471
FXUS62 KCHS 301754
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
154 PM EDT FRI MAY 30 2025
SYNOPSIS
A COLD FRONT WILL SWEEP THROUGH OUR AREA THIS EVENING. HIGH
PRESSURE WILL BUILD IN OVER THE WEEKEND AND PREVAIL THROUGH THE
MIDDLE OF NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
1PM: REGIONAL RADARS CURRENTLY SHOW THE LINE OF CONVECTION WELL
UPSTREAM AND MOVING INTO THE APPALACHIANS. TIMING STILL LOOKS
TO BE ON TRACK FOR AN ETA AROUND 4PM (+/- 1 HR) INTO OUR FAR
WESTERN COUNTIES AND THUS WE INCREASED POPS TO LIKELY ACROSS THE
AREA TO ACCOUNT FOR THE GREATER CONFIDENCE. CAMS HAVE BEEN
CONSISTENTLY SHOWING BOWING SEGMENTS APPEAR IN SIMULATED
REFLECTIVITY MOVING ACROSS SOME PORTIONS OF THE SOUTHEAST SOUTH
CAROLINA COUNTIES, WHICH CONFIRMS THE WIND THREAT IS STILL A
MAJOR PLAYER ESPECIALLY FOR THAT AREA. OTHERWISE, OUR EARLIER
THINKING STILL REMAINS THE SAME.
TODAY: A SHORTWAVE WILL MOVE EAST OF THE AREA BY DAYBREAK.
LINGERING DEBRIS CLOUDINESS SHOULD BURN OFF BY MID-MORNING AS
NVA DEVELOPS IN ITS WAKE. VEERING BL WIND PROFILES WILL PRODUCE
SOME COMPRESSIONAL HEATING WHICH, ALONG WITH MOSTLY SUNNY SKIES
LATE MORNING INTO EARLY AFTERNOON, SHOULD PUSH TEMPS INTO THE
MID TO UPPER 80S. WITH THE MIXED LAYER EXPANDING TO ABOUT 5 KFT,
SURFACE DEWPOINTS MAY MIX OUT SOMEWHAT, THOUGH BLENDED GUIDANCE
STILL KEEPS VALUES IN THE UPPER 60S IN MOST AREAS. PWS WILL SEE
A LATE MORNING MINIMUM BEFORE INCREASING BACK ABOVE 1.75" LATER
THIS AFTERNOON. A SHORTWAVE WILL MOVE THROUGH CENTRAL AND
EASTERN NC LATER THIS AFTERNOON WITH A WEAKER VORT MOVING
THROUGH SC/GA. A COLD FRONT IS EXPECTED TO DROP SOUTHEAST INTO
OUR FORECAST AREA LATE THIS AFTERNOON AND MOVE OFFSHORE BY
MIDNIGHT.
THE MAIN QUESTION IS COVERAGE AND INTENSITY OF CONVECTION AHEAD
OF THE COLD FRONT. THE VEERING BL FLOW WILL RESULT IN WINDS
RELATIVELY PARALLEL TO THE FRONT BY THE TIME IT REACHES OUR
AREA. THIS DECREASE IN LOW-LEVEL CONVERGENCE MAY RESULT IN A
THINNING OR WEAKENING CONVECTIVE BAND AS IT MOVES THROUGH.
HOWEVER, IF A PARTICULARLY ROBUST MCS DEVELOPS UPSTREAM IT COULD
HOLD ITS MOMENTUM AS IT MOVES INTO OUR AREA. CONVECTIVE INDICES
ARE FORECAST TO BE FAIRLY IMPRESSIVE. 0-6 KM BULK SHEAR APPROACHES
45 KT ALONG THE SC/GA COAST LATE THIS AFTERNOON WHILE SBCAPE
COULD BE PUSHING 2000 J/KG IN SPOTS. DAMAGING WINDS WOULD BE THE
PRIMARY THREAT, THOUGH LIFTED INDICES OF -6C WOULD SUPPORT SOME
HAIL RISK, AND 1-2 EHI WOULDN'T COMPLETELY RULE OUT AN ISOLATED
TORNADO. IT APPEARS THE EARLIEST WE COULD SEE THE STORMS MOVING
INTO OUR NORTHWESTERN ZONES WOULD BE 2-3PM WITH THE GREATEST
THREAT WINDOW 4-8PM.
