732
FXUS62 KCHS 090740
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
340 AM EDT FRI MAY 9 2025
SYNOPSIS
A FRONT WILL REMAIN STALLED NEAR THE AREA THROUGH EARLY NEXT
WEEK. LOW PRESSURE WILL MOVE THROUGH MONDAY AND TUESDAY,
FOLLOWED BY HIGH PRESSURE.
NEAR TERM /THROUGH TONIGHT/
EARLY THIS MORNING: WE CONTINUE TO WATCH THE ONGOING CONVECTION
ACROSS THE SC MIDLANDS AND ANTICIPATE ITS ARRIVAL IN A FEW
HOURS. THOUGH THIS CONVECTION IS MOSTLY MOVING WEST TO EAST,
KCAE DOES SHOW A FEW SOUTHWARD MOVING OUTFLOW BOUNDARIES THAT
WILL LIKELY PUSH INTO THE FORECAST AREA BY 4-5 AM. THESE
BOUNDARIES WILL LIKELY PROVIDE ENOUGH LIFT TO SUPPORT THE
DEVELOPMENT OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS,
MOSTLY FOR SOUTHEAST SC. THIS ACTIVITY SHOULD THEN STEADILY
PROGRESS TO THE EAST AND EVENTUALLY OFFSHORE BY 8-9 AM. IT
CERTAINLY ISN'T THE MOST FAVORABLE TIME OF DAY FOR SEVERE
WEATHER, BUT SPC MESOANALYSIS INDICATES THAT THERE IS 500-1,000
J/KG OF MLCAPE ALONG WITH 30-40 KNOTS OF BULK SHEAR. SO WHILE WE
DON'T ANTICIPATE ANY SEVERE WEATHER, IT ISN'T OUT OF THE
QUESTION FOR THESE STORMS TO PRODUCE SOME GUSTY WINDS.
TODAY: ALOFT, SOUTHWEST FLOW WILL SPREAD ACROSS THE FORECAST
AREA AS THE POSITIVELY TILTED TROUGH THAT STRETCHES FROM THE
SOUTHERN APPALACHIANS BACK INTO THE SOUTHERN PLAINS CLOSES OFF
INTO A LOW AND SLOWLY DROPS SOUTHWARD ACROSS THE LOWER MS
VALLEY. AT THE SURFACE, THE UPSTREAM COLD FRONT IS EXPECTED TO
PUSH SOUTHWARD ACROSS THE SOUTHERN APPALACHIANS AND STEADILY
APPROACH THE FORECAST AREA. ONCE THE MORNING SHOWERS AND
THUNDERSTORMS PUSHES OFFSHORE, WE SHOULD SEE A PERIOD WITH NO
CONVECTIVE DEVELOPMENT THROUGH AT LEAST MIDDAY. THEN FOR THE
AFTERNOON, HI-RES MODEL GUIDANCE IS PRETTY MUTED WITH CONVECTIVE
COVERAGE AND FAVORS MOSTLY ISOLATED TO SCATTERED THUNDERSTORMS.
THERE IS DECENT CONSENSUS THAT DEVELOPMENT WILL TAKE PLACE
ALONG THE SEA BREEZE BY THE MID TO LATE AFTERNOON AND GENERALLY
KEEP THE BEST COVERAGE ALONG THE COASTAL CORRIDOR. AS FAR AS THE
SEVERE POTENTIAL, IT APPEARS MLCAPE VALUES WILL BE ON THE ORDER
OF 1,000-1,500 J/KG WITH DEEP LAYER SHEAR ON THE ORDER OF ~30
KNOTS. ALSO OF NOTE, MODEL SOUNDINGS SHOW A NICE MID-LEVEL LAYER
OF DRY AIR WHICH WILL RESULT IN DCAPE VALUES UPWARDS OF 1,000
J/KG. THE AREA IS IN A SPC DAY 1 MARGINAL RISK AREA FOR SEVERE
WEATHER, ACCOUNTING FOR THE POTENTIAL FOR LARGE HAIL AND
DAMAGING WIND GUSTS. AHEAD OF THE FRONT, WINDS WILL HAVE A MORE
WESTERLY COMPONENT UNTIL THE DIURNAL SEA BREEZE GETS GOING. THIS
SHOULD CONTRIBUTE TO WARM TEMPERATURES AND WE HAVE HIGHS IN THE
MID TO UPPER 80S.
TONIGHT: THE UPPER LOW IS EXPECTED TO BE CENTERED ACROSS THE
LOWER MS VALLEY AND WILL DRIVE GULF COAST CONVECTION AND THE
DEVELOPMENT OF A SURFACE LOW. THE FRIDAY FRONT WILL DROP
SOUTHWARD THROUGH THE AREA OVERNIGHT AS THE SURFACE HIGH BUILDS
IN AND BEGINS TO TAKE ON A COLD-AIR DAMMING CONFIGURATION.
