955
FXUS62 KCHS 291250
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
850 AM EDT THU MAY 29 2025
SYNOPSIS
A STRONG UPPER DISTURBANCE WILL MOVE THROUGH THIS AFTERNOON AND
EVENING, THEN A COLD FRONT WILL SWEEP THROUGH LATE FRIDAY. HIGH
PRESSURE WILL BUILD IN OVER THE WEEKEND INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AT 845 AM: SATELLITE IMAGES AND DOPPLER RADAR DATA INDICATED A
WEAK LAND BREEZE JUST OFF THE SC COAST. SATELLITE AND WEB CAMS
INDICATED ON SHALLOW CUMULUS CLOUDS ALONG THE LAND BREEZE. GIVEN
THE SHALLOW CLOUD DEVELOPMENT AND NON-SUPERCELL TORNADO VALUES
LESS THAN 1 UNIT, IT APPEARS THAT THE WATERSPOUT RISK IS LOW.
RECENT RUNS OF THE HRRR AND RRFS INDICATES THAT SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG AND INLAND
OF THE SEA BREEZE AND COLD POOL(S) SOURCED FROM THE MCS. THE
FORECAST UPDATE WILL FEATURE HIGHER POPS BEGINNING AN HOUR OR
TWO EARLIER. THE ENVIRONMENT APPEARS VERY SUPPORTIVE FOR STRONG
TO DAMAGING WET MICROBURST, WITH DCAPE VALUES BETWEEN 500-1000
J/KG AND MLCAPE AROUND 2000 J/KG. A SEVERE THUNDERSTORM WATCH
APPEARS POSSIBLE FOR THIS AFTERNOON AND EVENING.
PREVIOUS DISCUSSION:
TODAY: A CLOSED LOW AT 500 MB WILL BE POSITIONED JUST WEST OF THE
GREAT LAKES. ACROSS THE SOUTHEASTERN STATES THIS WILL YIELD
SOUTHWESTERLY FLOW TO PREVAIL ALOFT. A MID-LEVEL SHORTWAVE
TROUGH IS FORECAST TO PASS OVER THE SOUTHEASTERN STATES,
RIPPLING ACROSS THE SOUTHERN PERIPHERY OF THE CYCLONIC FLOW
AROUND THE CLOSED LOW. THE MAIN FORECAST HIGHLIGHT OF TODAY WILL
BE THE SHOWERS AND THUNDERSTORMS THIS AFTERNOON. CAMS HAVE BEEN
CONSISTENT IN SHOWING AN MCS OF SORTS PUSHING INTO THE WESTERN
PORTION OF THE CWA MID- AFTERNOON, BEFORE PUSHING TO THE
COASTLINE IN THE EARLY EVENING. WITH HIGH TEMPERATURES TODAY
FORECAST TO REACH INTO THE MID TO UPPER 80S, DESTABILIZATION
WILL OCCUR ACROSS THE REGION, SUPPORTING CONVECTIVE INITIATION.
DEW POINTS ARE FORECAST TO REACH INTO THE LOW TO EVEN MID 70S
THIS AFTERNOON, COINCIDING WITH PEAK HEATING. FORECAST
SOUNDINGS SHOW THAT THIS WARM AND MOIST AIRMASS WILL HAVE
BETWEEN 1500-2000 J/KG OF CAPE AS WELL AS AROUND 25 KNOTS OF
SHEAR. STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE, WITH
DAMAGING WIND GUSTS THE MAIN HAZARD AS DCAPE VALUES ARE FORECAST
TO APPROACH 800 J/KG. HOWEVER, HAIL AND AN ISOLATED TORNADO
CANNOT BE RULED OUT. THE STORM PREDICTION CENTER HAS INTRODUCED
A SLIGHT RISK (RISK LEVEL 2 OF 5) ACROSS THE FORECAST AREA FOR
TODAY. IN ADDITION TO THE SEVERE THREAT THERE IS ALSO A THREAT
OF HEAVY RAINFALL, WITH PWAT VALUES FORECAST TO REACH AROUND 2
INCHES THIS AFTERNOON. EVEN THOUGH THE SHOWERS AND THUNDERSTORMS
APPEAR TO BE RATHER PROGRESSIVE, 1-2.5 INCHES OF RAINFALL IS
FORECAST ACROSS THE FORECAST AREA THIS AFTERNOON AND INTO THIS
EVENING, WITH LOCALLY HIGHER AMOUNTS POSSIBLE.
TONIGHT: CONVECTION WILL LIKELY BE ONGOING TO START THE
OVERNIGHT PERIOD, PUSHING OFF THE COASTLINE BY MIDNIGHT.
OVERNIGHT LOWS ARE FORECAST TO DIP INTO THE MID TO UPPER 60S,
WITH AROUND 70 ALONG THE COASTLINE.
