977
FXUS62 KCHS 091122
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
722 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: THE UPSTREAM CONVECTION WE WATCHED ALL NIGHT
FINALLY MADE ITS WAY INTO SOUTHEAST SC AND CONTINUES TO PUSH TO
THE COAST AND THE COASTAL WATERS. THERE COULD STILL BE A FEW
ADDITIONAL SHOWERS THAT DEVELOP ALONG THE OUTFLOW BOUNDARY, BUT
MOST OF THIS ACTIVITY SHOULD BE FINISHED UP BY AROUND 9-10AM.
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 /11Z FRIDAY THROUGH TUESDAY/
KCHS AND KJZI: A FEW SHOWERS WILL LINGER AROUND THE TERMINALS
THROUGH ABOUT 13Z AND THEN IT SHOULD COME TO AN END. MVFR
CEILINGS COULD LINGER AS WELL THROUGH MID MORNING. THEN FOR THE
AFTERNOON, ATTENTION TURNS TO THE POTENTIAL FOR THUNDERSTORMS.
GIVEN THE STORMS THAT CAME THROUGH THIS MORNING, IT IS LIKELY
THAT THE ENVIRONMENT IS WORKED OVER AND WE WILL SEE LITTLE TO NO
DEVELOPMENT. WE HAVE MAINTAINED THE VCTS MENTION, BUT THERE
ISN'T MUCH CONFIDENCE IN POSSIBLE DIRECT IMPACTS. THE FRONT WILL
PASS THROUGH LATE TONIGHT AND WE WILL SEE NORTHEAST FLOW BUILD
INTO THE AREA.
KSAV: MORNING SHOWER AND THUNDERSTORM ACTIVITY HAS STAYED AWAY
FROM KSAV AND THAT SHOULD CONTINUE INTO THE AFTERNOON. THE
SOUTHEAST GA AREA COULD END UP BEING WHERE MOST OF THE
THUNDERSTORM ACTIVITY IS IN THE AFTERNOON HOURS. STILL, THERE IS
LOW CONFIDENCE IN DIRECT IMPACTS AT THE TERMINAL SO FOR NOW WE
JUST HAVE VCTS. PERIODIC SHOWERS COULD PASS THROUGH EVEN DURING
THE LATE NIGHT HOURS BEFORE A COLD FRONT PASSES THROUGH AND
WINDS TURN NORTHEASTERLY RIGHT NEAR SUNRISE SATURDAY.
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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