609
FXUS62 KCHS 080012
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
812 PM EDT WED OCT 7 2026
WHAT HAS CHANGED
KEY MESSAGE 1, THE AVIATION SECTION, AND THE MARINE SECTION HAVE
BEEN UPDATED.
KEY MESSAGES
- 1) THE RISK FOR COASTAL FLOODING AND COASTAL HAZARDS CONTINUES.
- 2) SEASONABLE TEMPERATURES AND GENERALLY DRY CONDITIONS ARE
EXPECTED THROUGH THURSDAY.
- 3) ISAIAS IS EXPECTED TO STRENGTHEN INTO A STRONG HURRICANE
BEFORE APPROACHING THE NORTHERN GULF COAST ON FRIDAY. ALTHOUGH
THE CENTER OF THE STORM WILL REMAIN WELL WEST OF THE REGION,
HEAVY RAINFALL IS POSSIBLE ACROSS SOUTHEAST GEORGIA AND THE
SOUTH CAROLINA LOWCOUNTRY FRIDAY INTO THE WEEKEND. FLASH AND
URBAN FLOODING ALONG WITH COASTAL FLOODING WILL BE POSSIBLE.
DISCUSSION
KEY MESSAGE 1: THE RISK FOR COASTAL FLOODING AND COASTAL
HAZARDS CONTINUES.
FOR CHARLESTON AND COASTAL COLLETON COUNTIES, GUSTY/PERSISTENT
NORTHEAST WINDS ASSOCIATED WITH A WEDGE OF HIGH PRESSURE INLAND AND
LOW PRESSURE OFFSHORE IN COMBINATION WITH HIGH ASTRONOMICAL TIDE
LEVELS WILL LIKELY SUPPORT ADDITIONAL COASTAL FLOODING ISSUES DURING
HIGH TIDE CYCLES THROUGH THURSDAY, AND POSSIBLY INTO FRIDAY.
THE MORNING HIGH TIDE AT THE CHARLESTON HARBOR IS FORECAST TO
REACH 7.0 FT MLLW (MINOR FLOODING). THIS WOULD REQUIRE A
DEPARTURE OF ~0.8 FT. GIVEN THAT THIS EVENING'S HIGH TIDE HAD A
DEPARTURE OF ~1.2 FT A DEPARTURE OF 0.8 FT IS ACHIEVABLE.
RIP CURRENTS/HIGH SURF/BEACH EROSION: GUSTY NORTHEASTERLY WINDS WILL
CONTINUE TO PROMOTE A HIGH RISK OF RIP CURRENTS ALONG THE GEORGIA
BEACHES THIS AFTERNOON, WITH A MODERATE RISK OF RIP CURRENTS ALONG
OUR SOUTH CAROLINA BEACHES. SHOULD SEE THE PRESSURE GRADIENT RELAX
HEADING INTO THURSDAY, RESULTING IN ONLY A MODERATE RISK FOR OUR
GEORGIA BEACHES THROUGH FRIDAY.
KEY MESSAGE 2: SEASONABLE TEMPERATURES AND GENERALLY DRY CONDITIONS
ARE EXPECTED THROUGH THURSDAY.
QUIET CONDITIONS CONTINUE TO PREVAIL ACROSS THE REGION, WITH LATEST
SATELLITE IMAGERY SHOWING A FAIRLY BROAD SWATH OF MID-UPPER LEVEL
CLOUDS ACROSS MUCH OF OUR AREA. GIVEN THAT THIS CLOUD COVER IS
EXPECTED TO LINGER FOR MUCH OF THE EVENING AND OVERNIGHT PERIOD,
SHOULD SEE AFTERNOON HIGHS REMAIN LIMITED INTO THE UPPER 70S TO LOW
80S. SIMILAR TO THIS MORNING, WILL ALSO SEE TONIGHT'S LOWS FALL INTO
THE 50S TO LOWER 60S. OTHERWISE, EXPECT WEAK RIDGING ALOFT AND DRY
NORTHEASTERLY SURFACE FLOW TO RESULT IN ANOTHER DRY DAY THURSDAY,
WITH TEMPERATURES ONCE AGAIN IN THE UPPER 70S TO LOW 80S.
KEY MESSAGE 3: ISAIAS IS EXPECTED TO STRENGTHEN INTO A STRONG
HURRICANE BEFORE APPROACHING THE NORTHERN GULF COAST ON FRIDAY.
ALTHOUGH THE CENTER OF THE STORM WILL REMAIN WELL WEST OF THE
REGION, HEAVY RAINFALL IS POSSIBLE ACROSS SOUTHEAST GEORGIA AND THE
SOUTH CAROLINA LOWCOUNTRY FRIDAY INTO THE WEEKEND. FLASH AND URBAN
FLOODING ALONG WITH COASTAL FLOODING WILL BE POSSIBLE.