TONIGHT: COOLER, DRIER AIR WILL SPREAD IN FROM THE WEST LATE
THIS EVENING AND OVERNIGHT. SATURDAY MORNING LOWS COULD DIP INTO
THE UPPER 50S AWAY FROM THE COAST.
SHORT TERM /SATURDAY THROUGH MONDAY/
THE MID-LEVELS WILL CONSIST OF A LONGWAVE TROUGH OVER THE EAST COAST
SATURDAY MORNING, WITH AN EMBEDDED LOW NORTH OF NEW ENGLAND. THESE
FEATURES SHOULD HOVER IN PLACE THROUGH SUNDAY. BY SUNDAY NIGHT, THE
LOW LIFTS FURTHER NORTH AND WEAKENS, WHILE A WEAK SHORTWAVE ROUNDS
THE BASE OF THE TROUGH, MOVING OVER OUR AREA LATE SUNDAY NIGHT OR
MONDAY MORNING. THE TROUGH AXIS SHOULD THEN SHIFT OFFSHORE LATE
MONDAY, FOLLOWED BY RIDGING BUILDING IN FROM THE WEST. AT THE
SURFACE, HIGH PRESSURE CENTERED OVER THE SOUTHERN PLAINS SATURDAY
MORNING WILL SHIFT OVER THE LOWER MS VALLEY SATURDAY EVENING, THEN
NEAR THE FL PANHANDLE SUNDAY MORNING, WHILE WEAKENING AND BECOMING
DIFFUSE. THE WEAK HIGH MAY BE IN THE VICINITY OF OUR AREA SUNDAY
EVENING. ADDITIONALLY, A DISSIPATING COLD FRONT MAY MOVE THROUGH OUR
AREA LATE SUNDAY NIGHT. AFTERWARDS, HIGH PRESSURE IS EXPECTED TO
STRENGTHEN OVER THE MIDDLE APPALACHIANS MONDAY MORNING, THEN PASSING
TO OUR NORTH BY LATER MONDAY. THE HIGH IS EXPECTED TO BE THE PRIMARY
SYNOPTIC FEATURE IN OUR AREA, LIMITING MOISTURE. PWATS SHOULD DROP
BELOW 1" ON SATURDAY BEFORE RISING BACK ABOVE 1" SATURDAY
EVENING/NIGHT, THEN CONTINUING TO RISE TO ~1.25" BY LATE SUNDAY.
ALL OF THESE VALUES ARE BELOW NORMAL. HENCE, THE DETERMINISTIC
MODELS KEEP OUR AREA DRY ON SATURDAY. SOME MODELS HINT AT UPSTREAM
CONVECTION MAKING IT TO OUR AREA LATE IN THE DAY SUNDAY AND MONDAY.
BUT GIVEN THE PWATS, IT MIGHT BE HARD TO GET ANY RAINFALL. SO WE
KEPT THE FORECAST DRY. HIGH TEMPERATURES WILL PEAK IN THE LOW TO MID
80S SATURDAY, THEN RISE TO THE MID TO UPPER 80S SUNDAY AND MONDAY,
EXCEPT COOLER AT THE BEACHES DUE TO THE SEA BREEZE. SATURDAY AND
SUNDAY NIGHT LOWS SHOULD RANGE FROM THE LOWER 60S FAR INLAND TO THE
UPPER 60S/LOWER 70S AT OR NEAR THE BEACHES.
