065
FXUS62 KCHS 180558
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
158 AM EDT MON MAY 18 2026
WHAT HAS CHANGED
ALL KEY MESSAGES AND SECTIONS WERE UPDATED.
KEY MESSAGES
- 1) MINOR COASTAL FLOODING IS POSSIBLE ALONG COASTAL AREAS OF
CHARLESTON AND COLLETON COUNTIES WITH HIGH TIDE THIS EVENING
AND POSSIBLY TUESDAY EVENING.
- 2) MOSTLY DRY CONDITIONS EXPECTED THROUGH MIDWEEK WITH
INCREASING RAIN CHANCES TO OCCUR LATE WEEK.
DISCUSSION
KEY MESSAGE 1: MINOR COASTAL FLOODING IS POSSIBLE ALONG COASTAL
AREAS OF CHARLESTON AND COLLETON COUNTIES WITH HIGH TIDE THIS
EVENING AND POSSIBLY TUESDAY EVENING.
ASTRONOMICAL INFLUENCES ASSOCIATED WITH THE RECENT NEW MOON AND
LUNAR PERIGEE ALONG WITH A MODEST ONSHORE FLOW WILL CONTINUE TO
DRIVE ELEVATED TIDE LEVELS, LEADING TO MINOR COASTAL FLOODING
ALONG PARTS OF THE LOWER SOUTH CAROLINA COAST THIS EVENING. THE
LATEST FORECAST ADVERTISES A PEAK HIGH TIDE 7.0-7.2 FT MLLW IN
THE CHARLESTON HARBOR THIS EVENING AND 6.9-7.1 FT MLLW TUESDAY
EVENING. A COASTAL FLOOD ADVISORY FOR COASTAL COLLETON AND
CHARLESTON COUNTIES COULD BE FOR THIS EVENING'S HIGH TIDE AND
POSSIBLY AGAIN TUESDAY EVENING ALTHOUGH CONFIDENCE IN REACHING
THE 7.0 FT MLLW MINOR FLOOD STAGE IS MUCH MORE UNCERTAIN BY THEN.
ASTRONOMICAL TIDE LEVELS THEN BEGIN TO FALL AND THE POTENTIAL
FOR MINOR COASTAL FLOODING WILL DIMINISH.
KEY MESSAGE 2: MOSTLY DRY CONDITIONS EXPECTED THROUGH MIDWEEK
WITH INCREASING RAIN CHANCES TO OCCUR LATE WEEK.
SFC HIGH PRESSURE AND UPPER LEVEL RIDGING HOLDS TIGHT ACROSS
THE REGION THROUGH MID-WEEK, ALLOWING LARGELY DRY CONDITIONS TO
PREVAIL. MODEL SOUNDINGS ALSO REMAIN QUITE CAPPED, SO IN THE OFF
CHANCE THAT PRECIPITATION DOES DEVELOP, EXPECT OVERALL
ACCUMULATIONS AND SEVERE POTENTIAL TO REMAIN LOW. OTHERWISE,
LOOK FOR AFTERNOON HIGHS TO WARM INTO THE UPPER 80S TO LOWER 90S
UNDER MOSTLY SUNNY SKIES, WITH LOWS ONLY DIPPING INTO THE MID
TO UPPER 60S.
UPPER LEVEL PATTERN SHIFTS HEADING INTO THE LATTER HALF OF THE
FORECAST PERIOD, RESULTING IN CHANCES FOR UNSETTLED WEATHER. AS
NOTED IN THE PREVIOUS DISCUSSION, A DECENT AMOUNT OF MODEL
UNCERTAINTY STILL EXISTS, MAKING IT HARD TO PUT TOO MUCH
CONFIDENCE IN ANY ONE SOLUTION JUST YET. WHILE DETAILS STILL
NEED TO BE IRONED OUT, MOST GUIDANCE DOES SHOWCASE A SHORTWAVE
TROUGH DIGGING ACROSS THE CENTRAL/NORTHERN PLAINS BY THURSDAY.
