443
FXUS62 KCAE 301731
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
131 PM EDT SUN AUG 30 2026
WHAT HAS CHANGED
HIGH PROBABILITIES OF ABOVE NORMAL TEMPERATURES AND HEAT
INDICES OVER 100 DEGREES THIS WEEK. AVIATION DISCUSSION UPDATED
FOR 18Z TAF ISSUANCE.
KEY MESSAGES
- 1. GENERALLY DRY WEATHER AND WELL ABOVE NORMAL TEMPERATURES
EXPECTED WITH DANGEROUS HEAT INDEX VALUES POSSIBLE NEXT WEEK.
- 2. ACTIVE WEATHER AND DECREASING TEMPERATURES POSSIBLE NEXT
WEEKEND.
- 3. DIURNAL THUNDERSTORMS EXPECTED THROUGH THIS WEEKEND WITH
THE MAIN THREAT OF LOCALLY HEAVY RAINFALL.
DISCUSSION
KEY MESSAGE 1. WELL ABOVE NORMAL TEMPERATURES EXPECTED WITH
DANGEROUS HEAT INDEX VALUES POSSIBLE NEXT WEEK.
ENSEMBLE GUIDANCE CONTINUES TO BE CONSISTENT IN SHOWING A
STRONG 596DM UPPER RIDGE CURRENTLY OVER THE SOUTHERN PLAINS AND
MID MS VALLEY AREA BUILDING EASTWARD THROUGH THE WEEK BECOMING
SITUATED OVER THE SOUTHERN OH VALLEY AND CAROLINAS BY MID WEEK
THEN GRADUALLY WEAKENING AND BEGINNING TO SLOWLY RETROGRADE BY
THE END OF THE WEEK. THIS SHOULD RESULT IN STRONG SUBSIDENCE
OVER THE REGION THROUGH THE WEEK WITH ENSEMBLE FORECAST 700MB
TEMPERATURES AT THE 99TH PERCENTILE WITH VALUES AROUND +10C.
THESE HIGH VALUES AND THE NOTABLE SUBSIDENCE INVERSION AT 700MB
INCREASES CONFIDENCE IN THE GENERAL LACK OF CONVECTION EXPECTED.
ENSEMBLE TEMPERATURES AT 850/1000MB ARE FORECAST TO BE ABOVE
THE 90TH PERCENTILE EARLY IN THE WEEK AND AT THE 99TH PERCENTILE
MID TO LATE WEEK SUGGESTING A STRONG WARMING TREND THROUGH THE
WEEK WITH ANOMALOUSLY HIGH TEMPERATURES (ABOUT 10 DEGREES ABOVE
NORMAL). MINIMUM TEMPERATURES ALSO EXPECTED TO BE ANOMALOUSLY
HIGH WITH EC EFI SHOWING VALUES AROUND 0.7-0.8 AND A NONZERO
SHIFT OF TAILS (SIMILAR TO THE MAX TEMPERATURES) WITH VALUES
ABOUT 5 TO 10 DEGREES ABOVE NORMAL. SOUTHEAST TO SOUTHWESTERLY
SURFACE FLOW THROUGH THE WEEK WILL KEEP THE LOW LEVEL MOISTURE
IN PLACE RESULTING IN HEAT INDICES RISING ABOVE 100 DEGREES ALL
WEEK AND APPROACHING HEAT ADVISORY CRITERIA MID TO LATE WEEK.
KEY MESSAGE 2. ACTIVE WEATHER AND DECREASING TEMPERATURES
POSSIBLE NEXT WEEKEND.
ENSEMBLES AND GLOBAL GUIDANCE IN GOOD AGREEMENT SHOWING THE
STRONG UPPER RIDGE RETROGRADING WESTWARD BACK OVER THE PLAINS
STATES ALLOWING FOR UPPER TROUGHING ALONG THE EAST COAST NEXT
WEEKEND. THIS SHOULD SUPPORT SLIGHTLY COOLING TEMPERATURES AND
ALSO ALLOW SHORTWAVE ENERGY TO DIVE DOWN THE BACK SIDE OF THE
RETREATING RIDGE, BRINGING INCREASED CHANCES OF RAINFALL BACK TO
THE FORECAST AREA. RAINFALL WILL BE WELCOMED AGAIN AFTER A LONG
HOT AND GENERALLY DRY WEEK AHEAD.
