338
FXUS62 KCHS 301115
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
715 AM EDT SUN AUG 30 2026
WHAT HAS CHANGED
ALL KEY MESSAGES AND SECTIONS WERE UPDATED.
KEY MESSAGES
- 1) RAIN CHANCES TO LOWER THIS WEEK.
DISCUSSION
KEY MESSAGE 1: RAIN CHANCES TO LOWER THIS WEEK.
TODAY: THE SYNOPTIC PATTERN, BOTH AT THE SURFACE AND ALOFT, HAS
CHANGED LITTLE SINCE YESTERDAY. THE REGION IS STILL POSITIONED
WITHIN A BROAD MID-LEVEL WEAKNESS BETWEEN DUAL SUBTROPICAL
RIDGES, ONE CENTERED OVER THE MID-MISSISSIPPI VALLEY WITH THE
SECOND WELL OFFSHORE ACROSS THE WESTERN ATLANTIC. 30/00Z
GUIDANCE STILL ANALYZES A NEARLY CONTINUOUS STREAM OF VORTICITY
ADVECTING INTO THE REGION FROM THE NORTHEAST GULF AND OFF THE
ATLANTIC WITHIN A RIBBON OF PWATS 2.25-2.40". KCLX SHOWS A
LARGE AREA OF CONVECTION BEGINNING TO DEVELOP OFFSHORE.
CONVERGENCE IS EXPECTED TO SHIFT CLOSER TO THE UPPER GEORGIA
AND LOWER SOUTH CAROLINA COAST THROUGH DAYBREAK AS WINDS ALONG
THE BEACHES BACK IN RESPONSE TO INLAND COOLING. THIS WILL INDUCE
WEAK COASTAL TROUGHING ALONG THE BEACHES. THIS SHOULD ALLOW
CONVECTION OVER THE ATLANTIC TO TRANSLATE INTO THE SAVANNAH-
CHARLESTON CORRIDOR, POSSIBLY REACHING AS FAR WEST AS I-95
LATER THIS MORNING. CONVECTIVE CELLS WILL TEND TO SLOW AND
POSSIBLY STALL OR TRAIN AS THEY APPROACH THE COASTAL TROUGH.
GIVEN THE DEGREE OF MOISTURE IN PLACE, A RISK FOR FLOODING COULD
DEVELOP WITH A QUICK 1-2" IN AN HOUR POSSIBLE. BOTH THE
SAVANNAH AND CHARLESTON METRO AREAS WILL NEED TO BE WATCHED FOR
AN ISOLATED FLOOD RISK THIS MORNING.
HOW CONVECTION EVOLVES THROUGH THE AFTERNOON/EVENING IS IN
QUESTION AS MUCH WILL DEPEND ON HOW MUCH CONVECTION FORMS THIS
MORNING AND THE DEGREE OF ATMOSPHERIC OVERTURNING. AS WAS
OBSERVED YESTERDAY, MORNING CONVECTION HAD A SIGNIFICANT IMPACT
ON INSTABILITY WHICH ULTIMATELY LIMITED THE COVERAGE AND
INTENSITY OF CONVECTION. SOMETHING SIMILAR COULD OCCUR TODAY
WITH THE 30/00Z CAMS SHOWING A NUMBER OF POSSIBLE OUTCOMES, ALL
LIKELY TIED TO THE AMOUNT HOW MUCH THE ATMOSPHERE CAN RECOVER
INSTABILITY WISE. FOR NOW, POPS FOR TODAY WERE LIMITED TO
40-60% ALONG/EAST OF I-95 WITH 20-40% WEST OF THERE. ADJUSTMENTS
WILL MOST LIKELY BE NEEDED AS TRENDS BECOME CLEARER LATER
TODAY. HIGHS LOOK TO WARM INTO THE UPPER 80S/LOWER 90S WITH
LOWER-MID 80S CLOSER TO THE IMMEDIATE COAST.
TONIGHT: ANY EVENING CONVECTIVE ACTIVITY SHOULD WANE BY EARLY-
MID EVENING. LOW-LEVEL CONVERGENCE SHOULD SHIFT BACK CLOSER TO
THE WEST WALL OF THE GULF STREAM LATE. ANOTHER WEAK COASTAL
TROUGH COULD DEVELOP OVER THE NEARSHORE WATERS LATE TONIGHT, BUT
THE LOW-LEVEL STEERING FLOW DOES NOT LOOK AS FAVORABLE AS THE
PAST FEW MORNING. STILL, A FEW SHOWERS/TSTMS COULD MAKE A RUN
FOR THE COAST EARLY MONDAY MORNING.
MONDAY: AS RIDGING ALOFT CONTINUES AND HIGH PRESSURE REMAINS
THE MAIN SURFACE FEATURE, EXPECT MUCH OF THE SAME FOR MONDAY.
