371
FXUS62 KCHS 021047
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
647 AM EDT SUN AUG 2 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR THE 12Z TAFS.
KEY MESSAGES
- 1) ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BRING A RISK FOR
HEAVY RAINFALL AND LOCALIZED FLOODING THROUGH THIS EVENING. A
FEW STRONG TO MARGINALLY SEVERE THUNDERSTORMS COULD ALSO
OCCUR.
- 2) WET CONDITIONS WILL BRING THE POTENTIAL FOR HEAVY RAINFALL
AND LOCALIZED FLOODING MONDAY, WITH THE THREAT POSSIBLY
LINGERING INTO TUESDAY.
- 3) THERE IS A HIGH RISK FOR RIP CURRENTS FOR THE CHARLESTON
COUNTY BEACHES TODAY THROUGH MONDAY WITH A MODERATE RISK
ELSEWHERE.
DISCUSSION
KEY MESSAGE 1: ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BRING A
RISK FOR HEAVY RAINFALL AND LOCALIZED FLOODING THROUGH THIS
EVENING. A FEW STRONG TO MARGINALLY SEVERE THUNDERSTORMS COULD
ALSO OCCUR.
THE REGION WILL REMAIN EMBEDDED WITHIN THE WARM SECTOR OF A
MATURING STORM SYSTEM CENTERED OVER THE OHIO VALLEY THROUGH
TONIGHT. TWO DISTINCT ROUNDS OF SHOWERS/TSTMS ARE EXPECTED TO
IMPACT THE AREA TODAY.
ROUND 1: THE FIRST ROUND WILL BE ASSOCIATED WITH SHORTWAVE
ENERGY EXITING OUT OF THE NORTHEAST GULF. THIS FEATURE IS
ALREADY PRODUCING DEEP CONVECTION OVER APALACHEE BAY EARLY THIS
MORNING AND IS POISED TO SPARK ADDITIONAL CONVECTION OFF THE
GEORGIA AND LOWER SOUTH CAROLINA COAST THROUGH DAYBREAK AS
FORCING FOR ASCENT PROPAGATES IN FROM THE SOUTH AND SOUTHWEST.
GUIDANCE IS GENERALLY SIMILAR IN SHOWING THE BULK OF THIS
ACTIVITY REMAINING JUST OFFSHORE WITH ITS WESTERN PERIPHERY
IMPACTING COASTAL AREAS OF COLLETON, CHARLESTON INTO EASTERN
BERKELEY COUNTIES THROUGH MID-MORNING. ELEVATED PWATS 2.35-2.50"
COUPLED WITH MLCAPE 1000-1500 J/KG SOURCED FROM OFF THE ATLANTIC
WILL SUPPORT A RISK FOR LOCALLY HEAVY RAINFALL, WHICH COULD
POISE A RISK FOR SOME URBAN FLOODING FOR PARTS OF THE CHARLESTON
METRO AREA, ESPECIALLY DOWNTOWN CHARLESTON. BOTH THE 02/00Z
HREF AND REFS SUGGEST A QUICK 1.5-2.5" COULD FALL IN SPOTS OVER
A VERY SHORT PERIOD WITH NEIGHBORHOOD PROBABILITIES FOR >1"/3-HR
RUNNING ABOUT 50-70% AND FOR >3"/3-HR RUNNING 20-30%. THANKFULLY,
THE MEAN 850-250 HPA STEERING FLOW LOOKS TO REMAIN FAIRLY
PROGRESSIVE WHICH SHOULD LIMIT THE FLOOD POTENTIAL SOMEWHAT, BUT
FEW FLOOD ADVISORIES OR EVEN AN ISOLATED BASE-LEVEL FLASH FLOOD
WARNING MAY BE NEEDED LATER THIS MORNING.
