435
FXUS62 KCHS 021034
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
634 AM EDT WED APR 2 2025
SYNOPSIS
A WARM FRONT WILL BE LIFTING NORTHWARDS ACROSS THE REGION
TODAY. STRONG ATLANTIC HIGH PRESSURE WILL THEN PREVAIL INTO
THIS WEEKEND, BEFORE A COLD FRONT APPROACHES EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
EARLY THIS MORNING: WIDESPREAD STRATUS AND AREAS OF FOG, MUCH
OF WHICH WILL BE DENSE AS WE START THE DAY. BASED ON
OBSERVATIONS, TRENDS, AND MOST OF THE GUIDANCE, WE HAVE A DENSE
FOG ADVISORY IN EFFECT FOR ALL BUT THE CHARLESTON TRI-COUNTY
REGION. THOSE LOCATIONS HAVE A LITTLE MORE WIND OFF THE SURFACE,
AND A LESS PRONOUNCED INVERSION THAN ELSEWHERE. THE DENSE FOG
ADVISORY GOES THROUGH 9 AM, AND ALL FOG SHOULD HAVE DISSIPATED
BY 10 AM WHEN THE INVERSION BREAKS.
FOR TODAY: MOISTURE CONVERGENCE AND A MODEST AMOUNT OF
INSTABILITY OFF THE COAST WILL GENERATE ISOLATED SHOWERS AND
T-STORMS. WHILE WE CAN'T RULE OUT SOME OF THAT ACTIVITY MAKING
IT ONSHORE, THE BETTER PROBABILITIES REMAIN OVER THE ATLANTIC.
WE'VE UPDATED THE FORECAST TO INCLUDE A FEW SHOWERS BRUSHING
ONSHORE AT TIMES THIS MORNING. MEANWHILE, THE LARGE SCALE
PATTERN FEATURES A STRENGTHENING 500 HPA RIDGE CENTERED BETWEEN
THE BAHAMAS AND BERMUDA, ALLOWING US TO HAVE A SOUTHWEST FLOW
ALOFT. AT THE SURFACE, A WARM FRONT WILL LIFT OF THE AREA THIS
AFTERNOON, WITH STRONG HIGH PRESSURE TO EXPAND IN FROM THE
NORTHEAST AND EAST THEREAFTER. THIS WILL ALLOW FOR A FAIRLY
DECENT SEA BREEZE TO FORM DURING MIDDAY AS IT PROGRESSES INLAND.
BY LATE AFTERNOON, WITH THE SEA BREEZE INLAND FROM I-95, IT
WILL ENCOUNTER A FAIRLY DECENT ENVIRONMENT FOR ISOLATED TO
PERHAPS SHOWERS AND T-STORMS. MUCAPE IS EXPECTED TO BE AS GREAT
AS 1500-2500 J/KG, OVERLAPPED BY A REGION WHERE THERE IS A
30-50% PROBABILITY OF MAX 2-5 KM UPDRAFT STRENGTH OF GREATER
THAN 20 M/SEC. WE HAVE 20-30% POPS AS A RESULT. WE HAVE ALSO
INCLUDED A SLIGHT CHANCE OF SHOWERS AND T-STORMS ALONG HE
NORTHWARD MOVING WARM FRONT THIS AFTERNOON OVER PARTS OF THE
SOUTH CAROLINA COASTAL COUNTIES.
ALTHOUGH INSOLATION IS CUT DOWN BY THE MORNING FOG/STRATUS, 850
HPA TEMPS REACH 15-17C THIS AFTERNOON. THIS SUPPORTS HIGHS IN
THE LOWER AND MIDDLE 80S FOR MOST COMMUNITIES. WITH A
SOUTHEASTERLY SEA BREEZE AROUND 15 MPH, COASTAL SECTIONS WILL BE
COOLER AND IN THE 70S.
