973
FXUS62 KCHS 300627
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
227 AM EDT SAT MAY 30 2026
WHAT HAS CHANGED
ALL SECTIONS HAVE BEEN UPDATED.
KEY MESSAGES
- 1) LOCALLY HEAVY RAINFALL AND ISOLATED FLASH FLOODING
POSSIBLE ACROSS PORTIONS OF SOUTHEAST GEORGIA AND SOUTHEAST
SOUTH CAROLINA TODAY.
- 2) UNSETTLED WEATHER CONDITIONS PERSIST ACROSS PORTIONS OF
SOUTHEAST GEORGIA AND THE SOUTH CAROLINA LOWCOUNTRY ON SUNDAY
AND MONDAY.
- 3) EVENING HIGH TIDES COULD BRING MINOR INUNDATION OF VERY
LOW-LYING AREAS ALONG THE CHARLESTON AND COLLETON COUNTY
COASTLINES THROUGH THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: LOCALLY HEAVY RAINFALL AND ISOLATED FLASH
FLOODING POSSIBLE ACROSS PORTIONS OF SOUTHEAST GEORGIA AND
SOUTHEAST SOUTH CAROLINA TODAY.
ALOFT, THE PATTERN WILL TRANSITION TO BECOME MORE ZONAL WITH
EMBEDDED SHORTWAVE SHORTWAVE ENERGY POISED TO PASS THROUGH THE
FORECAST AREA DURING THE DAY. AT THE SURFACE, ANALYSIS SHOWS A
SUBTLE STATIONARY BOUNDARY CURRENTLY STRETCHING WEST TO EAST
ACROSS THE FORECAST AREA WILL SLOWLY MEANDER BACK TO THE NORTH
FOR THE DAYTIME HOURS. ALSO OF NOTE, THE ATMOSPHERE WILL REMAIN
QUITE MOIST WITH PRECIPITABLE WATER VALUES EXPECTED TO BE IN THE
1.8-2.0 RANGE WHICH WOULD BE ABOVE THE 90 PERCENTILE AND
APPROACHING THE DAILY MAX ACCORDING TO THE SPC SOUNDING
CLIMATOLOGY. ALL OF THIS TO SAY THAT WITH SOME SHORTWAVE ENERGY
ALOFT, A BOUNDARY NEARBY AT THE SURFACE, ALL WITHIN A VERY MOIST
ATMOSPHERE, WE EXPECT TO SEE ANOTHER CONVECTIVELY ACTIVE DAY.
ONE MAIN DIFFERENCE FROM THE LAST FEW DAYS WILL BE THE STEERING
FLOW IN THE MID-LEVELS. MODELS CONSISTENTLY SHOW ~20-25 KNOTS
OF WEST-NORTHWEST MID-LEVEL FLOW WHICH WILL PRODUCE A MUCH
DIFFERENT STORM MOTION. THOUGH THERE IS A SURFACE BOUNDARY
ACROSS THE AREA, IT IS QUITE SUBTLE AND THE GENERAL CONSENSUS
AMONG HI-RES MODELS AND THE HREF IS THAT CONVECTION WILL NOT
TEND TO FOCUS ON ONE PARTICULAR AREA. THEREFORE, THE THREAT FOR
INTENSE RAINFALL WILL COME MAINLY FROM CLUSTERS OF STORMS
TRAINING OVER THE SAME AREAS WITHIN THE RELATIVELY PROGRESSIVE
FLOW. SO WHILE THE HREF HIGHLIGHTS MUCH OF THE AREA IN 30-50%
PROBABILITIES FOR >1" IN 3 HOURS, THE PROBABILITIES FOR >3" IN 3
HOURS IS QUITE LOW FOR ANY ONE PARTICULAR AREA. SO, IT SEEMS
REASONABLE TO SAY THAT THERE IS CERTAINLY THE POTENTIAL FOR A
FEW ISOLATED POCKETS OF 1-3" RAINFALL AMOUNTS IN 1-3 HOUR TIME
PERIODS. THIS THINKING FOLLOWS WITH THE ENTIRE FORECAST AREA
BEING HIGHLIGHTED IN THE WPC DAY 1 EXCESSIVE RAINFALL OUTLOOK
MARGINAL RISK AREA. CONVECTION WILL LIKELY INITIATE BY AROUND
MIDDAY AND THE THREAT FOR LOCALLY HEAVY RAINFALL WILL CONTINUE
INTO THE EVENING HOURS.
