211
FXUS62 KCHS 020606
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
206 AM EDT WED SEP 2 2026
WHAT HAS CHANGED
ALL KEY MESSAGES AND SECTIONS WERE UPDATED.
KEY MESSAGES
- 1) LOCALLY DENSE FOG POSSIBLE THIS MORNING AND AGAIN THURSDAY
MORNING.
- 2) BELOW NORMAL RAIN CHANCES THROUGH SATURDAY WITH INCREASING
RAIN CHANCES THROUGH LABOR DAY.
- 3) HOT AND HUMID CONDITIONS EXPECTED INTO THE UPCOMING
WEEKEND.
DISCUSSION
KEY MESSAGE 1: LOCALLY DENSE FOG POSSIBLE THIS MORNING AND AGAIN
THURSDAY MORNING.
THE BOUNDARY LAYER HAS CHANGED LITTLE SINCE TUESDAY AND
CONDITIONS APPEAR FAVORABLE FOR ANOTHER ROUND OF LOW CLOUDS AND
FOG TO DEVELOP. THE LOWEST 1000 HPA CONDENSATION PRESSURE
DEFICITS ARE PROGGED TO OCCUR ACROSS THE COASTAL CORRIDOR (AWAY
FROM THE BEACHES) AND THIS IS WHERE THE GREATEST RISK FOR SOME
LOCALLY DENSE FOG WILL OCCUR. IT IS UNCLEAR HOW EXPANSIVE ANY
FOG WILL BECOME, ESPECIALLY IF LOW STRATUS BUILDS DOWN TO THE
SURFACE SIMILAR TO WHAT OCCURRED AROUND THE CHARLESTON METRO
AREA TUESDAY MORNING. DEPENDING ON HOW CONDITIONS TREND THROUGH
DAYBREAK, A SPECIAL WEATHER STATEMENT, OR WORSE A DENSE FOG
ADVISORY, MAY BE NEEDED.
ANOTHER ROUND OF FOG/STRATUS APPEARS LIKELY AGAIN EARLY THURSDAY
MORNING WITH SIMILAR BOUNDARY LAYER CONDITIONS EXPECTED. MODEL
1000 HPA CONDENSATION PRESSURE DEFICITS ARE ACTUALLY LOWER
COMPARED TO THE PAST FEW DAYS WITH MORE OF A DEEPER ONSHORE FLOW,
SO THE RISK FOR MORE EXTENSIVE FOG SEEMS TO BE TRENDING HIGHER.
FOG WITH "PATCHY" AND "AREAS OF" QUALIFIERS WERE INTRODUCED TO
ACCOUNT FOR THIS.
KEY MESSAGE 2: BELOW NORMAL RAIN CHANCES THROUGH SATURDAY WITH
INCREASING RAIN CHANCES THROUGH LABOR DAY.
TODAY: A POWERFUL 595 DM UPPER-LEVEL ANTICYCLONE CENTERED OVER
THE SOUTHERN APPALACHIANS WILL MAINTAIN ITS INFLUENCE ON THE
REGION TODAY. MODEL SOUNDINGS SUGGEST THE ATMOSPHERE WILL REMAIN
QUITE DRY THROUGHOUT THE COLUMN WITH EXTENSIVE MID-LEVEL DRY
AIR NOTED. PWATS ARE PROGGED TO LOWER TO 1.60-1.90" WITH 850
HPA THETA-E VALUES DROPPING BELOW 330K, ESPECIALLY ALONG THE
COASTAL CORRIDOR. WHILE MODIFIED MODEL SOUNDINGS DO NOT
EXPLICITLY SHOW A CAPPING INVERSION THIS FAR TO THE SOUTH,
SYNOPTIC-SCALE SUBSIDENCE ACROSS THE AREA IS CERTAINLY INFERRED
GIVEN THE POSITION OF THE UPPER HIGH. DESPITE SOME WEAK
CONVERGENCE ALONG THE AFTERNOON SEA BREEZE, ATMOSPHERIC PROFILES
ARE JUST NOT OVERLY FAVORABLE THE DEVELOPMENT OF MOIST
CONVECTION AND A RAIN-FREE FORECAST WAS MAINTAINED WITH GRIDDED
POPS GENERALLY <10%.
THURSDAY THROUGH SATURDAY: THE UPPER HIGH IS FORECAST TO
GRADUALLY SHIFT TO EAST AND SOUTHEAST THURSDAY INTO FRIDAY
BEFORE RETROGRADING BACK INTO THE CENTRAL PLAINS SATURDAY AS A
BROAD, LONGWAVE TROUGH BEGINS TO SHARPEN ALONG EASTERN CONUS.