KEY MESSAGE 3. DIURNAL THUNDERSTORMS EXPECTED THROUGH THIS
EVENING WITH THE MAIN THREAT OF LOCALLY HEAVY RAINFALL.
STRATUS CLOUDS HAVE TRANSITIONED TO A STRATOCUMULUS DECK AS
DAYTIME HEATING CONTINUES AND TEMPERATURES RISE THROUGH THE 80S.
DEWPOINTS ARE GENERALLY IN THE LOWER 70S AND SHOULD SUPPORT
MODERATE INSTABILITY AS HIGHER CLOUDS ARE DIMINISHING AND MORE
SUN IS EXPECTED. HOWEVER, WIND SHEAR REMAINS WEAK AND ORGANIZED
CONVECTION IS NOT ANTICIPATED. HI-RES GUIDANCE SUGGESTS ISOLATED
CONVECTION THROUGH THE AFTERNOON INTO EARLY EVENING FAVORING
THE EASTERN MIDLANDS CLOSER TO THE DEEPER MOISTURE (PWATS AROUND
2 INCHES) AND BETTER UPPER FORCING ALONG THE COAST (500MB
VORTICITY). DUE TO SLOW STORM MOTION AND PWATS AROUND 2 INCHES,
HEAVY RAINFALL COULD BE A CONCERN FOR MORE INTENSE STORMS
PROVIDING HIGH RAIN RATES.
AVIATION /18Z SUNDAY THROUGH FRIDAY/
VFR EXPECTED THROUGH THIS EVENING, WITH VIS/CIG RESTRICTIONS
EXPECTED AGAIN TOWARDS MONDAY MORNING.
MVFR AND IFR CEILINGS FROM EARLIER THIS MORNING HAVE GIVEN WAY
TO SOME RELATIVELY FLAT CUMULUS THIS AFTERNOON. EXPECTING THIS
TO REMAIN LARGELY THE CASE DESPITE PWS AND CAPE BEING RELATIVELY
SEASONAL FOR AUGUST. HEIGHTS ARE GRADUALLY RISING AS A RIDGE
FROM THE WEST BUILDS OVERHEAD AND THIS IS LIKELY TO KEEP
CONVECTION ISOLATED TO SCATTERED AT BEST. THE SEA BREEZE DOES
LOOK TO BE GOING TO OUR SOUTHEAST AND SHOULD BRING A THREAT FOR
SHOWERS AT OGB LATER, PROMPTING A PROB30 GROUP THERE. AS WE GET
INTO TONIGHT, MOSTLY CLEAR SKIES, MOISTURE RICH LOW-LEVELS, AND
VERY LIGHT WINDS IN THE LOWER 5KFT OF THE ATMOSPHERE ARE LIKELY
TO PROMPT ANOTHER ROUND OF FOG/STRATUS. IT LOOKS LIKE IT MAY
FAVOR FOG TONIGHT, SO HAVE TRENDED MORE TOWARDS THAT IN THE
PREDOMINANT AND TEMPO GROUPS. AS WITH MOST FOG FORECASTS, THIS
IS NOT AN OVERLY CONFIDENT FORECAST BUT THE SETUP IS GOOD AND
GUIDANCE IS CONFIDENT ENOUGH THAT ITS IN THE TAF FROM 08Z TO 14Z
AT ALL SITES. MONDAY LOOKS NICE AND VFR ONCE THE RESTRICTIONS
BREAK.
EXTENDED AVIATION OUTLOOK...DRIER CONDITIONS EXPECTED EARLY
NEXT WEEK, BUT BRIEF EARLY MORNING RESTRICTIONS STILL POSSIBLE.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...23
AVIATION...PL
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