MEANWHILE, AT THE SFC, WILL SEE A COLD FRONT DIVE SOUTHEASTWARD
ACROSS THE OHIO/TENNESSEE RIVER VALLEY, SENDING THE
AFOREMENTIONED HIGH PRESSURE INTO THE ATLANTIC. THERE ARE SOME
INDICATIONS THAT THIS BOUNDARY COULD STALL ACROSS OUR AREA
THROUGH SATURDAY, WHICH WOULD SUPPORT INCREASING MOISTURE AND
HIGHER RAIN CHANCES. HOWEVER, IF THE RIDGE REMAINS STRONGER, THE
FRONT AND BETTER FORCING COULD REMAIN FARTHER TO THE WEST AND
NORTH, RESULTING IN LOWER RAIN CHANCES THAN CURRENTLY FORECAST.
DO THINK IT IS WORTH NOTING THOUGH, THAT LATEST ENSEMBLE
PROBABILITIES FOR ACCUMULATED RAINFALL > 1" NOW SHOWCASE A
20-60% CHANCE (HIGHEST INLAND). CERTAINLY SOMETHING TO KEEP AN
EYE ON IN THE COMING DAYS.
AVIATION /04Z MONDAY THROUGH FRIDAY/
18/06Z TAF DISCUSSION:
KCHS/KJZI/KSAV: VFR, ALTHOUGH A BRIEF PERIOD OF SHALLOW GROUND
COULD DEVELOP 09-12Z. VSBYS AT KJZI COULD VARY SIGNIFICANTLY
SINCE THERE IS NOT AN OBSERVER ON SITE AT THIS LOCATION AND THE
AWOS IS PRONE TO LARGE VSBY SWINGS. A TEMPO GROUP FOR MVFR
VSBYS WAS INTRODUCED 10-18Z TO ACCOUNT FOR THIS. OTHERWISE,
GUSTY WINDS WILL IMPACT ALL TERMINALS THIS AFTERNOON WITH THE
PASSAGE OF THE SEA BREEZE.
EXTENDED AVIATION OUTLOOK: THERE ARE NO HIGH CONFIDENCE
CONCERNS.
MARINE
THROUGH TONIGHT: THE SYNOPTIC FLOW REGIME WILL CHANGE LITTLE
THROUGH TONIGHT AS ATLANTIC HIGH PRESSURE REMAINS CENTERED WELL
OFFSHORE. A EASTERLY FLOW REGIME WILL PREVAIL WITH EAST WINDS 15
KT OR LESS PREVAILING. SOME LOCAL ENHANCEMENT COULD OCCUR ALONG
THE LAND/SEA INTERFACE AND CHARLESTON HARBOR THIS AFTERNOON WITH
SEA BREEZE. SEAS WILL AVERAGE 2-4 FT.
MONDAY THROUGH FRIDAY: NO MARINE CONCERNS ARE EXPECTED. HIGH
PRESSURE TO THE EAST WILL DRIVE ONSHORE EAST-SOUTHEASTERLY FLOW
EACH DAY, WITH WIND SPEEDS MOSTLY TOPPING OUT IN THE 10-15 KNOT
RANGE. EACH AFTERNOON AND EVENING THERE COULD BE SOME LOCAL
ENHANCEMENT ALONG THE LAND/SEA INTERFACE WITH THE DIURNAL SEA
BREEZE. SEAS SHOULD AVERAGE 2-4 FEET THROUGH THE PERIOD.
RIP CURRENTS: INFLUENCES FROM THE NEW MOON CYCLE COMBINED WITH
PERSISTENT ONSHORE FLOW WILL PRODUCE AN ELEVATED RISK OF RIP
CURRENTS THROUGH MIDWEEK. A MODERATE RISK FOR RIP CURRENTS IS
IN PLACE FOR ALL BEACHES THROUGH TUESDAY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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