ROUND 2: THE SECOND ROUND SHOULD HOLD OFF UNTIL LATER THIS
AFTERNOON AS THE FIRST BATCH OF CONVECTION EXITS THE AREA AND
INSTABILITY STEADILY BUILDS IN ITS WAKE. GUIDANCE SUGGESTS
ANOTHER SHORTWAVE ROUNDING THE SHARPENING/ELONGATING BASE OF THE
WEAKENING UPPER LOW OVER THE MID-MISSISSIPPI VALLEY WILL
APPROACH THE REGION LATER THIS AFTERNOON AND PUSHING OFFSHORE
PRIOR TO MIDNIGHT. SIMILAR TO YESTERDAY, BUILDING MIXED-LAYER
INSTABILITY COUPLED WITH NEAR RECORD PWATS OF 2.35-2.50" WILL
SUPPORT SEVERAL LARGE CLUSTERS OF SHOWERS/TSTMS MOVING IN FROM
NORTHERN FLORIDA AS WELL AS SOUTHWEST/CENTRAL GEORGIA. THIS
ACTIVITY WILL POSE A RISK FOR HEAVY RAINFALL AND LOCALIZED
FLOODING, BUT AS THE 850-250 HPA MEAN FLOW STRENGTHENS THROUGH
THE DAY, STORMS SHOULD BECOME INCREASINGLY MORE PROGRESSIVE,
THUS CURTAILING THE FLOOD POTENTIAL SOMEWHAT. STILL, SOME
FLOODING OF LOW-LYING AND POOR DRAINAGE AREAS APPEARS LIKELY
AND FLOOD ADVISORIES COULD BE NEEDED, MAYBE EVEN AN ISOLATED
BASE-LEVEL FLASH FLOOD WARNING WHERE TRAINING AND/OR BACK-
BUILDING OCCURS ALONG MESOSCALE BOUNDARIES. IN ADDITION TO
HEAVY RAIN, INCREASING WIND FIELDS COULD SUPPORT A RISK FOR
STRONG TO MARGINALLY SEVERE TSTMS WITH DAMAGING WIND GUSTS AND
CLOUD-TO- GROUND LIGHTNING POSSIBLE.
KEY MESSAGE 2: WET CONDITIONS WILL BRING THE POTENTIAL FOR
HEAVY RAINFALL AND LOCALIZED FLOODING MONDAY, WITH THE THREAT
POSSIBLY LINGERING INTO TUESDAY.
SURFACE LOW PRESSURE WILL LIFT NORTHEAST INTO EASTERN CANADA
MONDAY, WITH ITS TRAILING COLD FRONT EXTENDING SOUTHWARD ALONG
THE WESTERN SLOPES OF THE APPALACHIANS. MEANWHILE, THE UPPER
TROUGH DIGGING ACROSS THE OHIO VALLEY IS FORECAST TO EVOLVE INTO
A CUTOFF LOW OVER THE SOUTHEAST, ALLOWING A SERIES OF EMBEDDED
SHORTWAVES TO CONTINUE LIFTING NORTHWARD ACROSS THE FORECAST
AREA. AHEAD OF THE FRONT, AN ANOMALOUSLY MOIST AIRMASS WILL
REMAIN IN PLACE WITH PWATS AROUND 2.3 INCHES DURING THE FIRST
HALF OF THE DAY, OR ROUGHLY TWO STANDARD DEVIATIONS ABOVE
CLIMATOLOGY, BEFORE GRADUALLY DECREASING INTO THE 2.0-2.2 INCH
RANGE BY THE EVENING. ALTHOUGH INSTABILITY IS EXPECTED TO
DIMINISH TO GENERALLY LESS THAN 1000 J/KG, FORECAST SOUNDINGS
CONTINUE TO DISPLAY LONG, NARROW CAPE PROFILES, FAVORING
EFFICIENT WARM-RAIN PROCESSES AND THE POTENTIAL FOR HIGH
RAINFALL RATES DESPITE THE WEAKER INSTABILITY.