TONIGHT: WITH THE LOSS OF DIURNAL HEATING AND THE LACK OF
FORCING, SHOWERS AND T-STORMS WILL QUICKLY FADE DURING THE
EARLY AND MIDDLE EVENING HOURS, AND THE REST OF THE NIGHT WILL
BE RAINFREE. THE MID LEVEL RIDGE SLOWLY STARTS EXP[ANDING WEST
AND NORTHWEST, AND HEIGHTS LOCALLY BEGIN A SLOW CLIMB, WHILE A
LARGE REGION OF ATLANTIC HIGH PRESSURE ENCOMPASSES THE LOCAL
COUNTIES. WHILE THERE COULD BE A LITTLE FOG WHERE EARLIER RAIN
OCCURS, GIVEN 15-20 KT OF 1000 MB GEOSTROPHIC WINDS, NO MENTION
IS REQUIRED AS OF THIS TIME. THOSE WINDS WILL PREVENT FULL
DECOUPLING OVER MOST OF THE REGION, AND THAT ALONG WITH A SOUTH-
SOUTHEAST LOW LEVEL FLOW WILL LIMIT MINIMUM TEMPS TO JUST THE
MIDDLE 60S, OR AROUND 15F ABOVE CLIMO.
SHORT TERM /THURSDAY THROUGH SATURDAY/
WARM/HOT TEMPERATURES ARE THE MAIN STORY FOR THE SHORT TERM. UPPER
LEVEL RIDGING STRENGTHENS ON THURSDAY AND AGAIN ON FRIDAY, AND WITH
SITUATIONAL AWARENESS TABLES (ESATS) SHOWING RECORD HIGH 500 HPA
GEOPOTENTIAL HEIGHTS OCCURRING IN RELATION TO 30-YEAR NORMALS,
WARM/HOT TEMPERATURES ARE EXPECTED. ESATS ALSO SHOW TEMPERATURES AT
850 HPA OVER THE 90TH PERCENTILE OF CLIMATOLOGY ARE EXPECTED,
RESULTING IN AFTERNOON HIGHS IN THE LOWER TO UPPER 80S FOR INLAND
AREAS, AND MID 70S TO LOWER 80S ALONG THE COAST. FRIDAY IS LOOKING
TO BE A DEGREE OR TWO WARMER GIVEN THE CONTINUED STRENGTHENING OF
THE UPPER LEVEL RIDGE, WITH AFTERNOON HIGHS IN THE MID 80S TO LOWER
90S FOR INLAND AREAS, AND UPPER 70S TO MID 80S ALONG THE COAST. THE
GOOD NEWS? THESE TEMPERATURES WILL BE BROUGHT DOWN TO THE SURFACE BY
MIXY WINDS, SO EXPECT AT LEAST A SLIGHT BREEZE TO HELP COOL-DOWN.
CAN'T RULE OUT SOME 90 DEGREE TEMPERATURES ON THURSDAY, AS NBM
PROBABILITIES SHOW 20-30% CHANCES ACROSS INLAND SC COUNTIES,
REACHING UP INTO THE 50-70% RANGE FOR INLAND GA COUNTIES.
PROBABILITIES INCREASE ON FRIDAY, WITH NBM PROBABILITIES SHOW 30-50%
CHANCES ACROSS INLAND SC COUNTIES, REACHING UP INTO THE 60-80% RANGE
FOR INLAND GA COUNTIES. THE ADDITIONAL 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.
