804
FXUS62 KCHS 300539
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
139 AM EDT SUN MAR 30 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL THROUGH TONIGHT, THEN RAIN AND
THUNDERSTORM CHANCES INCREASE INTO SUNDAY AND MONDAY AHEAD OF
AN APPROACHING COLD FRONT. A FRONT COULD LINGER NEARBY
MID-WEEK, BEFORE STRONGER HIGH PRESSURE PREVAILS LATE NEXT
WEEK.
NEAR TERM /UNTIL 6 AM THIS MORNING/
BASED ON DIMINISHING CLOUD COVER PER RECENT SATELLITE TRENDS
AND FORECAST GUIDANCE, PLUS LIGHT OR CLAM WINDS, WE HAVE LOWERED
OUR MIN TEMPS A BIT FROM PREVIOUSLY. EVEN SO, THIS IS STILL
WARMER THAN LAST NIGHT GIVEN A LOW LEVEL SOUTH TO SOUTHERLY
FLOW AND WEAK WARM AIR ADVECTION. SUBTLE MID LEVEL SHORT WAVE
WILL MOVE IN LATE, PERHAPS ALLOWING FOR A FEW SHOWERS TO OCCUR.
PROBABILITIES THOUGH ARE TOO LOW TO MENTION IN THE FORECAST.
SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/
SUNDAY: SURFACE HIGH PRESSURE WILL SLOWLY SHIFT OFF THE EAST COAST
THROUGH THE DAY. ALOFT A TROUGH INITIALLY OVER TEXAS WILL SWING
EASTWARD, APPROACHING THE FORECAST AREA LATE SUNDAY. THE
SOUTHWESTERLY FLOW ALOFT WILL YIELD WARM AIR ADVECTION (WAA) INTO
THE REGION AS WELL AS USHER IN MORE LOW-LEVEL MOISTURE. HIGH
TEMPERATURES ARE FORECAST TO REACH INTO THE MID 70S TO AROUND 80.
DIURNALLY DRIVEN SHOWERS AND POSSIBLE THUNDERSTORMS WILL APPROACH
THE REGION FROM THE WEST IN THE AFTERNOON HOURS, WELL AHEAD OF AN
APPROACHING COLD FRONT. LINGERING HIGH PRESSURE ALONG THE CHARLESTON
TRI-COUNTY AREA WILL HELP KEEP PRECIPITATION CHANCES FURTHER INLAND
UNTIL LATER IN THE EVENING. MODELS GENERALLY SHOW ML CAPE VALUES IN
THE 400-800 J/KG RANGE AND WITH ONLY AROUND 20 KNOTS OF SHEAR THE
SEVERE THUNDERSTORM RISK IS NEAR ZERO. RAINFALL AMOUNTS WILL VARY
GREATLY ACROSS THE FORECAST AREA, WITH SE GA UP TO AROUND 0.5 INCHES
POSSIBLE AND SE SC GENERALLY LESS THAN 0.1 INCHES. PRECIPITATION WILL
DIMINISH WITH NIGHTFALL AS SHOWERS RUN OUT OF INSTABILITY. A MILD
NIGHT IS FORECAST SUNDAY NIGHT DUE TO CLOUD COVER, WAA, AND
LINGERING PRECIPITATION. LOW TEMPERATURES WILL ONLY DIP INTO THE LOW
60S.
MONDAY: THE FORECAST TURNS MORE ACTIVE ON MONDAY AS A COLD FRONT
APPROACHES THE REGION FROM THE WEST. AHEAD OF THE COLD FRONT A LINE
OF SHOWERS AND THUNDERSTORMS IS POISED TO PUSH THROUGH THE FORECAST
AREA, BRINGING THE RISK FOR SEVERE THUNDERSTORMS. WITH THE REGION
WELL IN THE WARM SECTOR HIGH TEMPERATURES WILL ONCE AGAIN BE ABOVE
NORMAL, REACHING INTO THE LOW TO EVEN MID 80S. ADDITIONALLY, DEW
POINTS WILL SURGE INTO THE MID TO UPPER 60S. INSTABILITY VALUES WILL
PEAK IN THE AFTERNOON, GENERALLY AROUND 1000-2000 J/KG, WITH SEAR
VALUES AROUND 30 KNOTS. STRONG, DAMAGING WIND GUSTS APPEAR THE MAIN
THREAT WITH ANY SEVERE THUNDERSTORMS. THE 12Z MODELS CONTINUE THE
TREND OF THE LINE OF SHOWERS AND THUNDERSTORMS ARRIVING IN THE LATE
AFTERNOON/EVENING HOURS. DUE TO THE LATER TIMING THE SHOWERS AND
THUNDERSTORMS WOULD LIKELY STRUGGLE TO HOLD TOGETHER AS THEY
APPROACH THE FORECAST AREA AS THE BEST INSTABILITY WOULD HAVE BEEN
REALIZED EARLIER IN THE AFTERNOON. HOWEVER, IF THE SHOWERS AND
THUNDERSTORMS APPROACH QUICKER, THERE WOULD BE A GREATER SEVERE
WEATHER CHANCE. THE COLD FRONT WILL PUSH THROUGH THE REGION IN THE
OVERNIGHT PERIOD, WITH LOW TEMPERATURES DROPPING INTO THE LOW 50S
INLAND AND AROUND 60 ALONG THE COASTLINE.
