846
FXUS62 KCHS 131121
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
721 AM EDT SUN SEP 13 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR THE 12Z TAFS.
KEY MESSAGES
- 1) ISOLATED SHOWERS AND THUNDERSTORMS ARE FORECAST TO DEVELOP ALONG
THE SEA BREEZE THIS AFTERNOON.
DISCUSSION
KEY MESSAGE 1: ISOLATED SHOWERS AND THUNDERSTORMS ARE FORECAST TO
DEVELOP ALONG THE SEA BREEZE THIS AFTERNOON.
EARLY THIS MORNING, SATELLITE WATER VAPOR SHOWS DRY AIR BUILDING
EAST OF THE SOUTHERN APPALACHIANS WITH THE PASSAGE OF H5 TROUGH. THE
TROUGH AXIS IS TIMED TO PUSH OVER THE CWA BY 15Z, SLIDING OFFSHORE
BETWEEN 18-21Z. PW VALUES ACROSS THE FORECAST AREA WILL BEGIN THE
DAY IN EXCESS OF 2.2", BEFORE FALLING TO BELOW 1.7" BY LATE
THIS AFTERNOON. FORECAST SOUNDINGS SHOWS DEEP DRY AIR INCREASING
ABOVE H6 THIS AFTERNOON, WITH A SIGNIFICANT INVERSION CENTERED
AT H65. HIGH RESOLUTION GUIDANCE SHOWS ISOLATED SHOWERS AND
THUNDERSTORMS DEVELOPING NEAR THE SEA BREEZE THIS AFTERNOON.
HOWEVER, WITH INCREASING DRY AIR, SHALLOW LAPSE RATES, AND A H65
INVERSION ANY CONVECTION SHOULD REMAIN GENERAL. HIGH
TEMPERATURES SHOULD RISE ABOVE YESTERDAY'S VALUES, RANGING
BETWEEN 90 TO 95 DEGREES.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
PRIOR TO THE 12Z TAFS, IR SATELLITE AND OBSERVATIONS INDICATED A
SMALL PATCH OF MVFR CEILINGS OVER KCHS, EXPECTED TO DISSIPATE BY
14Z. OTHERWISE, CONDITIONS ACROSS THE TERMINALS THIS MORNING
SHOULD FEATURE LIGHT WEST-SOUTHWEST WINDS AND VFR CONDITIONS.
THE SEA BREEZE SHOULD ADVANCE INLAND THIS AFTERNOON, SHIFTING
WINDS FROM THE SOUTHWEST. ISOLATED SHOWERS AND THUNDERSTORMS
SHOULD DEVELOP ALONG THE SEA BREEZE THIS AFTERNOON, BUT COVERAGE
APPEARS TOO LOW TO HIGHLIGHT IN THE TAFS AT THIS TIME.
EXTENDED AVIATION OUTLOOK: VFR.
MARINE
TODAY AND TONIGHT: WEAK SURFACE TROUGHING INLAND WILL CAUSE WSW
WINDS THIS MORNING TO BACK TO THE SSW THIS AFTERNOON. WINDS WILL
START TO VEER IN THE EVENING, BECOMING W LATE TONIGHT. SUSTAINED
WINDS SHOULD BE IN THE 5-15 KT RANGE. SEAS WILL AVERAGE 2-3 FT.
EXTENDED MARINE: EXPECT LIGHT AND VARYING WINDS ALONG WITH LOW SEAS
MONDAY MORNING AND AFTERNOON. A COLD FRONT WILL MOVE SOUTH THROUGH
OUR WATERS LATE MONDAY INTO TUESDAY, FOLLOWED BY HIGH PRESSURE
PERSISTING TO OUR NORTH, POSSIBLY INTO THURSDAY. THIS WILL CAUSE NE
WINDS TO INCREASE TO A STRONG BREEZE LATE MONDAY INTO TUESDAY. GUSTS
COULD EVEN REACH NEAR GALE ACROSS PORTIONS OF OUR WATERS ON TUESDAY.
WINDS SHOULD EASE LATE TUESDAY, BEFORE INCREASING AGAIN ON WEDNESDAY
AND THURSDAY. WIND-DRIVEN SEAS WILL ALSO BUILD TUESDAY, THEN REMAIN
ELEVATED THROUGH THURSDAY. SMALL CRAFT ADVISORIES WILL BE NEEDED
STARTING LATE MONDAY ACROSS OUR SC WATERS, AND EARLY TUESDAY ACROSS
OUR GA WATERS. SOME OF THESE ADVISORIES COULD REMAIN IN EFFECT
THROUGH THURSDAY.
COASTAL FLOODING: MINOR COASTAL FLOODING IS POSSIBLE WITH THE
TUESDAY MID-DAY HIGH TIDE ALONG THE CHARLESTON AND COLLETON COUNTY
COASTS. STRENGTHENING NORTHEAST WINDS ARE EXPECTED, WHICH WILL
INCREASE TIDAL DEPARTURES. THE TIDE WOULD NEED ~1 FT DEPARTURE TO
REACH MINOR FLOODING THRESHOLDS OF 7 FT MLLW IN THE CHARLESTON
HARBOR. MOST GUIDANCE INDICATES TIDE LEVELS COULD RISE TO THAT
LEVEL. A COASTAL FLOOD ADVISORY COULD BE NEEDED. NO FLOODING IS
EXPECTED FURTHER SOUTH ALONG THE LOWER SC AND SOUTHEAST GA
COASTS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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