274
FXUS62 KCHS 291057
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
657 AM EDT SAT AUG 29 2026
WHAT HAS CHANGED
ALL SECTIONS AND KEY MESSAGES WERE UPDATED.
KEY MESSAGES
- 1) UNSETTLED WEATHER WILL CONTINUE, WITH INCREASING CHANCES
OF SHOWERS AND THUNDERSTORMS THIS WEEKEND.
DISCUSSION
KEY MESSAGE 1: UNSETTLED WEATHER WILL CONTINUE, WITH INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS THIS WEEKEND.
TODAY: THE REGION WILL REMAIN EMBEDDED WITHIN A LARGE MID-LEVEL
WEAKNESS BETWEEN A LARGE SUBTROPICAL RIDGE CENTERED OVER NEW
MEXICO AND WEST TEXAS WITH A SECONDARY RIDGE OVER THE OPEN
WESTERN ATLANTIC. GUIDANCE SHOWS A WELL PRONOUNCED CONVEYOR OF
MID-LEVEL VORTICITY STREAMING OUT OF THE NORTHEASTERN GULF
ACROSS SOUTHEAST GEORGIA, THE SOUTH CAROLINA LOWCOUNTRY AND
INTO THE NORTH CAROLINA OUTER BANKS. THESE IMPULSES COUPLED
WITH A RIBBON OF DEEP MOISTURE CHARACTERIZED BY PWATS 2.0-2.3"
AND SOME MODEST MIXED-LAYER INSTABILITY WILL SUPPORT ANOTHER
ROUND OF SHOWERS/TSTMS TODAY. INITIALLY, CONVECTION IS EXPECTED
TO DEVELOP ALONG/JUST OFFSHORE OF THE LOWER SOUTH CAROLINA COAST
PRIOR TO DAYBREAK WITHIN A REGION OF WEAK/MODEST CONVERGENCE
ASSOCIATED WITH WHAT APPEARS TO BE A LAND BREEZE CIRCULATION.
THIS ACTIVITY IS POISED TO SPREAD/REDEVELOP FARTHER NORTH INTO
THE CHARLESTON TRI-COUNTY THEN TRANSLATE EVER SLOW SLOWLY
INLAND THROUGH THE MORNING HOURS WITH ADDITIONAL ACTIVITY
POSSIBLY DEVELOPING LATER THIS AFTERNOON AS TEMPERATURES RISE
INTO THE 80S. THE VARIOUS CAMS ARE HAVING A HARD TIME RESOLVING
HOW MUCH AND WHERE CONVECTION WILL CONCENTRATE LATER IN THE DAY
WITH SOME REFOCUSING ACTIVITY CLOSER TO I-95 WHILE OTHERS ARE
KEEPING ACTIVITY ACROSS THE LOWCOUNTRY REDEVELOPING CLOSER TO
THE BEACHES AND ACROSS DOWNTOWN CHARLESTON. SUFFICE TO SAY,
THERE IS MUCH UNCERTAINTY HOW MUCH THE ATMOSPHERE WILL RECOVER
LATER THIS AFTERNOON ALONG THE LOWER SOUTH CAROLINA COAST WITH
MORNING CONVECTION LIKELY OVERTURNING THE ATMOSPHERE PRETTY WELL
THERE. FOR NOW, POPS WERE LIMITED TO 50-70% ACROSS THE REGION
WITH THE HIGHEST POPS CLUSTERED ACROSS THE CHARLESTON TRI-COUNTY
WHERE CONFIDENCE IN MORNING CONVECTION IS THE HIGHEST.
ADJUSTMENTS WILL LIKELY BE NEEDED LATER AS TRENDS BECOME
CLEARER.
HEAVY RAINFALL WITH A POTENTIAL FOR SOME LOCALIZED FLASH
FLOODING WILL BE THE PRIMARY HAZARD TODAY, ESPECIALLY WHERE
CONVECTIVE TRAINING OCCURS. THERE COULD ALSO BE A BRIEF
WATERSPOUT AND/OR TORNADO THROUGH LATE MORNING/EARLY AFTERNOON
ACROSS THE COAST WHERE RAP AND H3R SOUNDINGS SHOW LOW-LEVEL WIND
FIELDS VEERING WITH HEIGHT ATOP THE LOW-LEVEL EAST/NORTHEAST
FLOW. WHILE THE LACK OF STRONGER INSTABILITY WILL LIKELY BE THE
LIMITING FACTOR FOR A HIGHER LOCALIZED TORNADO THREAT, IT IS
CERTAINLY SOMETHING TO WATCH OUT FOR, ESPECIALLY AS CONVECTIVE
OUTFLOWS AND THE SEA BREEZE BECOME BETTER DEFINED.
TONIGHT: CONVECTION IS EXPECTED WANE FAIRLY QUICKLY THIS
EVENING. AS INLAND AREAS COOL AND LOW-LEVEL WINDS BACK, A
CORRIDOR OF MODEST CONVERGENCE IS FORECAST TO DEVELOP ALONG
MAINLY THE LOWER SOUTH CAROLINA COAST FROM ROUGHLY MIDNIGHT
THROUGH DAYBREAK SUNDAY. WITH SUCH A WARM AND MOIST ATMOSPHERE
IN PLACE, IT WILL NOT TAKE MUCH TO INITIATE ADDITIONAL
SHOWERS/TSTMS DURING THE EARLY MORNING HOURS. THERE IS A
POTENTIAL FOR SOME CONVECTIVE TRAINING TO OCCUR WITHIN THE
PLUME OF PWATS >2" AND THE 29/00Z HREF ARE SHOWING SOME
ELEVATED PROBABILITIES FOR >1"/3-HR IN THE VICINITY OF DOWNTOWN
CHARLESTON. THIS WILL NEED TO BE MONITORED AS A QUICK INCH IN
DOWNTOWN CHARLESTON IS KNOWN TO CAUSE FLASH FLOODING.
