493
FXUS62 KCHS 021113
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
713 AM EDT FRI OCT 2 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED TO REFLECT THE 12Z TAFS.
KEY MESSAGES
- 1) WIDESPREAD FOG EXPECTED TONIGHT ACROSS INTERIOR SOUTHEAST
SOUTH CAROLINA AND SOUTHEAST GEORGIA. A DENSE FOG ADVISORY IS
IN EFFECT FROM 3 AM TO 9 AM.
- 2) UNSETTLED WEATHER WILL RETURN TODAY AND LINGER THROUGH
MONDAY.
- 3) COOLER TEMPERATURES ALONG WITH BREEZY TO WINDY CONDITIONS
ARE LIKELY NEXT WEEK.
- 4) COASTAL FLOODING IS LIKELY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: WIDESPREAD FOG EXPECTED TONIGHT ACROSS INTERIOR
SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA. A DENSE
FOG ADVISORY IS IN EFFECT FROM 3 AM TO 9 AM.
CLEAR SKIES AND CALM WINDS ARE PRESENT ACROSS A MAJORITY OF THE
FORECAST AREA TONIGHT AS HIGH PRESSURE HOLDS STRONG OVER THE REGION.
THESE CONDITIONS ARE IDEAL FOR FOG DEVELOPMENT, WITH SOME LOCATIONS
ALREADY SHOWING DECREASED VISIBILITIES DUE TO FOG AS OF MIDNIGHT.
GUIDANCE CONTINUES TO SHOW THE POTENTIAL FOR DENSE FOG (VISIBILITIES
<1/4 MI) ESPECIALLY ACROSS INLAND LOCATIONS AND THE CHARLESTON TRI-
COUNTY. A DENSE FOG ADVISORY REMAINS IN EFFECT FROM 3 TO 9 AM THIS
MORNING. AN EXPANSION OF THE DENSE FOG ADVISORY INTO SOUTHEASTERN GA
IS POSSIBLE, WITH MODELS SHOWING VERY LOW CONDENSATION PRESSURE
DEFICIT VALUES ACROSS FAR INLAND GA. SIMILAR TO THURSDAY MORNING THE
FOG COULD TAKE A COUPLE OF HOURS TO DISSIPATE AFTER SUNRISE,
LINGERING UNTIL AROUND 10 OR 11 AM.
KEY MESSAGE 2: UNSETTLED WEATHER WILL RETURN TODAY AND LINGER
THROUGH MONDAY.
MOISTURE WILL CONTINUE TO INCREASE TODAY AS AN ATLANTIC SURFACE HIGH
PRESSURE REMAINS PARKED EAST OF NORTH CAROLINA, WITH PRECIPITABLE
WATER VALUES (PWATS) EXPECTED TO BREACH THE 2.0" MARK LATER TODAY
ACROSS SOUTHEAST GEORGIA. ALOFT, WE REMAIN UNDER A RIDGE OF HIGH
PRESSURE, SO WHILE WE WILL LIKELY SEE SHOWERS AND THUNDERSTORMS
LATER TODAY, THE SUBSIDENCE ALOFT SHOULD KEEP COVERAGE RATHER
SCATTERED. GIVEN THE INCREASING PWATS AND SLOW STORM MOTIONS,
LOCALLY HEAVY RAINFALL CAN'T BE RULED OUT TODAY ESPECIALLY ACROSS
SOUTHEAST GEORGIA, BUT GIVEN THE LACK OF STRONG FORCING TODAY IT
APPEARS UNLIKELY.
THE RIDGE OF HIGH PRESSURE SLOWLY NUDGES SOUTHEASTWARDS THROUGHOUT
THE WEEKEND, WITH PWATS REMAINING IN EXCESS OF 2 INCHES OVER THE
WEEKEND AHEAD OF AN APPROACHING COLD FRONT. WHILE SHORTWAVES ALOFT
DO BEGIN TO MOVE THROUGH THE REGION ON SATURDAY, FORCING OVERALL
REMAINS RATHER WEAK, WITH THE MAIN ROUND OF SHOWERS AND
THUNDERSTORMS EXPECTED AS THE SEA-BREEZE PUSHES ASHORE. COVERAGE IN
SHOWERS AND THUNDERSTORMS IS EXPECTED TO INCREASE ON SUNDAY AS H500
SHORTWAVES AND H850 WARM-AIR ADVECTION OVERSPREADS THE AREA, WITH
HIGHEST COVERAGE EXPECTED SUNDAY AFTERNOON INTO MONDAY AFTERNOON.