THERE ARE SIGNALS THAT A PLUME OF DEEPER MOISTURE COULD BRUSH
AREAS CLOSEST TO THE ALTAMAHA RIVER BOTH DAYS AS WHAT APPEARS TO
BE A WEAK MID-LEVEL (850-700 HPA) CIRCULATION OR SHEAR AXIS
LIFTS INTO NORTHERN FLORIDA. DESPITE THE PROXIMITY OF THIS
FEATURE AND THE ASSOCIATED MOISTURE PLUME, IT IS NOT EXACTLY
CLEAR HOW MUCH OF A RISK FOR MEASURABLE RAINFALL WILL OCCUR
ACROSS SOUTHEAST GEORGIA AND THE SOUTH CAROLINA LOWCOUNTRY GIVEN
A GOOD BIT OF SYNOPTIC-SCALE SUBSIDENCE AND MID-LEVEL DRY AIR
WILL LIKELY STILL BE IN PLACE GIVEN THE EXPECTED POSITION AND
ORIENTATION OF THE UPPER-LEVEL HIGH. THE GFS ENSEMBLES ARE IN
VERY GOOD AGREEMENT IN A DRY FORECAST, WHILE THE EUROPEAN
ENSEMBLES ARE IN GOOD AGREEMENT (VERY SMALL INTERQUARTILE RANGE
[IQR] FOR 0.01-0.07") THAT A FEW HUNDREDTHS OF RAIN WILL FALL
BOTH DAYS (ESPECIALLY FRIDAY)--HENCE THE UNCERTAINTY. THE 02/01Z
NBM APPEARS TOO AGGRESSIVE WITH RAINFALL CHANCES BOTH DAYS
GIVEN THE SYNOPTIC PATTERN AND WERE LOWERED BY ABOUT 20-30% FOR
THIS CYCLE. POPS THURSDAY WILL RUN 20-30% ACROSS SOUTHEAST
GEORGIA AND 20-40% ACROSS THE ENTIRE AREA FRIDAY (HIGHEST NEAR
THE ALTAMAHA RIVER).
SATURDAY NIGHT INTO LABOR DAY: A COLD FRONT WILL APPROACH THE
AREA FROM THE NORTH SATURDAY NIGHT AND MOVE SOUTH INTO NORTHERN
FLORIDA ON SUNDAY AS A STRONG CYCLONE TAKES SHAPE OFFSHORE OF NEW
ENGLAND. UNSETTLED CONDITIONS LOOK INCREASINGLY LIKELY THROUGH
LABOR DAY WITH BREEZY CONDITIONS POSSIBLE AT THE COAST AS A
WEDGE OF HIGH PRESSURE BUILDS ACROSS THE CAROLINAS INTO GEORGIA.
DRIER CONDITIONS COULD RETURN BY TUESDAY.
KEY MESSAGE 3: HOT AND HUMID CONDITIONS EXPECTED INTO THE
UPCOMING WEEKEND.
THE CENTER OF A HIGH PRESSURE RIDGE WILL SHIFT TO BECOME JUST
NORTH OF THE FORECAST AREA TODAY, CONTINUING THE HOT AND HUMID
CONDITIONS ACROSS THE REGION. WITH H850 TEMPERATURES NEAR 19
DEGREES C, AFTERNOON MAX TEMPERATURES ARE EXPECTED TO PEAK IN
THE UPPER 80S ALONG THE COAST INTO THE MID 90S FOR INLAND AREAS.