THUS, EXPECT LOWER CHANCES FOR RAIN DURING THE MORNING HOURS,
WITH PROBABILITIES BUILDING INTO THE AFTERNOON HOURS AS
INSTABILITY INCREASES AND THE SEA-BREEZE PUSHES ASHORE. WITH
PWATS REMAINING JUST ABOVE 2 INCHES, LOCALLY HEAVY RAINFALL
CANNOT BE RULED OUT FROM ANY STATIONARY/SLOW MOVING STORMS,
THOUGH THE RISK IS QUITE LOW. THE EASTERN EDGE OF THE RIDGE AXIS
DOES BEGIN TO SLIDE OVER THE REGION BY THE AFTERNOON HOURS,
WHICH SHOULD HELP TO RAISE MAX TEMPERATURES UP INTO THE UPPER
80S TO LOWER 90S.
TUESDAY THROUGH SATURDAY: EXPECT SIMILAR CONDITIONS INTO THE
WEEK AS RIDGING ALOFT CONTINUES, THOUGH THERE WILL LIKELY BE
LESSER CONVECTIVE COVERAGE AS THE CENTER OF THE RIDGE AXIS
BEGINS TO MOVE OVERHEAD. IN ADDITION TO LOWERING CONVECTIVE
POTENTIAL, THIS WILL KEEP MAX TEMPERATURES IN THE UPPER 80S TO
MID 90S, NORMAL TO JUST ABOVE NORMAL FOR THIS TIME OF YEAR. THE
DEWPOINT TEMPERATURES TREND CONTINUES TO SUGGEST DEWPOINTS
SHOULD REMAIN IN THE MID 70S, KEEPING HEAT INDEX VALUES BELOW
CRITICAL THRESHOLDS.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
30/12Z TAFS:
KCHS/KJZI: THE BRIEF LIFR CIGS AT KCHS HAVE MIXED OUT. RADAR
SHOWS CONVECTION FIRING TO THE SOUTH AT DAYBREAK WHICH MAY
SLOWLY EXPAND NORTH CLOSER TO THE TERMINALS LATER THIS MORNING.
RIGHT NOW, CURRENT DATA SUGGEST ACTIVITY WILL WEAKEN BEFORE
BRINING IMPACTS. THE RISK FOR TSTMS COULD INCREASE BY MID-
AFTERNOON AS THE SEA BREEZE MOVES INLAND. THERE ARE
UNCERTAINTIES ON HOW MUCH ACTIVITY WILL DEVELOP IN THE WAKE OF
THIS MORNING'S ACTIVITY. PROB30 GROUPS FOR TSRA WERE MAINTAINED
17-20 AT KJZI AND 19-21Z AT KCHS TO TREND GIVEN THESE
UNCERTAINTIES.
KSAV: CONVECTION FIRING NEAR THE BEACHES IS OCCURRING A BIT
FARTHER SOUTH THAN EARLIER EXPECTED. A FEW TSTMS COULD REACH
KSAV LATER THIS MORNING AND A TEMPO GROUP FOR TSRA WAS
INTRODUCED 14-17Z TO ACCOUNT FOR THIS. RISK FOR TSTMS WILL
INCREASE MID- AFTERNOON AS THE SEA BREEZE MOVES INLAND. THERE
ARE UNCERTAINTIES ON HOW MUCH ACTIVITY WILL DEVELOP IN THE WAKE
OF THIS MORNING'S ACTIVITY. PROB30 FOR TSRA WAS MAINTAINED
18-21Z TO TREND GIVEN THESE UNCERTAINTIES.
EXTENDED AVIATION OUTLOOK: SHOWERS AND THUNDERSTORMS WILL BRING
BRIEF FLIGHT RESTRICTIONS INTO NEXT WEEK, ESPECIALLY DURING THE
AFTERNOON HOURS.
MARINE
THROUGH TONIGHT: EAST/NORTHEAST WINDS THIS MORNING WILL VEER
MORE EASTERLY THROUGH AFTERNOON AS THE SEA BREEZE DEVELOPS AND
WEAK COASTAL TROUGHING ALONG THE COAST DISSIPATES.
EAST/NORTHEAST WINDS WILL REDEVELOP AGAIN TONIGHT. SPEEDS LOOK
TO REMAIN LESS THAN 15 KT (OUTSIDE OF CONVECTION) WITH SEAS 2-3
FT. CONVECTION THIS MORNING COULD PRODUCE GUSTY WINDS, LOCALLY
HEAVY RAINFALL REDUCING VSBYS TO 1 NM OR LESS AND A FEW CLOUD-
TO-WATER LIGHTING STRIKES.
MONDAY THROUGH THURSDAY: NO MARINE CONCERNS EXPECTED. LIGHT AND
VARIABLE PREVAILING FLOW WILL SHIFT ONSHORE EACH AFTERNOON AS
THE SEA BREEZE CIRCULATION DEVELOPS ALONG THE COAST, WITH 2-3 FT
SEAS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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