LINGERING DIURNAL CONVECTION SHOULD STEADILY DISSIPATE AND
BECOME CONFINED TO THE SOUTH. THEN OVERNIGHT WE WILL SEE THE
TRANSITION TO MORE SIGNIFICANT SYNOPTIC SCALE FORCING. WE WILL
LIKELY SEE A PERIOD OF TIME IN THE LATE EVENING AND EARLY
MORNING HOURS WHERE THERE ISN'T MUCH PRECIPITATION ONGOING. THEN
AS WE MOVE TOWARDS SUNRISE, DEEP MOISTURE WILL START TO
TRANSPORT NORTHWARD ALONG WITH INCREASING DEEP LAYER FORCING. WE
SHOULD SEE LIGHT STRATIFORM PRECIPITATION START TO DEVELOP
ACROSS SOUTHEAST GA AND THEN GRADUALLY SHIFT NORTHWARD THROUGH
SUNRISE. AS SUCH, RAIN CHANCES INCREASE FROM SOUTH TO NORTH.
COOLER AIR WILL FILTER IN WITH THE ARRIVAL OF THE LOW-LEVEL
NORTHEAST FLOW AND WE COULD SEE SOME UPPER 50S FOR LOWS ACROSS
THE INLAND TIER. LOWS CLOSER TO THE COAST WILL BE MORE INTO THE
LOW TO MID 60S.
SHORT TERM /SATURDAY THROUGH MONDAY/
AN ACTIVE PERIOD IS FORECAST THROUGH THE WEEKEND AND INTO EARLY
NEXT WEEK. ALOFT, AN UPPER LEVEL LOW WILL BE SITUATED OVER THE
SOUTHEASTERN STATES, PERSISTING THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK. AT THE SURFACE A FRONT WILL REMAIN STALLED IN
THE VICINITY OF THE FORECAST AREA. WITH THE PLACEMENT OF THE
UPPER LEVEL LOW AND THE RESULTANT SOUTHWESTERLY FLOW , MOISTURE
WILL BE ADVECTED INTO THE FORECAST AREA. PWATS THROUGH THE
WEEKEND ARE FORECAST TO REACH 1.6-1.7", POSSIBLY REACHING CLOSE
TO 2" ON MONDAY. THESE VALUES WOULD BE CLOSE TO THE DAILY
MAXIMUM ACCORDING TO THE SPC CLIMATOLOGY. SEVERAL ROUNDS OF
SHOWERS AND THUNDERSTORMS ARE FORECAST THROUGH THE PERIOD.
SATURDAY AND SUNDAY THE GREATEST COVERAGE OF SHOWERS AND STORMS
WILL LIKELY BE ASSOCIATED WITH THE AFTERNOON SEA BREEZE
CIRCULATION. MONDAY IS FORECAST TO HAVE THE GREATEST
PRECIPITATION COVERAGE AS THE UPPER LEVEL LOW PROGRESSES
SLIGHTLY TO THE NORTHEAST AND THE HIGHEST PWATS ARE ADVECTED
INTO THE REGION.
THERE IS THE POTENTIAL FOR STRONG THUNDERSTORMS THROUGH THE
WEEKEND, HOWEVER THE OVERALL SEVERE THREAT APPEARS LOW. FORECAST
SOUNDINGS SHOW INSTABILITY VALUES PEAKING AROUND 800-1000 J/KG
WITH MEAGER SHEAR VALUES OF 20-25 KNOTS. THE MAIN HIGHLIGHT OF
THE PERIOD WILL BE THE THREAT FOR HEAVY RAINFALL. THE WPC
CONTINUES TO HIGHLIGHT THE FORECAST AREA IN A MARGINAL RISK FOR
EXCESSIVE RAINFALL SATURDAY AND SUNDAY, WITH A SLIGHT RISK
FEATURED ON MONDAY. WHILE ANTECEDENT CONDITIONS HAVE BEEN DRY
ACROSS THE REGION, THERE IS THE POTENTIAL FOR MINOR FLOODING OF
URBAN, LOW-LYING, AND POOR DRAINAGE AREAS. RAINFALL TOTALS
SATURDAY THROUGH MONDAY ARE CURRENTLY FORECAST TO RANGE FROM 3
TO 4 INCHES, WITH LOCALLY HIGHER AMOUNTS POSSIBLE.
HIGH TEMPERATURES THROUGH THE PERIOD WILL BE BELOW NORMAL,
GIVEN PRECIPITATION AND CLOUD COVER. HIGHS EACH DAY WILL REACH
INTO THE LOW TO MID 70S, WITH SOME UPPER 70S ALONG THE ALTAMAHA
RIVER IN GA. WITH EXPECTED CLOUD COVER, OVERNIGHT LOWS WILL
REMAIN MILD, ONLY DROPPING INTO THE 60S.
