674
FXUS62 KCHS 032328
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
728 PM EDT MON AUG 3 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR THE 00Z TAFS.
KEY MESSAGES
- 1) CONTINUED UNSETTLED THROUGH TUESDAY WITH A RISK FOR HEAVY
RAINFALL, LOCALIZED FLOODING AND POSSIBLY AN ISOLATED STRONG
TO MARGINALLY SEVERE TSTM.
DISCUSSION
KEY MESSAGE 1: CONTINUED UNSETTLED THROUGH TUESDAY WITH A RISK FOR
HEAVY RAINFALL, LOCALIZED FLOODING AND POSSIBLY AN ISOLATED STRONG
TO MARGINALLY SEVERE TSTM.
AN UPPER-LVL TROUGH WILL CONTINUE TO ADVANCE SLOWLY THROUGH THE DEEP
SOUTH THIS AFTERNOON, WHILE SOUTHEAST SOUTH CAROLINA AND SOUTHEAST
GEORGIA REMAIN WITHIN A VERY MOIST WARM-SECTOR ENVIRONMENT. A
PERSISTENT PLUME OF TROPICAL MOISTURE WILL MAINTAIN PWAT VALUES
AROUND 2.2 TO 2.5 INCHES, WITH THE HIGHEST MOISTURE GENERALLY
LOCATED ALONG AND EAST OF I-95 CORRIDOR. EMBEDDED SHORTWAVES MOVING
THROUGH THE SOUTHWESTERLY FLOW ALOFT, COMBINED WITH WITH THE INLAND-
MOVING SEA BREEZE AND LINGERING CONVECTIVE BOUNDARIES, SHOULD
SUPPORT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS THROUGH THE
LATE EVENING.
LIKE SUGGESTED IN THE LAST FORECAST UPDATE, CONVECTIVE TEMPERATURES
IN THE MID 80S HAS ALLOWED FOR CONVECTION TO INITIATE A BIT EARLIER
THAN THE PAST SEVERAL DAYS. THIS WILL LIMIT THE AMOUNT OF AVAILABLE
INSTABILITY FOR THIS AFTERNOON/EVENING GIVEN THE INCREASED CLOUD
COVERAGE. HOWEVER, POCKETS OF 1000-1500 J/KG OF MLCAPE STILL APPEAR
POSSIBLE WHERE SUFFICIENT HEATING OCCURS. HEAVY RAINFALL WILL THE
MAIN THREAT FOR THIS AFTERNOON INTO THE EVENING (AND POSSIBLY
OVERNIGHT), ALONG WITH LOCALIZED FLOODING. HIGH PWAT VALUES COMBINED
WITH DEEP WARM-CLOUD LAYERS WILL SUPPORT VERY EFFICIENT RAINFALL
PRODUCTION, WITH RATES OF 2-3 INCHES PER HOUR POSSIBLE BENEATH THE
STRONGEST THUNDERSTORMS.
THESE SHOWERS AND THUNDERSTORMS SHOULD BE MOVING THROUGH RATHER
QUICKLY (STORM MOTIONS OF 20-25 KT), THUS THIS SHOULD PREVENT MOST
OF THE CONVECTION FROM REMAINING STATIONARY FOR AN EXTENDED PERIOD
OF TIME. HOWEVER, LOCALIZED FLOODING WILL BE POSSIBLE WHERE STORMS
REPEATEDLY MOVE ACROSS THE SAME LOCATION AND/OR TEMPORARILY ANCHORS
ALONG THE SEA BREEZE, OR AN OUTFLOW BOUNDARY. THEREFORE, THE RISK
FOR FLOODING LOOKS FAIRLY LOW-END AND LIKELY REMAINING CONFINED TO
LOW-LYING AND POOR DRAINAGE AREAS (I.E. FLOOD ADVISORY LEVELS).
ALSO, AN ISOLATED SEVERE THUNDERSTORM CANNOT BE RULED OUT COMPLETELY
FOR THIS AFTERNOON/EVENING AS DAMAGING WIND GUSTS AND CLOUD-TO-
GROUND LIGHTNING COULD BE POSSIBLE WITHIN A STRONGER CELL.
CONVECTION SHOULD GRADUALLY DIMINISH THROUGHOUT THE EVENING AS
INSTABILITY WANES, THOUGH ISOLATED SHOWERS AND THUNDERSTORMS COULD
LINGER ALONG THE COASTLINE. ADDITIONAL CONVECTION IS EXPECTED TO
DEVELOP OVER THE COASTAL WATERS LATE TONIGHT AS LOW-LVL CONVERGENCE
STRENGTHENS NEAR THE WESTERN EDGE OF THE GULF STREAM. SOME OF THIS
ACTIVITY COULD SHIFT ONTO THE IMMEDIATE COASTLINE LATE TONIGHT INTO
DAYBREAK TUESDAY (ESP. ACROSS THE CHARLESTON COUNTY). ANY OVERNIGHT
COASTAL STORMS COULD STILL PRODUCE LOCALLY HEAVY RAINFALL, FREQUENT
LIGHTNING, AND GUSTY WINDS, BUT THE INLAND SEVERE THREAT SHOULD
DIMINISH CONSIDERABLY AFTER SUNSET.
