713
FXUS62 KCHS 042356
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
756 PM EDT SUN OCT 4 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED.
KEY MESSAGES
- 1) UNSETTLED WEATHER WITH A RISK FOR MINOR/FLASH FLOODING INTO
MONDAY.
- 2) COOLER TEMPERATURES ALONG WITH BREEZY TO WINDY CONDITIONS ARE
EXPECTED INTO THE MIDDLE OF THE WEEK.
- 3) COASTAL FLOODING AND SIGNIFICANT COASTAL HAZARDS ARE
EXPECTED THIS WEEK.
DISCUSSION
KEY MESSAGE 1: UNSETTLED WEATHER WITH A RISK FOR MINOR/FLASH
FLOODING INTO MONDAY.
OUR UNSETTLED AND SOGGY PATTERN CONTINUES ON THROUGHOUT THE NEXT
24 HOURS AS DEEP UPPER TROUGHING SWINGS THROUGH THE EASTERN US.
THE NEXT WAVE SHOULD BE MOVING INTO THE AREA THIS EVENING AND
THE INFLUENCES OF THIS FEATURE CAN BE NOTED WITH PRECIPITATION
STARTING TO BLOSSOM ACROSS CENTRAL GEORGIA THE LAST FEW HOURS.
WITH PWATS IN AND AROUND 2.3 TO 2.4 INCHES, WIDESPREAD SHOWERS
AND EMBEDDED STORMS SHOULD CONTINUE TO DEVELOP ACROSS GEORGIA
INTO SOUTH CAROLINA. RAINFALL SHOULD CONTINUE TO MOVE THROUGH
THE AREA THROUGH MUCH OF THE LATE AFTERNOON AND INTO THE
OVERNIGHT HOURS. PRECIP TOTALS OF 1 TO 3 INCHES LOOK POSSIBLE
ACROSS MUCH OF SOUTH CAROLINA THIS EVENING AND OVERNIGHT WITH 2
TO 4 INCHES POSSIBLE ACROSS EASTERN GEORGIA. GIVEN THE
ABNORMALLY HIGH PWAT VALUES, SOME STORMS WILL BE CAPABLE OF
LOCALLY HEAVIER RATES THAT COULD RESULT IN SOME MINOR FLOOD.
ESPECIALLY WHERE STORMS ARE ABLE TO TRAIN AND LOCATIONS WHERE
RAIN HAS ALREADY FALLEN THE LAST 24 HOURS. RAIN SHOULD PERSIST
THROUGH THE OVERNIGHT AND INTO MONDAY MORNING BEFORE THE
TRAILING COLD FRONT SLOWLY PUSHES THROUGH THE AREA. RAIN CHANCES
SHOULD DIMINISH FROM NORTH TO SOUTH MONDAY AFTERNOON WITH MAYBE
SOME HEAVIER RAIN LINGERING ACROSS COASTAL GEORGIA INTO THE
EVENING.
KEY MESSAGE 2: COOLER TEMPERATURES ALONG WITH BREEZY TO WINDY
CONDITIONS ARE EXPECTED INTO THE MIDDLE OF THE WEEK
MODELS ARE STILL EXHIBITING A CONSISTENT SIGNAL FOR STRONG COLD AIR
DAMMING (CAD) TO RAPIDLY DEVELOP TUESDAY AS A COLD FRONT DROPS
FARTHER TO THE SOUTH ACROSS FLORIDA AND 1025 HPA HIGH PRESSURE
WEDGES SOUTH OUT OF THE CENTRAL APPALACHIANS/MID-ATLANTIC REGION.
THE PRESSURE GRADIENT IS FORECAST TO QUICKLY TIGHTEN OVER THE
LOWCOUNTRY AND SOUTHEAST GEORGIA TUESDAY AFTERNOON INTO TUESDAY
NIGHT AS CYCLOGENESIS INITIATES OFFSHORE OF THE GEORGIA AND
NORTHEAST FLORIDA COASTS. WHERE THE SURFACE LOW EVENTUALLY DEVELOPS
WILL HAVE A DIRECT IMPACT ON THE LOCAL WIND FORECAST WITH THE LATEST
BLENDED DATA SUGGESTING THE GRADIENT MAY NOT QUIET AS TIGHT AS WHAT
PREVIOUS RUNS INDICATED. WHETHER THIS TEMPORARY OR THE BEGINNING OF
A MORE DEFINITIVE SHIFT IS TO BE DETERMINED; HOWEVER, THE VARIOUS
GUIDANCE PACKAGES TEND TO UNDER FORECAST WIND/WIND GUSTS AND OVER
FORECAST HIGH TEMPERATURES IN STRONG CAD EVENTS. THE FORECAST
CONTINUES TO MAKE LOCAL ADJUSTMENTS TO REFLECT THESE BIASES.
