938
FXUS62 KCHS 291121
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
721 AM EDT FRI MAY 29 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED FOR THE 12Z TAFS.
KEY MESSAGES
- 1) A COLD FRONT WILL STALL OVER SOUTHEAST GEORGIA TODAY. WIDESPREAD
SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG AND SOUTH OF THE
BOUNDARY. THESE STORMS WILL PRODUCE TORRENTIAL DOWNPOURS, 50%
CHANCE OF RAINFALL RATES OF 3"/3HR OR GREATER EXPECTED THIS
AFTERNOON INTO EARLY THIS EVENING. LOCALIZED FLASH FLOODING IS
POSSIBLE.
- 2) LOCALIZED FLASH FLOODING POSSIBLE ACROSS PORTIONS OF
SOUTHEAST GEORGIA AND THE SOUTH CAROLINA LOWCOUNTRY ON
SATURDAY.
- 3) EVENING HIGH TIDES COULD BRING MINOR INUNDATION OF VERY LOW LYING
AREAS ALONG THE CHARLESTON AND COLLETON COUNTY COASTS THIS
EVENING THROUGH THIS WEEKEND.
DISCUSSION
KEY MESSAGE 1: A COLD FRONT WILL STALL OVER SOUTHEAST GEORGIA TODAY.
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG AND SOUTH OF
THE BOUNDARY. THESE STORMS WILL PRODUCE TORRENTIAL DOWNPOURS, 50%
CHANCE OF RAINFALL RATES OF 3"/3HR OR GREATER EXPECTED THIS
AFTERNOON INTO EARLY THIS EVENING. LOCALIZED FLASH FLOODING IS
POSSIBLE.
A BACKDOOR COLD FRONT, OBSERVED ON SATELLITE AND SFC OBSERVATIONS,
WILL PUSH SOUTH ACROSS THE SC LOWCOUNTRY THIS MORNING. THE FRONT IS
EXPECTED TO SLOW AS IT CROSSES THE SAVANNAH RIVER LATE THIS MORNING,
THEN STALLING OVER SE GA. HIGH RESOLUTION GUIDANCE SHOWS A SEA
BREEZE DEVELOPING EARLY THIS AFTERNOON, PUSHING INLAND THROUGH THE
REST OF THE AFTERNOON.
SATELLITE WATER VAPOR SHOWS A PLUME OF DEEP MOISTURE ACROSS SE GA.
SPC MESOANALYSIS INDICATED A TIGHT GRADIENT OF PW ACROSS THE
FORECAST AREA, RANGING FROM AROUND 1 INCHES ACROSS THE SANTEE RIVER
TO 2.1 ACROSS EXTREME SE GA. BASED ON BLEND OF MOS, HIGH
TEMPERATURES MAY RANGE FROM THE MID TO UPPER 80S ACROSS THE SC
LOWCOUNTRY TO THE MID 80S ACROSS SE GA. SFC DEWPOINTS ALONG AND
SOUTH OF THE STATIONARY FRONT WILL REMAIN IN THE MID 70S. THE WARM
AND HUMID CONDITIONS SHOULD YIELD A LARGE FIELD OF SBCAPE BETWEEN
1500-1800 J/KG ACROSS SE GA. AS THE ENVIRONMENT DESTABILIZES, SHOWERS
AND THUNDERSTORMS SHOULD DEVELOP NEAR THE STALLED FRONT AND ALONG
THE SEA BREEZE, GENERALLY ALONG AND SOUTH OF THE SAVANNAH.
INTERESTINGLY, NEAR TERM GUIDANCE INDICATE AN AMPLIFYING H5
SHORTWAVE WILL LIFT ACROSS THE REGION DURING THE HEAT OF THE
AFTERNOON. THE SHORT WAVE MAY TRIGGER A BAND OF THUNDERSTORMS OVER
THE DEEP SOUTH, TRACKING NE, REACHING SE GA LATE THIS AFTERNOON AND
EVENING. SE GA MAY SEE COLLISIONS OF MULTIPLE BOUNDARIES, PRIMARILY
THE SEA BREEZE, STATIONARY FRONT, AND OUTFLOW FROM DEEP SOUTH
STORMS. THESE BOUNDARIES WILL LIKELY ALLOW FOR BACK-BUILDING AND
SLOW MOVING THUNDERSTORMS, WITH STORM MOTIONS LESS THAN 15 MPH.
GIVEN PW IN EXCESS OF 2 INCHES AND WARM CLOUD LAYER OF 12 KFT, THESE
STORMS SHOULD TAP INTO THE TROPICAL MOISTURE AND PRODUCE TORRENTIAL
DOWNPOURS. 0Z RUN OF THE HREF HIGHLIGHTS SE GA WITH A 50% CHANCE OF
RAINFALL RATES OF 3"/3HR OR GREATER EXPECTED THIS AFTERNOON INTO
EARLY THIS EVENING. LOCALIZED FLASH FLOODING IS POSSIBLE. WPC HAS
HIGHLIGHTED THIS REGION WITH A SLIGHT RISK IN THE EXCESSIVE RAINFALL
OUTLOOK. FLOOD ADVISORIES AND FLASH FLOOD WARNINGS MAY BE NEEDED FOR
PORTIONS OF SE GA LATER TODAY.