KEY MESSAGE 2: UNSETTLED WEATHER CONDITIONS PERSIST ACROSS
PORTIONS OF SOUTHEAST GEORGIA AND THE SOUTH CAROLINA LOWCOUNTRY
ON SUNDAY AND MONDAY.
NUMEROUS SHOWERS AND THUNDERSTORMS POSSIBLE ON SUNDAY AND
MONDAY AS THE STALLED FRONTAL BOUNDARY LINGERS ACROSS THE
SOUTHEAST AND A VERY MOIST AIRMASS CHARACTERIZED BY ANOMALOUSLY
HIGH PWAT VALUES CONTINUES TO STREAM NORTHWARD INTO THE REGION.
WHILE LARGE-SCALE FORCING APPEARS RELATIVELY WEAK, SEVERAL
SUBTLE DISTURBANCES EMBEDDED WITHIN SOUTHWESTERLY FLOW ALOFT
SHOULD BE SUFFICIENT TO SUPPORT UNSETTLED WEATHER CONDITIONS
THROUGHOUT SUNDAY AND MONDAY. THERE IS A MARGINAL RISK (LEVEL
1/4) FOR EXCESSIVE RAINFALL ON SUNDAY TO HIGHLIGHT THE RISK OF
LOCALIZED FLOODING. ALTHOUGH ACTIVITY SHOULD REMAIN SOMEWHAT
DISORGANIZED, LOCALIZED TRAINING AND REPEATED ROUNDS OF RAINFALL
COULD BE POSSIBLE WHERE OUTFLOW BOUNDARIES BECOME ESTABLISHED.
AS A RESULT, LOCALIZED FLOODING COULD BE POSSIBLE ON SUNDAY AND
MONDAY, PARTICULARLY IN URBAN AREAS AND LOW-LYING LOCATIONS.
KEY MESSAGE 3: EVENING HIGH TIDES COULD BRING MINOR INUNDATION
OF VERY LOW-LYING AREAS ALONG THE CHARLESTON AND COLLETON COUNTY
COASTLINES THROUGH THE WEEKEND.
ELEVATED TIDAL DEPARTURES MAY PERSIST THROUGH THE WEEKEND FOR
THIS EVENING'S AND SUNDAY EVENING'S HIGH TIDE. THE MAJORITY OF
GUIDANCE SUGGESTS THAT TIDAL LEVELS SHOULD REMAIN SHY OF MINOR
COASTAL FLOOD CRITERIA FOR THIS EVENING, HOWEVER MINOR
INUNDATION OF VERY LOW-LYING AREAS COULD BE POSSIBLE ALONG
CHARLESTON AND COASTAL COLLETON COUNTIES ESPECIALLY IF SHOWERS
AND THUNDERSTORMS TRACK OVER THE REGION AROUND THE TIME OF HIGH
TIDE (8:27 EDT). THE BETTER CHANCE FOR MINOR COASTAL FLOOD
CRITERIA BEING MET WILL BE WITH SUNDAY'S EVENING HIGH TIDE (9:05
EDT).
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
WHILE THE 06Z TAF PERIOD BEGINS WITH VFR CONDITIONS AT KCHS,
KJZI, AND KSAV, THERE ARE A FEW LOW CONFIDENCE FORECAST ISSUES
TO DISCUSS. FIRST, MODEL GUIDANCE SUGGESTS THERE COULD BE A
PERIOD OF MVFR OR IFR CEILINGS CLOSER TO SUNRISE. THE BEST
CHANCE FOR IFR APPEARS TO BE AT KSAV, WHERE WE ARE ADVERTISING
IFR CEILINGS AND LIGHT FOG BETWEEN 09-12Z. FURTHER EAST, CHANCES
APPEAR LESS FOR IFR AND MVFR SEEMS MORE LIKELY. KCHS AND KJZI
BOTH CONTAIN MVFR CEILINGS AROUND OR JUST AFTER SUNRISE FOR A
FEW HOURS THROUGH MID MORNING. THE NEXT ISSUE WILL BE
THUNDERSTORM POTENTIAL IN THE AFTERNOON AND EVENING. STORM
MOTION WILL BE DIFFERENT TODAY, WITH STORMS GENERALLY TRACKING
FROM WEST-NORTHWEST TO EAST-SOUTHEAST. CURRENT TIMING IS FOR
STORMS TO BEGIN AROUND KCHS AND KJZI FIRST, GENERALLY IN THE
18-22Z TIME PERIOD. CURRENT THINKING IS THAT KSAV WILL BE A BIT
LATER, MORE INTO THE LATE AFTERNOON AND EARLY EVENING TIME
PERIOD.
