809
FXUS62 KCHS 031123
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
623 AM EST SAT JAN 3 2026
SYNOPSIS
A STORM SYSTEM WILL MOVE THROUGH OUR REGION TODAY, YIELDING
WIDESPREAD SHOWERS AND SOME THUNDERSTORMS. HIGH PRESSURE AND
DRIER CONDITIONS RETURN THEREAFTER, WITH GRADUALLY WARMING
TEMPERATURES.
NEAR TERM /THROUGH TONIGHT/
TODAY: ALOFT, A FAST MOVING SHORTWAVE WILL MOVE INTO THE MID
AND LOWER MS VALLEY EARLY THIS MORNING THEN SHIFT EASTWARD INTO
THE FORECAST AREA BY THE AFTERNOON. AT THE SURFACE, THE
SHORTWAVE ALOFT WILL DRIVE AN ELONGATED LOW ACROSS THE DEEP
SOUTH THROUGH THE MORNING AND EVENTUALLY OFF THE COAST OF THE
FORECAST AREA BY THE EARLY EVENING HOURS. DEEP MOISTURE WILL
SURGE INTO THE FORECAST AREA BY SUNRISE, PRODUCING IMPROVING
MOISTURE PROFILES AND PRECIPITABLE WATER VALUES THAT ARE PROGGED
TO MAX OUT IN THE 1.25-1.50" RANGE THIS AFTERNOON. THE NORTHERN
EXTENT OF THE SURFACE LOW WILL RIDE ALONG A WEST TO EAST
ORIENTED STATIONARY BOUNDARY THAT SHOULD BE POSITIONED ALONG THE
NORTHERN EDGE OF THE FORECAST AREA. THIS BOUNDARY WILL HAVE
NOTABLE IMPLICATIONS REGARDING TEMPERATURES, POTENTIAL
INSTABILITY, AND ANY RESULTING SEVERE WEATHER THREAT. AT
SUNRISE, RAIN HAS ALREADY SPREAD TO THE COAST AND OFFSHORE, WITH
A STRIPE OF RAIN GAUGES FROM AROUND MILLEN, TO SYLVANIA,
ALLENDALE, HAMPTON, AND WALTERBORO ALREADY REPORTING BETWEEN
0.25-0.50" OR RAINFALL. THIS FIRST ROUND OF RAINFALL IS
EXPECTED TO BE MOSTLY STRATIFORM AND IMPACT THE STRETCH OF AREA
ALONG AND NORTH OF I-16. AS WE MOVE INTO THE AFTERNOON, THE
NATURE OF THE PRECIPITATION WILL CHANGE AS TEMPERATURES IN THE
WARM SECTOR WARM INTO THE MID TO UPPER 60S ALONG AND SOUTH OF A
LINE THAT STRETCHES GENERALLY FROM AROUND STATESBORO TO
BEAUFORT. THIS AFTERNOON ROUND WILL BE MORE CONVECTIVE AS WEAK
INSTABILITY DEVELOPS COINCIDENT WITH THE AFOREMENTIONED
INCREASED MOISTURE AS WELL AS AN AREA OF UPPER LEVEL DIVERGENCE
IN THE RIGHT ENTRANCE REGION OF A 140 KT UPPER- LEVEL JET.
RAINFALL COVERAGE MIGHT BE LESS, BUT THE THREAT OF LOCALLY HEAVY
RAINFALL WILL BE HIGHER IN THE PRESENCE OF CONVECTION. BY
SUNSET, HI-RES MODELS SUGGEST A BROKEN LINE OF CONVECTION SHOULD
BE ONGOING FROM ACROSS AN AREA SOUTH OF I-16 UP THROUGH
BEAUFORT COUNTY.
SEVERE WEATHER POTENTIAL: WITH MOST OF THE FORECAST AREA
REMAINING IN THE WARM SECTOR AND TEMPERATURES WARMING INTO THE
MID TO UPPER 60S, AT LEAST WEAK INSTABILITY IS EXPECTED TO
DEVELOP GENERALLY ALONG AND SOUTH OF A LINE THAT RUNS FROM
AROUND STATESBORO TO AROUND BEAUFORT. HREF PROBABILITIES SUGGEST
MLCAPE WILL MOSTLY TOP OUT IN THE 250-500 J/KG RANGE, WITH ONLY
LOW PROBABILITIES FOR GREATER THAN 500 J/KG. MODEL SOUNDINGS
SHOW A STRENGTHENING WIND FIELD, WITH A 30 KNOT LOW-LEVEL JET
AND 50-70 KNOTS OF MID-LEVEL FLOW, AS WELL AS SOME VEERING IN
THE LOWEST LEVELS RESULTING IN SRH VALUES AS HIGH AS 200 M2/S2.
DAMAGING WIND GUSTS ARE THE PRIMARY SEVERE THREAT, BUT AN
ISOLATED TORNADO THREAT IS ALSO PRESENT GIVEN THE NOTED VEERING
AND HIGHER 0-1 KM SRH VALUES. THE MAIN TIME PERIOD OF CONCERN
CONTINUES TO BE 1-7 PM.
