434
FXUS62 KCAE 281821
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
221 PM EDT FRI AUG 28 2026
WHAT HAS CHANGED
CONFIDENCE IN ABOVE NORMAL TEMPERATURES INCREASING FOR NEXT
WEEK. AVIATION DISCUSSION UPDATED FOR 18Z TAF ISSUANCE.
KEY MESSAGES
- 1. DIURNAL THUNDERSTORMS EXPECTED THROUGH THE WEEKEND WITH THE
MAIN THREAT OF LOCALLY HEAVY RAINFALL.
- 2. WELL ABOVE NORMAL CONDITIONS EXPECTED TO RETURN BY NEXT
WEEK, WITH DANGEROUS HEAT INDEX VALUES AGAIN POSSIBLE.
DISCUSSION
KEY MESSAGE 1: DIURNAL THUNDERSTORMS EXPECTED THROUGH THE
WEEKEND WITH THE MAIN THREAT OF LOCALLY HEAVY RAINFALL.
TROUGHING TO OUR WEST REMAINS ENTRENCHED AND PERSISTENT TODAY AS
SHOWN BY CURRENT WV IMAGERY. TO OUR SOUTHWEST, A PLUME OF ROBUST
MOISTURE IS PUSHING NORTHEASTWARD OUT OF THE GULF OF MEXICO,
WHICH IS CURRENTLY YIELDING SOME SCATTERED SHOWERS, STORMS, AN
MAINLY WIDESPREAD HIGH CLOUD COVER ACROSS GA AND SC. THIS SURGE
IN MOISTURE IS EXPECTED TO CONTINUE PUSHING TOWARDS OUR FORECAST
AREA THROUGH THE DAY TODAY, WITH AT LEAST SCATTERED SHOWERS AND
STORMS FORECAST TO DEVELOP AS A RESULT. THE COPIOUS HIGH CLOUD
COVER BLANKETING THE EASTERN 2/3RDS OF THE FORECAST AREA
CURRENTLY IS ADDING A NICE FLY IN THE OINTMENT TO THE FORECAST,
THOUGH. UNLIKE THE STRATUS WE HAVE HAD IN RECENT MORNINGS, THIS
IS LESS LIKELY TO THIN AS THE DAY GOES ALONG AND MAY ACT AS AN
INHIBITOR TO CONVECTIVE DEVELOPMENT ACROSS A LOT OF THE AREA
THIS AFTERNOON. FOR INSTANCE, IT IS NOON AND WE ARE ONLY IN THE
LOW 80S ACROSS MUCH OF THE FA. MEAN HREF AND RRFS SOUNDINGS SHOW
CONVECTIVE TEMPS ONLY ~86F-89F ACROSS THE AREA THIS AFTERNOON,
SO IT REALLY WILL NOT TAKE MUCH TO GET CONVECTION GOING. IF/WHEN
IT DOES GET GOING, MOISTURE-RICH PROFILES WILL FAVOR HEAVY,
EFFICIENT RAINFALL. WPC HAS INCLUDED THE EASTERN 2/3RDS OF THE
FORECAST AREA IN A SLIGHT RISK FOR EXCESSIVE RAINFALL THIS
AFTERNOON AND EVENING AS A RESULT. DESPITE CAPE PROFILES >2500
J/KG, SEVERE WEATHER SEEMS UNLIKELY. DCAPE & TEI VALUES REALLY
AREN'T ROBUST ENOUGH TO YIELD STRONG MICROBURSTS, SO IT WILL
REALLY TAKE AN IMPRESSIVE CORE ALOFT TO GET A SEVERE DOWNBURST
TODAY.
MORE OF THE SAME IS EXPECTED ON SATURDAY AND SUNDAY. CLOUD
COVERAGE WILL LIKELY HANG AROUND IN THE MORNING HOURS, AND ITS
EXTENT AND DURATION IS EXPECTED TO MODULATE STORM CHANCES &
TIMING EACH AFTERNOON. WITH PWS >2" BOTH DAYS, EXPECT SHOWERS
AND STORMS TO CONSISTENTLY BE A THREAT. THE BETTER FORCING DOES
LOOK TO BE IN PLACE ON SATURDAY AS THE TROUGH WILL STILL BE IN
PLACE TO OUR WEST (DESPITE IT GRADUALLY WEAKENING AND LIFTING
NORTHWARD). ISOLATED INSTANCE OF FLASH FLOODING WILL REMAIN A
THREAT BOTH DAYS, WITH HIGHS IN THE MID TO UPPER 80S.