EXTENDED AVIATION OUTLOOK: EXPECT PERIODIC FLIGHT RESTRICTIONS
THROUGH EARLY NEXT WEEK AS UNSETTLED WEATHER CONDITIONS WILL
PERSIST. PATCHY OVERNIGHT FOG AND/OR STRATUS POSSIBLE AS WELL.
MARINE
TODAY: LIGHT NORTHWESTERLY WINDS WILL BE APPARENT THIS MORNING,
AND THEN VEER OUT OF SOUTHWEST BY THE AFTERNOON INTO THE
OVERNIGHT AS A STALLED FRONTAL BOUNDARY LINGERS ACROSS THE LOCAL
WATERS. SEAS WILL RANGE FROM 2 TO 3 FT.
SUNDAY: BREEZY EAST-NORTHEASTERLY WINDS AT 15 TO 20 KT WITH
GUSTS NEAR 30 KT POSSIBLE ACROSS THE NEARSHORE SOUTH CAROLINA
WATERS AS THE REGION BECOMES SANDWICHED BETWEEN A STALLED
FRONTAL BOUNDARY AND A SURFACE HIGH PRESSURE SYSTEM. SEAS WILL
ALSO INCREASE AS A SHORT-LIVED EAST-SOUTHEASTERLY SWELL SURGES
INTO THE LOCAL WATERS. EXPECT THE NEARSHORE AND OFFSHORE
SOUTHEAST SOUTH CAROLINA WATERS TO PEAK TO 5 TO 7 FT, WHILE THE
NEARSHORE AND OFFSHORE WATERS SOUTHEAST GEORGIA WATERS TO PEAK
4-6 FT. THEREFORE, SMALL CRAFT ADVISORIES (SCAS) HAVE BEEN
ISSUED FOR THE NEARSHORE SOUTH CAROLINA WATERS ON SUNDAY, AND
THEN ALSO THE OUTER GEORGIA WATERS LATE SUNDAY INTO MONDAY. IT'S
POSSIBLE TO SEE THE CHARLESTON HABOR GUST NEAR 25 KT EARLY
SUNDAY MORNING THROUGH MID-DAY, HOWEVER OPTED OUT OF A SCA AS
CONDITIONS REMAIN BORDERLINE.
MONDAY AND TUESDAY: EXPECT MODERATE NORTH-NORTHEASTERLY FLOW TO
PERSIST THROUGH MID-WEEK AS SEVERAL SUBTLE DISTURBANCES
EMBEDDED WITHIN SOUTHWESTERLY FLOW ALOFT TRAVERSES ACROSS THE
LOCAL WATERS. SEAS WILL RANGE FROM 2 TO 4 FT ON MONDAY, AND THEN
BECOME 2 TO 3 FT ON TUESDAY.
RIP CURRENTS: THERE IS A LOW RISK OF RIP CURRENTS AT ALL
BEACHES TODAY. FOR SUNDAY, THE INTERNAL CALCULATOR HAS A
BORDERLINE MODERATE/HIGH RISK, WHILE RCMOS HAS A HIGH RISK.
THUS, OPTED TO KEEP THE HIGH RISK FOR ALL BEACHES ON SUNDAY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 10 PM EDT SUNDAY FOR AMZ360.
SMALL CRAFT ADVISORY FROM 6 AM TO 10 PM EDT SUNDAY FOR AMZ362.
SMALL CRAFT ADVISORY FROM 6 PM SUNDAY TO 8 AM EDT MONDAY FOR
AMZ384.
BSH/DENNIS
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