WITH DEWPOINTS IN THE LOWER TO UPPER 70S, HEAT INDEX VALUES
WILL PEAK IN THE 100-105 DEGREE RANGE. WHILE THE RIDGE STRENGTH
BEGINS TO SLOWLY WEAKEN THROUGH FRIDAY, SIMILAR H850
TEMPERATURES NEAR 19 DEGREES C WILL RESULT IN DAYTIME HIGHS
REMAINING IN THE UPPER 80S ALONG THE COAST INTO THE MID 90S FOR
INLAND AREAS, WITH HEAT INDEX VALUES IN THE 100- 105 DEGREE
RANGE. THE WARMEST DAY IS EXPECTED ON SATURDAY AS A TROUGH
BUILDS ALONG THE EAST COAST, WITH FRONT MOVING TOWARDS THE
REGION FROM THE NORTH. COMPRESSIONAL HEATING AHEAD OF THE FRONT
IN TANDEM WITH THE H850 TEMPERATURES NEAR 20 DEG C ARE EXPECTED
TO RESULT IN WIDESPREAD TEMPERATURES IN THE MID 90S WITH
ISOLATED SPOTS IN THE UPPER 90S. COMBINED WITH DEWPOINT
TEMPERATURES IN THE MID TO UPPER 70S, HEAT INDEX VALUES WILL
RISE INTO THE 103 TO 112 DEGREE RANGE, WHICH MAY REQUIRE A HEAT
ADVISORY ACROSS PORTIONS OF THE REGION ON SATURDAY. A COLD FRONT
LOOKS TO PUSH THROUGH ON SUNDAY, BRINGING AN END TO THIS
STRETCH OF HOT AND HUMID CONDITIONS, THOUGH DON'T BE EXPECTING
ANY COLD TEMPERATURES.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
02/06Z TAFS:
KCHS/KJZI/KSAV: THE MAIN FORECAST CHALLENGE AGAIN REVOLVES
AROUND THE POTENTIAL FOR LOW STRATUS AND FOG AT ALL 3 TAF SITES.
MODEL GUIDANCE IS A BIT MIXED WITH THE POTENTIAL COVERAGE AND
DENSITY OF FOG. BUT GIVEN THAT A FEW HOURS OF IFR CONDITIONS
WERE NOTED TUESDAY THIS MORNING, IT SEEMS LIKELY SIMILAR
SITUATION COULD EVOLVE GIVEN THAT THE AIRMASS HAS NOT CHANGED
SIGNIFICANTLY IN THE PAST 24 HOURS. LIFR CONDITIONS WERE
MAINTAINED ROUGHLY IN THE 10-14Z TIME PERIOD. DENSE FOG IS
POSSIBLE, AND COULD NEED TO BE ADDED TO THE TAFS WITH FUTURE
ISSUANCES. VFR WILL RETURN BY MID-MORNING.
EXTENDED AVIATION OUTLOOK: ISOLATED SHOWERS AND THUNDERSTORMS
MAY BRING BRIEF FLIGHT RESTRICTIONS ON THURSDAY AND FRIDAY FOR
SOUTHEAST GEORGIA DURING THE MORNING AND AFTERNOON HOURS.
REGIONAL CHANCES FOR SCATTERED SHOWERS AND THUNDERSTORMS RETURN
SATURDAY AFTERNOON.
MARINE
THROUGH TONIGHT: SOME PATCH FOG COULD OOZE INTO THE CHARLESTON
HARBOR PRIOR TO DAYBREAK. OTHERWISE, EAST/NORTHEAST WINDS THIS
MORNING WILL VEER TO THE EAST THIS AFTERNOON, THEN SOUTHEAST
TONIGHT. WINDS WILL REMAIN LESS THAN 10 KT WITH SEAS 2-4 FT,
MAINLY IN EAST/SOUTHEAST SWELL WITH 11-13 SEC PERIODS.
THURSDAY THROUGH MONDAY: EXPECT CONDITIONS TO REMAIN WELL BELOW
SMALL CRAFT ADVISORY LEVELS THROUGH FRIDAY WITH LIGHT ONSHORE
FLOW BECOMING SLIGHTLY ENHANCED (10-15 KT) ALONG THE COAST AS
DAILY SEA BREEZES DEVELOP, THEN SHIFT INLAND. THUNDERSTORM
CHANCES COULD ALSO INCREASE ACROSS LOCAL WATERS ON THURSDAY WITH
SFC TROUGHING, WITH REGIONAL CHANCES FOR SCATTERED SHOWERS AND
THUNDERSTORMS RETURNING SATURDAY AFTERNOON. AHEAD OF AN
APPROACHING COLD FRONT, WINDS BECOME SOUTHWESTERLY OVERNIGHT
INTO SATURDAY, WITH SOUTHERLY GUSTS TO NEAR 20 KNOTS BY THE
AFTERNOON HOURS. WINDS DECREASE OVERNIGHT INTO SUNDAY, BECOMING
EASTERLY SUNDAY AFTERNOON AGAIN GUSTING 15-20 KNOTS WHICH MAY
CONTINUE INTO MONDAY.
RIP CURRENTS: THERE IS A MODERATE RISK FOR RIP CURRENTS ALONG
THE SOUTHEAST GEORGIA COAST TODAY AND THURSDAY, WITH BUILDING
2-3 FT SWELLS EVERY 11-13 SECONDS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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