642
FXUS62 KCHS 181055
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
655 AM EDT FRI SEP 18 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR THE 12Z TAFS AND FOG SECTION OF KEY
MESSAGE 1.
KEY MESSAGES
- 1) WARMING TEMPERATURES AND MOSTLY DRY CONDITIONS TODAY. RAIN
CHANCES WILL THEN GRADUALLY INCREASE THIS WEEKEND AND
ESPECIALLY BY EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: WARMING TEMPERATURES AND MOSTLY DRY CONDITIONS
TODAY. RAIN CHANCES WILL THEN GRADUALLY INCREASE THIS WEEKEND
AND ESPECIALLY BY EARLY NEXT WEEK.
RECENT RUNS OF THE HRRR INDICATED THAT SFC CONDENSATION PRESSURE
DEFICITS ARE FORECAST TO LOWER BELOW 3 MBS ACROSS THE I-26 CORRIDOR
DURING THE PRE-DAWN HOURS. THE FORECAST HAS BEEN UPDATED TO ADD
A MENTION OF PATCHY FOG FOR PORTIONS DORCHESTER, BERKELEY, AND
CHARLESTON COUNTIES EARLY THIS MORNING. ANY FOG THAT DEVELOPS
SHOULD DISSIPATE DURING THE FIRST HOUR OR TWO OF SUNSHINE.
TODAY, THE FORECAST AREA WILL REMAIN BETWEEN A CLOSED LOW OVER
CENTRAL FL AND A H5 RIDGE AXIS RUNNING WEST TO EAST ACROSS NC.
FORECAST SOUNDINGS INDICATE A DRY MIXED LAYER WITH WEAK LAPSE RATES
BETWEEN 800-500 MB THROUGH THIS AFTERNOON. THE FORECAST WILL REMAIN
DRY TODAY. HIGH TEMPERATURES ARE FORECAST TO RANGE IN THE LOW TO MID
90S THIS AFTERNOON.
CONVECTION-ALLOWING MODELS SHOW A BAND OF THUNDERSTORMS DEVELOPING
FROM THE MIDLANDS EAST ACROSS THE PEE DEE REGION LATE THIS AFTERNOON
INTO THIS EVENING AHEAD OF A SFC TROUGH. THESE STORMS SHOULD PUSH
SOUTH, BUT SHOULD WEAKEN AS THEY REACH AN INCREASINGLY STABLE
ENVIRONMENT ACROSS SE GA AND THE LOWCOUNTRY. THE FORECAST WILL
FEATURE A TIER OF SCHC POPS ACROSS INLAND SC FOR SHOWERS AND
THUNDERSTORMS THIS EVENING. ANY DEEP CONVECTION SHOULD DISSIPATE
BEFORE MIDNIGHT. LOW TEMPERATURES SHOULD RANGE BETWEEN 70-75
DEGREES.
THE OVERALL PATTERN WILL CHANGE THIS WEEKEND AS A WEAK COLD FRONT
APPROACHES FROM THE NORTH. TRANSPORT OF DEEP MOISTURE WILL DRIVE
PRECIPITABLE WATER VALUES UP TO 2.1-2.3 INCHES BY SATURDAY EVENING.
THIS SET UP WILL FAVOR UNSETTLED CONDITIONS AND INCREASED RAIN
CHANCES THIS WEEKEND. GIVEN THE MOISTURE-RICH AIRMASS AND THE
PRESENCE OF ROUNDS OF CONVECTION (PRIMARILY IN THE AFTERNOON AND
EVENINGS), THERE WILL BE AT LEAST A LOW END THREAT FOR LOCALLY HEAVY
RAINFALL. HOWEVER, MINIMAL SHEAR AND MODEST INSTABILITY WILL LIMIT
THE SEVERE WEATHER THREAT.
AN UNSETTLED PATTERN COULD CONTINUE INTO THE MIDDLE OF NEXT WEEK AS
A STRONGER COLD FRONT ADVANCES ACROSS THE AREA.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
12Z TAFS: ANY GROUND FOG THIS MORNING SHOULD DISSIPATE DURING
THE FIRST HOUR OR TWO OF DAYLIGHT THIS MORNING. VFR CONDITIONS
WITH LIGHT NORTHWEST WINDS THIS MORNING. A WEAK SEA BREEZE
SHOULD ADVANCE ACROSS THE TERMINALS BETWEEN 19-20Z, TURNING
WINDS FROM THE SOUTHEAST. RECENT RUNS OF THE HRRR INDICATES THAT
ISOLATED SHOWERS AND THUNDERSTORMS THIS EVENING, GREATEST CHANCE
ACROSS KCHS AND KJZI. THE COVERAGE APPEARS TOO LIMITED TO
MENTION IN THE TAFS AT THIS TIME.
EXTENDED AVIATION OUTLOOK: RAIN CHANCES ARE EXPECTED TO INCREASE
LATE THIS WEEKEND AND INTO EARLY NEXT WEEK WHICH COULD RESULT IN
PERIODIC FLIGHT RESTRICTIONS.
MARINE
TODAY AND TONIGHT: LIGHT NORTHEAST WINDS THIS MORNING SHOULD TURN
FROM THE SOUTHEAST THIS AFTERNOON FOLLOWING THE SEA BREEZE. WINDS
MAY VEER FROM THE SOUTHWEST TONIGHT, SPEEDS LESS THAN 10 KTS. WAVE
HEIGHTS SHOULD CONTINUE TO DIMINISH TODAY, SETTLING TO AROUND 2 FT
TONIGHT.
SATURDAY THROUGH WEDNESDAY: WINDS AND SEAS ARE EXPECTED TO REMAIN
WELL BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH THE PERIOD. WINDS
WILL BE 10 KNOTS OR LESS FOR MUCH OF THIS PERIOD, WITH SEAS
GENERALLY IN THE 2-3 FT RANGE. THE MAIN FORECAST CONCERN WILL BE
INCREASING COVERAGE OF SHOWERS AND THUNDERSTORMS ACROSS THE LOCAL
WATERS, ESPECIALLY EARLY NEXT WEEK.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
BRS/NED
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