WINDS: BREEZY TO WINDY CONDITIONS APPEAR LIKELY WITH THE HIGHEST
WINDS OCCURRING ACROSS THE COASTAL CORRIDOR, ESPECIALLY AT THE
BEACHES. EXPECT WIND GUSTS OF 20-30 MPH INLAND WITH 30-40 MPH AT THE
COAST. SOME EXPOSED BEACH LOCATIONS SUCH AS TYBEE ISLAND, HUNTING
ISLAND, PARTS OF HILTON HEAD AND SAPELO ISLAND COULD SEE GUSTS
APPROACH 45 MPH AT TIMES. WINDS COULD ALSO END UP BEING A BIT HIGHER
ON SOME OF THE TALLER BRIDGES AROUND THE CHARLESTON AND SAVANNAH
METRO AREAS (I.E. THE RAVENEL, DON HOLT AND TALMADGE BRIDGES) AND
OVER THE ELEVATED, EXPOSED BRIDGES AND HIGHWAYS HEADING OUT TO THE
VARIOUS BARRIER ISLANDS (I.E. US-80 HEADING TO TYBEE ISLAND, THE
ISLE OF PALMS CONNECTOR, HARBOR RIVER BRIDGE AND THE MCKINLEY
WASHINGTON JR. BRIDGE). A WIND ADVISORY (MINIMUM CRITERIA: SUSTAINED
30 MPH OR WIND GUSTS 40 MPH) COULD BE NEEDED FOR PARTS OF THE COAST,
MAINLY FOR THE TUESDAY AFTERNOON/EVENING TIME PERIOD WHEN THE
GRADIENT IS FORECAST TO BE AT ITS TIGHTEST AND NBM PROBABILITIES FOR
WIND GUSTS >40 MPH ARE AT THEIR HIGHEST. BREEZY TO LOCALLY WINDY
CONDITIONS WILL LINGER AT THE COAST INTO WEDNESDAY, BUT SHOULD
REMAIN BELOW WIND ADVISORY LEVELS. FOR LAKE MOULTRIE, HAZARDOUS
CONDITIONS ARE POSSIBLE BY EARLY TUESDAY MORNING WITH NORTHEAST
WINDS AROUND 20 KT WITH GUSTS 25-30 KT. WAVES ON THE OPEN LAKE
WATERS COULD REACH AS HIGH AS 2-3 FT AT TIMES, ESPECIALLY OVER THE
CENTRAL AND SOUTHWEST PORTIONS OF THE LAKE. A LAKE WIND ADVISORY MAY
BE NEEDED.
TEMPERATURES/RAIN CHANCES: THERE LOOKS TO BE A LARGE MOISTURE
GRADIENT THAT SETS UP ACROSS THE AREA TUESDAY WITH THE STRONG
ONSHORE FLOW LIKELY KEEPING A MODEST DEGREE OF LOW-LEVEL MOISTURE IN
PLACE ACROSS PARTS OF SOUTHEAST GEORGIA (ESPECIALLY AT THE COAST)
WHILE DRIER AIR FROM DEEPER WITHIN THE CAD REGION ADVECTS TO THE
SOUTH/SOUTHWEST. PWATS WILL RANGE FROM AS LOW AS 0.60-0.80" WELL
INLAND FOR AREAS ADJACENT TO THE CSRA/SOUTHERN MIDLANDS AND AS HIGH
AS 1.85" ACROSS THE FAR SOUTH NEAR DARIEN, GA. AS RAINFALL SPREADS
INLAND ACROSS THE FAR SOUTH FROM OFF THE ATLANTIC, THERE WILL LIKELY
BE A SHARP CUT OFF ALONG THE NORTHERN PERIPHERY OF ANY SHOWER
ACTIVITY AS IT ENCOUNTERS INCREASINGLY DEEPER/DRIER AIR. RAINFALL
FALLING INTO THE DRIER AIR WILL ALSO LIKELY HELP REINFORCE THE CAD
DUE TO DIABATIC EFFECTS. THE COLDER SIDE OF THE NBM GUIDANCE ENVELOP
IS STILL FAVORED OVER THE NBM 50%, ESPECIALLY INLAND. IN FACT, THE
COOLEST TEMPERATURES TUESDAY AFTERNOON MAY BE OBSERVED IN THE AREA
FROM FAR INTERIOR SOUTHEAST GEORGIA INTO THE FAR SOUTHERN PORTIONS
OF THE LOWCOUNTRY WHERE THE POTENTIAL FOR DIABATIC COOLING ALONG THE
NORTHERN FRINGE OF THE AREA OF GREATEST RAINFALL COULD BE MAXIMIZED.