SATURDAY WILL BEGIN TO SEE THE WEAKENING/SHIFTING OF THE UPPER LEVEL
RIDGE AXIS, BUT GIVEN THE LACK OF A FRESH AIRMASS EXPECT A NEAR
CARBON COPY OF FRIDAY FOR SATURDAY. OVERNIGHT LOWS THURSDAY NIGHT
THROUGH SATURDAY FALL INTO THE MID TO UPPER 60S. RECORD HIGH DAILY
MAXIMUMS MAY OCCUR ON SATURDAY, THOUGH THE CURRENT FORECAST FALLS
ABOUT 2 DEGREES SHY AT THE CHARLESTON AIRPORT. RECORD HIGH DAILY
MINIMUMS LOOK MUCH MORE LIKELY, WITH THE CURRENT FORECAST WITHIN 2-3
DEGREES THURSDAY-SUNDAY, BUT IS GOING TO BE LARGELY DEPENDENT ON THE
STRENGTH OF THE AFTERNOON SEA-BREEZE.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/
A STRONG UPPER LEVEL WAVE MOVES OUT OF THE ONTARIO PROVIDENCE SUNDAY
INTO MONDAY, BUT BEFORE THAT REACHES THE AREA ANOTHER DAY WITH HIGHS
IN THE MID 80S TO LOWER 90S ARE EXPECTED. RELIEF IS IN SIGHT AS THE
STRONG AFOREMENTIONED WAVE IS ACCOMPANIED BY A SURFACE HIGH PRESSURE
MOVING INTO THE CENTRAL PLAINS, WHICH WILL HELP SEND A COLD FRONT
TOWARDS THE REGION SOMETIME SUNDAY/MONDAY. SCATTERED SHOWERS ARE
EXPECTED PRIOR TO THE FRONTAL PASSAGE, WITH THE NBM BRINGING CHANCES
(20-30%) FOR SCATTERED SHOWERS STARTING LATE SUNDAY AFTERNOON,
THOUGH THE BULK OF THE RAIN IS EXPECTED MONDAY MORNING INTO THE
AFTERNOON HOURS AS THE FRONT PUSHES. NBM DOES SEEM TO HANG ONTO THE
CHANCES FOR RAINFALL FOR TOO LONG, BUT LOOKING AT THE ENSEMBLES THIS
LARGELY DUE TO THE TIMING DIFFERENT AMONGST THE MODELS. CURRENT
FORECASTED HIGHS ON MONDAY ARE IN THE LOWER/MID 70S, FALLING INTO
THE UPPER 60S LOWER 70S ON TUESDAY.
AVIATION /11Z WEDNESDAY THROUGH SUNDAY/
KCHS/KJZI: IT LOOKS LIKE THE WORST OF THE STRATUS AND FOG WILL
STAY TO THE SOUTH AND SOUTHWEST OF THE TERMINALS INTO WEDNESDAY
MORNING. BUT EVEN SO, MVFR OR POSSIBLE IFR WILL OCCUR UNTIL
AROUND 1330Z, WITH A MOISTURE TRAPPED BENEATH A 1-2C INVERSION.
CONDITIONS RETURN TO VFR THEREAFTER AS THE INVERSION CLIMBS.
WE'LL HAVE TO KEEP WATCH FOR A RETURN OF FLIGHT RESTRICTIONS
LATER TONIGHT. MEANWHILE, AS A WARM FRONT LIFTS PAST THESE SITES
THIS MORNING, THERE COULD BE A FEW SHOWERS AROUND THE AREA.
COVERAGE IS TOO SMALL TO INCLUDE ANYTHING AT THIS TIME.
KSAV: THERE IS ALREADY LOW CEILINGS AS WE BEGIN THE 06Z TAF
CYCLE, AND WITH A STRONGER INVERSION THAN THOSE SITES TO THE
NORTH, WE ANTICIPATE EVEN WORSE CONDITIONS WILL DEVELOP,
POTENTIALLY DOWN NEAR AIRFIELD MINS. WHILE THERE IS IMPROVING
CEILINGS/VISIBILITIES BY 1330Z, IT'LL TAKE UNTIL AROUND 16Z
BEFORE VFR RETURNS. FLIGHT RESTRICTIONS COULD RETURN AGAIN LATER
TONIGHT.
WITH THE PASSAGE OF THE SEA BREEZE THIS AFTERNOON, GUSTY S-SE
WINDS WILL PEAK AROUND 18-22 KT UNTIL CLOSE TO SUNSET.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS MAY BE POSSIBLE
THURSDAY MORNING DUE TO BOTH SEA AND LAND FOG, WITH PATCHY MVFR/IFR
VSBYS POSSIBLE. AFTER THAT, GENERALLY QUIET AVIATION CONDITIONS
ARE EXPECTED THROUGH SUNDAY.
