897
FXUS62 KCAE 291032
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
632 AM EDT SAT AUG 29 2026
WHAT HAS CHANGED
CONFIDENCE IN CONVECTIVE COVERAGE TODAY IS LOW GIVEN CHANCE OF
PERSISTENT CLOUD COVER. AVIATION DISCUSSION UPDATED FOR 12Z TAF
ISSUANCE.
KEY MESSAGES
- 1. DIURNAL THUNDERSTORMS EXPECTED THROUGH THIS WEEKEND WITH
THE MAIN THREAT OF LOCALLY HEAVY RAINFALL.
- 2. WELL ABOVE NORMAL TEMPERATURES WITH DANGEROUS HEAT INDEX
VALUES POSSIBLE NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: DIURNAL THUNDERSTORMS EXPECTED THROUGH THIS
WEEKEND WITH THE MAIN THREAT OF LOCALLY HEAVY RAINFALL.
OVERALL, THERE HAS NOT BEEN A SIGNIFICANT SHIFT IN THINKING
THIS WEEKEND, BUT CONFIDENCE IN CONVECTIVE COVERAGE IS LOW
TODAY. SOME SHOWER ACTIVITY COULD DEVELOP IN THE EARLY MORNING
HOURS BUT THE MAIN WINDOW WOULD STILL COME DURING THE AFTERNOON
INTO THE EVENING. A SIMILAR SET UP TO YESTERDAY IS EXPECTED WITH
THE UPPER TROUGH REMAINING IN PLACE AND PWAT'S NEAR 2" AS
DEEP/MOIST SOUTHERLY TO SOUTHWESTERLY FLOW PERSISTS OVER THE
REGION. LOOKING AT FORECAST SOUNDINGS, THIS BRINGS A NEARLY
SATURATED COLUMN WITH MUCH OF GUIDANCE INCLUDING THE NBM AND
MEAN HREF SOLUTION, HAVING CLOUD COVER HANG ON MUCH OF THE DAY.
IN RAP MODEL SOUNDINGS, THIS IS LIMITING SURFACE TEMPERATURES
TOWARD THE LOWER 80S, BUT DEWPOINTS IN THE LOW TO MID 70S STILL
ALLOW AROUND 1500-2000 J/KG OF MLCAPE TO DEVELOP. THIS CLOUD
COVER WILL LIKELY MODULATE STORM COVERAGE AND TIMING THIS
AFTERNOON, WHERE AT LEAST ISOLATED CHANCES ARE POSSIBLE, BUT
CANNOT RULE OUT MORE SCATTERED TO NUMEROUS STORMS IF MORE ROBUST
HEATING IS REALIZED. WITH SATURATED PROFILES, THE SEVERE RISK
IS LOW, BUT EFFICIENT RAIN RATES AND SLOW STORM MOTIONS UNDER
15-20 KTS WOULD BRING AN ISOLATED FLASH FLOOD RISK. SUNDAY IS
EXPECTED TO BE FAIRLY SIMILAR ENVIRONMENT WISE, BUT WITH
TROUGHING NOW WEAKENING AND LIFTING NORTHWARD, CONVECTIVE
COVERAGE HAS TRENDED A BIT MORE ISOLATED AS LITTLE IN WAY OF
FORCING REMAINS IN THE REGION.
KEY MESSAGE 2: WELL ABOVE NORMAL TEMPERATURES WITH DANGEROUS
HEAT INDEX VALUES POSSIBLE NEXT WEEK.