WEDGE CONDITIONS WILL LINGER INTO WEDNESDAY WITH LOWER RAIN CHANCES
BEFORE MODERATING THURSDAY INTO FRIDAY, ALTHOUGH HOW QUICKLY THIS
OCCURS IS IN QUESTION.
KEY MESSAGE 3: COASTAL FLOODING AND SIGNIFICANT COASTAL HAZARDS
ARE EXPECTED NEXT WEEK.
COASTAL FLOODING: STRONG NORTHEAST WINDS ASSOCIATED WITH A WEDGE OF
HIGH PRESSURE INLAND AND LOW PRESSURE OFFSHORE IN COMBINATION WITH
HIGH ASTRONOMICAL TIDE LEVELS WILL LIKELY SUPPORT COASTAL FLOODING
ISSUES THIS WEEK. THE PATTERN SUGGESTS A MINOR/MODERATE SALTWATER
INUNDATION SETUP BY MID-WEEK, BUT EVEN MAJOR COASTAL FLOODING CANNOT
BE RULED OUT DURING THE PEAK OF THE EVENT GIVEN PERSISTENT/STRONG
NORTHEASTERLY WINDS AND BUILDING SEAS ALONG THE SOUTHEAST U.S.
COAST. COASTAL FLOOD WATCHES/WARNINGS AND/OR ADVISORIES COULD BE
NEEDED.
RIP CURRENTS/HIGH SURF/BEACH EROSION: THE SETUP LOOKS HIGHLY
FAVORABLE FOR STRONG AND DANGEROUS RIP CURRENTS TUESDAY INTO
WEDNESDAY WITH BREEZY TO WINDY NORTHEAST WINDS EXPECTED. IN
ADDITION, THERE WILL BE AN INCREASED RISK FOR HIGH SURF ALONG THE
BEACHES WITH THE LATEST NWPS GUIDANCE STILL SHOWING A POTENTIAL FOR
4-7 FT BREAKERS (HIGHEST COASTAL GEORGIA) DEVELOPING IN THE SURF
ZONE BY TUESDAY AFTERNOON AND LINGERING INTO WEDNESDAY. A HIGH SURF
ADVISORY MAY EVENTUALLY BE NEEDED FOR SOME BEACHES. SIGNIFICANT
BEACH EROSION IS ALSO LIKELY, PARTICULARLY AROUND TIMES OF HIGH
TIDE. NWPS BEACH EROSION PROBABILITIES ARE HIGHEST AROUND THE
TUESDAY AFTERNOON HIGH TIDE.
AVIATION /00Z MONDAY THROUGH FRIDAY/
00Z TAFS: RADAR SHOWS WIDESPREAD SHOWERS ACROSS THE AREA,
GENERALLY BRINGING MVFR. AS THESE SHOWERS INCREASE IN INTENSITY
IN THE NEXT FEW HOURS, IFR WILL DEVELOP ACROSS OUR AREA, THEN
PERSIST THROUGH MONDAY MORNING. CONDITIONS SHOULD START TO
IMPROVE LATE MONDAY MORNING, AS SHOWERS LESSEN IN BOTH
INTENSITY AND COVERAGE. THOUGH, THE MORE NOTICEABLE IMPROVEMENTS
SHOULD BE FOR CHS AND JZI.
EXTENDED AVIATION OUTLOOK: GUSTY WINDS AND LOW CLOUDS ARE POSSIBLE
TUESDAY ALL TERMINALS. SHOWER IMPACTS ARE POSSIBLE, MAINLY AT KSAV.