NHC EXPECTS THAT ISAIAS WILL MOVE NORTHEAST ACROSS THE SOUTHERN GULF
THROUGH MUCH OF THURSDAY. ONCE THE STORM PASSES NORTH OF THE YUCATAN
PENINSULA, THE STORM MOTION WILL TURN NORTH AND IS FORECAST TO
DEVELOP INTO A STRONG HURRICANE. ISAIAS IS EXPECTED TO APPROACH THE
NORTHERN GULF COAST ON FRIDAY. GUIDANCE SHOWS A LARGE PLUME OF
TROPICAL MOISTURE SURGING NORTHWARD ACROSS THE DEEP SOUTH AND
SOUTHEAST U.S. BEGINNING ON FRIDAY, BY LATE FRIDAY NIGHT PW VALUES
MAY EXCEED 2.2 INCHES. DEEP TROPICAL MOISTURE IS EXPECTED TO PEAK
LATE SATURDAY INTO SATURDAY NIGHT, THEN DRIER AIR ARRIVING WITH A
COLD FRONT SUNDAY NIGHT.
NAM12 INDICATES THAT A RIDGE OF HIGH PRESSURE WILL STRENGTHEN ACROSS
THE CAROLINAS AND GEORGIA ON FRIDAY. THE WEDGE SHOULD PEAK FRIDAY
NIGHT AS THE CENTER OF 1032MB HIGH SLIDES OVER NEW ENGLAND AND
WIDESPREAD RAINFALL COOLS THE RIDGE OVER THE SOUTHEAST U.S. ON
FRIDAY, NAM12 H85 WINDS TURN FROM THE NORTHEAST AND STRENGTHEN TO 40
KTS, DEVELOPING A BAND OF ISENTROPIC LIFT, ADVANCING SOUTH TO NORTH
ACROSS THE FORECAST AREA. FLOW WILL TURN FROM THE EAST FRIDAY NIGHT
INTO SATURDAY AS ISAIAS BEGINS TO TRACK NORTH ACROSS THE DEEP SOUTH.
IN ADDITION, THE STRONG EAST FLOW SHOULD DRAW INSTABILITY OFF THE
ATLANTIC, ACROSS THE CWA. THE PATTERN BECOME MORE INTERESTING ON
SATURDAY AFTERNOON INTO SATURDAY EVENING AS A COASTAL TROUGH DEEPENS
AND INLAND WEDGE BEGINS TO ERODE. STRONG MOISTURE CONVERGENCE MAY
SUPPORT A CONCENTRATED AREA OF RAIN SHOWERS AND THUNDERSTORMS ALONG
THE COAST, THIS BAND COULD PRODUCE EXCESSIVE RAINFALL RATES. THE GFS
AND ECMWF ALONG WITH THE AI VERSIONS INDICATE THAT THE HEAVIEST
RAINFALL MAY OCCUR ALONG THE SC COAST. IN ADDITION, NEW MOON HIGH
TIDES WITH ELEVATED ASTRONOMICAL TIDES WILL OCCUR THIS WEEKEND. ANY
ELEVATED RAINFALL RATES DURING HIGH TIDES MAY LEAD TO FLOODING OF
COASTAL AREAS, INCLUDING SAVANNAH AND CHARLESTON. UNFORTUNATELY, THE
GREATEST COASTAL FLOODING IS EXPECTED WITH BOTH HIGH TIDES ON
SATURDAY, CURRENTLY WITH 10 PERCENT RISK OF MAJOR COASTAL FLOODING
FOR THE CHARLESTON HARBOR. THE LATEST WPC EXCESSIVE RAINFALL OUTLOOK
PLACES MUCH OF SOUTHEAST GEORGIA IN A MARGINAL RISK FOR EXCESSIVE
RAINFALL FRIDAY AND A SLIGHT RISK FOR PORTIONS SOUTHEAST GEORGIA AND
SOUTHEAST SOUTH CAROLINA ON SATURDAY.
RAINFALL WILL CONTINUE SATURDAY NIGHT THROUGH SUNDAY, SUPPORTED BY
THE APPROACH OF H5 SHORTWAVE AND SFC COLD FRONT. RAINFALL RATES
SHOULD GRADUALLY DECREASE ON SUNDAY.
BREEZY CONDITIONS WILL LIKELY DEVELOP ACROSS SE GA AND SC ON
SATURDAY, ESPECIALLY AS THE WEDGE BEGINS TO ERODE. WIND GUSTS OVER
INLAND GA AND SC MAY RANGE BETWEEN 25 TO 30 MPH. COASTAL COUNTIES,
ESPECIALLY NEAR THE WATER'S EDGE OR ELEVATED BRIDGES, COULD SEE
GUSTS OF 40 MPH AT TIMES.