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
MID-LEVEL RIDGING WILL BUILD OVER THE EAST COAST MONDAY NIGHT INTO
TUESDAY, THEN POSSIBLY PREVAIL THROUGH THURSDAY. SURFACE HIGH
PRESSURE INITIALLY OVER THE MIDDLE APPALACHIANS SHOULD SHIFT INTO
THE ATLANTIC, ALL WHILE BEING THE DOMINANT WEATHER FEATURE FOR OUR
WEATHER. THIS WILL LEAD TO MOSTLY DRY CONDITIONS AND GRADUALLY
RISING TEMPERATURES EACH DAY.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
A LINE OF THUNDERSTORMS IS EXPECTED TO PRECEDE A COLD FRONT
AND MOVE ACROSS THE TERMINALS EARLY THIS EVENING. WE INTRODUCED
A 2-HR TEMPO OF TSRA WITH GUSTY WINDS AND LOWERED VISIBILITIES
DURING THE TIME OF IMPACT. STORMS WILL BE MOVING FROM THE
NORTHWEST AND LIKELY TO REACH KCHS/KJZI AROUND 22Z AND THEN
KSAV ABOUT AN HOUR LATER. ALSO STORMS SHOULD BE MOVING
RELATIVELY QUICK SO THE 2 HOUR WINDOW WOULD LIKELY BE PLENTY
LONG ENOUGH TO COVER THE IMPACTS. THESE STORMS COULD BE STRONG
TO SEVERE, WITH THE GREATER CHANCE ACROSS KCHS/KJZI. THEREFORE
WE INCLUDED GUSTS OF 30-35 KT AT KCHS AND KJZI WITH 25 KT AT
KSAV, BUT THERE COULD BE STRONGER GUSTS IF THE SEVERE THREAT
COMES TO REALIZATION. HOWEVER, THE ACTIVITY COULD BE ON A
DIMINISHING TREND BY THE TIME IT REACHES THE TERMINALS, SO THERE
IS STILL SOME UNCERTAINTY REGARDING THE STRENGTH. ONCE
CONVECTION ENDS, WE EXPECT FAIRLY RAPID CLEARING WITH CLEAR
SKIES AND SOLID VFR CONDITIONS BY SATURDAY MORNING.
EXTENDED AVIATION OUTLOOK: GUSTY W WINDS ARE POSSIBLE ON SATURDAY.
OTHERWISE, VFR SHOULD PREVAIL.
MARINE
WE OPTED TO ISSUE A SMALL CRAFT ADVISORY FOR THE CHARLESTON
COUNTY NEARSHORE WATERS INTO TONIGHT, CONSIDERING SOME OBS HAVE
BEEN SHOWING GUSTS 23-25 KT SO FAR THIS MORNING.
SW TO WSW WINDS WILL INCREASE LATE THIS MORNING THROUGH THE
AFTERNOON AS A COLD FRONT APPROACHES. WIND GUSTS IN CHARLESTON
HARBOR AND THE NEARSHORE CHARLESTON COUNTY WATERS COULD REACH 25
KT FOR A FEW HOURS LATE THIS AFTERNOON THROUGH EARLY EVENING.
FOR NOW WE CAPPED WINDS AT 15-20 KT IN BOTH ZONES GIVEN THE
MARGINAL NATURE AND LOW-CONFIDENCE, HOWEVER LATER SHIFTS MAY
NEED TO REASSESS FOR A POSSIBLE SMALL CRAFT ADVISORY. WINDS
BECOME W OR NW LATER TONIGHT.
THERE SHOULD BE A SURGE IN SW WINDS LATER SATURDAY. BUT WIND
GUSTS SHOULD STAY BELOW 25 KT, SO NO SMALL CRAFT ADVISORIES ARE
EXPECTED. CONDITIONS IMPROVE MORE ON SUNDAY, WITH NO MAJOR
CONCERNS LATER INTO THE WEEK.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 AM EDT SATURDAY FOR AMZ350.
NEAR TERM...BRS/JRL
SHORT TERM...MS
LONG TERM...MS
AVIATION...BRS/MS
MARINE...JRL/MS
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