857
FXUS62 KCHS 270724
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
324 AM 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 /THROUGH TONIGHT/
EARLY THIS MORNING KCLX DETECTED A CLUSTER OF SHOWERS AND
THUNDERSTORMS PROGRESSING EASTWARD TOWARDS THE FAR INTERIOR GA
COUNTIES. EVEN THOUGH MODEL GUIDANCE SUGGESTS THAT THESE SHOWERS
WILL DISSIPATE BEFORE IMPACTING THE LOCAL CWA RADAR TRENDS
SUGGEST THAT THEY WILL IN FACT HOLD TOGETHER AND BRING SOME
EARLY MORNING RAINFALL TO SOUTHEASTERN GA.
TODAY: THE MORNING WILL START WITH COLD AIR DAMMING EXTENDING
ACROSS THE REGION AS HIGH PRESSURE PREVAILS OVER NEW ENGLAND.
DUE TO THE WEDGE PATTERN EXPECT CLOUDY CONDITIONS AND A GRADIENT
OF HIGH TEMPERATURES TODAY. NORTHERN LOCATIONS IN SC HAVE
FORECAST HIGHS IN THE LOW 80S WHILE SOUTHEASTERN GA SHOULD SEE
MID TO EVEN UPPER 80S. ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS IS FORECAST THIS AFTERNOON, WITH THE BULK OF THE
PRECIPITATION OCCURRING IN THE LATE AFTERNOON TO EARLY EVENING.
CONDITIONS ACROSS THE REGION ARE VERY SIMILAR TO PREVIOUS DAYS,
WITH PWAT VALUES APPROACHING 2.0" AND ML CAPE VALUES AROUND
1500 J/KG. HEAVY RAINFALL AS WELL AS A FEW STRONG TO MARGINALLY
SEVERE THUNDERSTORMS WILL ONCE AGAIN BE POSSIBLE. MODEL
SOUNDINGS INDICATE ROUGHLY 500 J/KG OF DCAPE, LEADING TO A RISK
OF DAMAGING WIND GUSTS. SEVERE HAIL (1" DIAMETER) ALSO CANNOT BE
RULED OUT. THE HREF SHOWS PROBABILITIES FOR 1" OF RAINFALL
HIGHEST ACROSS THE FAR INTERIOR COUNTIES, WHICH MATCHES WITH
WHERE THE WEATHER PREDICTION CENTER HAS A SLIGHT RISK OF
EXCESSIVE RAINFALL.
TONIGHT: SHOWERS AND THUNDERSTORMS ARE FORECAST TO LINGER INTO
THE EVENING, DISSIPATING BY AROUND MIDNIGHT. A MILD NIGHT IS IN
STORE FOR THE REGION, WITH LOWS ONLY DROPPING INTO THE UPPER 60S
TO AROUND 70 ALONG THE COASTAL COUNTIES.
SHORT TERM /WEDNESDAY THROUGH FRIDAY/
A PROGRESSIVE PATTERN WILL CONTINUE ON WEDNESDAY WITH A FEW
SHORTWAVES MOVING THROUGH DURING THE DAY. AT THE SURFACE, A WEAK
TROUGH WILL LINGER JUST OFF THE COAST. CAPES 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. OVERALL FORCING LOOKS A BIT LOWER THAN THE
OTHER DAYS, SO WE SHOW 30-40% POPS, HIGHEST IN SOUTHERN SC.
THE 500 MB PATTERN BEGINS TO AMPLIFY ON THURSDAY WITH A STRONG
SHORTWAVE LIFTING THROUGH THE AREA IN THE AFTERNOON AND EVENING.
DEEP TROPICAL MOISTURE WILL REMAIN IN PLACE WHILE CAPES REACH
1000-1500 J/KG LATER IN THE DAY. GOOD COVERAGE OF SHOWERS AND
TSTMS EXPECTED DURING THIS PERIOD, WITH MANY AREAS PICKING UP
1-2" OF RAINFALL.
THE LONGWAVE UPPER TROUGH WILL SWING THROUGH LATE FRIDAY,
PUSHING A COLD FRONT THROUGH THE AREA. WE'LL MAINTAIN PWS ABOVE
1.9" AHEAD OF THE FRONT, AND CAPES EXPECTED TO REACH 1000-1500
J/KG. WIND FIELDS ARE ACTUALLY PRETTY 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. SEVERE THUNDERSTORMS CAN'T BE
RULED OUT AT THIS POINT, WITH DAMAGING WINDS THE MAIN CONCERN AT
THIS POINT.
