097
FXUS62 KCHS 071418
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1018 AM EDT WED MAY 7 2025
SYNOPSIS
A FRONT WILL REMAIN STALLED NEARBY THROUGH THE WEEKEND AS
CUT-OFF LOW CONTINUES TO MOVE CLOSER TO THE REGION. THIS WILL
ALLOW AN UNSETTLED, WET PATTERN TO PERSIST OVER THE NEXT
SEVERAL DAYS.
NEAR TERM /THROUGH TONIGHT/
TODAY: ALOFT, H5 SHORTWAVE ENERGY WILL ROUND THE NORTHERN PERIPHERY
OF A RIDGE EXTENDING ACROSS THE NORTHEAST GULF TO THE WESTERN
ATLANTIC. AT THE SFC, THE SETUP IS QUITE NEBULOUS WITH A SUBTLE
BOUNDARY SITUATED TO THE SOUTH THAT RUNS ACROSS SOUTHERN GEORGIA AND
WESTWARD TO ALABAMA. OVERALL, FORCING IS NOT ALL THAT IMPRESSIVE
LOCALLY. INSTEAD, MOST PRECIP CHANCES APPEAR TO BE ASSOCIATED WITH
THE ARRIVAL OR REMNANT CONVECTION UPSTREAM, WHICH IS ENTERING FAR
WESTERN ZONES LATE THIS MORNING, INTERACTING WITH A SEA BREEZE THIS
AFTERNOON. HI-RES GUIDANCE IS IN GOOD GENERAL AGREEMENT THAT THE
UPSTREAM CONVECTION WILL STEADILY DIMINISH AS IT PUSHES INTO THE FAR
WESTERN ZONES LATE MORNING, FOLLOWED BY NEW DEVELOPMENT CLOSER TO
THE GEORGIA COAST AND NORTH TO AROUND BEAUFORT COUNTY, SC MID DAY,
PERHAPS ASSOCIATED WITH THE REMNANT CONVECTION/OUTFLOW EARLIER IN
THE DAY. THE FORECAST CONTINUES TO HIGHLIGHT THE AFOREMENTIONED
COASTAL AREA WITH 60-80% PRECIP CHANCES WITH MODEST SBCAPE AROUND
1000 J/KG AND 0-6 KM BULK SHEAR AROUND 25 KT SUGGESTING THE
POTENTIAL FOR A STRONGER THUNDERSTORM OR TWO. ELSEWHERE, WEAK
INSTABILITY DEPICTED ON MODEL SOUNDINGS SUPPORTS LESS PRECIP
COVERAGE, GENERALLY 20-40% MID AFTERNOON INTO EARLY EVENING.
DEPENDING ON HOW CONVECTION DEVELOPS AND EVOLVES, THERE IS POTENTIAL
FOR LOCALIZED HEAVY RAINFALL AND 0.50-1.00" OF RAIN ALONG THE
GEORGIA COAST WHERE STORMS TRACK. ELSEWHERE, RAINFALL SHOULD BE
LIGHT, NO MORE THAN 1/10 OF AN INCH. HIGH TEMPS WILL RANGE IN THE
UPPER 70S/LOWER 80S, THOUGH SOME DISRUPTION TO THE TYPICAL DIURNAL
TREND IS EXPECTED ALONG AND SOUTH OF I-16 AS SHOWERS AND THUNDERSTORMS
OCCUR.
