141
FXUS62 KCHS 282010
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
410 PM EDT FRI MAR 28 2025
SYNOPSIS
DRY, HIGH PRESSURE WILL PREVAIL THROUGH SATURDAY, THEN RAIN AND
THUNDERSTORM CHANCES INCREASE INTO SUNDAY AND MONDAY FOLLOWED BY
A STRONG COLD FRONT MONDAY EVENING. A FRONT COULD LINGER NEARBY
MID-WEEK, BEFORE STRONGER HIGH PRESSURE PREVAILS LATE NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AFTERNOON COMPOSITE ANALYSIS REVEALS SUBTROPICAL UPPER LEVEL
RIDGING ACROSS THE SOUTHEAST, UPSTREAM FROM A SOUTHERN STREAM
SHORT-WAVE OVER THE LOWER MISSISSIPPI RIVER VALLEY/NORTHWEST
GULF REGION. ELONGATED ATLANTIC HIGH PRESSURE EXTENDS FROM
AROUND BERMUDA BACK INTO THE SOUTHEAST U.S. WEAK INVERTED TROUGH
IS STILL OFF THE COAST KICKING OFF ISOLATED-SCATTERED SHOWER
ACTIVITY IN THE COASTAL WATERS, SOME OF WHICH IS TRYING TO
MIGRATE INTO THE UPPER CHARLESTON COUNTY AREA.
MEANWHILE, HIGHER DEWPOINT AIR HAS SPREAD BACK INTO THE
SOUTHEAST COAST WITH DEWPOINTS IN THE 50S MOST AREAS, AND A BIT
OF AN AFTERNOON CU FIELD ACROSS MUCH OF THE FORECAST AREA.
REST OF THE AFTERNOON: A FEW SPRINKLES OR A REMNANT SHOWER
REMAINS A POSSIBILITY ALONG THE CHARLESTON COUNTY COAST THROUGH
EARLY EVENING, PARTICULARLY THE UPPER CHARLESTON COUNTY COAST
AREA. A VERY SMALL POP WAS ADDED TO THE FORECAST THROUGH 7 PM.
TONIGHT: THE WESTWARD EXTENSION OF ATLANTIC HIGH PRESSURE WILL
REMAIN ACROSS THE SOUTHEAST U.S. TONIGHT AS SUBTROPICAL RIDGING
HOLDS ALOFT. EXTENSIVE CIRRUS WILL SPREAD ACROSS THE REGION AS
THE SOUTHERN STREAM STORM SYSTEM OVER TEXAS BEGINS TO WEAKEN AND
EJECT OUT ACROSS THE LOWER MISSISSIPPI VALLEY. SIGNALS REMAIN
THAT THERE MAY BE A BAND OF DIMINISHING SHOWERS/SPRINKLES
MIGRATING OUT OF THE GULF COAST REGION INTO SOUTHEAST GEORGIA
LATE OVERNIGHT IN SATURDAY MORNING. BUT PRECIP PROBABILITIES ARE
FAR TOO LOW TO MENTION IN THE FORECAST. LOWS TONIGHT WILL RANGE
FROM THE LOWER-MID 50S INLAND TO THE LOWER 60S AT THE BEACHES
AND DOWNTOWN CHARLESTON.
SHORT TERM /SATURDAY THROUGH MONDAY/
SATURDAY: ALOFT, H5 SHORTWAVE ENERGY SHOULD BEGIN TO RIPPLE ACROSS
THE REGION LATE DAY ALONG THE NORTHEASTERN EDGE OF A BROAD RIDGE
AXIS PLACED WELL OFFSHORE. AT THE SFC, WEAK COASTAL TROUGHING SHOULD
SLOWLY TRACK ALONG THE WESTERN PERIPHERY OF THE ATLANTIC HIGH,
PERHAPS SPAWNING A FEW SHOWERS ACROSS COASTAL WATERS THAT ATTEMPT TO
REACH COASTAL AREAS. HOWEVER, MOST GUIDANCE SUGGESTS DEEPER MOISTURE
TO BE SOMEWHAT LACKING, WITH PWATS AROUND 1 INCH OR LESS FOR THE
BULK OF THE DAY. AT THIS TIME, DRY CONDITIONS REMAIN IN THE FORECAST
FOR ALL ZONES, BUT AN ISOLATED SHOWER CAN NOT BE RULED OUT DURING
PEAK DIURNAL HEATING. AFTERNOON HIGHS SHOULD RANGE IN THE UPPER 70S
TO AROUND 80 INLAND. A SEA BREEZE SHOULD LIMIT TEMPS TO THE LOW-MID
70S CLOSER TO THE BEACHES. LIGHT ONSHORE WINDS AND SOME CLOUDS
DURING THE NIGHT WILL LIMIT RADIATIONAL COOLING, SO LOW TEMPS ARE
EXPECTED TO REMAIN MILD, GENERALLY IN THE UPPER 50S INLAND TO LOWER
60S NEAR THE COAST.
