278
FXUS62 KCHS 031400
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1000 AM EDT FRI OCT 3 2025
SYNOPSIS
A STRONG HIGH PRESSURE WILL EXTEND ACROSS THE REGION INTO THE
WEEKEND, WITH RAIN CHANCES INCREASING ON SUNDAY INTO EARLY NEXT
WEEK. A STRONG COLD FRONT WILL LIKELY CROSS THE AREA LATER NEXT
WEEK.
NEAR TERM /THROUGH TONIGHT/
LATE THIS MORNING: OVERALL, NO CHANGES TO THE FORECAST FOR
TODAY. WE WILL CONTINUE TO SEE SCATTERED SHOWER ACTIVITY REMAIN
CONFINED MOSTLY TO THE COASTAL WATERS, WITH CLUSTERS OF SHOWERS
OCCASIONALLY PUSHING ONSHORE ALONG THE GA COAST. THESE SHOWERS
ARE DEVELOPING WITHIN AN AREA OF PRECIPITABLE WATER VALUES OF
1.1 INCHES OR HIGHER, WHILE INLAND AREAS ARE SEEING VALUES DOWN
AS LOW AS 0.75" ACROSS THE MOST INLAND OF OUR COUNTIES. FORECAST
HIGHS IN THE UPPER 70S TO LOW 80S ARE ON TRACK.
AT H5, A WEAK REX BLOCK WILL REMAIN ACROSS THE SOUTHEAST U.S.
TODAY INTO MOST OF TONIGHT. AT THE SFC, THE CENTER OF HIGH
PRESSURE WILL REMAIN ACROSS THE MID-ATLANTIC STATES, RIDGING SW
ALONG THE EAST FACING SLOPES OF THE SOUTHERN APPALACHIANS. TO
THE SOUTHEAST, A BROAD AREA OF LOW PRESSURE WILL PERSIST OVER
FL, GENERALLY OVER THE GULF STREAM NORTH TO THE OFF SHORE WATERS
OF SC. THIS PATTERN SHOULD SUPPORT NORTHEAST WINDS ACROSS THE
SC LOWCOUNTRY AND SE GA AND THE ADJACENT ATLANTIC WATERS THROUGH
TODAY AND TONIGHT. ISOLATED TO SCATTERED SHOWERS WILL LIKELY
REMAIN WITH THE SFC TROUGH OVER THE ATLANTIC WATERS. ISOLATED
SHOWERS MAY TRACK ONSHORE ALONG THE GA COAST DURING THE DAYLIGHT
HOURS TODAY, WITH A SLIGHT INCREASE IN COVERAGE TONIGHT. HIGH
TEMPERATURES ARE FORECAST TO GENERALLY RANGE IN THE LOW 80S
TODAY. LOW TEMPERATURES ARE FORECAST TO RANGE FROM THE LOW 60S
INLAND TO THE UPPER 60S ALONG THE COAST.
SHORT TERM /SATURDAY THROUGH MONDAY/
LOW AMPLITUDE REX BLOCK-LIKE PATTERN SETS UP OVER THE EASTERN
US FOR THE WEEKEND WITH OUR AREA BETWEEN THE H5 RIDGE TO THE
NORTH AND TROUGH TO THE SOUTH. AT THE SURFACE, THE SURFACE HIGH
OVER THE DELMARVA PENINSULA BRINGS PERSISTENT NE TO E FLOW WITH
AN INVERTED COASTAL TROUGH/WEAK BOUNDARY ALONG THE COAST
SATURDAY. EXPECT SHOWER ACTIVITY TO REMAIN FOCUSED OFFSHORE,
WITH A FEW SHOWERS POSSIBLY WORK BACK TOWARD THE SE GA COAST,
BUT WITH MINIMAL IMPACT. ELSEWHERE, LACK OF FORCING AND MID-
LEVEL DRY AIR KEEP A MAINLY DRY FORECAST IN PLACE ON SATURDAY.
SUNDAY, MID AND UPPER LEVEL HEIGHT FALLS AND INCREASING 850 MB
MOISTURE ADVECTION BRING INCREASING DEEP MOISTURE AND A MORE
UNSETTLED PATTERN INTO MONDAY. ADDITIONAL LIFT ARRIVES LATER IN
THE DAY SUNDAY AS A BAND OF VORTICITY MOVING ACROSS THE FLORIDA
PENINSULA WILL PROPAGATE INTO THE SOUTHEAST U.S. AND INTERACT
WITH THE LINGERING COASTAL TROUGH OFFSHORE TO ALSO AID IN RAIN
PRODUCTION. SCATTERED TO WIDESPREAD SHOWERS EXPECT BOTH DAYS,
WITH GREATEST COVERAGE/CONFIDENCE FROM BEAUFORT COUNTY SOUTHWARD
ALONG THE SE GA COAST. PWATS REACH 2-2.25 INCHES, OR AROUND THE
90TH PERCENTILE, ACROSS SE GA LATER SUNDAY INTO MONDAY, WITH
500-1000 J/KG OF CAPE SIGNALING THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL. TOTAL SUNDAY AND MONDAY RAINFALL AMOUNTS OF 3 TO 5
INCHES ARE WELL WITHIN REASON FOR COASTAL AREAS FROM BEAUFORT
COUNTY SOUTHWARD, INCLUDING THE SAVANNAH METRO AREA, WITH
LOCALIZED/REASONABLE WORST CASE SCENARIO AMOUNTS REACH UP TOWARD
6-7 INCHES.