TONIGHT: AFTERNOON SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
PUSH OFFSHORE BY THE EARLY EVENING AND FROM THEN ON THERE ISN'T
A TON OF CONFIDENCE IN HOW SHOWER POTENTIAL WILL WORK OUT
OVERNIGHT. WE WILL REMAIN LARGELY DEVOID OF ANY LARGE SCALE
FORCING, THOUGH THERE ARE SOME SUGGESTIONS THAT SUBTLE SHORTWAVE
ENERGY WILL PASS THROUGH WITHIN THE WESTERLY FLOW. THE ILL-
DEFINED SURFACE BOUNDARY IS EXPECTED TO BE ALIGNED SOUTH OF THE
AREA NEAR THE FL STATE LINE. SO, THE FORECAST ALLOWS FOR RAIN
CHANCES TO END IN THE EVENING BUT WE DO ALLOW 20 PERCENT CHANCES
TO COME BACK IN LATE TO ACCOUNT FOR POSSIBLE ISOLATED SHOWER
DEVELOPMENT WITHIN THE WARM AND MOIST ENVIRONMENT. LOWS ARE
FORECAST TO BE IN THE UPPER 50S TO LOW 60S INLAND, AND THE MID
60S ALONG THE COAST.
SHORT TERM /THURSDAY THROUGH SATURDAY/
THURSDAY: AS AN UPPER-LVL LOW SITUATED OVER THE MID-MISSISSIPPI
VALLEY APPROACHES THE REGION, THE ALMOST STATIONARY FRONT WILL
CONTINUE TO LINGER NEARBY. COMPARED TO THE PAST WEEK OF
GUIDANCE, THIS PATTERN HAS BEEN MORE SLOW TO PROGRESS AND MAY
SUPPORT ADDITIONAL RAINFALL IF THIS TREND CONTINUES OVER THE
NEXT COUPLE DAYS. WHILE GFS/CMC POINT TO A RATHER DRY FORECAST
TODAY, ALL OTHER GUIDANCE SUGGESTS OTHERWISE. EXPECT SHOWERS AND
THUNDERSTORMS TO DEVELOP IN THE MORNING (~12-13Z) ACROSS
SOUTHEAST GEORGIA AND EVENTUALLY INTO SOUTHEAST SOUTH CAROLINA
IN THE EARLY AFTERNOON (~18- 19Z). LOCATED ON THE COOLER SIDE OF
THE UPPER-LVL LOW, INSTABILITY REMAINS QUITE LIMITED THROUGHOUT
THE DAY WITH SBCAPE VALUES MOSTLY WAVERING ~1000 J/KG. HOWEVER
HEADING INTO THE AFTERNOON, SRH VALUES BECOME MORE IMPRESSIVE
AND THE POTENTIAL TO SEE SOME ORGANIZED THUNDERSTORMS IS NOT
TOTALLY OFF THE TABLE. WITH A FRONTAL BOUNDARY PUSHING OFFSHORE
IN THE EVENING, MOST OF THE SHOWERS AND THUNDERSTORMS WILL SHIFT
OVER THE WATERS. ADDITIONALLY, WPC HAS HIGHLIGHTED SOUTHEAST
GEORGIA IN A MARGINAL RISK AS THIS AREA WILL MOST LIKELY SEE THE
MOST RAINFALL (~0.25-0.50"). SOUTHEASTERLY WINDS COULD BECOME
QUITE GUSTY ALONG THE COASTLINE IN THE EVENING WITH THE
SEABREEZE AND THE FRONT SHIFTING OFFSHORE. DESPITE THE LACK OF
SUN, HIGHS WILL CLIMB INTO THE LOW TO MID 80S AND OVERNIGHT LOWS
WILL DROP INTO THE LOW TO MID 60S INLAND AND UPPER 60S CLOSER
TO THE COASTLINE.
FRIDAY: AS THIS UPPER-LVL LOW SITUATES ITSELF IN THE DEEP
SOUTH, AN ASSOCIATED COLD FRONT WILL PASS THROUGH THE REGION
THROUGHOUT THE DAY. A GOOD AMOUNT OF GUIDANCE INDICATES THAT
THIS LOW WILL YIELD NUMEROUS SHOWERS AND THUNDERSTORMS
THROUGHOUT THE DAY. ADDITIONALLY, WPC HAS HIGHLIGHTED THE ENTIRE
REGION UNDER A MARGINAL RISK FOR EXCESSIVE RAINFALL. WITH PWAT
VALUES RANGING ~1.50-2.00 INCHES AND EXTREMELY MOIST
SOUTHWESTERLY FLOW BEING ADVECTED INTO THE REGION, DECENT
AMOUNTS OF RAINFALL COULD BE SEEN. RAINFALL AMOUNTS FOR FRIDAY
RANGE FROM 0.75 TO 1.25 INCHES, WITH MOST PRECIPITATION FALLING
IN SOUTHEAST GEORGIA AGAIN. EXPECT TEMPERATURES TO BE NEAR
NORMAL ON FRIDAY.