THE OUTLOOK FOR THE END OF AUGUST AND START OF SEPTEMBER
REMAINS ON TRACK WITH HOT/HUMID CONDITIONS EXPECTED, ESPECIALLY
TUESDAY THROUGH THE END OF THE FORECAST PERIOD. THE WELL
ADVERTISED UPPER RIDGE IS EXPECTED TO SLOWLY BUILD OVERHEAD INTO
THE MID TO LATE WEEK WITH 500 MB HEIGHTS IN BOTH THE EC
ENSEMBLE AND MEAN GEFS SOLUTIONS BECOMING NEARLY 2 STANDARD
DEVIATIONS ABOVE NORMAL. AS THIS OCCURS, 850MB TEMPERATURES ARE
EXPECTED TO REACH NEAR THE NAEFS 99.5TH PERCENTILE. WHEN THESE
FIELDS ARE COUPLED WITH SEASONABLE MOISTURE IN PLACE, HOT AND
HUMID CONDITIONS BECOME LIKELY. THERE IS INCREASING CONFIDENCE
TEMPERATURES IN THE MID TO UPPER 90S WILL BE SEEN DURING THE
PERIOD AS SEEN IN DECREASING NBM IQR RANGES FOR MAXIMUM
TEMPERATURES. PROBABILITIES FOR HEAT INDICES ABOVE 100F TUESDAY
THROUGH FRIDAY HAVE ALSO INCREASED FROM 24 HOURS AGO WITH
CHANCES NOW REACHING 60- 80% IN THE LATEST LREF RUN. THIS ALL
GOES TO SAY, BE PREPARED FOR ANOTHER SHOT OF HEAT AND HUMIDITY
TO START SEPTEMBER WITH LIMITED RAIN CHANCES AS THE RIDGE SHOULD
ACT TO LARGELY SUPPRESS DIURNAL CONVECTION.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
ALTHOUGH SOME RESTRICTIONS EXPECTED THIS MORNING, IT IS A LOWER
CONFIDENCE FORECAST DUE TO HIGHER CLOUDINESS AND ITS IMPACT.
GUIDANCE REMAINS RATHER INCONSISTENT REGARDING DEVELOPMENT OF
IFR/LIFR CONDITIONS THIS MORNING. GFS KEEPS MAINLY VFR
CONDITION, NAM IS MVFR, WHILE THE LAMP GUIDANCE HAS NOW TRENDED
FROM IFR BACK INTO VFR MUCH UNCERTAINTY WITH THE INCONSISTENCY
IN THE MODELS, ALONG WITH CURRENT CONDITIONS FLUCTUATING AT
TIMES BETWEEN MVFR AND BACK TO VFR AT ALL LOCATIONS. HAVE GONE
MOSTLY WITH PREDOMINANT VFR, AND A TEMPO FOR LOWER RESTRICTIONS
THROUGH 14Z. OUTLIER MAY BE KOGB AND AREAS FURTHER EAST WHERE
DEEPER MOISTURE AND POTENTIAL RAIN COULD KEEP LOWER CONDITIONS
IN FOR A GOOD PORTION OF THE DAY, BUT EVEN THAT ISN'T A GIVEN.
SHOWERS ALONG THE COASTAL PLAIN THIS MORNING, WITH ISOLATED
SHOWERS DEVELOPING IN THE MIDLANDS COULD IMPACT SEVERAL
AIRPORTS. HAVE INCLUDED VCSH AT LEAST TO START WITH, AND CAN
AMEND IF ANY ACTIVITY LOOKS TO IMPACT TAF SITES. THEN FOR THIS
AFTERNOON, ISOLATED TO SCATTERED SHOWERS AND STORMS ARE
EXPECTED TO DEVELOP AGAIN. WILL CONTINUE WITH MENTION OF PROB30
IN ALL TERMINALS, ALTHOUGH CLOUD COVER MAY CAUSE SOME
ADDITIONAL UNCERTAINTY IN DEVELOPMENT. A RETURN OF AT LEAST
CEILING RESTRICTIONS LOOKS MORE LIKELY AGAIN AFTER 03Z TONIGHT.
EXTENDED AVIATION OUTLOOK...MORNING CEILINGS AND VISIBILITY
RESTRICTIONS POSSIBLE INTO SUNDAY, ALONG WITH AFTERNOON
RESTRICTIONS FROM SHOWERS AND THUNDERSTORMS. DRIER CONDITIONS
EXPECTED EARLY NEXT WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH
AVIATION...73
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page