522
FXUS62 KCHS 140157
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
957 PM EDT THU MAR 13 2025
SYNOPSIS
A WEAK COLD FRONT WILL APPROACH OVERNIGHT INTO FRIDAY, BEFORE
LIFTING BACK NORTH AS A WARM FRONT. A STRONGER COLD FRONT WILL
PUSH THROUGH THE REGION ON SUNDAY. HIGH PRESSURE WILL RETURN TO
THE REGION EARLY NEXT WEEK.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
SHORT-WAVE TROUGH AXIS IS PUSHING OFF THE SOUTHEAST COAST THIS
EVENING. EARLIER SHOWERS/THUNDERSTORMS MOVING THROUGH
CENTRAL/SOUTHERN GEORGIA WITH THIS FEATURE HAVE FIZZLED NEARLY
COMPLETELY AT THIS JUNCTURE. THUS SHOWER/THUNDER MENTION HAS
BEEN REMOVED FROM THE FORECAST WITH THE MID EVENING UPDATE.
SKIES WILL CLEAR IN WAKE OF THE SHORT WAVE OVERNIGHT, BEFORE
THE DEVELOPMENT OF FOG AND STRATUS MOVING IN FROM THE SOUTH-
SOUTHWEST AFTER 3 OR 4 AM. THESE CONDITIONS LOOK TO ADVECT IN
FROM THE SOUTH AND WEST OF THE AREA, AS SHOWN BY A VARIETY OF
GUIDANCE. THIS INCLUDES THE NBM, LAMP, SIMULATED SATELLITE, ETC.
THIS LOOKS TO RESULT IN LOCATIONS MAINLY SOUTH OF THE
CHARLESTON TRI-COUNTY DISTRICT WHERE THE BETTER CONDENSATION
PRESSURE DEFICITS OVERLAP WITH GREATER LOW LEVEL MOISTURE.
FOG WORDING HAS BEEN NUDGED UP A BIT ACROSS SOUTHEAST
GEORGIA...PATCHY-AREAS...BUT THERE IS A CHANCE FOR GREATER
COVERAGE, AND EVEN A RISK FOR DENSE FOG. OVERNIGHT SHIFT WILL
NEED TO MONITOR CONDITIONS FOR POSSIBLE DFA TOWARD MORNING.
WINDS WILL DECOUPLE SHORTLY RESULTING IN MANY PLACES GOING
LIGHT OR CALM. ONCE THE CLOUDS WITH THE SHORT WAVE DIMINISH,
THIS WILL RESULT IN DECENT RADIATIONAL COOLING. AS SUCH, LOWS
WILL DROP INTO THE MIDDLE 40S AND LOWER 50S INLAND, WITH MIDDLE
50S NEAR AND ALONG THE COAST.
THERE WILL CONTINUE TO BE SMOKE/HAZE IN THE SKIES DUE TO A
CONSIDERABLE AMOUNT OF WILDFIRES IN THE SOUTHEAST. THERE HAVE
BEEN SOME INDICATIONS OF REDUCED VISIBILITY AT A FEW SITES, AS
WELL AS ON WEBCAMS. THE HRRR SMOKE GRAPHICS DON'T SHOW ANY
REDUCTIONS IN SURFACE VISIBILITY, SO WE HAVE NOT INCLUDED IT IN
THE FORECAST.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/
A MID LEVEL RIDGE WILL BUILD OVER THE AREA ON FRIDAY AND THEN WILL
SHIFT OFFSHORE ON SATURDAY IN ADVANCE OF THE NEXT WEATHER SYSTEM. AT
THE SURFACE, A WEAK FRONT LINGERING NEAR THE REGION WILL LIFT BACK
NORTH AS A WARM FRONT, WITH THE FORECAST AREA BECOMING POSITIONED IN
BETWEEN HIGH PRESSURE OFFSHORE AND A COLD FRONT APPROACHING FROM THE
WEST. MODELS HINT AT A FEW SHOWERS POSSIBLY MAKING A RUN FOR THE
COAST ON SATURDAY, BUT PROBABILITIES REMAIN LESS THAN 20%, SO A DRY
FORECAST PREVAILS BOTH DAYS. A TIGHTENING PRESSURE GRADIENT WILL
LEAD TO GUSTY SOUTH WINDS DEVELOPING ON SATURDAY INTO SATURDAY
NIGHT, AND A LAKE WIND ADVISORY FOR LAKE MOULTRIE COULD BE REQUIRED.
TEMPERATURES WILL BE SEASONABLY WARM, ESPECIALLY ON SATURDAY WHEN
HIGHS REACH THE UPPER 70S TO LOWER 80S, PERHAPS EVEN MID 80S IN
SPOTS, OVER MOST LOCATIONS AWAY FROM THE IMMEDIATE COAST. LOWS WILL
BE IN THE MID/UPPER 50S FRIDAY NIGHT, THEN ONLY FALLING TO THE
LOW/MID 60S FOR SATURDAY NIGHT. CONDITIONS COULD BECOME FAVORABLE
FOR FOG LATE FRIDAY NIGHT INTO SATURDAY MORNING.
MOST ACTIVE DAY OF THE SET WILL BE SUNDAY AS A STRONG COLD FRONT
IMPACTS THE REGION. GUIDANCE IS CONSISTENT IN BRINGING A BAND OF
SHOWERS WITH EMBEDDED THUNDERSTORMS THROUGH THE AREA AHEAD OF THE
FRONT. THERE REMAINS A RISK FOR STRONG TO POTENTIALLY SEVERE STORMS
WITH DEEP LAYER SHEAR INCREASING TO 50+ KNOTS. INSTABILITY PROGS ARE
NOT SUPER IMPRESSIVE, WITH MOST INDICATING LESS THAN 500 J/KG CAPE,
THOUGH SOME PLACES OVER SOUTHEAST GEORGIA COULD EXCEED THAT.
