142
FXUS62 KCAE 120609
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
209 AM EDT WED AUG 12 2026
WHAT HAS CHANGED
UNCERTAINTY REMAINS IN CONVECTION EVOLUTION LATER TODAY INTO
THIS EVENING. AVIATION DISCUSSION UPDATED FOR 06Z TAFS.
KEY MESSAGES
- 1. STORMS WITH STRONG DOWNBURST WINDS POSSIBLE THROUGH
THURSDAY BEFORE ADDITIONAL SHOWER/STORM CHANCES POSSIBLE
FRIDAY AND SATURDAY.
- 2. ABOVE NORMAL TEMPERATURES LIKELY, HEAT ADVISORIES
POSSIBLE, THROUGH EARLY NEXT WEEK.
DISCUSSION
- 1. STORMS WITH STRONG DOWNBURST WINDS POSSIBLE THROUGH
THURSDAY BEFORE ADDITIONAL SHOWER/STORM CHANCES POSSIBLE
FRIDAY AND SATURDAY.
AS OF WRITING THIS, A WEAKENING MCS THAT HAS BECOME MORE
OUTFLOW DOMINANT IS PUSHING INTO NORTHERN GA WITH THE FAR
EASTERN END OF THIS WELL BEHIND THE OUTFLOW. THIS IS FORCING A
FEW WEAK STORMS AND ADDITIONAL SHOWERS IN THE UPSTATE THAT COULD
GRADUALLY PUSH INTO THE CWA INTO THE EARLY MORNING HOURS, BUT
THE OVERALL SEVERE RISK CONTINUES TO DIMINISH AS MLCAPE FALLS
UNDER 1000 J/KG WITH MORE STABLE CONDITIONS SETTING UP. THE
UPPER RIDGE REMAINS OFF TO THE WEST AND ADDITIONAL PIECES OF
SHORTWAVE ENERGY ARE SPARKING NEW CONVECTION IN THE MIDWEST.
LARGE SPREAD EXISTS ACROSS INDIVIDUAL CAM'S IN THE PROGRESSION
OF THIS CONVECTION, BUT THE MEAN HREF SOLUTION DEPICTS THIS
REACHING THE WESTERN SLOPES OF THE APPALACHIANS BY THE LATE
MORNING HOURS. AS HEATING AND DEEP MIXING OCCUR, SBCAPE VALUES
COULD APPROACH 2000 J/KG, BUT WITH DRIER AIR IN THE MID LEVELS,
PWAT'S REMAIN CLOSER TO 1.50-1.75". OVERALL, HIGH UNCERTAINTY IN
CONVECTION EVOLUTION EXISTS TODAY, BUT IF OUTFLOW FROM THIS
CONVECTION REACHES THE FA WITH MILD SHORTWAVE ENERGY, IT IS NOT
UNREASONABLE TO THINK ADDITIONAL SEMI-ORGANIZED STORMS DURING
THE AFTERNOON WILL BE POSSIBLE WITH THE MAIN THREAT OF DAMAGING
STRAIGHT LINE WIND GUSTS. OUTSIDE OF THIS, ANY ISOLATED PULSE
VARIETY CONVECTION COULD BRING THE RISK OF STRONG-DAMAGING
DOWNBURST WINDS WITH DCAPE VALUES LIKELY EXCEEDING 1000 J/KG.
A SIMILAR SETUP IN THIS NORTHWEST FLOW REGIME IS EXPECTED
THURSDAY, WHERE A WEAK SHORTWAVE COULD AID IN SPARKING
ADDITIONAL ISOLATED CONVECTION DURING THE AFTERNOON. A DIFFUSE
FRONTAL BOUNDARY THEN IS EXPECTED TO NEAR THE AREA FRIDAY AND
SATURDAY, WHERE ADDITIONAL SHOWER/STORM CHANCES WILL BE
POSSIBLE, MAINLY SATURDAY AS THE FRONT COULD STALL IN THE CWA.
