169
FXUS62 KCAE 121821
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
221 PM EDT WED AUG 12 2026
WHAT HAS CHANGED
A HEAT ADVISORY MAY BE NEEDED LATER THIS WEEK. AVIATION
DISCUSSION UPDATED FOR 18Z TAFS.
KEY MESSAGES
- 1. HEAT INDEX BETWEEN 105 AND 110 POSSIBLE THU AND FRI
- 2. STRONG STORMS POSSIBLE TODAY, RAIN CHANCES PICK BACK UP
LATE THIS WEEKEND AND EARLY NEXT WEEK.
DISCUSSION
- 1. HEAT INDEX BETWEEN 105 AND 110 POSSIBLE THU AND FRI
RIDGING ALOFT SHIFTS FURTHER EAST LATE THURSDAY AND FRIDAY
HELPING TO SUPPRESS CONVECTION AND PUSHING DAYTIME HIGHS INTO
THE MID TO UPPER 90S, POSSIBLY AROUND 100 DEGREES. DOWNSLOPE
WINDS ARE EXPECTED OVER THE REGION WITH ADIABATIC HEATING
HELPING TO PUSH TEMPS ABOVE NORMAL BOTH DAYS.
THURSDAY: THE RIDGE AXIS WILL STILL BE TO OUR WEST WHICH COULD
ALLOW SHORTWAVE ENERGY TO DIG DOWN INTO THE FORECAST AREA AND
PROMOTE CONVECTION WITH JUST A WEAK CAPPING INVERSION IN PLACE.
DOWNSLOPE FLOW AND DEEP MIXING WILL ALLOW DEWPOINTS TO DROP INTO
THE LOW 70S OR AROUND 70 DEGREES IN THE AFTERNOON. THE NBM,
WHICH HAD TD VALUES 5 TO 8 DEGREES TOO WARM THE PREVIOUS DAY WAS
DISREGARDED. WE SHOULD SEE HEAT INDEX VALUES REACH 105 FOR MOST
AREAS THURSDAY, BUT A FEW LOCATIONS COULD NEAR 108 (HEAT
ADVISORY CRITERIA). BETWEEN THE CHANCE OF AFTERNOON CONVECTION
AND MARGINAL HI VALUES, WE BELIEVE CONFIDENCE IS TOO LOW TO
ISSUE A HEAT ADVISORY AT THIS POINT.
FRIDAY: WITH RIDGING ALMOST DIRECTLY OVERHEAD WE SHOULD SEE
GREATER SUPPRESSION OF CONVECTIVE DEVELOPMENT. TEMPERATURES WILL
ONCE AGAIN APPROACH 100 DEGREES. EVEN AFTER ACCOUNTING FOR THE
WARM BIAS IN THE NBM, DEWPOINTS SHOULD BE HIGH ENOUGH TO NEAR OR
POSSIBLY EXCEED HEAT ADVISORY CRITERIA.
- 2. STRONG STORMS POSSIBLE TODAY, RAIN CHANCES PICK BACK UP
LATE THIS WEEKEND AND EARLY NEXT WEEK.
WEDNESDAY: STORMS DEVELOPING ACROSS THE MIDWEST WILL LIKELY DIG
INTO THE SOUTHEAST/MID-ATLANTIC STATES LATER TODAY AND THIS
EVENING. SIMILAR TO THE PREVIOUS DAY MODELS SHOW THIS CONVECTION
DIMINISHING THROUGH THE EVENING. GIVEN THE VERIFICATION FROM THE
PREVIOUS NIGHT, THERE IS CONCERN THAT THE COLD POOL DRIVEN
SYSTEM WILL HOLD TOGETHER LONGER THAN CAMS SHOW. SO IT APPEARS
THERE WILL BE A LOW CHANCE OF SEVERE WEATHER DUE TO A LARGE
SCALE OUTFLOW MOVING THROUGH THE FA LATE THIS EVENING OR
OVERNIGHT. STRONG WINDS WILL BE THE GREATEST CONCERN BUT THERE
COULD BE POCKETS OF SEVERE WINDS IN SOME OF THE DEEPER
CONVECTION.
GLOBAL ENSEMBLES FAVOR RIDGING FLATTENING OUT LATE THIS WEEKEND
AND EARLY NEXT WEEK WITH TROUGHING POSSIBLY DEVELOPING OVER THE
EASTERN US NEAR THE END OF THE FORECAST PERIOD. ATMOSPHERIC
MOISTURE WILL BE ABOVE NORMAL DURING THIS TIME FRAME WITH MEAN
PWAT VALUES NEAR OR ABOVE 2 INCHES. ABOVE NORMAL MOISTURE AND
ZONAL FLOW FAVORS AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
VFR CONDITIONS GENERALLY EXPECTED THROUGH THE TAF PERIOD, WITH
TSRA POSSIBLE THIS AFTERNOON AND EVENING BUT TIMING REMAINS
UNCERTAIN.
VFR CONDITIONS ARE BEING NOTED THROUGH THE TAF PERIOD. WITH
CLOUD DEBRIS HANGING AROUND, CONVECTIVE INITIATION HAS HELD OFF
LOCALLY THUS FAR. STILL ANTICIPATE SOME DEVELOPMENT LATER THIS
AFTERNOON/EVENING, BUT CONFIDENCE IS LOW THAT THE TERMINALS WILL
BE AFFECTED, SO LEAVING THE VCSH IN FOR THE TIME BEING AND WILL
AMEND AS NEEDED SHOULD CONVECTION THREATEN ANY OF THE TAF
TERMINALS. OUTSIDE OF THUNDERSTORM CHANCES, WINDS ARE FORECAST
TO BE WNW AROUND 8-10 KTS BEFORE TRANSITIONING TO MORE
SOUTHWESTERLY AROUND 20Z-21Z. WINDS BECOME LIGHT AND VARIABLE TO
CALM OVERNIGHT, INCREASING OUT OF THE WEST AFTER ABOUT 15Z.
EXTENDED AVIATION OUTLOOK...DIURNAL CHANCES FOR THUNDERSTORMS
CONTINUE EACH DAY THROUGH THE WEEKEND.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...CJR
AVIATION...29
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