840
FXUS62 KCHS 310604
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
204 AM EDT MON AUG 31 2026
WHAT HAS CHANGED
ALL KEY MESSAGES AND SECTIONS WERE UPDATED.
KEY MESSAGES
- 1) LOCALLY HEAVY RAINFALL POSSIBLE AGAIN TODAY WITH A RISK FOR
A FEW DAMAGING WIND GUSTS. RAIN CHANCES DIMINISH THROUGH THE
WEEK INTO THE WEEKEND.
- 2) HOT AND HUMID CONDITIONS WILL RETURN TUESDAY AND CONTINUE
INTO THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: LOCALLY HEAVY RAINFALL POSSIBLE AGAIN TODAY WITH
A RISK FOR A FEW DAMAGING WIND GUSTS. RAIN CHANCES DIMINISH
THROUGH THE WEEK INTO THE WEEKEND.
TODAY: EARLY MORNING WATER VAPOR AND 31/00Z UPPER AIR ANALYSIS
SHOW THE SYNOPTIC PATTERN ALOFT IS BEGINNING TO CHANGE ACROSS
THE SOUTHEAST U.S. WITH THE PRONOUNCED UPPER RIDGE CENTERED
OVER THE MID-MISSISIPPI VALLEY SHOWING SIGNS OF BUILDING EAST.
GUIDANCE SUGGESTS THE MAIN MID-LEVEL WEAKNESS THAT HAS BEEN IN
PLACE FOR THE PAST FEW DAYS WILL BEGIN TO STEADILY WEAKEN TODAY
AND GRADUALLY SHIFT OFFSHORE AS 500 HPA HEIGHTS SLOWLY RISE.
WHILE SUBSIDENCE WITH THE UPPER RIDGE WILL GRADUALLY STRENGTHEN
THIS WEEK, MODIFIED RAP SOUNDINGS ACROSS SOUTHEAST GEORGIA AND
THE SOUTH CAROLINA LOWCOUNTRY SHOW NO SIGNS OF A CAPPING
INVERSION THROUGH THE AFTERNOON WITH BOTH MOISTURE AND
INSTABILITY REMAINING AT LEVELS SUFFICIENT FOR SCATTERED
SHOWERS/TSTMS AGAIN TODAY.
CONVECTION IS EXPECTED TO DEVELOP ALONG THE MAINLY THE GEORGIA
COAST LATER THIS MORNING AS WEAK COASTAL TROUGHING DEVELOPS NEAR
THE BEACHES. NEAR TERM INSTABILITY PROGS SUGGEST MLCAPE AS HIGH
AS 1000-1500 J/KG COULD MOVE ACROSS THE COASTAL COUNTIES FROM
OFF THE ATLANTIC PRIOR TO DAYBREAK AS LOW-LEVEL CONVERGENCE
BUILDS. THIS COULD SUPPORT A ROUND OF SHOWERS/TSTMS WITH THE
GREATEST CONCENTRATION EXPECTED TO OCCUR ACROSS THE MIDDLE AND
UPPER GEORGIA COASTAL COUNTIES. PWATS AROUND 2.25" ARE EXPECTED
IN THIS AREA WITH VERY WEAK WIND FIELDS NOTED ALOFT. THIS COULD
SUPPORT A RISK FOR MINOR FLOODING OF LOW-LYING AND POOR
DRAINAGE AREAS, BUT THANKFULLY MUCH OF THE GEORGIA COAST OUTSIDE
OF THE SAVANNAH METRO AREA AND SMALLER URBAN CENTERS SUCH AS
RICHMOND HILL, HINESVILLE AND DARIEN CAN TYPICALLY HANDLE QUITE
A BIT OF RAINFALL BEFORE PROBLEMS OCCUR. THE 31/00Z REFS
SUPPORTS A POTENTIAL FOR LOCALIZED RAINFALL AMOUNTS IN EXCESS OF
3"/3-HR IN THIS AREA.
LATER THIS AFTERNOON, BUILDING INSTABILITY AHEAD OF MODEST SEA
BREEZE CIRCULATION SHOULD SUPPORT ANOTHER ROUND OF SHOWER/TSTMS.
