346
FXUS62 KCHS 311520
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1120 AM EDT MON MAR 31 2025
SYNOPSIS
SHOWERS AND THUNDERSTORM WILL OCCUR THIS AFTERNOON AND EVENING
AHEAD OF AN APPROACHING COLD FRONT. THE FRONT LINGERS NEARBY
MID-WEEK, BEFORE STRONGER HIGH PRESSURE PREVAILS LATE THIS WEEK.
NEAR TERM /THROUGH TONIGHT/
TODAY INTO EARLY EVENING: ALOFT, A H5 SHORTWAVE WILL QUICKLY MOVE
WITHIN A WEST-SOUTHWEST FLOW ACROSS ALABAMA AND MISSISSIPPI THIS
MORNING AND INTO GEORGIA THIS AFTERNOON, REACHING SOUTHERN SOUTH
CAROLINA LATE DAY. AT THE SFC, A STRONG COLD FRONT WILL CROSS THE
APPALACHIAN MOUNTAINS LATE DAY, APPROACHING THE REGION DURING THE
EVENING AND OVERNIGHT, KEEPING THE LOCAL AREA SOLIDLY WITHIN A MOIST
WARM-SECTOR THROUGHOUT THE DAY AND EARLY EVENING HOURS. WIDESPREAD
STRATUS AND EARLY MORNING FOG WILL LIMIT THE POTENTIAL FOR SHOWER
ACTIVITY TO DEVELOP THROUGH AT LEAST MID-DAY, BUT WARM AIR ADVECTION
ACROSS THE REGION AND BREAKS IN CLOUDS DURING AFTERNOON HOURS WILL
STILL LIKELY SUPPORT HIGH TEMPS IN THE LOW-MID 80S, EXCEPT LOW-MID
70S NEAR COASTAL COMMUNITIES WHERE A RESULTANT SEA BREEZE CREATES AN
ONSHORE FLOW OFF COOLER OCEAN WATERS.
BY EARLY-MID AFTERNOON, PRE-STORM ENVIRONMENTAL MOISTURE LEVELS AND
INSTABILITY WILL CLIMB, WITH PWATS APPROACHING 1.60-1.80 INCHES AND
WARMER SFC TEMPS LEADING TO AN AXIS OF SBCAPE STRETCHED ACROSS THE
LOCAL AREA, GENERALLY IN THE 2000-3000 J/KG RANGE. THIS COINCIDES
WITH 0-6 KM BULK SHEAR NEAR 30-35 KT, SUPPORTIVE OF CONVECTIVE
ORGANIZATION FOR ACTIVITY THAT DEVELOPS WELL AHEAD OF A SQUALL LINE
CURRENTLY MAKING WAY ACROSS ALABAMA LATE THIS MORNING. HOWEVER, MOST
GUIDANCE SUGGESTS THIS TO BE A VERY LIMITED CASE DURING EARLY-MID
AFTERNOON HOURS. THE BULK OF SHOWERS AND THUNDERSTORM ACTIVITY IS
MORE LIKELY TO OCCUR IN AN INCREASINGLY SHEARED, BUT UNIDIRECTIONAL
ENVIRONMENT, IN THE FORM OF A SQUALL LINE ENTERING WESTERN MOST
ZONES LATE DAY AND QUICKLY PROGRESSING TOWARD THE COAST BY EARLY-
MID EVENING (GENERALLY IN THE 4-9 PM RANGE). THUNDERSTORMS ALONG
AND/OR NEAR THE PASSING SQUALL LINE WILL BE CAPABLE OF BECOMING STRONG
AND/OR SEVERE, BUT TIMING WILL PLAY A ROLE IN OVERALL COVERAGE,
GIVEN INSTABILITY IS LIKELY TO START DECREASING BY AROUND SUNSET.
