/MODERATE COASTAL FLOODING
EXPECTED, WITH ANOTHER CHANCE FOR MAJOR COASTAL FLOODING LATE
SATURDAY MORNING INTO THE EARLY AFTERNOON HOURS AS ASTRO TIDE
PEAKS NEAR 6.72 FT MLLW, THOUGH WE'LL NEED TO SEE HOW THE TIDAL
DEPARTURES END UP TRENDING AS THE COASTAL LOW DEVELOPS TO OUR
SOUTH. DUE TO THE RISK OF MAJOR COASTAL FLOODING, A COASTAL
FLOOD WATCH HAS BEEN ISSUED FOR COASTAL CHARLESTON AND COLLETON
COUNTIES, VALID FROM 8 AM THURSDAY THROUGH 3 PM FRIDAY.
AT FORT PULASKI, WHICH IMPACTS AREAS FROM BEAUFORT COUNTY IN
SOUTH CAROLINA DOWN TO MCINTOSH COUNTY IN GEORGIA, LATE THURSDAY
MORNING'S ASTRONOMICAL TIDE OF 9.1 FT MLLW COMBINED WITH TIDAL
DEPARTURES OF JUST UNDER A FOOT WILL BRING THE AREA RIGHT TO
MODERATE FLOOD STAGE, WITH THE CURRENT FORECAST CRESTING AT 10
FT MLLW (MODERATE FLOOD STAGE). AT THESE LEVELS, HIGHWAY-80
CONNECTING TO TYBEE ISLAND STARTS TO SEE WATER ON IT AND
NUMEROUS ROADS BECOME IMPASSABLE SUCH AS SHIPYARD ROAD,
ISOLATING RESIDENTS ON BURNSIDE ISLAND. FLOODING WILL ALSO
IMPACT AREAS ON TYBEE ISLAND, WILMINGTON ISLAND, THE COFFEE
BLUFF COMMUNITY, OSSABAW ISLAND, SAPELO ISLAND, PORTIONS OF
HIGHWAY 17 SOUTH OF DARIEN. IN BRYAN COUNTY, WATER COULD BREACH
DOCKS NEAR FT MCALLISTER AND FLOODING IMPACTING PORTIONS OF MILL
HILL ROAD. IN LIBERTY COUNTY, FLOODING IMPACTS THE HALFMOON
LANDING AREA AND CATTLE HAMMOCK ROAD NEAR BERMUDA BLUFF
SUBDIVISION.
WE WILL LIKELY SEE MINOR COASTAL FLOODING LATE THURSDAY EVENING
AS ASTRO TIDE PEAKS AT 7.74 FT MLLW, WITH TIDAL DEPARTURES
RISING THROUGHOUT THE DAY CLOSE TO 2 FT. SIMILAR TO CHARLESTON,
THE TIDE OF GREATEST CONCERN OCCURS LATE FRIDAY MORNING, AS THE
ASTRO TIDE IS AT 8.91 FT MLLW AND WITH THE CONTINUED STRONG
GRADIENT WINDS ELEVATED TIDAL DEPARTURES IS EXPECTED. CURRENT
FORECAST PEAKS AT 10.4 FT MLLW, BUT AS DISCUSSED ABOVE, THE
EXACT WIND DIRECTION AND SPEED IS GOING TO PLAY A BIG ROLE IN
HOW HIGH ABOVE 10 FT MLLW THE TIDE GAGE WILL GO. IF THE WIND
DIRECTION WERE TO SHIFT CLOSER TO NORTHERLY, TIDAL READINGS
CLOSER TO 10 FT MLLW WOULD BE EXPECTED, WHEREAS NORTHEASTERLY
WINDS ARE CURRENTLY EXPECTED RESULTING IN THE FORECAST OF 10.4
FT MLLW. AS THE TIDAL READINGS APPROACH 10.5 FT MLLW, COASTAL
FLOODING IMPACTS EXPAND ALONG THE ENTIRE SOUTHEAST GEORGIA
COAST. WILL LIKELY SEE A BREAK FROM COASTAL FLOODING LATE FRIDAY
EVENING AS THE ASTRO TIDES FALLS TO 7.41 FT MLLW, THOUGH THERE
IS A RISK FOR ANOTHER ROUND OF MODERATE COASTAL FLOODING.
HOWEVER, AS MENTIONED ABOVE, WILL NEED TO SEE HOW THE TIDAL
DEPARTURES TREND AS THE COASTAL LOW DEVELOPS TO OUR SOUTH.
REMEMBER, FLOODING CAN OCCUR SEVERAL HOURS BEFORE AND AFTER
HIGH TIDE. IF TRAVEL IS REQUIRED, ALLOW EXTRA TIME AS SOME ROADS
MAY BE CLOSED. DO NOT DRIVE AROUND BARRICADES OR THROUGH WATER
OF UNKNOWN DEPTH. TAKE THE NECESSARY ACTIONS TO PROTECT FLOOD-
PRONE PROPERTY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...HIGH RISK FOR RIP CURRENTS FROM THURSDAY MORNING THROUGH THURSDAY
EVENING FOR GAZ117-119-139-141.
HIGH SURF ADVISORY FROM 2 PM THURSDAY TO 8 AM EDT SUNDAY FOR
GAZ117-119-139-141.
SC...HIGH RISK FOR RIP CURRENTS FROM THURSDAY MORNING THROUGH THURSDAY
EVENING FOR SCZ048>051.
HIGH SURF ADVISORY FROM 2 PM THURSDAY TO 8 AM EDT SUNDAY FOR
SCZ048>051.
LAKE WIND ADVISORY FROM 2 AM THURSDAY TO 2 PM EDT SATURDAY FOR
SCZ045.
COASTAL FLOOD WATCH FROM THURSDAY MORNING THROUGH FRIDAY
AFTERNOON FOR SCZ049-050.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM THURSDAY TO 6 AM EDT SUNDAY FOR
AMZ330.
SMALL CRAFT ADVISORY FROM 2 AM TO 2 PM EDT THURSDAY FOR AMZ350.
GALE WARNING FROM 2 PM THURSDAY TO 11 PM EDT SATURDAY FOR
AMZ350-352.
SMALL CRAFT ADVISORY FROM 5 AM TO 2 PM EDT THURSDAY FOR AMZ352.
SMALL CRAFT ADVISORY FROM 8 AM TO 2 PM EDT THURSDAY FOR AMZ354-
374.
GALE WARNING FROM 2 PM THURSDAY TO 8 PM EDT SATURDAY FOR
AMZ354.
GALE WARNING FROM 2 PM THURSDAY TO 2 AM EDT SUNDAY FOR AMZ374.
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...
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