CURRENT GUIDANCE CONTINUES TO FOCUS THE GREATEST QPF ALONG THE
COASTAL CORRIDOR, ESPECIALLY NORTH OF THE SC/GA BORDER. GIVEN
ANTECEDENT RAINFALL EXPECTED THROUGH THE REMAINDER OF THE
WEEKEND, LOCALIZED FLOODING CONCERNS WILL INCREASE, ESPECIALLY
WHERE STORMS MOVE OVER THE SAME LOCATIONS. URBAN AND POOR-
DRAINAGE AREAS, INCLUDING THE CHARLESTON METRO AREA, COULD BE
PARTICULARLY SUSCEPTIBLE, POTENTIALLY WARRANTING FLOOD
ADVISORIES OR FLASH FLOOD WARNINGS. THE LATEST NBM AND HREF
INDICATE AN ADDITIONAL 1 TO 2 INCHES OF RAINFALL ALONG THE
IMMEDIATE COAST ON MONDAY.
A SIMILAR PATTERN IS EXPECTED TO PERSIST INTO TUESDAY AS THE
COLD FRONT STALLS INLAND WHILE THE CUTOFF LOW REMAINS ANCHORED
OVER THE SOUTHEAST. ALTHOUGH PWATS SHOULD DECREASE SLIGHTLY,
VALUES NEAR 2 INCHES WILL REMAIN ABOVE NORMAL. COMBINED WITH
MODESTLY HIGHER INSTABILITY THAN MONDAY, THE ENVIRONMENT WILL
CONTINUE TO SUPPORT ADDITIONAL ROUNDS OF SHOWERS AND
THUNDERSTORMS WHICH COULD BE CAPABLE OF PRODUCING HEAVY RAINFALL
AND LOCALIZED FLOODING.
KEY MESSAGE 3: THERE IS A HIGH RISK FOR RIP CURRENTS FOR THE
CHARLESTON COUNTY BEACHES TODAY THROUGH MONDAY WITH A MODERATE
RISK ELSEWHERE.
TODAY: THE COMBINATION OF BUILDING SEAS AND INCREASING WINDS
WILL SUPPORT A HIGH RISK FOR RIP CURRENTS ALONG THE CHARLESTON
COUNTY BEACHES WITH A MODERATE RISK FOR THE BEACHES FROM EDISTO
BEACH SOUTH ALONG THE GEORGIA COAST.
MONDAY: A MODERATE RISK OF RIP CURRENTS CONTINUE FOR AREAS FROM
COASTAL COLLETON COUNTY/EDISTO ISLAND SOUTH TO THE ALTAMAHA
RIVER. ADDITIONALLY, THE HIGH RISK WILL CONTINUE FOR THE
CHARLESTON COUNTY COASTLINE WHERE THE STRONGEST WINDS ARE
EXPECTED TO OCCUR.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
02/06Z TAF DISCUSSION:
KCHS/KJZI: THE BULK OF THIS MORNING'S CONVECTION HAS REMAINED
OFFSHORE, BUT STILL EXPECT SOME IMPACTS TO KJZI THROUGH MID-
MORNING. TEMPO FOR MVFR CONDITIONS IN SHRA WAS INCLUDED 12-14Z.
LATEST DATA HAVE SLOWED DOWN CONVECTION NEAR KCHS AND KJZI THIS
AFTERNOON/EVENING. TEMPO FOR TSRA WAS PUSHED BACK TO 19-22Z AT
KCHS AND PROB30S FOR TSRA WERE HELD 00-03Z AT BOTH KCHS AND
KJZI. GUSTY WINDS ARE EXPECTED FROM LATE MORNING INTO EARLY
EVENING WITH GUSTS NEAR 25 KT AT TIMES.