TUESDAY: A SIMILAR PATTERN IS EXPECTED TO PERSIST INTO TUESDAY AS A
STATIONARY FRONT REMAINS INLAND WHILE A CUTOFF LOW STAYS ANCHORED
OVER THE SOUTHEAST. THIS SETUP WILL CONTINUE TO SUPPORT PERIODIC
ROUNDS OF ASCENT AND SCATTERED SHOWERS AND THUNDERSTORMS. ALTHOUGH
THE AXIS OF DEEPEST MOISTURE IS FORECAST TO SHIFT OFFSHORE, GUIDANCE
STILL INDICATES POCKETS WHERE PWAT VALUES COULD REACH 2 INCHES OR
GREATER, REMAINING WELL ABOVE CLIMATOLOGICAL NORMALS. COMBINED WITH
MODESTLY HIGHER INSTABILITY (SBCAPE ~1500 J/KG), THE ENVIRONMENT
WILL REMAIN FAVORABLE FOR ADDITIONAL ROUNDS OF SHOWERS AND
THUNDERSTORMS CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL AND
ISOLATED FLOODING. SIMILAR TO TODAY, THE HIGHEST QPF TOTALS ARE
EXPECTED ACROSS THE SOUTH CAROLINA COAST, INCLUDING THE
CHARLESTON METRO AREA. THE FLOOD THREAT WILL BE HIGHLY DEPENDENT
ON ANTECEDENT CONDITIONS, AS LOCATIONS RECEIVING HEAVY RAINFALL
SUNDAY AND/OR MONDAY WILL HAVE LIMITED TIME TO DRAIN BEFORE
ANOTHER ROUND OF POTENTIALLY HEAVY RAIN DEVELOPS TUESDAY.
MEANWHILE, POCKETS OF INCREASING MID-LEVEL DRY AIR ARE EXPECTED
TO PROMOTE DCAPE VALUES APPROACHING OR EXCEEDING 1000 J/KG.
THEREFORE, AN ISOLATED STRONG TO SEVERE STORM IS POSSIBLE WITH
DAMAGING WIND GUSTS THE PRIMARY HAZARD.
AVIATION /00Z TUESDAY THROUGH SATURDAY/
0Z TAFS: STRATIFORM RAINFALL WILL REMAIN ACROSS KCHS AND KJZI,
WITH VCTS AT KJZI UNTIL AT LEAST 2Z. SOME HIGH RESOLUTION
GUIDANCE SHOWS AN INVERTED COASTAL TROUGH MAY TRIGGER A BAND OF
SHOWERS AND THUNDERSTORMS ALONG THE CHARLESTON COUNTY COAST
DURING THE PRE-DAWN HOURS. GIVEN THE TIME OF THE DAY, THE KCHS
AND KJZI TAFS WILL INDICATE SHOWERS, WITH MVFR VIS RESTRICTIONS
AT KJZI. ON TUESDAY AFTERNOON, SEA BREEZE THUNDERSTORMS APPEAR
MORE LIKELY NEAR KSAV, HIGHLIGHTED WITH A TEMPO FROM 19-23Z.
EXTENDED AVIATION OUTLOOK: PERIODIC FLIGHT RESTRICTIONS ARE EXPECTED
IN SHOWERS AND THUNDERSTORMS THIS WEEK.
MARINE
THROUGH TONIGHT: CONVECTION ALONG THE COAST AND OFFSHORE HAS
DISRUPTED THE WIND FIELD, CAUSING WINDS AND SEAS TO BE BELOW SMALL
CRAFT ADVISORY CRITERIA. THEREFORE, ALL OF THE ADVISORIES HAVE BEEN
CANCELLED. OTHERWISE, EXPECT SW WINDS 15-20 KT THIS EVENING, EASING
TO 10-15 KT BY DAYBREAK TUESDAY. SEAS WILL SUBSIDE TO 3-4 FT
OVERNIGHT.
EXTENDED MARINE: HIGH PRESSURE IN THE ATLANTIC WILL BE THE DOMINANT
SYNOPTIC FEATURE THIS WEEK. THIS WILL GENERATE A TYPICAL SUMMERTIME
WIND FIELD WITH INCREASED WINDS ALONG THE LAND/SEA INTERFACE EACH
AFTERNOON, ASSOCIATED WITH THE SEA BREEZE.
RIP CURRENTS:
TUESDAY: THERE IS A MODERATE RISK OF RIP CURRENTS FOR THE CHARLESTON
COUNTY BEACHES DUE TO LINGERING 2 FOOT SWELLS AT 8 SECONDS, COMBINED
WITH ELEVATED ONSHORE FLOW. EDISTO BEACH SOUTHWARD INTO GA HAS A LOW
RISK.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NED
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