NEVERTHELESS, THE OVERALL ENVIRONMENT REMAINS MOST CONDUCIVE FOR
DAMAGING WIND GUSTS GIVEN DCAPE VALUES AROUND 1000 J/KG, LOW-LVL
LAPSE RATES NEAR 7-7.5 C/KM AND STRONGER LOW-LVL WIND FIELDS OF AT
LEAST 40 KT. THE TORNADO RISK APPEARS MORE LIMITED WITH SOUNDINGS
DISPLAYING UNIDIRECTIONAL WIND PROFILES, BUT CAN NOT BE RULED
OUT IF ANY REAR-INFLOW JETS DEVELOP NEAR CONVECTION, ORIENTING
PARTS OF THE QLCS IN A MORE NORTHWEST TO SOUTHEAST FASHION (LINE
NORMAL BULK SHEAR). THE HREF ENSEMBLE DOES PAINT A FEW PATHS OF
2-5 KM UPDRAFT HELICITIES IN EXCESS OF 75 M2/S2 ACROSS PARTS OF
THE LOCAL AREA (MAINLY INLAND AND ACROSS GEORGIA). THE RISK OF
HAIL LOOKS THE LOWEST GIVEN THE WBZ AND FREEZING LEVEL ARE QUITE
HIGH, BUT COULD STILL REACH SEVERE LIMITS (1 INCH) GIVEN MID-
LVL LAPSE RATES BETWEEN 6.5 TO 7 C/KM AND MODEST HAIL GROWTH
ZONE CAPE. A CONVECTIVE WATCH SHOULD EVENTUALLY BE NEEDED LATER
TODAY.
GIVEN THE PROGRESSIVE NATURE OF THE SQUALL LINE, RAINFALL AMOUNTS
WILL BE ON THE ORDER OF 1/3 TO 2/3 INCHES, BUT WITH LOCALLY HIGHER
AMOUNTS APPROACHING 1 INCH. FORTUNATELY THE HIGH TIDE OCCURS AFTER
THE SQUALL LINE PASSES OFFSHORE.
FOR THE REST OF THE NIGHT, SINCE THE TRAILING COLD FRONT DOESN'T
MOVE IN UNTIL OVERNIGHT, A FEW MORE SHOWERS WILL BE POSSIBLE.
PATCHY FOG WILL LIKELY FORM DUE TO SOME CLEARING OF THE SKIES,
LIGHT WINDS, AND THE WET GROUNDS. LOWS WILL GENERALLY BE ONLY
DOWN INTO THE UPPER 50S AND LOWER 60S.
SHORT TERM /TUESDAY THROUGH THURSDAY/
TUESDAY: PATCHY FOG ERODES AFTER SUNRISE, THOUGH IT MAY LINGER
A TOUCH LONGER FOR THOSE ALONG THE COAST. A SURFACE HIGH
PRESSURE BUILDS IN FROM THE NORTH THROUGHOUT THE DAY, WITH UPPER
LEVEL RIDGING TAKING PLACE ALOFT. THIS WILL RESULT IN HIGHS
ONLY A COUPLE DEGREES COOLER DESPITE THE RECENT FROPA, WITH
AFTERNOON HIGHS IN THE UPPER 70S TO LOWER 80S.
WEDNESDAY: UPPER LEVEL RIDGING STARTS TO STRENGTHEN THROUGHOUT THE
DAY, WHICH IN COMBINATION WITH WARM AIR ADVECTION (WAA) IN THE MID-
LEVELS WILL RESULT IN AFTERNOON HIGHS IN THE LOWER TO UPPER 80S
ACROSS THE REGION, CLOSER TO THE MID/UPPER 70S ALONG THE COAST. THE
WAA AND MOISTURE IN THE MID-LEVELS WILL RESULT IN PARTLY TO MOSTLY
CLOUDY SKIES THROUGHOUT THE DAY. CAN'T RULE OUT A FEW SCATTERED
SHOWERS AS WELL, THOUGH RAINFALL AMOUNTS WILL REMAIN ON THE LOW SIDE
(< 0.05").