KSAV: IFR CIGS WERE ABLE TO WORK INTO THE TERMINAL OVER THE PAST
FEW HOURS DESPITE NO REAL SUPPORT FROM GUIDANCE. SUSPECT CIGS
WILL BEGIN TO LIFT/MIX OUT BY MID-MORNING (15Z). CHANCES FOR
TSRA WILL INCREASE BY LATE AFTERNOON, SO TEMPO FOR TSRA WAS
MAINTAINED 20-23Z. GUSTY WINDS ARE EXPECTED FROM LATE MORNING
INTO THE EARLY EVENING WITH GUSTS NEAR 25 KT AT TIMES.
EXTENDED AVIATION OUTLOOK: PERIODIC FLIGHT RESTRICTIONS ARE
EXPECTED IN SHOWERS AND THUNDERSTORMS THROUGH MIDWEEK.
MARINE
THROUGH TONIGHT: THE PRESSURE GRADIENT WILL STEADILY TIGHTEN
THIS AFTERNOON INTO TONIGHT AS HIGH PRESSURE STRENGTHENS
OFFSHORE AND THE STORM SYSTEM TO THE WEST AND NORTHWEST DRAWS
CLOSER. SOUTHWEST WINDS ARE EXPECTED TO INCREASE TO 20-25 KT
THIS AFTERNOON AND LINGER INTO TONIGHT WITH SEAS BUILDING AS
HIGH AS 4-7 FT, HIGHEST OVER ALL THE OFFSHORE LEGS AS WELL AS
THE SOUTH SANTEE-EDISTO BEACH NEARSHORE LEGS. FOR CHARLESTON
HARBOR, WINDS AS HIGH AS 15-20 KT WITH GUSTS TO 25 KT IS
EXPECTED WITH WAVES 1-2 FT. SMALL CRAFT ADVISORIES ARE IN PLACE
FOR ALL WATERS BEGINNING THIS AFTERNOON AND CONTINUING THROUGH
TONIGHT.
MONDAY THROUGH FRIDAY: A STATIONARY FRONT INLAND WILL WEAKEN
THROUGH THE EARLY WEEK ALLOWING THE PRESSURE GRADIENT OVER THE
WATERS TO RELAX. ONGOING SMALL CRAFT ADVISORIES ARE PROGGED TO
DROP OFF THROUGHOUT THE DAY MONDAY AS CONDITIONS GRADUALLY
IMPROVE. BENIGN WIND AND SEA CONDITIONS ARE TO EXPECTED TO
RETURN BY TUESDAY MORNING, PREVAILING THROUGH THE WEEK.
HIGH SURF: THE LATEST NWPS BREAKING WAVE HEIGHT GUIDANCE
SUGGESTS A FEW CHARLESTON COUNTY BEACHES COULD SEE A BREAKERS AS
HIGH AS 5 FT AT TIMES, MAINLY FROM LATE AFTERNOON INTO THE
TONIGHT PERIOD. THESE INSTANCES LOOK PRETTY SPARSE AND WITH MOST
BREAKERS HOLDING IN THE 3-4 FT. THE NEED FOR A HIGH SURF
ADVISORY WAS DEFERRED TO THE DAY SHIFT GIVEN THE MARGINAL NATURE
OF THE EVENT.
CLIMATE
RECORD HIGH MINIMUM TEMPERATURES:
AUGUST 2:
KCHS: 79/2022
KCXM: 84/1999
KSAV: 80/1886
AUGUST 5:
KCHS: 79/1980
KCXM: 82/1991
KSAV: 80/1883
AUGUST 6:
KCHS: 79/1991
KCXM: 82/2006
KSAV: 80/1899
AUGUST 7:
KCHS: 79/2007
KCXM: 83/2007
KSAV: 80/1879
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...HIGH RISK FOR RIP CURRENTS THROUGH THIS EVENING FOR SCZ150.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 2 AM EDT MONDAY FOR
AMZ340.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 2 AM EDT TUESDAY FOR
AMZ360-362.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 AM EDT MONDAY FOR
AMZ364.
SMALL CRAFT ADVISORY FROM NOON TODAY TO NOON EDT MONDAY FOR
AMZ384.
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