- 2. ABOVE NORMAL TEMPERATURES LIKELY, HEAT ADVISORIES
POSSIBLE, THROUGH EARLY NEXT WEEK.
MINIMAL CHANGE TO THE TEMPERATURE FORECAST IS SEEN AS
NORTHWEST, DOWNSLOPING FLOW AND RISING 500MB HEIGHTS FAVOR ABOVE
NORMAL TEMPERATURES PERSISTING INTO EARLY NEXT WEEK. IF
CONVECTION DOES NOT KEEP HIGH TEMPERATURES IN CHECK, IT WILL BE
REASONABLE TO SEE MAX TEMPERATURES IN THE MID TO UPPER 90S THE
COMING DAYS. DEEPER MIXING SHOULD ALLOW DEWPOINTS TO MIX OUT
SLIGHTLY BETTER, TOWARD THE UPPER 60S TO LOWER 70S, BUT
NONETHELESS, HOT/HUMID CONDITIONS ARE VERY LIKELY. HEAT INDICES
UP TO NEAR 105F ARE EXPECTED TODAY BEFORE THEY COULD TOP OUT
BETWEEN 105-110F THURSDAY THROUGH SATURDAY. LREF PROBABILITIES
FOR REACHING HEAT ADVISORY CRITERIA ARE HIGHEST (BETWEEN 40-50%)
FRIDAY AND SATURDAY AND ARE A BIT LOWER THURSDAY (AROUND
30-40%), BUT WITH THE EXPECTATION OF AT LEAST ISOLATED
CONVECTION EACH AFTERNOON, CONFIDENCE IN A WIDESPREAD AREA
REACHING ADVISORY CRITERIA IS LOW. THESE TRENDS WILL CONTINUE TO
BE MONITORED OVER THE COMING DAYS, BUT EVEN IF HEAT PRODUCTS
ARE NOT ISSUED, A PROLONGED PERIOD OF HEAT IS LIKELY OVER THE
COMING 7 DAYS SO PRECAUTIONS SHOULD STILL BE TAKEN.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
VFR CONDITIONS EXPECTED TO DOMINATE THE TAF PERIOD, WITH OCCASIONAL
SHRA THIS MORNING AND ADDITIONAL TSRA EXPECTED THIS AFTERNOON.
CONVECTION HAS MOSTLY CLEARED THE TERMINALS EARLY THIS MORNING, BUT
ANOTHER AREA OF SHOWERS/STORMS ACROSS THE UPSTATE IS MOVING IN OUR
DIRECTION. GIVEN THE ATMOSPHERE IS PRETTY WORKED OVER FROM EARLIER
CONVECTION, HANDLED THIS WITH VCSH AND WILL CONTINUE TO MONITOR OVER
THE NEXT SEVERAL HOURS. BESIDES THIS, LIGHT WESTERLY WINDS ARE
EXPECTED WITH LINGERING DEBRIS CLOUDINESS. THESE CLOUDS SHOULD
HINDER THE DEVELOPMENT OF WIDESPREAD FOG/STRATUS THIS MORNING. WINDS
PICK UP AGAIN AROUND 15Z OUT OF THE WEST NEAR 5-10 KTS. SCATTERED
CUMULUS SHOULD DEVELOP THROUGH THE DAY WITH ISOLATED STORM CHANCES
POSSIBLE THROUGH THE AFTERNOON, BUT FOR NOW HEDGED WITH VCSH UNTIL
THE TIMING BECOMES BETTER DEFINED. WIND GUSTS IN THE STRONGER STORMS
COULD APPROACH 30 KTS WITH BRIEF HEAVY DOWNPOURS AND ASSOCIATED
RESTRICTIONS.
EXTENDED AVIATION OUTLOOK...A HOT AND DRIER WEATHER PATTERN
DEVELOPS THROUGH THE WEEK. CONVECTIVE COVERAGE WILL LIKELY BE
LOW AND RESTRICTIONS LIMITED.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH
AVIATION...EC
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