921
FXUS62 KCHS 271947
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
347 PM EDT TUE MAY 27 2025
SYNOPSIS
A SERIES OF DISTURBANCES WILL AFFECT THE AREA THROUGH THURSDAY,
THEN A COLD FRONT WILL SWEEP THROUGH LATE FRIDAY. HIGH PRESSURE
WILL THEN BUILD IN FROM THE WEST.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
THIS AFTERNOON, SATELLITE RGB DAYTIME CONVECTION PRODUCT SHOWED
CLEARING OF THE COLD AIR DAMMING (CAD) STRATUS FROM THE MOUTH OF THE
SAVANNAH RIVER SOUTH ACROSS SE GA . IN FACT, KCLX DETECTED A LINE OF
SHOWERS AND ISOLATED THUNDERSTORMS ALONG THE EDGE OF THE CAD, FROM
NORTHERN TATTNALL TO THE ENTRANCE OF THE SAVANNAH HARBOR. NORTH
ALONG THE SC COAST, SFC OBSERVATIONS INDICATE WINDS HAVE VEERED FROM
THE EAST WITH TEMPERATURES IN THE LOW TO MID 80S. THE 12Z KCHS
SOUNDING INDICATED A STRONG INVERSION UP TO 970 MB WITH A ANOTHER
INVERSION UP TO 850 MB. HIGH RESOLUTION GUIDANCE INDICATES THAT
COASTAL TROUGH OR SEA BREEZE DRIFT INLAND THROUGH THE REST OF THE
AFTERNOON. INSTABILITY SHOULD INCREASE TO 1500-2500 J/KG IN THE WAKE
OF THE SEA BREEZE. SHOWERS AND THUNDERSTORMS SHOULD GRADUALLY
INCREASE IN COVERAGE WITHIN THE UNSTABLE ENVIRONMENT, ESPECIALLY
ACROSS SE GA THIS AFTERNOON. A FEW OF THESE STORMS MAY BECOME SEVERE
THROUGH EARLY THIS EVENING, HAIL AND DAMAGING WIND GUSTS WILL REMAIN
THE PRIMARY HAZARDS.
IN ADDITION, A MCS IS EXPECTED TO EXIT AL AND MOVE ACROSS WESTERN
AND CENTRAL GA LATE THIS AFTERNOON. THE MCS IS EXPECTED TO BE FAIRLY
ORGANIZED AND MAY PRODUCE A SWATH OF STRONG TO DAMAGING WIND GUSTS
AS IT REACH SE GA EARLY THIS EVENING. SPC HAS HIGHLIGHTED A PORTION
OF SE GA WITH A SLIGHT RISK FOR SEVERE WEATHER, A SEVERE
THUNDERSTORM WATCH IS POSSIBLE THIS EVENING. THIS STORM COMPLEX
SHOULD BEGIN TO WEAKEN AS IT CROSS THE SAVANNAH RIVER AND REACHES
THE COAST, ENCOUNTERING LESS INSTABILITY.
IN ADDITION, PW VALUES ACROSS THE REGION WILL REMAIN VERY HIGH, WITH
1.9 INCHES COMMON OVER THE CWA. THE 12Z HREF INDICATES THAT THE
ENTIRE FORECAST AREA HAS AT LEAST A 10% CHANCE FOR 3 INCH/3HR WITH A
SWATH OF 30% ACROSS THE INLAND COUNTIES. TORRENTIAL DOWNPOURS MAY
YIELD FLOODING OF LOW OR POOR DRAINAGE AREAS. WPC HAS HIGHLIGHTED
MOST OF THE REGION WITH A SLIGHT RISK FOR EXCESSIVE RAINFALL. ALSO,
COASTAL FLOODING THIS EVENING MAY RESTRICT STORM WATER DRAINAGE THIS
EVENING, ANY HEAVY DOWNPOUR OVER A COASTAL CITY MAY PRODUCE SOME
STREET FLOODING.
TONIGHT, CONVECTION SHOULD GRADUALLY DISSIPATE LATE TONIGHT, WITH
ONLY ISOLATED ACTIVITY EXPECTED DURING THE PRE-DAWN HOURS. AS THE
CONVECTION ASHES OUT, STRATUS SHOULD SPREAD ACROSS THE FORECAST AREA
LATE TONIGHT. LOW TEMPERATURES ARE FORECAST TO RANGE FROM THE MID
60S INLAND TO AROUND 70 DEGREES ALONG THE COAST.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/
AN ACTIVE WEATHER PATTERN WILL CONTINUE THROUGH THE PERIOD.