THE PASSAGE OF THE SHORTWAVE WILL LIKELY ALLOW SHOWERS TO DRIFT NE
TONIGHT. HOWEVER, NORTH OF THE STATIONARY FRONT, THE ENVIRONMENT
WILL BECOME DRYER WITH LESS INSTABILITY. DEEP CONVECTION SHOULD
GRADUALLY DISSIPATE AS IT MOVES NORTHWARD.
KEY MESSAGE 2: LOCALIZED FLASH FLOODING POSSIBLE ACROSS PORTIONS OF
SOUTHEAST GEORGIA AND THE SOUTH CAROLINA LOWCOUNTRY ON SATURDAY.
A LOCALIZED FLASH-FLOOD THREAT IS EXPECTED ON SATURDAY AS THE
STALLED FRONTAL BOUNDARY ACROSS SOUTHEAST GEORGIA SLOWLY LIFTS
NORTHWARDS ACROSS EASTERN SOUTH CAROLINA. WITH THE BOUNDARY LIFTING
NORTHWARD, A MID-LVL SHORTWAVE WILL APPROACH THE REGION FROM THE
WEST YIELDING AN INCREASINGLY FAVORABLE CORRIDOR OF LOW-LVL
CONVERGENCE FROM THE SAVANNAH METRO TOWARDS THE CHARLESTON METRO AND
PORTIONS OF THE SOUTH CAROLINA LOWCOUNTRY. THIS FORCING WILL OVERLAP
WITH A VERY MOIST AIRMASS CHARACTERIZED BY ANOMALOUSLY HIGH PWAT
VALUES, GENERALLY AROUND, OR ABOVE 2 INCHES. THIS WILL SUPPORT
EFFICIENT WARM-RAIN PROCESSES AND HIGH RAINFALL RATES.
THE MAIN FORECAST CHALLENGE REMAINS THE EXACT PLACEMENT OF THE FRONT
AND THE ASSOCIATED CONVERGENCE AXIS. A FARTHER SOUTH SOLUTION WOULD
FOCUS THE HEAVIER RAINFALL ACROSS SOUTHEAST GEORGIA AND THE SAVANNAH
METRO, HOWEVER A FARTHER NORTH SOLUTION WOULD BRING A GREATER
FLOODING CONCERN INTO THE CHARLESTON METRO AND THE BROADER SOUTH
CAROLINA LOWCOUNTRY.
OVERALL, THE ENVIRONMENT APPEARS MORE FAVORABLE FOR A HEAVY
RAINFALL/FLOODING THREAT RATHER THAN A ORGANIZED SEVERE WEATHER
THREAT. INSTABILITY SHOULD BE SUFFICIENT ENOUGH FOR SOME EMBEDDED
THUNDERSTORMS, BUT THE PRIMARY THREAT WILL BE LOCALIZED FLOODING
ESPECIALLY WHERE TRAINING DEVELOPS. LOCALIZED RAINFALL TOTALS OF 2
TO 3 INCHES COULD BE POSSIBLE, ESPECIALLY FROM THE SAVANNAH METRO
NORTHEAST TOWARDS CHARLESTON METRO DEPENDING ON THE WHERE THE FRONT
SETS UP. IT'S IMPORTANT TO NOTE THAT THE WEATHER PREDICTION CENTER
(WPC) HAS HIGHLIGHTED THE REGION UNDER A MARGINAL RISK (LEVEL 1/4)
FOR EXCESSIVE RAINFALL ON SATURDAY. SHOWERS AND THUNDERSTORMS WILL
LIKELY BEGIN TO WANE LATE SATURDAY NIGHT AS A SURFACE RIDGE STARTS
TO BUILD ACROSS THE REGION INTO SUNDAY.
KEY MESSAGE 3: EVENING HIGH TIDES COULD BRING MINOR INUNDATION OF
VERY LOW LYING AREAS ALONG THE CHARLESTON AND COLLETON COUNTY COASTS
THIS EVENING THROUGH THIS WEEKEND.