KEY MESSAGE 2: WELL ABOVE NORMAL CONDITIONS EXPECTED TO RETURN
BY NEXT WEEK, WITH DANGEROUS HEAT INDEX VALUES AGAIN POSSIBLE.
AS WE GET INTO NEXT WEEK (AND REALLY INTO THE BEGINNING OF
SEPTEMBER), THERE REMAINS A STRONG SIGNAL FOR ABOVE NORMAL
TEMPERATURES. AN ANOMALOUS 500 HPA RIDGE IS FORECAST TO BUILD
ACROSS THE CENTRAL PLAINS ON SUNDAY AND BEGIN TO FLEX ITS
STRENGTH EASTWARD ACROSS THE SOUTHEASTERN CONUS BY THE MIDDLE OF
NEXT WEEK. ENSEMBLES ARE ALREADY PAINTING A STRONG SIGNAL FOR AN
ANOMALOUS AND EXTENDED HEAT WAVE. ECE EFI VALUES FOR TEMPERATURE OF
0.7-0.8 & NON-ZERO SHIFT OF TAILS VALUES IN THE 4-8 AND 5-9 DAY
PERIODS SUGGEST THE POTENTIAL FOR ANOMALOUS TEMPS ACROSS THE
AREA FOR AN EXTENDED PERIOD FROM TUESDAY OF NEXT WEEK THROUGH
THE END OF THIS FORECAST PERIOD. SOME GUIDANCE DISAGREES ON
WHERE THE RIDGE SETTLES BY THE END OF NEXT WEEK BUT CONFIDENCE
IS INCREASING IN ANOMALOUS TEMPS IN THE MID/UPPER 90S IN THE
TUES- FRI PERIOD OF NEXT WEEK. SURFACE DEWPOINTS LOOK HIGH AS
WELL, INCREASING THE PROBABILITY THAT WE SEE HEAT INDEX VALUES
OF AT LEAST 100F-105F MULTIPLE DAYS IN A ROW NEXT WEEK, WITH
LIMITED SHOWER/STORM CHANCES TO HELP AID IN THE HEAT.
AVIATION /18Z FRIDAY THROUGH TUESDAY/
OVERCAST SKIES HAVE LIMITED DESTABILIZATION THROUGH EARLY
AFTERNOON. HREF MEMBERS DO SHOW CONVECTION DEVELOPING IN THE
UPSTATE OF SC ALONG A STALLED FRONT, AND ALONG THE COASTAL
PLAIN, THEN CONVERGING ACROSS THE AREA LATER THIS AFTERNOON AND
EVENING. INCONSISTENCIES IN COVERAGE/TIMING OF THE VARIOUS
MEMBERS DO MAKE FOR A SOMEWHAT UNCERTAIN FORECAST. HAVE INCLUDED
A PROB30 AT EACH TERMINAL, BUT HAVE TRENDED LATER WITH THE
TIMING, GENERALLY SHOWING POTENTIAL THUNDERSTORMS BETWEEN
20Z-02Z AT MOST TERMINALS ALONG WITH SOME FLIGHT RESTRICTIONS.
GUIDANCE IS FAIRLY CONSISTENT SHOWING ADDITIONAL LOW STRATUS AND
FOG LATE TONIGHT INTO SATURDAY MORNING. EXPECT IFR OR LIFR
CONDITIONS AT ALL TERMINALS FROM ABOUT 09-14Z. HAVE ALSO
INTRODUCED SHOWERS AT KOGB AFTER 14Z AS GUIDANCE IS SUGGESTING
CONVECTION REDEVELOPING ALONG THE COASTAL PLAIN BY SATURDAY
MORNING. IT'S VERY POSSIBLE THAT CEILINGS MAY NOT RISE TO VFR
LEVELS AT MOST TERMINALS UNTIL THE END OF THE FORECAST PERIOD.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE FROM SHOWERS
AND THUNDERSTORMS INTO THIS WEEKEND. DRIER CONDITIONS EXPECTED
EARLY NEXT WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...PL
AVIATION...JAQ
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