SHORT TERM /FRIDAY THROUGH SUNDAY/
A POTENT SHORTWAVE WILL PASS WELL NORTH OF THE REGION ON FRIDAY,
PUSHING A COLD FRONT INTO THE AREA DURING THE AFTERNOON. LOW AND
MID LEVEL FLOW WILL VEER AHEAD OF THE FRONT. THIS WILL RESULT IN
SOME SUBSIDENCE WHICH COULD LEAD TO A DECREASE IN OVERALL
CONVECTIVE COVERAGE ALONG AND AHEAD OF THE FRONT. HOWEVER, WITH
PWS REMAINING ABOVE 1.75", IT SHOULDN'T BE DIFFICULT TO MAINTAIN
AT LEAST SCATTERED SHOWERS AND TSTMS AHEAD OF THE FRONT. WIND
FIELDS WILL BE FAIRLY STRONG SO SOME CONVECTIVE ORGANIZATION IS
POSSIBLE. DAMAGING WINDS WOULD BE THE MAIN THREAT. THE LATEST
SPC DAY 2 CONVECTIVE OUTLOOK SEEMS REASONABLE WITH THE GREATEST
SEVERE THREAT ACROSS THE WESTERN HALF OF OUR AREA. THE LINE
COULD BE DECAYING BY THE TIME IT REACHES THE COAST.
DRY HIGH PRESSURE WILL BUILD OVER THE AREA FRIDAY NIGHT THROUGH
SUNDAY. THE 50S DEWPOINTS WILL MARK A NOTICEABLE AIRMASS CHANGE.
OVERNIGHT LOWS COULD DIP INTO THE UPPER 50S INLAND, WITH DAYTIME
HIGHS IN MOST SPOTS IN THE LOW/MID 80S.
LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/
MAINLY DRY WEATHER EXPECTED DURING THE EXTENDED AS A DEEP
LAYERED RIDGE BUILDS OVER THE AREA. WE'LL SEE A WARMING TREND
INTO THE MIDDLE OF NEXT WEEK WITH HIGHS PUSHING BACK INTO THE
UPPER 80S.
AVIATION /13Z THURSDAY THROUGH MONDAY/
LINGERING LOW STRATUS AND FOG WILL QUICKLY SCOUR OUT THIS
MORNING, WITH PREVAILING VFR THROUGH THE REMAINDER OF THE
MORNING. THUNDERSTORMS WILL IMPACT ALL OF THE TERMINALS THIS
AFTERNOON, AND THE 12Z TAFS FEATURE A TEMPO GROUP WITH TSRA,
GUSTS TO 20 KNOTS, AND MVFR CIGS FROM ROUGHLY 20Z TO 00Z. TIMING
OF THE IMPACTS FROM THE THUNDERSTORMS WILL LIKELY NEED TO BE
IRONED OUT WITH FUTURE TAF UPDATES. ONCE THUNDERSTORMS CLEAR THE
REGION LATE THIS EVENING PREVAILING VFR IS EXPECTED.
EXTENDED AVIATION OUTLOOK: OCCASIONAL VISIBILITY REDUCTIONS
EXPECTED THROUGH FRIDAY EVENING, MAINLY IN SHOWERS AND
THUNDERSTORMS.
MARINE
TODAY: THE FORECAST TODAY WILL FEATURE SOUTHERLY WINDS AROUND 10
KNOTS, WITH SEAS AVERAGING 2 TO 3 FT. A DISTURBANCE ALOFT WILL
PASS OVER THE REGION THIS AFTERNOON WITH SHOWERS AND
THUNDERSTORMS PUSHING THROUGH THE FORECAST AREA AND INTO THE
MARINE WATERS. SOME STORMS MAY PRODUCE GUSTY WINDS, POSSIBLY
NECESSITATING SPECIAL MARINE WARNINGS INTO THE EVENING.
TONIGHT: SHOWERS AND THUNDERSTORMS WILL LIKELY BE ONGOING TO
START THE OVERNIGHT PERIOD, PUSHING FURTHER INTO THE ATLANTIC
WATERS BY AROUND MIDNIGHT. THERE AFTER WINDS WILL BEGIN TO
INCREASE HEADED TOWARDS SUNRISE AS A COLD FRONT APPROACHES FROM
THE WEST. BY THE EARLY MORNING HOURS SOUTHWESTERLY WINDS 10 TO
15 KNOTS ARE FORECAST, WITH SEAS AVERAGING 2 TO 3 FT.
LOW-LEVEL WINDS WILL INCREASE ON FRIDAY AHEAD OF THE COLD FRONT.
WARMING AFTERNOON TEMPS WILL PRODUCE RELATIVELY DEEP MIXING,
WITH SOME 25 KT WIND GUSTS POSSIBLE IN CHARLESTON HARBOR. IT
CURRENTLY LOOKS TOO MARGINAL TO PULL THE TRIGGER ON A SMALL
CRAFT ADVISORY. WINDS/SEAS COULD BE CLOSE TO SCA CRITERIA ACROSS
THE CHARLESTON NEARSHORE AND GA OFFSHORE WATERS FRIDAY NIGHT
AFTER THE FRONT PASSES THROUGH, BUT AGAIN IT LOOKS PRETTY
MARGINAL.
MODERATE NW WINDS SATURDAY MORNING WILL SUBSIDE DURING THE DAY.
QUIET CONDITIONS THEN EXPECTED THROUGH EARLY NEXT WEEK.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...CPM/NED
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...CPM/JRL
MARINE...CPM/JRL
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