THURSDAY: AS UPPER LEVEL RIDGING CONTINUES ON THURSDAY, WITH
SITUATIONAL AWARENESS TABLES SHOWING RECORD HIGH 500 HPA
GEOPOTENTIAL HEIGHTS OCCURRING IN RELATION TO 30-YEAR NORMALS,
WARM/HOT TEMPERATURES ARE EXPECTED. THE NBM CONTINUES TO WARM-UP
TOWARDS THE 50TH PERCENTILE, AND WITH THE AFOREMENTIONED
SIGNALS IN THE ENSEMBLES, DID MIX IN SOME TEMPERATURES NEAR THE
75TH PERCENTILE OF GUIDANCE, RESULTING IN AFTERNOON HIGHS IN THE
LOWER TO UPPER 80S FOR INLAND AREAS, AND MID 70S TO LOWER 80S
ALONG THE COAST. CAN'T RULE OUT SOME 90 DEGREE TEMPERATURES, AS
NBM PROBABILITIES SHOW 40-60% CHANCES ACROSS INLAND SC COUNTIES,
REACHING UP INTO THE 60-80% RANGE FOR INLAND GA COUNTIES. THE
GOOD NEWS IS THE AFTERNOON SEA-BREEZE WILL BE COMING ASHORE IN
THE MID/LATE AFTERNOON HOURS, WHICH WILL HELP COOL THE REGION
BACK DOWN AGAIN.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
THE LONG TERM CONTINUES TO REMAIN LARGELY WARM AND DRY AS A STRONG
UPPER LEVEL RIDGE SETS UP JUST OFF TO OUR SOUTH. ACCORDING TO THE
SITUATIONAL AWARENESS DISPLAYS, 1000 HPA TEMPERATURE ARE ALL IN THE
90+ PERCENTILE COMPARED TO 30-YEAR NORMALS, WITH 850 HPA
TEMPERATURES AT THE MAX OF 30-YEAR NORMALS AT TIMES...FROM BOTH THE
NAEFS AND ECMWF. THE EURO EFI IS ALSO COMING IN WARM, WITH A COUPLE
SHIFT OF TAILS BEING NOTED AS WELL. SO, EXPECT WELL ABOVE NORMAL
TEMPERATURES THURSDAY THROUGH SATURDAY, WITH DAILY CHANCES FOR
REACHING 90+ DEGREES HIGHEST (70-90% CHANCES) FOR AREAS WELL WEST OF
THE I-95 CORRIDOR, WHILE ALSO INCLUDING THE NORTHERN HALF OF
BERKELEY AND DORCHESTER COUNTIES IN SC. RECORD HIGH DAILY MAXIMUMS
MAY OCCUR, THOUGH THE CURRENT FORECAST FALLS ABOUT 1-2 DEGREES SHY
FRIDAY-SUNDAY AT THE CLIMATE SITES. RECORD HIGH DAILY MINIMUMS ALSO
MAY OCCUR, WITH THE CURRENT FORECAST WITHIN 2-3 DEGREES THURSDAY-
SATURDAY, AND IS GOING TO BE LARGELY DEPENDENT ON THE STRENGTH OF
THE AFTERNOON SEA-BREEZE.
A STRONG UPPER LEVEL WAVE MOVING OUT OF THE ONTARIO PROVIDENCE
SUNDAY INTO MONDAY, ACCOMPANIED BY A SURFACE HIGH PRESSURE MOVING
INTO THE CENTRAL PLAINS, WILL SEND A COLD FRONT TOWARDS THE REGION
SOMETIME SUNDAY/MONDAY. SCATTERED SHOWERS ARE EXPECTED PRIOR TO THE
FRONTAL PASSAGE, WITH CURRENT FORECASTED HIGHS ON MONDAY IN THE
LOWER/MID 70S.