BY THIS TIME, HOWEVER, DRIER AIR ASSOCIATED WITH THE BUILDING
RIDGE ALOFT WILL BEGIN TO ARRIVE WITH A PRONOUNCED DROPPING OF
K-INDEX VALUES ACROSS THE FAR INTERIOR NOTED (ROUGHLY THE
MILLEN- ALLENDALE-SAINT GEORGE-MONCKS CORNER CORRIDOR). MODEST
MOISTURE STILL LOOKS TO HOLD FOR AREAS SOUTH OF THIS CORRIDOR
THROUGH PEAK HEATING, BUT CONVECTION MAY STILL NOT END UP BEING
QUITE AS PRONOUNCED AS WOULD TYPICALLY BE OBSERVED DURING THE
LATE SUMMER GIVEN THE INCREASING INFLUENCE OF THE UPPER RIDGE.
WIND FIELDS ARE FORECAST TO REMAIN PRETTY LIGHT ALOFT (850-200
HPA STEERING FLOW OF 10 KT OR LESS) SO ANY TSTMS THAT DEVELOP
(ESPECIALLY CLOSER TO THE COAST WHERE PWATS WILL REMAIN ABOVE
2") HAVE THE POTENTIAL TO DROP SOME TORRENTIAL RAINFALL IN A
SHORT PERIOD. THIS COULD YIELD SOME FLOODING ISSUES WITH THE
31/00Z REFS SUPPORTING A POTENTIAL FOR LOCALIZED RAINFALL
AMOUNTS IN EXCESS OF 4"/3-HR, MAINLY ASSOCIATED WITH SEA BREEZE
CONVECTION ACROSS PARTS OF CHARLESTON, BERKELEY, DORCHESTER AND
COLLETON COUNTIES. INCREASING DRY AIR ALOFT COULD ALSO INCREASE
THE RISK FOR A FEW LOCALLY DAMAGING WIND GUSTS. SHEAR WILL BE
WEAK, SO TSTMS WILL BE HEAVY INFLUENCES BY MESOSCALE PROCESSES
SUCH OUTFLOW BOUNDARY COLLISIONS AND THE SEA BREEZE. CONVECTION
WILL QUICKLY WANE THIS EVENING.
REST OF THE WEEK: THE EDGE OF THE RIDGE AXIS ALOFT BEGINS TO
SLIDE OVER THE REGION ON TUESDAY, LOWERING THE CONVECTIVE
POTENTIAL A BIT DUE TO THE SUBSIDENCE THAT IT PROVIDES INTO THE
END OF THE WEEK. HOWEVER, WEAK ONSHORE FLOW, PERIODS OF WARM-AIR
ADVECTION IN THE MID-LEVELS, AND THE DAILY SEA-BREEZE WILL LEAD
TO ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS BEING
POSSIBLE. FOR TUESDAY, THERE IS A BIT OF A DISPARITY BETWEEN THE
GLOBAL MODELS AND THE HIGHER RESOLUTION CONVECTION ALLOWING
MODELS (CAMS), WHERE THE GLOBAL MODELS ARE MORE AGGRESSIVE AND
THE CAMS MORE RESERVED. SO, DON'T BE SURPRISED IF THE FORECAST
ENDS UP TRENDING DRIER FOR TUESDAY. FOR WEDNESDAY INTO THE END
OF THE WEEK, EXPECT MUCH OF THE SAME. BY SATURDAY, THE RIDGE
WEAKENS AND AN UPPER LEVEL TROUGH WILL BE DEVELOPING ALONG THE
EAST COAST, WITH SHORTWAVES MOVING THROUGH THE FLOW ALOFT. THIS
WILL BRING INCREASED RAINFALL CHANCES SATURDAY AFTERNOON INTO
SUNDAY.
KEY MESSAGE 2: HOT AND HUMID CONDITIONS WILL RETURN TUESDAY AND
CONTINUE INTO THE WEEKEND.