SUNDAY: ALOFT, CONDITIONS WILL BE QUITE SIMILAR TO THE PREVIOUS DAY,
WITH A CONTINUOUS STREAM OF H5 VORT ENERGY ACROSS THE SOUTHEAST FOR
MUCH OF THE DAY, BEFORE SHIFTING OFFSHORE LATE DAY AND INTO THE
NIGHT. AT THE SFC, SOUTH-SOUTHEASTERLY FLOW ALONG THE WESTERN
PERIPHERY OF THE ATLANTIC HIGH WILL CONTINUE TO ADVECT DEEPER
MOISTURE (PWATS 1.5 INCHES) ACROSS THE LOCAL AREA, LEADING TO A FEW
SHOWERS HEADING THROUGH DAYBREAK. MOISTURE ADVECTION ALONG WITH SFC
TEMPS APPROACHING THE UPPER 70S/LOWER 80S SHOULD EVENTUALLY SUPPORT
A FEW THUNDERSTORMS MID-LATE AFTERNOON, BUT ACTIVITY WILL LIKELY
FALL SHORT OF STRONG AND/OR SEVERE CRITERIA. PRECIP ACTIVITY APPEARS
DIURNALLY DRIVEN LATE DAY, WITH THE BULK OF ACTIVITY DISSIPATING
DURING THE NIGHT. HOWEVER, A FEW SHOWERS CAN NOT BE RULED OUT CLOSER
TO COASTAL AREAS WITH LINGERING MID-LVL ENERGY SHIFTING OFFSHORE.
PERSISTENT SOUTHERLY FLOW UNDER CLOUDS WILL MAINTAIN MILD TEMPS,
WITH LOWS GENERALLY IN THE LOW-MID 60S.
MONDAY: THIS SHOULD BE THE MOST ACTIVE DAY IN REGARDS TO SHOWER AND
THUNDERSTORM ACTIVITY. THE LOCAL AREA WILL REMAIN WARM-SECTORED IN
ADVANCE OF A COLD FRONT ARRIVING LATE DAY AND POTENTIALLY DURING THE
OVERNIGHT PERIOD. DEEP MOISTURE AND AMPLE SFC HEATING (HIGHS IN THE
LOW-MID 80S AWAY FROM THE COAST) SHOULD LEAD TO A MODERATELY
UNSTABLE ATMOSPHERE, WITH SBCAPE UPWARDS TO 1000-2000 J/KG AND LOW-
LVL LAPSE RATES BETWEEN 7-7.5 C/KM SUGGESTING A FEW THUNDERSTORMS
CAPABLE OF PRODUCING STRONG/DAMAGING WINDS. THE STORM PREDICTION
CENTER CONTINUES TO PLACE A 15% PROBABILITY FOR SEVERE WEATHER
ACROSS THE ENTIRE AREA AS WELL, ALTHOUGH SEVERITY AND TIMING OF
ACTIVITY COULD BE HIGHLY DEPENDENT ON FROPA ARRIVAL WITH SOME
GUIDANCE SUGGESTING THE BULK OF ACTIVITY ARRIVING IN A WEAKER STATE
DURING EVENING HOURS. SOME AREAS COULD EXPERIENCE 1/4 TO 1/2 INCH OF
RAINFALL PRIOR TO SUNSET (HIGHEST AMOUNTS INLAND).
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
A LINE OF SHOWERS AND THUNDERSTORMS WILL BE PUSHING ACROSS THE AREA
MONDAY NIGHT INTO TUESDAY, AS THE SURFACE COLD FRONT AND MAIN UPPER
LEVEL TROUGH AXIS MOVES ACROSS THE REGION. NBM 24 HOUR RAINFALL
PROBABILITIES FOR 0.10" (0.25") ARE IN THE 60S (30S) NEAR THE
CHARLESTON TRI-COUNTY AREA, FALLING INTO THE MID 40S (20S) ACROSS
OUR FAR SOUTHERN SOUTHEASTERN GEORGIA COUNTIES. DESPITE THE FRONTAL
PASSAGE (FROPA) TEMPERATURES ARE EXPECTED TO REBOUND BACK UP INTO
THE UPPER 70S TO LOWER 80S.
DETERMINISTIC AND ENSEMBLE GUIDANCE BEGIN TO DIVERGE IN TIMING OF
ADDITIONAL SHORTWAVES THAT MOVE THROUGH THE ZONAL FLOW, WHICH
RESULTS IN NUMEROUS PERIODS WHERE THE NBM HAS ADDED LOW CHANCES FOR
RAIN (~20%). EXPECT THIS TO BE REFINED WITH FURTHER MODEL RUNS.
OTHERWISE, WARM TEMPERATURES ARE EXPECTED TO CONTINUE INTO THE END
OF THE WEEK.
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
28/18Z TAF DISCUSSION:
KCHS/KJZI/KSAV: VFR WILL PERSIST AT ALL TERMINALS. A TOUCH OF
GUSTINESS WILL PERSIST THROUGH SUNSET WITH GUSTS AS HIGH AS
18-22 KT.
