475
FXUS62 KCAE 130020
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
820 PM EDT WED AUG 12 2026
WHAT HAS CHANGED
UPDATED KEY MESSAGE #2. AVIATION DISCUSSION UPDATED FOR 00Z
TAFS.
KEY MESSAGES
- 1. HEAT INDEX BETWEEN 105 AND 110 POSSIBLE THU AND FRI
- 2. A COUPLE STORMS POSSIBLE THIS EVENING, 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. A COUPLE STORMS POSSIBLE THIS EVENING, RAIN CHANCES PICK
BACK UP LATE THIS WEEKEND AND EARLY NEXT WEEK.
A COUPLE STORMS ARE PUSHING OUT OF THE UPSTATE TOWARD THE
NORTHERN MIDLANDS THIS EVENING AND HAVE EXHIBITED DECENT CORES
ON THEM, THUS A COUPLE STRONGER PULSE STORMS SNEAKING INTO THE
CWA COULD BE POSSIBLE OVER THE COMING HOUR OR TWO. ANOTHER
LOOSELY ORGANIZED MCS IS SEEN BACK INTO CENTRAL KY, NEARING
NORTHERN TN IN THE COMING TWO HOURS. MODEL GUIDANCE REMAINS
INSISTENT THAT THIS WILL LARGELY DECAY BEFORE MOVING DOWN THE
EASTERN SLOPES OF THE APPALACHIANS WITH LITTLE TO NO ACTIVITY
REACHING THE NORTHERN FA. GIVEN THE VERIFICATION FROM THE
PREVIOUS NIGHT, THERE IS CONCERN THAT THE COLD POOL DRIVEN
SYSTEM WILL HOLD TOGETHER A BIT LONGER THAN CAMS SHOW, SO THERE
IS THE LOW CHANCE SOME OF THIS ACTIVITY NEARS THE NORTHERN FA
DUE TO THE LARGE SCALE OUTFLOW POTENTIALLY REACHING THE FA. IF
THIS SOLUTION OCCURS, A COUPLE STRONGER WIND GUSTS CANNOT BE
RULED OUT BUT THE RISK FOR ANY SEVERE WEATHER IS QUITE LOW.
OVERALL, CONFIDENCE IN THIS SYSTEM REACHING IS LIMITED AS
INSTABILITY WANES AND THE MORE FAVORABLE ENVIRONMENT IS LOCATED
WEST OF THE APPALACHIANS.
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 /00Z THURSDAY THROUGH MONDAY/
VFR CONDITIONS GENERALLY EXPECTED THROUGH THE TAF PERIOD, WITH
LOW CONFIDENCE IN POSSIBLE SCATTERED OVERNIGHT CONVECTION.
RADAR SHOWING SOME ISOLATED STORMS IN THE UPSTATE BUT NOT SURE
THEY WILL HOLD TOGETHER LONG ENOUGH TO IMPACT TERMINALS. AIRMASS
GENERALLY UNCHANGED WITH WARM AND HUMID CONDITIONS EXPECTED TO
PERSIST. LIGHT AND VARIABLE TO NEAR CALM WINDS OVERNIGHT THEN
PICKING UP FROM THE WEST AROUND 6 TO 10 KNOTS AFTER 15Z.
ISOLATED DIURNAL CONVECTION POSSIBLE BUT CONFIDENCE TOO LOW TO
INCLUDE AT THIS TIME.
EXTENDED AVIATION OUTLOOK...DIURNAL CHANCES FOR THUNDERSTORMS
CONTINUE EACH DAY THROUGH THE WEEKEND.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH/CJR
AVIATION...23
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