GUSTY WINDS WILL LINGER INTO WEDNESDAY.
MARINE
TONIGHT THROUGH MONDAY: WIND/SEAS ARE EXPECTED TO REMAIN WELL
BELOW SMALL CRAFT ADVISORY LEVELS AS ATLANTIC HIGH PRESSURE
CONTINUES TO SHIFT FURTHER OFFSHORE IN AN ADVANCE OF A COLD
FRONT ENTERING THE AREA FROM THE NORTH AND STALLING NEARBY THIS
AFTERNOON INTO THE EVENING. THE GREATEST IMPACT ACROSS LOCAL
WATERS SHOULD OCCUR WITH GUSTY SHOWERS AND THUNDERSTORMS SOUTH
OF THE FRONT, WHICH COULD LEAD TO SPECIAL MARINE WARNINGS AND/OR
STATEMENTS. OUTSIDE OF THIS ACTIVITY, SOUTH/SOUTHEAST WINDS
AROUND 10 KT OR LESS TODAY ARE ANTICIPATED TO TURN MORE
NORTHERLY NEAR/BEHIND THE FRONT TONIGHT INTO THE DAY ON MONDAY.
SEAS WILL GENERALLY RANGE BETWEEN 1-3 FT, LARGEST ACROSS
OFFSHORE WATERS TODAY.
MONDAY NIGHT THROUGH THURSDAY: THE PRESSURE GRADIENT WILL RAPIDLY
TIGHTEN LATE MONDAY NIGHT INTO THE DAY TUESDAY AS COLD AIR DAMMING
SETS UP ACROSS THE CAROLINAS AND GEORGIA AND LOW PRESSURE DEVELOPS
WELL OFFSHORE OF THE GEORGIA AND NORTHEAST FLORIDA COAST. THE RISK
FOR GALES REMAINS ELEVATED WITH LITTLE CHANGE IN NET PROBABILITIES
FOR FREQUENT GUSTS TO 34 KT. THE GRADIENT LOOKS TIGHT, BUT MAY NOT
BE AS TIGHT AS SOME PREVIOUS RUNS HAD SUGGESTED, LIKELY DUE TO A
WEAKER/SLIGHTLY FARTHER OFFSHORE PROGRESSION OF THE SURFACE LOW.
WHETHER THIS IS A ONE CYCLE ARTIFACT, OR THE BEGINNING OF A MORE
DEFINITIVE TREND IS YET TO BE DETERMINED AS MODELS DO TO TEND TO
UNDER FORECAST PINCHED GRADIENT REGIMES ASSOCIATED WITH STRONG CAD
EVENTS. AT THIS POINT, CONFIDENCE IS HIGH ENOUGH TO HOIST A GALE
WATCH FOR ALL NEARSHORE AND OFFSHORE MARINE ZONES FROM TUESDAY
MORNING THROUGH LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING WITH
FREQUENT GUSTS TO 35-40 KT LIKELY. PROBABILITIES FOR STORM-FORCE
GUSTS HAVE DIMINISHED AND LOOK UNLIKELY AT THIS TIME, BUT THIS WILL
BE WATCHED CAREFULLY. FOR CHARLESTON HARBOR, THE RISK FOR GALES IS
NOT QUITE HIGH ENOUGH FOR A GALE WATCH THIS FAR OUT, BUT ONE MAY
EVENTUALLY BE NEEDED PENDING FURTHER DATA. AT THE VERY LEAST, A
SMALL CRAFT ADVISORY WILL BE REQUIRED. SEAS LOOK TO PEAK TUESDAY
NIGHT, RANGING FROM 6-10 FT NEARSHORE WATERS WITH 9-12 FT OFFSHORE
WATERS. BOTH WINDS AND SEAS WILL REMAIN WELL INTO SMALL CRAFT
ADVISORY LEVELS WEDNESDAY WITH 6 FT SEAS LINGERING INTO
THURSDAY.
CLIMATE
RECORD PRECIPITATION:
OCTOBER 5:
KCXM: 1.17/1915
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...GALE WATCH FROM LATE MONDAY NIGHT THROUGH LATE TUESDAY NIGHT
FOR AMZ360-362-380.
GALE WATCH FROM LATE MONDAY NIGHT THROUGH WEDNESDAY MORNING
FOR AMZ364-382-384.
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