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
UPPER RIDGING BUILDS MODESTLY TUESDAY BEFORE A SERIES OF
SHORTWAVES POTENTIALLY MOVE THROUGH MID-TO-LATE NEXT WEEK. AT
THE SURFACE, HIGH PRESSURE SHIFTS OVER BERMUDA TUESDAY, RIDGING
INTO OUR AREA FROM THE WEST INTO MIDWEEK, WITH ONLY LOW-END
PRECIP CHANCES. THEN, BY LATE WEEK, VERY STRONG HIGH PRESSURE
BUILDING OVER THE NORTHEAST IS EXPECTED TO FORCE A STRONG
BACKDOOR COLD FRONT DOWN THE EASTERN SEABOARD AS A CAD-LIKE
SETUP TAKES HOLD THURSDAY INTO FRIDAY. THE MOST IMPACTFUL ASPECT
OF THIS FORECAST COULD END UP BEING THE GOOD AGREEMENT ON NE
WINDS - 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 LEVEL, COULD BRING
A PERIOD OF VERY IMPACTFUL TIDAL FLOODING. SEE COASTAL FLOODING
SECTION FOR MORE.
AVIATION /13Z FRIDAY THROUGH TUESDAY/
12Z TAFS: VFR. EXPECT GUSTY NORTHEAST WINDS TO DEVELOP THIS
MORNING AND PERSIST THROUGH THE REST OF THE DAYLIGHT HOURS. THIS
EVENING, WINDS SHOULD SETTLE TO AROUND 10 KTS AT KCHS AND KSAV,
GUSTS AROUND 15 KTS EXPECTED TO REMAIN OVERNIGHT AT KJZI.
EXTENDED AVIATION FORECAST: THE RISK FOR RESTRICTIONS FROM
SHOWERS/TSTMS WILL INCREASE THIS WEEKEND INTO EARLY NEXT WEEK
FOR ALL TERMINALS. OTHERWISE, NO SIGNIFICANT AVIATION IMPACTS
EXPECTED.
MARINE
TODAY AND TONIGHT: THE MARINE ZONES WILL REMAIN BETWEEN A RIDGE
ACROSS THE WESTERN CAROLINAS AND COASTAL TROUGH. NORTHEAST
WINDS WILL REMAIN BETWEEN 20 TO 25 KTS WITH GUSTS BETWEEN 25 TO
30 KTS. SURGES OF WINDS GUSTS MAY ACCOMPANY SHOWERS, EXPECTED TO
REMAIN ISOLATED TO SCATTERED THROUGH THE NEAR TERM. SEAS SHOULD
GENERALLY RANGE FROM 6 TO 9 FT ACROSS ATLANTIC WATERS THROUGH
TODAY AND TONIGHT. SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT
FOR ALL MARINE ZONES OUTSIDE THE CHS HARBOR.
HIGH PRESSURE RIDGING INLAND AND INVERTED COASTAL TROUGHING OFF
THE COAST CONTINUE BREEZY N TO NE WINDS THROUGH THE WEEKEND.
WINDS TREND MORE E EARLY NEXT WEEK AS HIGH PRESSURE MOVES
FURTHER OFF THE MID-ATLANTIC COAST, BUT A VERY LONG EASTERN
FETCH IS LIKELY TO KEEP HAZARDOUS SEAS IN PLACE INTO MID-WEEK
DESPITE WINDS TRENDING MORE MODERATE.
RIP CURRENTS/HIGH SURF: A HIGH RISK RIP CURRENTS WILL CONTINUE
INTO SATURDAY IN PRIMARILY MEDIUM PERIOD E TO NE SWELL, THOUGH
SOME LONGER PERIOD COULD CONTINUE TO MIX IN THROUGH AT LEAST
TONIGHT. HIGH SURF ADVISORY HAS BEEN EXTENDED THROUGH SATURDAY,
WITH LOWER CONFIDENCE IN 6+ FT BREAKING WAVES SATURDAY NIGHT
INTO SUNDAY.
TIDES/COASTAL FLOODING
A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR THE UPCOMING
AFTERNOON HIGH TIDE AT CHARLESTON. TIDAL DEPARTURES REMAIN HIGH
AND WITH THE ASTRONOMICAL HIGH TIDE BEING AT 6.05 FT MLLW, WE
SHOULD GET UP INTO A RANGE OF 7.1-7.3 FT MLLW.
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.
CHS WATCHES/WARNINGS/ADVISORIES
GA...HIGH RISK FOR RIP CURRENTS UNTIL 8 PM EDT THIS EVENING FOR GAZ117-
119-139-141.
HIGH SURF ADVISORY UNTIL 8 PM EDT SATURDAY FOR GAZ117-119-139-
141.
SC...HIGH RISK FOR RIP CURRENTS UNTIL 8 PM EDT THIS EVENING FOR
SCZ048>051.
HIGH SURF ADVISORY UNTIL 8 PM EDT SATURDAY FOR SCZ048>051.
COASTAL FLOOD ADVISORY FROM 4 PM THIS AFTERNOON TO 8 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/NED
SHORT TERM...CEB
LONG TERM...CEB
AVIATION...CEB/NED
MARINE...CEB/NED
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