SHORTWAVE ACTIVITY ALOFT WILL MOVE ACROSS THE LOCAL AREA WEDNESDAY,
AND A WEAK SURFACE TROUGH WILL LINGER JUST OFF THE COAST. CAPE
VALUES ARE EXPECTED TO CLIMB ABOVE 1000 J/KG IN SOME AREAS DURING
THE AFTERNOON. A DECENT SEA BREEZE IS EXPECTED, THOUGH THE BEST
INLAND PENETRATION WILL OCCUR IN SOUTHERN SC. FORCING LOOKS A BIT
LOWER THAN THE OTHER DAYS AND MOISTURE WILL BE ON A SLIGHT DOWNWARD
TREND THROUGHOUT THE DAY, THEREFORE WE MAINTAIN 30-40% POPS. OVERALL
SEVERE POTENTIAL REMAINS LOW WITH 20 KT BULK SHEAR VALUES, ALTHOUGH
AN ISOLATED STRONG TO MARGINALLY SEVERE STORM CANNOT BE RULED OUT.
TEMPERATURES WILL REACH THE MID TO UPPER 80S MOST PLACES WITH A FEW
LOWER 90S ACROSS SOUTHEAST GEORGIA. MIN TEMPS WILL RANGE FROM THE
UPPER 60S TO LOWER 70S.
THE 500 MB PATTERN BEGINS TO AMPLIFY ON THURSDAY WITH A STRONG
SHORTWAVE LIFTING THROUGH THE AREA IN THE AFTERNOON AND EVENING.
DEEPER TROPICAL MOISTURE WILL ADVECT INTO THE AREA WHILE CAPES REACH
1000-1500 J/KG LATER IN THE DAY. GOOD COVERAGE OF SHOWERS AND TSTMS
EXPECTED DURING THIS PERIOD, WITH SOME AREAS PICKING UP TO 1-2" OF
RAINFALL. TEMPERATURES WILL AGAIN PEAK IN THE MID TO UPPER 80S MOST
PLACES WITH A FEW LOWER 90S ACROSS SOUTHEAST GEORGIA, AND MIN TEMPS
IN THE UPPER 60S TO LOWER 70S.
A LONGWAVE UPPER TROUGH WILL SWING THROUGH LATE FRIDAY, PUSHING A
COLD FRONT THROUGH THE AREA. PWATS WILL REMAIN ABOVE 1.9" AHEAD OF
THE FRONT, AND CAPE VALUES ARE EXPECTED TO REACH 1000-1500 J/KG.
WIND FIELDS ARE DECENT WITH 0-6 KM BULK SHEAR OF 35-40 KT LATER IN
THE AFTERNOON. AT A MINIMUM WE SHOULD SEE A FAIRLY CONTIGUOUS BAND
OF SHOWERS AND TSTMS SWEEP THROUGH THE AREA FRIDAY
AFTERNOON/EVENING. A FEW SEVERE THUNDERSTORMS ARE EVEN POSSIBLE,
WITH DAMAGING WINDS THE MAIN CONCERN. CONVECTION SHOULD HELP LIMIT
MAX TEMPERATURES TO THE LOW TO MID 80S WITH ISOLATED AREAS CLOSER TO
THE COAST REACHING THE UPPER 80S.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
SHOWERS AND TSTMS COULD BE ONGOING FRIDAY EVENING AS THE COLD FRONT
PUSHES THROUGH. HIGH PRESSURE WILL BUILD IN ON SATURDAY BRINGING
RELATIVELY DRIER AIR AND MOSTLY SUNNY CONDITIONS FOR THE WEEKEND. A
SECONDARY FRONT COULD MOVE THROUGH ON MONDAY, POTENTIALLY
ACCOMPANIED BY A POTENT UPPER SHORTWAVE. THIS COULD BRING A ROUND OF
CONVECTION. TEMPERATURES WILL BE SLIGHTLY COOLER BEHIND THE FRONT
SATURDAY, BUT SHOULD REBOUND TO NEAR NORMAL FOR THE REST OF THE
PERIOD.