SATURDAY: THIS UPPER-LVL LOW WILL ALMOST PARK ITSELF ACROSS THE
GULF STATES AND CONTINUE TO PUSH RICH MOISTURE INTO THE
SOUTHEAST. EXPECT SHOWERS AND THUNDERSTORMS TO CONTINUE
THROUGHOUT THE DAY. WPC HIGHLIGHTED THE ENTIRE REGION UNDER A
MARGINAL RISK FOR EXCESSIVE RAINFALL AGAIN. THIS APPEARS TO THE
HEAVIEST DAY OF RAINFALL WITH PRECIPITATION AMOUNTS RANGING FROM
1.0 TO 1.50 INCHES. DUE TO THE RELATIVELY DRY ANTECEDENT
CONDITIONS, THE OVERALL FLASH FLOODING POTENTIAL REMAINS ON THE
LOWER SIDE. GIVEN THE OVERALL PATTERN, TEMPERATURES WILL BE
BELOW NORMAL FOR THIS TIME OF YEAR WITH HIGHS ONLY REACHING INTO
THE LOW TO MID 70S WITH POCKETS OF UPPER 70S IN SOUTHEAST
GEORGIA. NORTHEASTERLY WINDS WILL LIKELY BECOME GUSTY AGAIN IN
THE EVENING (MAINLY ALONG THE COASTLINE) AS THE AFOREMENTIONED
FRONTAL BOUNDARY LINGERS NEARBY.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/
AS THIS CUT-OFF LOW CONTINUES TO SIT ACROSS THE DEEP SOUTH AND
A FRONTAL BOUNDARY LINGERS NEARBY, EXPECT AN EXTENDED PERIOD OF
UNSETTLED, WET WEATHER. WITH DEEP TROPICAL MOISTURE POOLING IN
FROM THE GULF, THIS PATTERN WILL SUPPORT DAILY HEAVY RAINFALL
THREATS INTO EARLY NEXT WEEK. THERE IS POTENTIAL TO SEE RAINFALL
AMOUNTS OF 2+ INCHES IN SOME SPOTS. EVENTUALLY THIS CLOSED LOW
WILL BEGIN TO SLOWLY SHIFT NORTHEASTWARD AND PLACE THE REGION IN
FAVORABLE LOCATION FOR STRONG UPPER-LVL DIVERGENCE. MULTIPLE
ROUNDS OF POTENTIALLY HEAVY SHOWERS AND THUNDERSTORMS WILL PASS
THROUGH THIS PERIOD AND ALLOW FOR SOME VERY NEEDED RAINFALL.
THIS SETUP WILL INDUCE NEAR AND BELOW NORMAL TEMPERATURES.
AVIATION /14Z WEDNESDAY THROUGH SUNDAY/
KCHS AND KJZI: THERE WILL BE THE POTENTIAL FOR SHOWERS TO MOVE
THROUGH IN THE EARLY TO MID AFTERNOON HOURS. MODEL GUIDANCE
GENERALLY HIGHLIGHTS THE MAIN TIME PERIOD OF CONCERN FROM 19-23Z AND
WE ARE CARRYING -SHRA. THERE REMAINS ENOUGH UNCERTAINTY REGARDING
THE POTENTIAL FOR THE SITES TO BE DIRECTLY IMPACTED, SO FURTHER
REFINEMENTS WILL LIKELY BE NEEDED WITH THE 18Z TAF ISSUANCE. IF
SHOWERS DO DIRECTLY IMPACT THE TERMINALS, BRIEF PERIODS OF MVFR
CONDITIONS WILL BE POSSIBLE.
