285
FXUS62 KCHS 121825
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
225 PM EDT SAT SEP 12 2026
WHAT HAS CHANGED
ALL SECTIONS UPDATED.
KEY MESSAGES
- 1) THE RISK FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE
THROUGH THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: THE RISK FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE
THROUGH THE WEEKEND.
REST OF TODAY: A SHORTWAVE TROUGH ALOFT CAN BE SEEN IN MID-LEVEL
WATER VAPOR SATELLITE IMAGERY TREKKING EASTWARD TOWARDS THE
LOCAL FORECAST AREA. SHOWERS AND THUNDERSTORMS HAVE BEGUN TO
DEVELOP, MAINLY ACROSS SOUTHEASTERN GA. COVERAGE WILL CONTINUE
TO SPREAD ACROSS THE REGION AS OUTFLOW BOUNDARIES INTERACT WITH
EACH OTHER AND THE SEA BREEZE. THIS MORNING'S 12Z KCHS RAOB
SOUNDING SHOWED A PWAT VALUE OF 2.23" POINTS TO A THREAT OF
HEAVY RAINFALL THIS AFTERNOON. SPC MESOANALYSIS SHOWS DCAPE
VALUES OF ONLY AROUND 600 J/KG, LIMITING THE OVERALL SEVERE
WEATHER THREAT THIS AFTERNOON. SHOWERS AND STORMS WILL WANE WITH
NIGHTFALL.
SUNDAY: THE MID-LEVELS WILL CONSIST OF A WEAK TROUGH MOVING OVER OUR
AREA IN THE MORNING, THEN OFFSHORE DURING THE AFTERNOON. THE SURFACE
PATTERN WILL BE RATHER DIFFUSE, WITH EITHER A WEAK FRONT WELL TO OUR
NORTH OR WEAK SURFACE TROUGHING OVER THE SOUTHEAST U.S.
SOUTHWESTERLY FLOW WILL CAUSE DEEP MOISTURE TO BE OVER OUR AREA IN
THE MORNING. PWATS SHOULD EASILY BE ABOVE 2". THIS IS WELL ABOVE
NORMAL PER CHS SOUNDING CLIMATOLOGY AND ABOUT 2 STANDARD DEVIATIONS
PER NAEFS. HOWEVER, LOWER PWATS WILL BUILD IN FROM THE WEST DURING
THE AFTERNOON, KEEPING THE HIGHEST PWATS ALONG THE IMMEDIATE COAST,
BEFORE THEY ARE PUSHED OFFSHORE IN THE EVENING. MOST CAMS POINT
TO SCATTERED COVERAGE FORMING NEAR THE COAST IN THE AFTERNOON,
THEN SHIFTING OFFSHORE AND DISSIPATING IN THE EVENING. HIGH
TEMPERATURES WILL BE A FEW DEGREES ABOVE NORMAL, LEADING TO
MODEST INSTABILITY. ADDITIONALLY, HIGHER DCAPES BUILD IN FROM
THE WEST DURING THE AFTERNOON. SO WHILE WE'RE NOT EXPECTING
WIDESPREAD SEVERE WEATHER, THERE COULD BE A FEW HOUR WINDOW
WHERE STRONG TO MARGINALLY SEVERE THUNDERSTORMS CANNOT BE RULED
OUT ALONG THE COAST. LOCALLY HEAVY RAINFALL WILL ALSO BE
POSSIBLE. BUT THE STEERING LEVEL WINDS MAY BE JUST STRONG ENOUGH
TO LIMIT SIGNIFICANT FLOODING.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
A TEMPO GROUP HAS BEEN INTRODUCED AT KCHS/KJZI/KSAV WITH THE 18Z
TAFS TO ACCOUNT FOR AFTERNOON SHOWERS AND THUNDERSTORMS.
THEREAFTER, PREVAILING VFR THROUGH THE REMAINDER OF THE 18Z TAF
PERIOD.
EXTENDED AVIATION OUTLOOK: PERIODIC FLIGHT RESTRICTIONS WILL BE
POSSIBLE SUNDAY AFTERNOON DUE TO SHOWERS AND THUNDERSTORMS. DRIER
CONDITIONS RETURN ON MONDAY, POSSIBLY PERSISTING THROUGH
WEDNESDAY.
MARINE
TODAY AND TONIGHT: THE PRESSURE PATTERN WILL GENERALLY SUPPORT SOUTH-
SOUTHWEST WINDS BETWEEN 10 TO 15 KTS ACROSS THE MARINE ZONES. WAVE
HEIGHTS ARE FORECAST TO REMAIN BETWEEN 2 TO 3 FT.
THROUGH THURSDAY: WEAK SURFACE TROUGHING INLAND WILL MAINTAIN
GENERALLY SOUTH TO SOUTHWEST WINDS THROUGH EARLY NEXT WEEK. SPEEDS
SHOULD AVERAGE 10-15 KNOTS WITH SEAS 2-3 FEET. THE MAIN TIME PERIOD
OF CONCERN WILL BE TUESDAY AND WEDNESDAY AS HIGH PRESSURE RIDGES
SOUTH INTO THE REGION AND WINDS TURN NORTHEAST AND STRENGTHEN. GUSTS
IN THE 25-30 KNOT RANGE AND 4-8 FOOT SEAS APPEAR LIKELY FOR MOST OF
THE WATERS, AND SMALL CRAFT ADVISORIES WILL BE POSSIBLE. THE
PRESSURE GRADIENT SHOULD EASE ON THURSDAY WITH CONDITIONS FALLING
BELOW ADVISORY LEVELS.
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 ON TUESDAY 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 FALL RIGHT AROUND
THERE. A COASTAL FLOOD ADVISORY COULD BE NEEDED. NO ISSUES EXPECTED
FURTHER SOUTH ALONG THE LOWER SC AND SOUTHEAST GA COASTS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
CPM/ETM
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