AVIATION /20Z TUESDAY THROUGH SUNDAY/
PRIOR TO THE 18Z TAFS, CAD WAS BEGINNING TO ERODE ACROSS THE
TERMINALS. MVFR CEILINGS ARE EXPECTED TO REMAIN ACROSS THE
TERMINALS UNTIL MID-AFTERNOON. WITH THE CAD BREAKDOWN, A SEA
BREEZE IS EXPECTED TO DEVELOP AND DRIFT SLOWLY INLAND. THIS
BOUNDARY SHOULD SERVE AS A FOCUS FOR SHOWER AND THUNDERSTORM
DEVELOPMENT. EACH TAF WILL FEATURE A MENTION OF VCSH WITH A
TEMPO FROM 19-24Z FOR TSRA. A SECONDARY WINDOW FOR THUNDERSTORMS
IS POSSIBLE LATE THIS EVENING WITH THE ARRIVAL OF A MCS SOURCED
FROM THE DEEP SOUTH. THE REST OF THE NIGHT, STRATUS WILL
GRADUALLY LOWER ACROSS THE REGION, WITH MVFR CEILINGS POSSIBLE.
EXTENDED AVIATION OUTLOOK: OCCASIONAL VISIBILITY REDUCTIONS
EXPECTED, MAINLY DURING DAYTIME SHOWERS AND THUNDERSTORMS.
MARINE
TONIGHT, THE WEATHER PATTERN WILL SUPPORT SOUTHEAST WINDS AROUND
10KTS WITH WINDS SHIFTING FROM THE SOUTH TONIGHT. SEAS ARE FORECAST
TO RANGE BETWEEN 2 TO 4 FT. IT IS POSSIBLE A THUNDERSTORM NEAR THE
COAST THIS EVENING MAY WARRANT A SPECIAL MARINE WARNING, ESPECIALLY
ALONG THE GA COAST.
WEDNESDAY THROUGH SUNDAY: SOUTH TO SOUTHWEST WINDS AND SEAS SHOULD
BE WELL BELOW ADVISORY THRESHOLDS THROUGH THURSDAY NIGHT. SW WINDS
WILL BEGIN TO INCREASE FRIDAY AHEAD OF A STRONG COLD FRONT. THERE
COULD BE GUSTS APPROACHING 25 KT AND SEAS APPROACHING 6 FEET IN THE
CHARLESTON COUNTY NEARSHORE WATERS AND GEORGIA OFFSHORE WATERS (FROM
20-60 NM) FRIDAY AFTERNOON INTO THE OVERNIGHT PERIOD. SMALL CRAFT
ADVISORIES COULD BE NEEDED. NO ADDITIONAL MARINE CONCERNS THROUGH
THE WEEKEND.
RIP CURRENTS: THE COMBINATION OF MODEST SWELLS AND HIGHER THAN
NORMAL TIDAL RANGE, A MODERATE RISK FOR RIP CURRENTS WILL REMAIN
FOR ALL BEACHES THROUGH THIS EVENING.
TIDES/COASTAL FLOODING
MODERATE COASTAL FLOODING IS EXPECTED THIS EVENING FOR
CHARLESTON AND COASTAL COLLETON COUNTIES. THE REST OF THE COAST,
MINOR COASTAL FLOODING IS EXPECTED. COASTAL FLOOD ADVISORIES
HAVE BEEN POSTED FOR THE ENTIRE COAST FROM 7 PM UNTIL 11 PM.
THE RISK FOR COASTAL FLOODING WILL PERSIST THROUGH AT LEAST
WEDNESDAY EVENING, ESPECIALLY ALONG THE CHARLESTON AND COLLETON
COUNTY COASTS. ADDITIONAL COASTAL FLOOD ADVISORIES COULD BE NEEDED.
CHS WATCHES/WARNINGS/ADVISORIES
GA...COASTAL FLOOD ADVISORY FROM 7 PM TO 11 PM EDT THIS EVENING FOR
GAZ117-119-139-141.
SC...COASTAL FLOOD ADVISORY FROM 7 PM TO 11 PM EDT THIS EVENING FOR
SCZ048>051.
MARINE...NONE.
NEAR TERM...NED
SHORT TERM...BRS
LONG TERM...BRS
AVIATION...BRS/NED
MARINE...BRS/NED
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