THE RIDGE OF HIGH PRESSURE ALOFT THAT WAS DISCUSSED ABOVE WILL ALSO
HELP TO KEEP TEMPERATURES ABOVE NORMAL NEXT WEEK, WITH THE RETURN OF
HOT AND HUMID CONDITIONS EXPECTED. ON TUESDAY, THE REGION WILL START
TO SLIDE UNDER THE EASTERN PERIPHERY OF THE RIDGE AXIS, BRINGING
WIDESPREAD TEMPERATURES IN THE UPPER 80S TO LOWER 90S, WITH HEAT
INDEX VALUES IN THE UPPER 90S TO LOWER 100S. BY WEDNESDAY, THE RIDGE
AXIS ACTUALLY SHIFTS A TOUCH NORTHWARDS, WITH THE REGION NOW ON THE
SOUTHERN PERIPHERY THROUGH SATURDAY. WITH CHANCES FOR RAINFALL
REMAINING ON THE LOWER SIDE TEMPERATURES WILL REMAIN ABOVE AVERAGE,
WITH TEMPERATURES PEAKING ON FRIDAY AND SATURDAY IN THE MID 90S. THE
NEED FOR HEAT ADVISORIES WILL CONTINUE TO BE ASSESSED, WITH THE
GREATEST RISK OCCURRING FOR THOSE ALONG THE COASTAL CORRIDOR WHERE
HEAT INDEX VALUES OF 105-110 DEG F MAY OCCUR. A COLD FRONT LOOKS TO
PUSH THROUGH ON SUNDAY, BRINGING AN END TO THIS STRETCH OF HOT AND
HUMID CONDITIONS.
AVIATION /06Z MONDAY THROUGH FRIDAY/
31/06Z TAFS:
KCHS/KJZI: A BRIEF PERIOD OF LOW CLOUDS COULD REACH KCHS PRIOR
TO 12Z AND LINGER THROUGH MID-MORNING. MVFR CIGS WERE
HIGHLIGHTED 10-15Z. IFR CAN NOT BE COMPLETELY RULED OUT, BUT
NEAR TERM STATISTICAL GUIDANCE SUGGESTS THE RISK IS STILL PRETTY
LOW. LOW CLOUDS SHOULD REMAIN WEST AND NORTHWEST OF KJZI. RISK
FOR SOME MARINE-BASED SHOWERS WILL INCREASE AT KJZI BY 13Z. VCSH
WAS NOTED FOR NOW WITH MOST OF ANY ACTIVITY THAT FORMS POISED TO
REMAIN TO THE SOUTH. AN AREA OF SCATTERED TSTMS IS EXPECTED TO
FORM ALONG THE SEA BREEZE NEAR KCHS BY MID-AFTERNOON. PROB30 FOR
TSRA WAS MAINTAINED 19-21Z TO ACCOUNT FOR THIS. TSTM RISK LOOKS
TO SMALL TO INCLUDE A MENTION AT KJZI AS THE SEA BREEZE SHOULD
CLEAR THAT TERMINAL BY 17Z.
KSAV: VFR THIS MORNING. A BRIEF PERIOD OF SOME MVFR CIGS SHOULD
OOZE INTO THE TERMINAL JUST BEFORE DAYBREAK, SO TEMPO WAS USED
10-12Z. RISK FOR SHOWERS AND POSSIBLY A FEW TSTMS WILL INCREASE
CLOSER TO DAYBREAK AS CONVECTION FIRES IN THE VICINITY OF A WEAK
COASTAL TROUGH ALONG THE BEACHES. RISK FOR TSTM IMPACTS LOOK
GREATEST 14-17Z SO A TEMPO GROUP WAS HIGHLIGHTED DURING THIS
TIME. A FEW TSTMS COULD LINGER NEAR KSAV THROUGH MID-AFTERNOON,
SO VCTS WAS NOTED. THE SEA BREEZE SHOULD CLEAR THE TERMINAL BY
20Z AND SHOULD END THE RISK FOR TSTM IMPACTS.
EXTENDED AVIATION OUTLOOK: SHOWERS AND THUNDERSTORMS WILL BRING
BRIEF FLIGHT RESTRICTIONS THROUGHOUT THE WEEK, ESPECIALLY
DURING THE AFTERNOON HOURS.
MARINE
THROUGH TONIGHT: WINDS SHOULD BACK TO THE NORTHEAST BY DAYBREAK,
BUT THEN VEER TO THE EAST TO LOCALLY SOUTHEAST BY THIS AFTERNOON
AS THE SEA BREEZE MOVES INLAND. ONSHORE WINDS WILL AGAIN BACK TO
MORE TO THE NORTHEAST TONIGHT. SPEEDS LOOK TO AVERAGE 10 KT OR
LESS THROUGH TONIGHT WITH SEAS 2-3 FT.
TUESDAY THROUGH SATURDAY: 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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