LONG TERM /FRIDAY NIGHT THROUGH MONDAY/
SHOWERS AND TSTMS COULD BE ONGOING FRIDAY EVENING AS THE COLD
FRONT PUSHES THROUGH. HIGH PRESSURE WILL BUILD IN ON SATURDAY,
BRINGING CONSIDERABLY DRIER DEWPOINTS. THERE COULD BE JUST
ENOUGH INSTABILITY ON SATURDAY TO SUPPORT AN ISOLATED SHOWER OR
TSTM BUT COVERAGE WOULD BE QUITE LOW. DRY WEATHER EXPECTED
SUNDAY. A SECONDARY FRONT COULD MOVE THROUGH ON MONDAY,
POTENTIALLY ACCOMPANIED BY A POTENT UPPER SHORTWAVE. THIS COULD
BRING ANOTHER ROUND OF CONVECTION.
AVIATION /07Z TUESDAY THROUGH SATURDAY/
27/06Z TAFS:
IFR CIGS ARE DEVELOPING ACROSS THE REGION AND WILL LIKELY BEGIN
IMPACTING KCHS/KJZI/KSAV SOON AFTER THE START OF THE 06Z TAF
PERIOD. ALL TAF SITES WILL INITIALIZE WITH MVFR CIGS AND FEATURE
A TEMPO FROM 06-08Z FOR IFR CIGS. CIGS SHOULD IMPROVE TO MVFR
AFTER SUNRISE AT ALL SITES AND PERSIST INTO THE AFTERNOON HOURS.
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS IS FORECAST, WITH
VCTS FEATURED IN THE TAF AFTER 18Z. EXACT TIMING OF IMPACTS FROM
SHOWERS/TSTORMS STILL HAS LOW CONFIDENCE SO ADDITIONAL
REFINEMENTS WILL BE MADE WITH FUTURE TAF ISSUANCES. MODELS ARE
AGAIN HINTING AT LOW CIGS DEVELOPING AT ALL TAF SITES TONIGHT.
HAVE INCLUDED MENTION OF MVFR CIGS AT KCHS/KSAV LATE IN THE TAF
PERIOD.
EXTENDED AVIATION OUTLOOK: OCCASIONAL VISIBILITY REDUCTIONS
EXPECTED, MAINLY DURING DAYTIME SHOWERS AND TSTMS, THOUGH
OVERNIGHT FOG IS ALSO POSSIBLE. LOW CEILINGS AGAIN POSSIBLE
TUESDAY NIGHT.
MARINE
TODAY: COLD AIR DAMMING WILL BE PRESENT ACROSS THE REGION TODAY
WITH HIGH PRESSURE LOCATED OVER NEW ENGLAND. THIS WILL YIELD
SLIGHTLY ELEVATED WINDS, ESPECIALLY IN THE MORNING OVER THE
CHARLESTON NEARSHORE WATERS AND THE CHARLESTON HARBOR. THE
CURRENT FORECAST FEATURES E TO SE WINDS GENERALLY 10 TO 15 KNOTS
WITH SOME GUSTS TO 20 KNOTS ACROSS THESE ZONES. THIS AFTERNOON
WINDS AROUND 10 KNOTS ARE EXPECTED ACROSS ALL MARINE ZONES. SEAS
ACROSS THE CHARLESTON NEARSHORE WATERS ARE FORECAST TO GENERALLY
BE 3 TO 4 FT, WITH 2 TO 3 FT ELSEWHERE. THIS AFTERNOON SHOWERS
AND THUNDERSTORMS WILL MOVE OFF THE SOUTHEASTERN COAST AND INTO
THE MARINE WATERS, LIKELY PERSISTING INTO THE EVENING HOURS.
TONIGHT: SHOWERS AND THUNDERSTORMS SHOULD WANE BY AROUND
MIDNIGHT, WITH SOUTHERLY WINDS AROUND 10 KNOTS AND SEAS 2 TO 3
FT, WITH SOME 4 FT SEAS IMPACTING THE CHARLESTON NEARSHORE
WATERS AND THE 20 TO 60 NM OFFSHORE GA WATERS.
WEDNESDAY THROUGH THURSDAY NIGHT, WINDS/SEAS SHOULD BE WELL
BELOW ADVISORY THRESHOLDS. SW WINDS INCREASE ON FRIDAY AHEAD OF
A STRONG COLD FRONT. WE COULD HAVE SOME GUSTS APPROACHING 25 KT
IN CHARLESTON HARBOR AND THE CHARLESTON NEARSHORE WATERS FRIDAY
AFTERNOON AND EVENING.
RIP CURRENTS: AS A MODEST SWELL BEGINS TO BUILD IN ON TODAY,
COMBINED WITH A HIGHER THAN NORMAL TIDAL RANGE, A MODERATE RISK
FOR RIP CURRENTS IS FORECAST TODAY AND WEDNESDAY AT ALL BEACHES.
TIDES/COASTAL FLOODING
THE RISK FOR COASTAL FLOODING WILL PERSIST FOR THE NEXT FEW
EVENINGS, ESPECIALLY ALONG THE CHARLESTON AND COLLETON COUNTY
COASTS. ADDITIONAL COASTAL FLOOD ADVISORIES MAY BE NEEDED.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR
AMZ350.
NEAR TERM...CPM
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...CPM/JRL
MARINE...CPM/JRL
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