FORECASTED RAINFALL TOTALS HAVE NOT CHANGED MUCH, WITH A
GENERAL 0.25-0.75" ACROSS THE ENTIRE FORECAST AREA. LOCALLY
HIGHER AMOUNTS OF UP TO AN INCH WILL BE POSSIBLE, PRIMARILY
THANKS TO HIGHER RAINFALL RATES WITHIN AFTERNOON CONVECTIVE
ELEMENTS. THE HREF SHOWS INCREASED 3-HOUR PROBABILITIES OF AN
INCH OR MORE IN THE AFTERNOON COINCIDENT WITH THE BEST FORCING
AND INSTABILITY. WHILE THERE COULD BE A MINOR FLOOD THREAT FOR
URBANIZED AREAS ALONG AND SOUTH OF A LINE FROM AROUND STATESBORO
TO AROUND BEAUFORT, THE OVERALL FLOOD THREAT IS LOW THANKS TO
THE SHORT WINDOW OF TIME FOR THE EVENT.
TONIGHT: THE SURFACE LOW AND FRONT WILL SHIFT OFFSHORE IN THE
EARLY EVENING HOURS AND WILL BRING THE RAINFALL EVENT TO AN END.
WINDS WILL TURN NORTHERLY BRINGING IN SOME COOLER TEMPERATURES,
BUT LOW STRATUS WILL LIKELY LINGER THROUGH THE OVERNIGHT. LOWS
ARE FORECAST TO FALL INTO THE UPPER 30S INLAND, RANGING TO THE
LOW TO MID 40S ALONG THE COAST.
SHORT TERM /SUNDAY THROUGH TUESDAY/
AS ZONAL FLOW TAKES CONTROL OF THE SOUTHEASTERN CONUS, EXPECT
CONDITIONS TO REMAIN RATHER QUIET THROUGH EARLY NEXT WEEK. WEAK
SURFACE HIGH PRESSURE AND RIDGING SHOULD EXPAND ACROSS THE
REGION IN WAKE OF THE MID-LVL SHORTWAVE SPRINTING FURTHER
OFFSHORE. SKIES SHOULD GRADUALLY CLEAR ON SUNDAY MORNING AS DRY
AIR FILTERS INTO THE REGION AND SUBSIDENCE ALLOWS FOR A RAIN-
FREE FORECAST THROUGH THE PERIOD. NOTICEABLE CAA WILL BE PRESENT
WITHIN A NORTHERLY FLOW ON SUNDAY AS HIGHS ONLY REACH INTO THE
UPPER 50S TO LOW 60S DESPITE THE AMPLE AMOUNT OF SUNSHINE.
THEREAFTER, THANKS TO THIS LOW AMPLITUDE RIDGING, TEMPERATURES
WILL WARM BACK UP ON MONDAY AND TUESDAY TO NEAR AND ABOVE NORMAL
VALUES.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
A QUIET AND RAIN-FREE FORECAST WILL PERSIST THROUGH THE PERIOD
AS HIGH PRESSURE CONTINUES TO DOMINATE THE REGION THROUGH THE
END OF THE WEEK. EXPECT THIS STRONG WARM-UP TO CONTINUE AS
TEMPERATURES REACH ABOVE NORMAL VALUES WITH HIGHS IN THE LOW TO
MID 70S ACROSS SOUTHEAST SC AND MID TO UPPER 70S ACROSS
SOUTHEAST GA. OVERNIGHT LOWS WILL BE MILD WITH TEMPS. ONLY
DIPPING INTO THE LOW TO MID 50S (WITH SOME UPPER 50S NEAR THE
COASTLINE).
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
KCHS AND KJZI: RAINFALL HAS SPREAD IN A BIT EARLIER THAN
PREVIOUSLY ANTICIPATED AND LOOKS AS THOUGH IT WILL PERSIST
THROUGH THE NEXT SEVERAL HOURS. CEILINGS ARE JUST STARTING TO
FORM AND LOWER, AND WE HAVE TIMED IN THE ARRIVAL OF IFR CEILINGS
AROUND MID MORNING. RAINFALL WILL BE STEADY THROUGH LATE MORNING
OR MIDDAY BEFORE TAPERING OFF TO JUST BE SHOWERS. CURRENT
THINKING IS THAT THUNDER WILL REMAIN JUST SOUTH WE HAVE NOT
INCLUDED ANY MENTION IN THE 12Z TAF'S. RAINFALL WILL SHIFT
OFFSHORE BY THE EARLY EVENING AND WINDS WILL TURN NORTHERLY.
THERE IS INCREASING CONFIDENCE THAT WIDESPREAD LOW IFR CEILINGS
WILL DEVELOP. THERE COULD EVEN BE SOME FOG, BUT CONFIDENCE IS
STILL LOW.