GIVEN THE ANOMALOUSLY HIGH PWATS (98TH PERCENTILE FOR THE DATE),
LOCALLY HEAVY RAINFALL WILL BE THE MAIN CONCERN WITH THIS RAINFALL
EVENT. NBM 24 HOUR RAINFALL PROBABILITIES OF >2 INCHES REMAIN
HIGHEST LATE SUNDAY GENERALLY IN THE 40-50% RANGE, LOWEST ALONG THE
COAST AND IN SOUTHERN GEORGIA. EXPANDING THE SCOPE TO INCLUDE 48
HOURS, ENSEMBLE QPF CLUSTERING REVEALS THE AXIS OF THE HEAVIEST
PRECIPITATION (3 TO 5 INCHES) RANGES FROM ALONG THE NORTHERN
PANHANDLE OF FL AND UP INTO EASTERN NC, TO POSSIBLE AS FAR WEST AS
SOUTHERN AL TO WESTERN NC, SO BE SURE TO REMAIN AWARE AS ADDITIONAL
DETAILS BECOME CLEAR.
MAJORITY OF THE HEAVY RAINFALL WILL COME TO AN END ON MONDAY AS THE
SURFACE COLD FRONT PUSHES SOUTH OF THE AREA AND STRONG COLD AIR
DAMMING SETS UP OVER THE CAROLINAS. SOME OVERRUNNING PRECIP WILL
LIKELY CONTINUE ACROSS PARTS OF GEORGIA THROUGH THE EARLY PART OF
NEXT WEEK AS SEVERAL WEAK SURFACE DISTURBANCES MOVE ALONG THE
STALLED WEDGE FRONT.
KEY MESSAGE 3: COOLER TEMPERATURES ALONG WITH BREEZY TO WINDY
CONDITIONS ARE LIKELY NEXT WEEK.
WHILE DAILY TEMPERATURES WILL ALREADY BE DROPPING FROM THE UPPER 80S
TO LOWER 90S TODAY INTO THE UPPER 70S TO MID 80S ON SUNDAY AS
RAINFALL CHANCES INCREASE OVER THE WEEKEND, A COLD FRONT IS EXPECTED
TO PUSH THROUGH THE REGION MONDAY MORNING. BEHIND THE FRONT A STRONG
SURFACE HIGH PRESSURE WILL BE BUILDING IN BEHIND IT, WITH A COLD AIR
DAMMING EVENT UNFOLDING INTO THE MIDDLE OF NEXT WEEK. INCREASING
CLOUD COVER AND STRONG NORTH-NORTHEASTERLY WINDS SUPPORTED BY THE
TIGHTENING SURFACE PRESSURE GRADIENT WILL SUPPORT RATHER MILD
TEMPERATURES, WITH DAILY HIGHS IN THE UPPER 60S TO MID 70S ON
TUESDAY AND WEDNESDAY. IN ADDITION, THE TIGHTENED SURFACE PRESSURE
GRADIENT WILL CREATE SOME BREEZY/WINDY CONDITIONS TUESDAY THROUGH
WEDNESDAY, WITH INLAND AREAS LIKELY SEEING GUSTS TO 30 MPH AND THOSE
ALONG THE COAST APPROACHING 40 MPH. A LAKE WIND ADVISORY FOR LAKE
MOULTRIE MAY BE NEEDED TUESDAY AND AGAIN WEDNESDAY.
KEY MESSAGE 4: COASTAL FLOODING IS LIKELY NEXT WEEK.