TUESDAY: HIGH PRESSURE WILL BUILD INTO THE REGION AT THE SURFACE
BEHIND THE DEPARTING COLD FRONT, WHILE SOUTHWESTERLY FLOW REMAINS
ALOFT. TEMPERATURES WILL ONCE AGAIN BE ABOVE NORMAL, REACHING TO
AROUND 80, OWING TO THE WAA ALOFT. SKIES WILL CLEAR, WITH PLENTIFUL
SUNSHINE BY THE AFTERNOON.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
THE REMAINDER OF THE WEEK WILL FEATURE HIGH PRESSURE BOTH ALOFT AND
AT THE SURFACE, YIELDING A MOSTLY DRY AND WARM FORECAST. DIURNALLY
DRIVEN ISOLATED SHOWERS WILL BE POSSIBLE ON WEDNESDAY, OTHERWISE A
DRY FORECAST HAS BEEN MAINTAINED. THE MAIN FORECAST HIGHLIGHT
THROUGH THE WEEK WILL BE THE WARM TEMPERATURES. HIGHS ON THURSDAY
AND FRIDAY COULD APPROACH 90 DEGREES IN SOME LOCATIONS, WITH MID TO
UPPER 80S ELSEWHERE.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
KCHS/KJZI/KSAV: VFR CONDITIONS WILL PREVAIL AT ALL SITES INTO
THE AFTERNOON, WITH LIGHT OR CALM WINDS TO SLOWLY INCREASE LATER
THIS MORNING, AND BECOME A BIT GUSTY THIS AFTERNOON DURING THE
WARMEST PART OF THE DAY. SHOWERS ASSOCIATED WITH A WEAK COASTAL
TROUGH, DEEPER MOISTURE, AND A SHORT WAVE ALOFT, WILL CAUSE THE
RISK FOR SOME SHOWER ACTIVITY LATER THIS AFTERNOON INTO THIS
EVENING. FLIGHT RESTRICTIONS MIGHT OCCUR, BUT THE HIGHER CHANCES
FOR FLIGHT RESTRICTIONS WILL BE TONIGHT AS THE SHOWERS END, AND
A STRENGTHENING LOW LEVEL INVERSION DEVELOPS, TRAPPING
CONSIDERABLE MOISTURE UNDERNEATH. FOR NOW WE HAVE MVFR AT ALL
TERMINALS, BUT IFR IS POSSIBLE.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS ARE POSSIBLE LATE
SUNDAY NIGHT INTO MONDAY WITH LOW CIGS DUE TO SHOWERS. A LINE
OF SHOWERS AND THUNDERSTORMS IS EXPECTED TO MOVE THROUGH MONDAY
AFTERNOON OR EVENING, POTENTIALLY LINGERING INTO THE OVERNIGHT
HOURS INTO EARLY TUESDAY MORNING.
MARINE
OVERNIGHT: WEAK COASTAL TROUGHING AND A WEAK PRESSURE GRADIENT
WILL PERSIST ALONG THE WESTERN PERIPHERY OF HIGH PRESSURE
CENTERED NEAR BERMUDA, LEADING TO A FEW LATE NIGHT SHOWERS, BUT
GENERALLY QUIET CONDITIONS ACROSS LOCAL WATERS FOR MUCH OF THE
NIGHT. IN GENERAL, SOUTH/SOUTHEAST WINDS WILL BE NO HIGHER THAN
10-15 KT WITH SEAS SLOWLY BUILDING TO 3-4 FT ACROSS NEARSHORE
WATERS. THE EXCEPTION WILL BE ACROSS OUTER GEORGIA WATERS, WHERE
SLIGHTLY LARGER SWELLS BUILD SEAS UP TO 6 FT BEYOND 30 NM FROM
THE COAST. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE
OUTER GEORGIA WATERS.
SUNDAY THROUGH WEDNESDAY: HIGH PRESSURE WILL PREVAIL OVER THE LOCAL
WATERS SUNDAY, WITH WINDS SE GENERALLY 10 TO 15 KNOTS AND SEAS
AVERAGING 3 TO 4 FT ACROSS THE NEARSHORE WATERS. IN THE 20-60 NM
OFFSHORE GA WATERS, SOME 6 FT SEAS WILL BE PRESENT THROUGH SUNDAY
AFTERNOON AND A SMALL CRAFT ADVISORY IS IN EFFECT. SOME GUIDANCE IS
HINTING AT THE DEVELOPMENT OF SEA FOG SUNDAY INTO MONDAY, HOWEVER
GIVEN BREEZY CONDITIONS AND THE WIND DIRECTION HAVE OPTED TO LEAVE
MENTION OUT OF THE FORECAST. ON MONDAY AND INTO TUESDAY A COLD FRONT
WILL PUSH THROUGH THE REGION, WITH A LINE OF SHOWERS AND
THUNDERSTORMS AHEAD OF THE FRONT. SOME THUNDERSTORMS COULD HAVE
GUSTY WINDS, OTHERWISE WINDS OUT OF THE S ON MONDAY WILL SHIFT TO
THE NE BY TUESDAY REMAINING AROUND 10 TO 15 KNOTS. HIGH PRESSURE
WILL BUILD INTO THE REGION ON WEDNESDAY, WITH WINDS SE 10 TO 15
KNOTS AND SEAS AVERAGING 3 TO 4 FT.
EQUIPMENT
THE KCLX RADAR REMAINS OFFLINE FOR DOME MAINTENANCE THROUGH
APRIL 1, 2025. RADAR DATA WILL NOT BE AVAILABLE DURING THIS
TIME. USERS ARE URGED TO USE ADJACENT WSR-88D SITES WHICH ALSO
COVER MUCH OF SOUTHEAST SOUTH CAROLINA, SOUTHEAST GEORGIA AND
THE ADJACENT COASTAL WATERS. THESE INCLUDE:
KCAE - COLUMBIA, SC
KLTX - WILMINGTON, NC
KJAX - JACKSONVILLE, FL
KVAX - MOODY AFB, GA
KJGX - ROBBINS AFB, GA
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR AMZ374.
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
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