A PERIOD OF MODERATE TO BREEZY NORTHEAST WINDS TODAY IN COMBINATION
WITH THE APPROACHING FULL MOON AND APOGEE WILL BRING ELEVATED HIGH
TIDE LEVELS THIS EVENING. ELEVATED TIDAL DEPARTURES MAY PERSIST
THROUGH THIS WEEKEND. MINOR INUNDATION OF VERY LOW LYING AREAS OF
CHARLESTON AND COLLETON COUNTIES IS POSSIBLE EARLY THIS EVENING,
WITH A SLIGHTLY LESSER THREAT SATURDAY AND SUNDAY EVENINGS. HOWEVER,
SHOWERS AND THUNDERSTORMS MAY TRACK ACROSS THE CITY OF CHARLESTON
DURING HIGH TIDE SATURDAY EVENING. THE COMBINATION OF MODERATE TO
HEAVY DOWNPOURS COINCIDING WITH HIGH TIDE MAY INCREASE THE POTENTIAL
FOR FLOODING.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
12Z TAFS: PERIODS OF IFR FOG AND CEILINGS ARE POSSIBLE ACROSS
THE TERMINALS THROUGH 14Z. A COLD FRONT IS TIMED TO REACH KCHS
AND KJZI BY 14Z, TURNING WINDS FROM THE NORTHEAST AND LIFTING
CLOUD BASES TO VFR. THE COLD FRONT WILL SLOW AS IT APPROACHES
THE SAVANNAH RIVER THIS MORNING, LIKELY STALLING OVER SE GA THIS
AFTERNOON. HIGH RESOLUTION GUIDANCE INDICATES THAT A SEA BREEZE
AND COVERAGE ALONG THE FRONT WILL TRIGGER NUMEROUS TO
WIDESPREAD THUNDERSTORMS ACROSS SE GA THIS AFTERNOON. SOME OF
THIS ACTIVITY MAY TRACK OVER KSAV TODAY, HIGHLIGHTED WITH A
PROB30 FROM 16-20Z, WITH -TSRA FROM 20-23Z. KCHS AND KJZI
SHOULD REMAIN TOO STABLE FOR DEEP CONVECTION. THE PASSAGE OF THE
SEA BREEZE SHOULD TURN WINDS FROM THE SE BY 19Z, SOME GUSTS
NEAR 20 KTS POSSIBLE. SHOWERS WITH PERIODS OF IFR CEILINGS AREA
POSSIBLE OVERNIGHT, PRIMARILY AFTER 7Z.
EXTENDED AVIATION OUTLOOK: MORE PERIODIC FLIGHT RESTRICTIONS ARE
POSSIBLE THIS WEEKEND AS THE POTENTIAL FOR WIDESPREAD SHOWERS AND
THUNDERSTORMS INCREASES. IN ADDITION, PATCHY OVERNIGHT FOG AND/OR
STRATUS CANNOT BE RULED OUT AFTER RECENT RAINS.
MARINE
TODAY, ENE WINDS MAY SURGE AS THE COLD FRONT PUSHES ACROSS THE SC
WATERS, WITH GUSTS APPROACHING 25 KTS. IT IS EXPECTED THAT GUSTS
WILL REMAIN JUST BELOW SMALL CRAFT ADVISORY CRITERIA. HOWEVER, WAVE
HEIGHTS SHOULD BUILD THROUGH THE DAY, REACHING 3-4 FT BY THIS
AFTERNOON. THE PRESSURE GRADIENT MAY LESSEN ON TONIGHT INTO SATURDAY
AS A FRONTAL WAVE DEVELOPS OVER THE MARINE ZONES.
SATURDAY THROUGH TUESDAY: MODERATE EAST SOUTHEASTERLY WINDS WILL BE
APPARENT ON SATURDAY IN THE WAKE OF A COLD FRONT, AND THEN VEER OUT
OF THE NORTHEAST OVERNIGHT INTO SUNDAY. ADDITIONALLY, EXPECT WINDS
TO BECOME QUITE BREEZY AS THIS COLD FRONT PUSHES SOUTHWARD ON SUNDAY
MORNING WITH SPEEDS RANGING FROM 20 TO 25 KT WITH GUSTS UP TO 30 KT
POSSIBLE INTO SUNDAY AFTERNOON. SEAS WILL ALSO INCREASE ON SUNDAY AS
A SHORT-LIVED SWELL BUILDS ACROSS THE LOCAL ATLANTIC WATERS. EXPECT
THE NEARSHORE AND OFFSHORE SOUTHEAST SOUTH CAROLINA WATERS TO PEAK
TO 6-8 FT, WHILE THE NEARSHORE AND OFFSHORE WATERS SOUTHEAST GEORGIA
WATERS TO PEAK 4-6 FT. THEREFORE, SMALL CRAFT ADVISORIES WILL LIKELY
BE NEEDED ON SUNDAY. EXPECT MARINE CONDITIONS SHOULD IMPROVE ON
MONDAY AND TUESDAY.
RIP CURRENTS: A MODERATE RISK OF RIP CURRENTS IS EXPECTED FOR TODAY
ACROSS ALL BEACHES AS MODEST EASTERLY SWELL AROUND 3 TO 4 FT EVERY 8
SECONDS PERSISTS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
DENNIS/NED
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