GUSTY NORTHEAST WINDS INDUCED BY STRONG COLD AIR DAMMING, COMBINED
WITH ALREADY HIGH ASTRONOMICAL HIGH TIDES, WILL LIKELY RESULT IN
COASTAL FLOODING ISSUES NEXT WEEK. MINOR TO MODERATE FLOODING IS
LIKELY, WITH A POSSIBILITY OF REACHING MAJOR LEVELS. COASTAL FLOOD
WATCHES, WARNINGS AND ADVISORIES COULD BE NEEDED.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
12Z TAFS: FOG AT THE TERMINALS IS SHALLOW, NOT RESTRICTIVE, AND
WILL MIX OUT QUICKLY AFTER THE SUN RISES. THEREAFTER, PREVAILING
VFR. THERE IS A SLIGHT CHANCE OF A SHOWER AT KSAV THIS
AFTERNOON, HOWEVER CONFIDENCE IN DIRECT IMPACTS TO THE TERMINAL
ARE TOO LOW TO INCLUDE MENTION OF PRECIP AT THIS JUNCTURE.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS ARE POSSIBLE WITH
INCREASING SHOWERS AND THUNDERSTORMS OVER THE WEEKEND INTO EARLY
NEXT WEEK. GUSTY WINDS ARE LIKELY ON TUESDAY AND WEDNESDAY.
MARINE
EARLY THIS MORNING: WITH LIGHT TO CALM WINDS AND CLEAR SKIES
FOG FORMATION IS A CONCERN EARLY THIS MORNING. WEBCAMS SHOW THE
BEGINNINGS OF REDUCED VISIBILITIES ACROSS THE CHARLESTON HARBOR
AS OF 2 AM. VISIBILITIES WILL LIKELY CONTINUE TO GET WORSE AS
DENSE FOG DEVELOPS, FALLING TO 1/2 MILE OR LESS. A MARINE DENSE
FOG ADVISORY COULD BE NEEDED UNTIL THE FOG CLEARS LATE MORNING
(10 TO 11 AM).
REST OF TODAY THROUGH SUNDAY: WINDS AND SEAS WILL REMAIN BELOW
SMALL CRAFT ADVISORY THRESHOLDS ACROSS ALL MARINE ZONES. WINDS
WILL SURGE A BIT EACH AFTERNOON AND EVENING, BUT SPEEDS SHOULD
MOSTLY TOP OUT IN THE 10-15 KNOT RANGE AND WILL BE STRONGEST
ALONG THE LAND/SEA INTERFACE. INCREASING SHOWERS AND
THUNDERSTORMS ARE EXPECTED OVER THE WEEKEND WITH SUNDAY
FEATURING THE HIGHEST RAIN CHANCES
MONDAY - WEDNESDAY: A COLD FRONT WILL BE PUSHING THROUGH THE REGION
MONDAY MORNING, PUSHING THE HEAVIEST RAINFALL SOUTH OF THE AREA BY
THE EVENING, THOUGH GREATER IMPACTS ARE EXPECTED FROM THE SWITCH TO
NORTHERLY WINDS THAT WILL BE STRENGTHENING THROUGH THE DAY AS
SURFACE HIGH PRESSURE MOVES IN. MARINE CONDITIONS ARE EXPECTED TO
WORSEN QUICKLY MONDAY EVENING INTO TUESDAY AS 25 TO 34 KNOT GUSTS
BUILD, FURTHER STRENGTHENING INTO GALES (35 TO 45 KNOTS) AT TIMES
THROUGH WEDNESDAY. 6 FOOT WAVES ARE EXPECTED TO QUICKLY MOVE IN
OVERNIGHT INTO TUESDAY, PUSHING ALONG THE COAST BY TUESDAY AFTERNOON
AS 10FT+ WAVES BUILD 20NM OFFSHORE. THE HAZARDOUS MARINE CONDITIONS
WILL LIKELY RESULT IN HAZARDOUS BEACH CONDITIONS, INCLUDING
DANGEROUS RIP CURRENTS AND HIGH SURF.
CHS WATCHES/WARNINGS/ADVISORIES
GA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR GAZ087-088-
099-100.
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ040-
042>045-149-150-152.
MARINE...NONE.
APT/CPM
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