EXTENDED AVIATION OUTLOOK: BRIEF FLIGHT RESTRICTIONS ARE POSSIBLE
SATURDAY NIGHT THROUGH MONDAY EVENING, MAINLY DUE TO LOW CEILINGS. A
LINE OF SHOWERS/THUNDERSTORMS COULD MOVE THROUGH MONDAY AFTERNOON OR
EVENING, PRODUCING ADDITIONAL FLIGHT RESTRICTIONS THAT POTENTIALLY
LINGER INTO THE OVERNIGHT HOURS. VFR CONDITIONS SHOULD THEN PREVAIL
AT ALL TERMINALS TUESDAY.
MARINE
TONIGHT: A MORE ESTABLISHED SOUTHERLY FLOW WILL DOMINATE
TONIGHT AS ATLANTIC HIGH PRESSURE HOLDS WELL OFFSHORE. SPEEDS
WILL HOLD 5-10 KT WITHIN 20 NM AND WILL INCREASE TO 10-15 KT
OVER THE GEORGIA OFFSHORE WATERS LATER THIS EVENING AND
OVERNIGHT. SEAS WILL BUILD 2-4 FT NEARSHORE WATERS AND 4-5 FT
OVER THE GEORGIA OFFSHORE WATERS.
SATURDAY AND SUNDAY: H5 SHORTWAVE ENERGY WILL RIPPLE ACROSS THE
REGION WHILE A SOUTH-SOUTHEASTERLY SFC FLOW OF 10-15 KT PREVAILS
ALONG THE WESTERN PERIPHERY OF HIGH PRESSURE EXTENDING ACROSS THE
ATLANTIC. WEAK COASTAL TROUGHING COULD HELP PRODUCE A FEW SHOWERS
OVER LOCAL WATERS SATURDAY, BEFORE INCREASING POTENTIAL OCCURS
SUNDAY AS THE AREA IS WARM-SECTORED WELL AHEAD OF A COLD FRONT
ARRIVING EARLY NEXT WEEK. AHEAD OF THE FRONT, SEAS COULD TOUCH 6 FT
ACROSS OUTER GEORGIA WATERS, LEADING TO A SMALL CRAFT ADVISORY
ISSUANCE. TIMING AND SPATIAL EXTENT OF 6 FT SEAS REMAINS SOMEWHAT
QUESTIONABLE SATURDAY AFTERNOON, SO OPTED TO MAINTAIN HEADLINE FREE
MARINE CONDITIONS FOR THE TIME BEING.
MONDAY THROUGH WEDNESDAY: BREEZY SOUTH-SOUTHEAST WINDS AHEAD OF AN
APPROACHING COLD FRONT LOOK TO REMAIN JUST BELOW SMALL CRAFT
CRITERIA ON THE WIND SIDE, THOUGH GREATER CHANCES FOR 6 FT SEAS
CONTINUE IN THE OFFSHORE GA WATERS MONDAY AFTERNOON, THEN ALSO
ACROSS NEARSHORE SC WATERS OFF THE CHARLESTON COUNTY COAST NEAR OR
POST FROPA MONDAY NIGHT. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE POSSIBLE, THOUGH THE BETTER CHANCES ARRIVE AS A
BROKEN LINE OF SHOWERS/THUNDERSTORMS IS EXPECTED TO PUSH THROUGH
MONDAY EVENING INTO EARLY TUESDAY. MAY CONTINUE TO SEE SOME ISOLATED
SHOWERS THROUGHOUT THE DAY ON TUESDAY (20% CHANCES), WITH VARYING
WINDS STARTING OUT OF THE WEST DURING THE MORNING, VEERING TO THE
NORTH-NORTHEAST IN THE AFTERNOON, AND CONTINUING TO VEER TO THE EAST
INTO THE EVENING HOURS. CONDITIONS APPEAR TO REMAIN BELOW SMALL
CRAFT ADVISORY LEVEL CONDITIONS DURING THE DAY ON WEDNESDAY, BUT
SOME GUIDANCE SUGGESTS A TIGHTENING OF THE PRESSURE GRADIENT
ASSOCIATED WITH A FRONT NEARBY. ANOTHER ROUND OF SMALL CRAFT
ADVISORIES COULD EVENTUALLY BE NEEDED WEDNESDAY NIGHT.
EQUIPMENT
THE KCLX RADAR REMAINS OFFLINE FOR DOME MAINTENANCE THROUGH
APRIL 1, 2025. RADAR DATA WILL NOT BE AVAILABLE DURING THIS
TIME. USERS ARE URGED TO USE ADJACENT WSR-88D SITES WHICH ALSO
COVER MUCH OF SOUTHEAST SOUTH CAROLINA, SOUTHEAST GEORGIA AND
THE ADJACENT COASTAL WATERS. THESE INCLUDE:
KCAE - COLUMBIA, SC
KLTX - WILMINGTON, NC
KJAX - JACKSONVILLE, FL
KVAX - MOODY AFB, GA
KJGX - ROBBINS AFB, GA
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...ADAM
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...ADAM/DPB
MARINE...ADAM/DPB
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