KSAV: THE MAIN FORECAST CHALLENGE CONCERNS THE POTENTIAL FOR
SHOWERS AND THUNDERSTORMS BEGINNING IN THE EARLY AFTERNOON. THE
COMBINATION OF THE ARRIVAL OF A DIMINISHING AREA OF SHOWERS AND
THUNDERSTORMS FROM THE WEST INTERACTING WITH THE SEA BREEZE
ALONG THE GA COAST SHOULD PRODUCE AN AREA OF SHOWERS AND
THUNDERSTORMS NEAR THE TERMINAL. AS SUCH, WE BRING IN VCSH AT
17Z AND HAVE A TEMPO GROUP FROM 17-20Z FOR TSRA TO ACCOUNT FOR
DIRECT IMPACTS BRINGING THE FLIGHT CATEGORY DOWN INTO THE MVFR
RANGE. ONCE THIS SHOWER AND THUNDERSTORM ACTIVITY MOVES OFF TO
THE EAST BY THE MID AFTERNOON, VFR CONDITIONS SHOULD PREVAIL.
EXTENDED AVIATION OUTLOOK: EXPECT MULTIPLE ROUNDS OF SCATTERED
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A NEARBY FRONT TO
DEVELOP THROUGH THE PERIOD. PERIODS OF MVFR/IFR CONDITIONS ARE
POSSIBLE AT CHS/JZI/SAV EACH DAY.
MARINE
TODAY THROUGH TONIGHT: A WEAK PRESSURE GRADIENT PLACED ACROSS
COASTAL WATERS WILL KEEP WINDS AND SEAS WILL BELOW SMALL CRAFT
ADVISORY THRESHOLDS. LIGHT AND VARIABLE WINDS THIS MORNING WILL TURN
ONSHORE THIS AFTERNOON (EAST/SOUTHEAST), WITH WIND SPEEDS GENERALLY
AROUND 10 KT OR LESS. OVERNIGHT, LIGHT SOUTHERLY FLOW SHOULD
CONTINUE WITH WIND SPEEDS NO MORE THAN 5-10 KT. SEAS WILL AVERAGE
AROUND 2 FT THROUGH THE PERIOD. ALTHOUGH 3 FT SEAS ARE POSSIBLE WELL
OFFSHORE ACROSS OUTER GEORGIA WATERS.
FRIDAY THROUGH MONDAY: AS THIS UPPER-LVL LOW APPROACHES THE
REGION OVER THE NEXT COUPLE DAYS, A NEARBY STATIONARY FRONT AT
THE SURFACE WILL FLUCTUATE BACK AND FORTH OVER THE ATLANTIC
WATERS. THIS WILL SUPPORT UNSETTLED WEATHER CONDITIONS AND
SHOWERS AND THUNDERSTORMS COULD POSSIBLE EACH DAY. HOWEVER,
CONDITIONS SHOULD REMAIN UNDER SMALL CRAFT ADVISORY CRITERIA. IN
GENERAL, OFFSHORE WINDS WILL PEAK ~10 TO 15 KT WITH GUSTS (~20
KT) BECOMING SLIGHTLY STRONGER WITH THE SEA BREEZE EACH EVENING.
THANKS TO WINDS IN THE TROPICAL EASTERLIES, EASTERLY SWELL
SHOULD BE ON TAP AND ALLOW FOR SOME GOOD SURF TO DEVELOP. SEAS
WILL BE FROM 2 TO 4 FT OVER THE WEEKEND AND THEN BECOMING 4 TO 5 FT
ON MONDAY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...DPB
SHORT TERM...DENNIS
LONG TERM...DENNIS
AVIATION...BSH/DENNIS
MARINE...DENNIS/DPB
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