DAMAGING WIND GUSTS WOULD BE THE PRIMARY THREAT, ALTHOUGH AN
ISOLATED TORNADO CANNOT BE RULED OUT. RAINFALL TOTALS FOR THIS EVENT
ARE FORECAST TO AVERAGE IN THE 1/2 - 1 INCH RANGE. OTHERWISE, IT
WILL REMAIN GUSTY OUTSIDE OF CONVECTION, WITH GUSTS UP TO AROUND 30
MPH. HIGHS SHOULD PEAK IN THE MID TO UPPER 70S.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
HIGH PRESSURE WILL BUILD IN ON MONDAY BEHIND A DEPARTING COLD FRONT
AND REMAIN THE PRIMARY FEATURE THROUGH WEDNESDAY. ALOFT, A TROUGH
AXIS WILL EXIT EAST OFF THE COAST MONDAY, ALLOWING HEIGHTS TO BUILD
OVER THE REGION. QUIET AND DRY WEATHER IS EXPECTED. TEMPERATURES A
TOUCH BELOW NORMAL ON MONDAY WILL WARM THROUGH THE PERIOD.
AVIATION /02Z FRIDAY THROUGH TUESDAY/
00Z TAFS: OVERALL VFR CONDITIONS WILL PREVAIL AT KCHS AND KJZI
THROUGH 00Z SATURDAY.
FOR KSAV, VFR WILL GENERALLY PREVAIL, ALTHOUGH THEY DO HAVE A
GREATER CHANCE OF EXPERIENCING SOME FOG AND/OR LOW STRATUS FROM
ABOUT 10-14Z FRIDAY. 00Z TERMINAL FORECASTS WILL HAVE A BRIEF
PERIOD OF MVFR VSBYS BETWEEN 10Z AND 14Z ALONG WITH A SCT CLOUD
BELOW 1K.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS ARE POSSIBLE IN
FOG/STRATUS LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING, AND THEN
IN SHOWERS AND THUNDERSTORMS SUNDAY ASSOCIATED WITH A COLD FRONT.
GUSTY WINDS ARE LIKELY SATURDAY AFTERNOON INTO SUNDAY.
MARINE
A WEAK COLD FRONT WILL APPROACH FROM THE NORTH LATE TONIGHT,
WHILE ATLANTIC HIGH PRESSURE IS POSITIONED TO OUR EAST, SOUTH,
AND SOUTHEAST. S AND SW WINDS WITH SEA BREEZE INFLUENCES WILL
WANE THIS EVENING, BEFORE THEY TURN MORE SW, THEN EVENTUALLY
TOWARD THE W LATE AS LAND BREEZE CIRCULATIONS DEVELOP LATE.
WINDS WILL BE AS HIGH AS 15 KT AND GUSTY EARLY ON, DROPPING TO
MAINLY 10 KT OR LESS LATE. SEAS WILL AVERAGE 2 OR 3 FEET,
FALLING UP TO A FOOT OR SO BEFORE MORNING WITH THE LIGHTER
WINDS AND OFFSHORE FETCH.
TWO ITEMS FOR MARINERS TO CONSIDER: FIRST WOULD BE THE RISK FOR
ISOLATED T-STORMS BETWEEN 10 PM AND 12 AM OVER THE NEARSHORE
GEORGIA WATERS, AS A SHORT WAVE MOVES THROUGH. SECONDLY, SOME
FOG IS EXPECTED VERY LATE TONIGHT INTO FRIDAY MORNING, MOST
LIKELY IN THE SAVANNAH RIVER/PORT OF SAVANNAH. DENSE FOG COULD
OCCUR. AS WINDS TURN WESTERLY, SOME OF THE FOG OVER LAND COULD
ADVECT INTO THE IMMEDIATE COASTAL WATERS CLOSE TO DAYBREAK,
MAINLY SOUTH OF THE EDISTO RIVER. WHILE WE CAN'T RULE OUT THE
FOG IMPACTING THE CHARLESTON WATERS, INCLUDING CHARLESTON
HARBOR, THE PROBABILITIES ARE LOW ENOUGH NOT TO MENTION IN THE
LATEST FORECAST.
FRIDAY THROUGH TUESDAY: EAST/SOUTHEAST WINDS ON FRIDAY WILL TURN
MORE SOUTHERLY ON SATURDAY WITH SPEEDS AND SEAS REMAINING BELOW
SMALL CRAFT ADVISORY LEVELS. CONDITIONS WILL DETERIORATE SATURDAY
EVENING INTO SUNDAY AHEAD OF AN APPROACHING COLD FRONT, WITH
ADVISORIES EXPECTED OVER ALL COASTAL WATERS, INCLUDING THE
CHARLESTON HARBOR. THERE IS A LOW-END CHANCE FOR GUSTS TO NEAR GALE
FORCE. THERE SHOULD BE IMPROVEMENT SUNDAY NIGHT INTO MONDAY
FOLLOWING FRONTAL PASSAGE, WITH ALL ADVISORIES EXPECTED BE DOWN BY
MID-DAY MONDAY. NO ADDITIONAL CONCERNS THROUGH TUESDAY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
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