SUNDAY: THERE MAY BE SOME LINGERING SHOWERS AND THUNDERSTORMS
SUNDAY MORNING, THOUGH EXPECT THAT ACTIVITY TO WANE AS
SHORTWAVES ALOFT MOVE NORTHWARDS. EXPECT RIDGING TO BUILD
THROUGHOUT THE DAY, LEADING TO AFTERNOON HIGHS BACK UP IN THE
UPPER 80S TO LOWER 90S ACROSS THE REGION. INSTABILITY VALUES
BUILD TO NEAR 2000 J/KG, THOUGH THE LACK OF FLOW ALOFT SHOULD
KEEP THUNDERSTORMS FROM GETTING WELL ORGANIZED, THUS KEEPING THE
RISK FOR STRONG-SEVERE THUNDERSTORMS ON THE LOW END AS THE
EXPECTED SEA-BREEZE LIKELY SPARKS OFF A FEW SHOWERS AND
THUNDERSTORMS. AS HAS BEEN THE CASE, WE WILL BE WATCHING FOR
LOCALLY HEAVY RAINFALL GIVEN THE LACK OF FLOW ALOFT AND
PRECIPITABLE WATER VALUES IN EXCESS OF 2 INCHES.
MONDAY AND TUESDAY: EXPECT MUCH OF THE SAME FOR MONDAY AS
RIDGING ALOFT CONTINUES, AND SURFACE HIGH PRESSURE REMAINS THE
MAIN SURFACE FEATURE. TUESDAY INTO THE WORK-WEEK WILL LIKELY SEE
LESSER CONVECTIVE COVERAGE AS THE CENTER OF THE RIDGE AXIS
MOVES OVER THE REGION, LEADING TO SLIGHTLY INCREASED HIGH
TEMPERATURES IN THE UPPER 80S TO MID 90S. DEWPOINT TEMPERATURES
CURRENTLY LOOK TO REMAIN IN THE MID 70S, KEEPING HEAT INDEX
VALUES BELOW CRITICAL THRESHOLDS.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
29/12Z TAFS:
KCHS/KJZI: SHOWERS WITH A FEW EMBEDDED TSTMS ARE MOVING THROUGH
BOTH KCHS AND KJZI AT DAYBREAK. SATELLITE AND TERRESTRIAL
LIGHTNING DATA SUGGEST LIGHTNING ACTIVITY HAS BEEN PRETTY SPARSE
OVER THE LAST HOUR OR SO. WILL INITIALIZE BOTH TAFS WITHOUT
TSRA GIVEN CURRENT TRENDS. RISK FOR TSTMS WILL INCREASE AGAIN
THIS AFTERNOON WITH 06Z GUIDANCE TRENDING CLOSER TO THE COAST.
PROB30 FOR TSRA WAS MAINTAINED AT KCHS 19-22Z WITH A TEMPO GROUP
FOR TSRA AT KJZI FOR THE SAME TIME PERIOD. RISK FOR ANOTHER
ROUND OF NOCTURNAL SHOWERS/TSTMS WILL INCREASE AGAIN EARLY
SUNDAY MORNING. A PROB30 GROUP FOR TSRA WAS INTRODUCED FOR BOTH
TERMINALS 08-12Z TO TREND.
KSAV: STRATUS HAS BACKED OFF AT KSAV OVER THE PAST HOUR SO WITH
KSVN REPORTING LIFR CIGS OVC002 AT 10Z. IT IS UNCLEAR HOW
EXPANSIVE THE STRATUS IS NEAR KSAV. WILL SHOW PREVAILING LOW-
END MVFR CIGS AT 14Z, BUT A LAST MINUTE ADJUSTMENT FOR LIFR CIGS
MAY NEED TO BE INCLUDED PENDING TRENDS. VFR SHOULD RETURN BY
16Z. RISK FOR TSTMS INCREASED 19-22Z SO A TEMPO GROUP WAS
INTRODUCED FOR NOW.
EXTENDED AVIATION OUTLOOK: SHOWERS AND THUNDERSTORMS WILL BRING
BRIEF FLIGHT RESTRICTIONS INTO EARLY NEXT WEEK, ESPECIALLY
DURING THE AFTERNOON HOURS.
MARINE
THROUGH TONIGHT: THERE WILL BE A RISK FOR WATERSPOUTS NEAR THE
COAST LATER THIS MORNING. OTHERWISE, NORTHERLY WINDS WITH THE
LAND BREEZE ALONG THE LOWER SOUTH CAROLINA COAST WILL GRADUALLY
VEER MORE ONSHORE THROUGH THE DAY AS THE SEA BREEZE DEVELOPS.
ONSHORE WINDS WILL LINGER THROUGH TONIGHT WITH DIRECTIONS NEAR
THE BEACHES LIKELY BACKING MORE EAST TO NORTHEAST LATE. SPEEDS
WILL REMAIN LESS THAN 15 KT THROUGH TONIGHT WITH SEAS 1-3 FT.
SUNDAY THROUGH WEDNESDAY: NO LARGE-SCALE MARINE CONCERNS. FLOW
WILL BECOME INCREASINGLY ONSHORE, THOUGH OVERALL FAIRLY WEAK,
STRONGEST DURING THE AFTERNOON HOURS AS THE SEA-BREEZE FORMS AND
MOVES ASHORE.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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