TORNADO THREAT: THE CONCERN FOR TORNADOES ALWAYS INCREASES WITH A
LANDFALLING HURRICANE IN THE REGION. CAD SHOULD DOMINATE THE REGION
OF FRIDAY, KEEPING INSTABILITY GENERALLY ELEVATED. HOWEVER, THE WEDGE
IS EXPECTED TO ERODE DURING THE DAYLIGHT HOURS ON SATURDAY. IN
ADDITION, WINDS WILL VEER FROM THE EAST AS ISAIAS TRACKS NORTH
ACROSS THE DEEP SOUTH. FORECAST SOUNDING SOUTH AND EAST OF THE WEDGE
BOUNDARY INDICATE SRH 0-3 KM IN EXCESS OF 250 M2/S2 AND SBCAPE
AROUND 1000 J/KG LATE SATURDAY AFTERNOON AND EVENING. THIS
ENVIRONMENT COULD SUPPORT BRIEF AND FAST-MOVING TORNADOES OR
WATERSPOUTS. INTERESTINGLY, GOOGLE DEEPMIND BASED AI CONVECTIVE
HAZARD FORECAST HIGHLIGHTS PORTIONS OF SE GA AND COASTAL SC WITH
A 15 PERCENT RISK OF SEVERE WEATHER.
AVIATION /00Z THURSDAY THROUGH MONDAY/
PREVAILING VFR AT KCHS/KJZI/KSAV THROUGH THE 00Z TAF PERIOD.
EXTENDED AVIATION OUTLOOK: VFR THROUGH LATE WEEK. THE RISK FOR
FLIGHT RESTRICTIONS RETURNS OVER THE WEEKEND WITH WIDESPREAD SHOWERS
AND/OR THUNDERSTORMS. GUSTY EAST-NORTHEAST WINDS POSSIBLE ON
SATURDAY.
MARINE
THROUGH TONIGHT: BREEZY WINDS CONTINUE OFFSHORE THANKS TO A
PINCHED PRESSURE GRADIENT, THOUGH THIS SHOULD BEGIN TO RELAX AS
WE HEAD INTO THE OVERNIGHT PERIOD. SMALL CRAFT ADVISORIES REMAIN
IN EFFECT FOR BOTH THE NEARSHORE AND OFFSHORE GA WATERS, WHERE
SEAS REMAIN IN THE 4-6 FT RANGE. DESPITE THE SC WATER HEADLINES
EXPIRING, STILL EXPECT GUSTS BETWEEN 10 TO 20 KTS TO PREVAIL
OVERNIGHT.
THURSDAY: THE LAST REMAINING 6 FOOT WAVES MOVE OUT OF THE MARINE
ZONE FROM SAVANNAH TO ALTAMAHA SOUND, GA 20-60NM OFFSHORE NEAR
DAYBREAK, ALLOWING FOR THE FINAL SMALL CRAFT ADVISORY TO EXPIRE.
WHILE THE SURFACE HIGH PRESSURE CONTINUE TO WEAKEN, THE PRESSURE
GRADIENT REMAINS ELEVATED WITH THE STALLED FRONT TO OUR SOUTH,
CONTINUING WIND GUSTS GENERALLY IN THE 15 TO 20 KNOT RANGE.
FRIDAY THROUGH SUNDAY: SEE NHC FORECAST FOR THE LATEST ON TROPICAL
CYCLONE ISAIAS. THE PRESSURE GRADIENT WILL INCREASE BETWEEN A
COASTAL TROUGH AND HIGH PRESSURE INLAND. WINDS SHOULD STRENGTHEN
THROUGH MOST OF THIS WEEKEND. SMALL CRAFT ADVISORIES ARE LIKELY BY
FRIDAY AFTERNOON AS 25+ KNOT GUSTS MOVE IN, WITH GALE WIND GUSTS
POSSIBLE BY SATURDAY. STRENGTHENING WINDS SHOULD DRIVE SEA HIGHER,
WITH 6-9 FT WAVE HEIGHTS POSSIBLE ON SATURDAY. SEAS MAY PEAK BETWEEN
9-11 FT BY SATURDAY EVENING. ELEVATED WIND AND SEA CONDITIONS WILL
LIKELY PERSIST THROUGH THE REST OF THE WEEKEND.
EQUIPMENT
THE METTER, GA, NOAA WEATHER RADIO STATION (WWH-25) WILL BE
OFFLINE FROM 8 AM WEDNESDAY, OCTOBER 7, THROUGH THE AFTERNOON
OF THURSDAY, OCTOBER 8. THE TRANSMITTER IS BEING RELOCATED.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT THURSDAY FOR AMZ364.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR AMZ384.
CPM/NED/SST
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