KSAV: STEADY RAIN WILL CONTINUE TO PASS TO THE NORTH WITH JUST
ISOLATED TO SCATTERED SHOWERS AT TIMES FOR THE NEXT SEVERAL
HOURS. GUIDANCE CONTINUES TO HIGHLIGHT THE POTENTIAL FOR
CEILINGS LOWERING INTO THE IFR RANGE, BUT WE THINK THAT MVFR
CONDITIONS WILL MOSTLY PREVAIL. THE BEST THUNDER CHANCES
CONTINUE TO BE AT KSAV AND WE HAVE INCLUDED A TEMPO GROUP FROM
19-22Z TO ACCOUNT. RAINFALL WILL SHIFT OFFSHORE DURING THE EARLY
EVENING AND WIDESPREAD LOW IFR CEILINGS ARE EXPECTED TO DEVELOP
AND STICK AROUND THROUGH THE END OF THE TAF PERIOD. THERE COULD
EVEN BE SOME FOG, BUT CONFIDENCE IS STILL LOW.
EXTENDED AVIATION OUTLOOK:VFR PREVAILS THROUGH MID-WEEK.
MARINE
TODAY THROUGH TONIGHT: SOUTHWEST FLOW WILL STRENGTHEN AHEAD OF
AN APPROACHING FRONT AND ASSOCIATED SURFACE LOW. WINDS SHOULD
MOSTLY TOP OUT IN THE 15-20 KNOT RANGE, BUT WILL BE A BIT HIGHER
IN THE OUTER GA WATERS WHERE BETTER MIXING WILL BE POSSIBLE.
GUSTS IN THE OUTER GA WATERS WILL LIKELY BE UP TO 25 KNOTS AND A
SMALL CRAFT ADVISORY GOES INTO EFFECT BY MID MORNING. THE FRONT
AND SURFACE LOW WILL SHIFT OFFSHORE DURING THE EARLY EVENING
HOURS AND WINDS WILL TURN NORTHWESTERLY AND THEN NORTHERLY.
WINDS SHOULD MOSTLY TOP OUT AROUND 15 KNOTS WITH GUSTS TO 20
KNOTS, EXCEPT AGAIN FOR THE OUTER GA WATERS. WIND SPEEDS AND
GUSTS SHOULD COME DOWN SUFFICIENTLY TO GET RID OF THE SMALL
CRAFT ADVISORY BY THE EARLY MORNING HOURS. SEAS ARE EXPECTED TO
PEAK IN THE 2-4 FT RANGE FOR MOST OF THE LOCAL WATERS, WITH UP
TO 5 FT IN THE OUTER GA WATERS.
SUNDAY THROUGH WEDNESDAY: NORTH-NORTHEASTERLY WINDS AT 5 TO 10
KTS SHOULD PREVAIL THROUGH MONDAY EVENING, BEFORE SHIFTING MORE
SOUTH- EASTERLY ON TUESDAY AND WEDNESDAY. SOUTH-SOUTHWESTERLY
SWELL SHOULD TAPER BACK ON SUNDAY WITH SEAS RANGING 2 TO 4 FT
THROUGH MID-WEEK. FORECAST NOTES POPS ACROSS THE ATLANTIC
THROUGH THE PERIOD, THUS SOME LIGHT SHOWERS COULD BE POSSIBLE
(ESP. OVERNIGHT).
TIDES/COASTAL FLOODING
UPCOMING MORNING HIGH TIDE (~7:45 AM): THE ASTRONOMICAL HIGH
TIDE IS 6.29 FT MLLW MEANING WE WOULD ONLY NEED A DEPARTURE OF
ABOUT 0.7 FT TO REACH THE MINOR COASTAL FLOOD THRESHOLD (7.0 FT
MLLW). HOWEVER, WINDS WILL NOT BE PARTICULARLY SUPPORTIVE OF
LARGE POSITIVE DEPARTURES SO THE TIDE IS FORECAST TO FALL
SEVERAL TENTHS SHORT OF MINOR COASTAL FLOODING.
SUNDAY: WINDS SHIFT TO THE NORTH-NORTHEAST IN THE MORNING,
LEADING TO A FAVORABLE WIND DIRECTION FOR GREATER TIDAL
DEPARTURES. RAINFALL SHOULD BE FINISHED WITH BEFORE THE
CHARLESTON HIGH TIDE ON SUNDAY MORNING (AT 829 AM), HOWEVER
GIVEN THE FAVORABLE CONDITIONS, THE FORECAST NOTES MINOR COASTAL
FLOODING WITH A PREDICTED WATER LEVEL OF 7.1 FT MLLW AS OF NOW.
THEREFORE, A COASTAL FLOOD ADVISORY COULD BE NEEDED ON SUNDAY
MORNING.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 3 AM EST
SUNDAY FOR AMZ374.
NEAR TERM...BSH
SHORT TERM...DENNIS
LONG TERM...DENNIS
AVIATION...BSH/DENNIS
MARINE...BSH/DENNIS
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