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
THE UPPER LEVEL LOW WILL BEGIN SLOWLY EJECTING NORTHEASTWARD
TOWARDS NEW ENGLAND IN THE MIDDLE OF THE WEEK. BY THE END OF THE
WEEK RIDGING ALOFT WILL BUILD INTO THE SOUTHEASTERN STATES. AT
THE SURFACE THE STALLED FRONT WILL MOVE INTO THE ATLANTIC WATERS
MID WEEK, WITH HIGH PRESSURE BUILDING IN THEREAFTER. WIDESPREAD
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY WITH
SCATTERED SHOWERS AND STORMS ON WEDNESDAY. AS RIDGING BUILDS IN
ALOFT WITH HIGH PRESSURE AT THE SURFACE A MAINLY DRY FORECAST IS
IN STORE THROUGH THE REMAINDER OF THE WEEK. TEMPERATURES
INITIALLY WILL BE AROUND NORMAL, WITH THE POTENTIAL TO INCREASE
TO WELL ABOVE NORMAL BY THE END OF THE WEEK.
AVIATION /07Z FRIDAY THROUGH TUESDAY/
KCHS AND KJZI: THERE ARE A COUPLE OF FORECAST CONCERNS THROUGH
THE NEXT 6-8 HOURS. FIRST, WEB CAMS AND SURFACE OBSERVATIONS
INDICATE THAT PATCHY FOG IS AROUND AND COULD DROP INTO THE IFR
RANGE AT TIMES. A TEMPO GROUP HAS BEEN ADDED FOR 06-10Z TO
ACCOUNT FOR THESE IFR CONDITIONS. SECOND, SHOWERS AND POSSIBLY A
FEW THUNDERSTORMS COULD DROP INTO THE AREA BY AROUND 09-10Z
FROM THE NORTH. SO THERE COULD BE BRIEF PERIODS OF RAINFALL AND
LOWER CEILINGS AND VISIBILITIES DUE TO SHOWERS THROUGH ABOUT
12-13Z. THEN FOR THE AFTERNOON, ATTENTION TURNS TO THE POTENTIAL
FOR THUNDERSTORMS. CURRENT HI-RES MODEL DATA SUGGESTS THAT
THUNDERSTORM COVERAGE WILL BE ISOLATED THIS AFTERNOON AND
EVENING. WE HAVE MAINTAINED THE VCTS BEGINNING AT 20Z.
CONFIDENCE IN DIRECT IMPACTS FROM THUNDERSTORMS ISN'T
PARTICULARLY HIGH.
KSAV: VFR CONDITIONS SHOULD PREVAIL THROUGH ABOUT SUNRISE. THEN
THERE ARE INDICATIONS THAT A BRIEF PERIOD OF IFR STRATUS WILL
BE POSSIBLE, GENERALLY AS EARLY AS 10-11Z AND CONTINUING THROUGH
ABOUT 13Z. WE HAVE ADDED A TEMPO GROUP TO ACCOUNT FOR THIS.
THEN FOR THE AFTERNOON, ATTENTION TURNS TO THE POTENTIAL FOR
THUNDERSTORMS. CURRENT HI-RES MODEL DATA SUGGESTS THAT
THUNDERSTORM COVERAGE WILL BE ISOLATED THIS AFTERNOON AND
EVENING. WE HAVE MAINTAINED THE VCTS BEGINNING AT 20Z.
CONFIDENCE IN DIRECT IMPACTS FROM THUNDERSTORMS ISN'T
PARTICULARLY HIGH.
EXTENDED AVIATION OUTLOOK: MVFR OR LOWER CIGS AND/OR VSBYS
POSSIBLE SATURDAY THROUGH TUESDAY AS A FRONT REMAINS STALLED
NEARBY AND SEVERAL ROUNDS OF SHOWERS/TSTMS MOVE THROUGH.
MARINE
TODAY THROUGH TONIGHT: SOUTH TO SOUTHWEST FLOW WILL MOSTLY
PREVAIL TODAY WITH WIND SPEEDS IN THE 10-15 KNOT RANGE. WINDS
WILL THEN DIMINISH OVERNIGHT BEFORE A NORTHEAST SURGE STARTS TO
PUSH IN ACROSS THE CHARLESTON COUNTY WATERS LATE. SEAS SHOULD
MOSTLY BE 2-3 FEET, WITH UP TO 4 FEET IN THE OUTER WATERS.
SATURDAY THROUGH TUESDAY: A STALLED FRONT WILL LINGER IN THE
VICINITY OF THE COASTAL WATERS THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK. SOUTHEASTERLY FLOW WILL INCREASE THROUGH THE
WEEKEND, WITH 15-20 KNOTS WITH GUSTS TO AROUND 23 KNOTS FORECAST
BY MONDAY. SEAS WILL BUILD TO 4 TO 5 FT, WITH SOME 6 FT
POSSIBLE ACROSS THE 20 TO 60 NM OFFSHORE GA WATERS ON MONDAY AND
INTO TUESDAY. A SMALL CRAFT ADVISORY MAY BE REQUIRED.
CLIMATE
RECORD PRECIPITATION:
MAY 10:
KCHS: 1.45/1961
KCXM: 1.72/1949
KSAV: 1.29/1989
MAY 11:
KCHS: 1.93/1952
KCXM: 1.57/1899
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...BSH
SHORT TERM...CPM
LONG TERM...CPM
AVIATION...BSH/CPM
MARINE...BSH/CPM
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