AVIATION /15Z MONDAY THROUGH FRIDAY/
KCHS/KJZI/KSAV: GIVEN THE BUILD DOWN OF LOW STRATUS, IFR OR
LIFR CONDITIONS WILL OCCUR THIS MORNING. CEILINGS WILL BE DOWN
AT LEAST IN THE AIRFIELD MINIMUM RANGE UNTIL ABOUT 14-15Z. AS
MIXING HEIGHTS CLIMB, A RETURN TO MVFR CEILINGS WILL THEN OCCUR,
BEFORE VFR RETURNS BY 17-18Z. A SQUALL LINE WITH ITS ASSOCIATED
CONVECTION WILL THEN SWEEP THROUGH FROM ABOUT 21Z TO 01Z,
RESULTING IN AT LEAST MVFR CONDITIONS AND BRIEFLY STRONG AND
GUSTY WINDS PEAKING AT LEAST AROUND 30 KT. VFR RETURNS
THEREAFTER, WITH SOME CHANCE FOR A FEW MORE SHOWERS LATER ON AS
THE COLD FRONT MOVES THROUGH. BEHIND THE FRONT THERE WILL ONCE
AGAIN BE THE DEVELOPMENT OF LOW STRATUS BUILDING DOWN, WITH SOME
CLEARING ATOP THE PRE-EXISTING WET GROUNDS. FLIGHT RESTRICTIONS
WILL ONCE AGAIN OCCUR LATE TONIGHT.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS CONTINUE TO REMAIN
POSSIBLE TUESDAY MORNING DUE TO BOTH SEA AND LAND FOG, WITH MVFR/IFR
VSBYS POSSIBLE. AFTER THAT, ASIDE FROM POSSIBLE LOW CEILINGS
WITH ANY ISOLATED SHOWER ACTIVITY ON WEDNESDAY, GENERALLY QUIET
AVIATION CONDITIONS ARE EXPECTED.
MARINE
TODAY AND TONIGHT: THE LOCAL AREA WILL REMAIN POSITIONED ALONG THE
WESTERN PERIPHERY OF HIGH PRESSURE CENTERED EAST OF BERMUDA WHILE A
STRONG COLD FRONT MOVES INTO THE SOUTHEAST THIS EVENING, AND MOVES
INTO OR NEAR THE LOCAL WATERS DURING THE NIGHT. SOUTH/SOUTHWEST
WINDS AROUND 15 KT OR LESS WILL OCCUR DURING THIS TIME, WITH
SOME GUSTS TO 20 KT ACROSS THE CHARLESTON HARBOR THIS AFTERNOON
AS A SEA BREEZE TAKES SHAPE. SEAS WILL GENERALLY RANGE BETWEEN
3-5 FT, LARGEST NEAR 20 NM AND FARTHER OFFSHORE ACROSS OUTER
GEORGIA WATERS.
THE BIGGEST CONCERN FOR MARINERS WILL BE STRONG AND SEVERE T-STORMS
THAT OCCUR WITH THE SQUALL LINE, AS IT IMPACTS THE LOCAL WATERS
AROUND 6-10 PM. DAMAGING WIND GUSTS IN EXCESS OF 40 OR EVEN 50 KT
CAN OCCUR, ALONG WITH FREQUENT LIGHTNING STRIKES AND BRIEF VERY
HEAVY RAINS THAT REDUCE VISIBILITIES UNDER 1 NM AT TIMES. SPECIAL
MARINE WARNINGS WILL LIKELY BE NEEDED DURING THIS TIME.
TUESDAY: PATCHY FOG WILL LIKELY LINGER/DEVELOP BEHIND THE EXITING
SHOWERS, WITH PERIODS OF WEAK AND VARIABLE WINDS ALLOWING FOR
CONVERGENCE OF HIGHER SURFACE MOISTURE.
WEDNESDAY-FRIDAY: SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTH,
WITH GENERALLY QUIET MARINE CONDITIONS FORECASTED THROUGH THE END OF
THE WEEK, WITH WINDS AROUND 10 KNOTS AND SEAS AVERAGING 3 TO 4 FT.
CLIMATE
RECORD HIGH TEMPERATURES:
APRIL 4:
KSAV: 91/1963
APRIL 5:
KCHS: 89/1978
KSAV: 90/1988
APRIL 6:
KCHS: 90/1967
KSAV: 90/1967
RECORD HIGH MINIMUM TEMPERATURES:
MARCH 31:
KCXM: 68/1938
APRIL 2:
KCHS: 65/2012
APRIL 3:
KCHS: 67/2012
KCXM: 68/2012
KSAV: 68/2012
APRIL 4:
KCHS: 70/1974
KCXM: 69/1974
KSAV: 69/1974
APRIL 5:
KCHS: 65/2017
KCXM: 67/2023
KSAV: 66/1957
APRIL 6:
KSAV: 68/2023
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
KJGX - ROBBINS AFB, GA
KVAX - MOODY AFB, GA (MAY ALSO BE UNAVAILABLE DUE TO
MAINTENANCE)
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...DPB
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...DPB
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