MARINE
TODAY: A WARM FRONT WILL LIFT NORTH OF THE WATERS THIS MORNING,
WITH STRONG HIGH PRESSURE TO EXPAND IN FROM THE NE AND E THE
REST OF THE DAY. THE LOCAL GRADIENT WILL TIGHTEN SOMEWHAT, AND
THAT ALONG WITH THE SEA BREEZE WILL RESULT IN WINDS VEERING TO
THE SE AS HIGH AS 10-15 OR 15 KT. CHARLESTON HARBOR WILL
EXPERIENCE SOME GUSTS AROUND 20 KT THIS AFTERNOON DUE TO DEEPER
MIXING DUE TO THE NEARBY WARMER LAND MASS. SEAS WILL BE A MIX
OF WIND DRIVEN WAVES AND SWELLS, CLIMBING TO 2-4 FEET.
THE COVERAGE OF THE FOG HAS DIMINISHED SINCE EARLIER, AND THE
DENSE FOG ADVISORY HAS BEEN CANCELLED. WE STILL MAINTAIN PATCHY
FOG THROUGH THE MORNING HOURS, BUT WITH THE FORMATION OF THE SEA
BREEZE, EDIFIER IS LEFT BY THEN WILL HAVE DISSIPATED.
TONIGHT: HIGH PRESSURE WILL CONTROL THE WEATHER ACROSS THE AREA,
AND WITH INCREASING LOW LEVEL WINDS, SURFACE WINDS WILL ALSO
RESPOND. SE WINDS WILL CLIMB UP TO ANOTHER 5 KT OR SO, EXCEPT
HOLDING AT SIMILAR SPEEDS WITH LESS GUSTINESS IN CHARLESTON
HARBOR. SEAS BUILD UP TO ANOTHER FOOT GIVEN THE HIGHER WINDS.
RIP CURRENTS: A MODEST ONSHORE WIND, AND SWELLS AROUND 3 FEET
EVERY 10 SECONDS, WILL RESULT IN A MODERATE RISK OF RIP
CURRENTS AT ALL BEACHES TODAY.
THURSDAY: MODERATE RISK FOR RIP CURRENTS CONTINUES ON THURSDAY, WITH
NEAR-SHORE WINDS REMAINING OUT OF THE SOUTH-SOUTHEAST AT AROUND 10-
12 KNOTS, BRINGING WAVES OF 3-4 FEET INTO THE BEACH ZONES EVERY 8-10
SECONDS.
THURSDAY - SATURDAY: SURFACE HIGH PRESSURE OFF TO OUR EAST,
WITH GENERALLY QUIET MARINE CONDITIONS FORECASTED INTO THE
WEEKEND, WITH WINDS AROUND 10 KNOTS AND SEAS AVERAGING 3 TO 4 FT
IN THE NEAR-SHORE WATERS, FAIRLY CONSISTENTLY NEAR 4 FEET IN
THE OFFSHORE GEORGIA ZONE
SUNDAY: THE SURFACE PRESSURE GRADIENT BEGINS TO RISE OVERNIGHT INTO
SUNDAY, REMAINING ELEVATED THROUGHOUT THE DAY. CURRENTLY HAVE WINDS
REMAINING BELOW SMALL CRAFT CRITERIA, BUT SOMETHING TO KEEP AN EYE
ON AS WE GET CLOSER TO THE WEEKEND.
CLIMATE
RECORD HIGH TEMPERATURES:
APRIL 5:
KSAV: 90/1988
APRIL 6:
KSAV: 90/1967
RECORD HIGH MINIMUM TEMPERATURES:
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:
KCHS: 68/2023 KSAV: 68/2023
CHS WATCHES/WARNINGS/ADVISORIES
GA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR GAZ087-088-
099>101-114>119-137>141.
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ040-042-
043-047>049-051.
MARINE...NONE.
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
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