716
FXUS62 KCAE 241739
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
139 PM EDT WED JUN 24 2026
WHAT HAS CHANGED
AVIATION DISCUSSION UPDATED FOR 18Z TAFS.
KEY MESSAGES
- 1. DANGEROUS HEAT IS EXPECTED THROUGH MUCH OF THE
PERIOD AND INTO NEXT WEEK AS AN UPPER LEVEL RIDGE BUILDS SOUTH
OF US AND THEN RETROGRADES INTO THE OH/TN VALLEY. SHOWERS AND
THUNDERSTORMS DURING THE PERIOD MAY HELP BUT THERE IS TOO MUCH
UNCERTAINTY TO SPECIFY WHEN OR WHERE THAT WILL OCCUR.
DISCUSSION
KEY MESSAGE 1: DANGEROUS HEAT IS EXPECTED THROUGH MUCH OF THE
PERIOD AND INTO NEXT WEEK AS AN UPPER LEVEL RIDGE BUILDS SOUTH
OF US AND THEN RETROGRADES INTO THE OH/TN VALLEY. SHOWERS AND
THUNDERSTORMS DURING THE PERIOD MAY HELP BUT THERE IS TOO MUCH
UNCERTAINTY TO SPECIFY WHEN OR WHERE THAT WILL OCCUR.
THE HOTTEST PORTION OF THE SUMMER THUS FAR IS EXPECTED TO ARRIVE
BEGINNING FRIDAY AND LASTING THROUGH MUCH OF THE NEXT 7 DAYS. OUR
WEATHER TODAY AND THURSDAY SHOULD CONTINUE TO BE QUITE NICE AS UPPER
LEVEL TROUGHING PUSHES OVER THE AREA AND WEAKENS BY FRIDAY. HIGHER
HEIGHTS AND AN INCREASE IN SURFACE MOISTURE IS EXPECTED TO BEGIN
YIELDING INTENSE HEAT BY FRIDAY. THE INCREASE IN SURFACE
MOISTURE, IN ADDITION TO THE APPROACHING & WEAKENING UPPER
TROUGH, IS FORECAST TO YIELD SCATTERED SHOWERS AND THUNDERSTORMS
ON FRIDAY AFTERNOON. STRONG STORMS AREN'T EXPECTED WITH THIS
ACTIVITY, JUST MAINLY GARDEN VARIETY THUNDERSTORMS.
FROM THIS POINT, THE UPPER LEVEL RIDGE IS FORECAST TO BEGIN
ESTABLISHING DOMINANCE ACROSS THE EASTERN 2/3RDS OF THE US. A STRONG
AND PERSISTENT WESTERN US TROUGH IS EXPECTED TO BE THE IMPETUS FOR
THE RIDGE BUILDING ACROSS THE OH/TN VALLEY REGION BY EARLY NEXT
WEEK, WITH SATURDAY AND SUNDAY (CURRENTLY) LOOKING LIKE THE MOST
OPPRESSIVE HEAT DAYS THROUGH NEXT WEDNESDAY. ECE EFI VALUES ARE
ELEVATED (0.7-0.8) WITH NEAR 0 SOT VALUES, INDICATING ANOMALOUS
HEAT WITHOUT EXTREME VALUES (ITS TOUGH TO GET HIGH SIGNALS THIS
TIME OF YEAR HERE SO THIS SIGNAL IS NOTEWORTHY). LOW-LEVEL
MIXING RATIOS ARE NEAR TO SLIGHTLY ABOVE NORMAL, MEANING WE ARE
UNLIKELY TO SEE DEWPOINTS REALLY MIX OUT TOO MUCH. THIS WILL
HELP KEEP HEAT INDICES HIGH AND POTENTIALLY NEAR HEAT ADVISORY
CRITERIA. THIS IS IN LINE WITH WPC HEAT RISK WHICH SHOWS A MAJOR
HEAT RISK FOR BOTH SATURDAY AND SUNDAY. THE OTHER THING TO
WATCH FOR IS STRONG STORMS ON SUNDAY. THE RIDGE IS EXPECTED TO
BUILD INTO THE TN VALLEY DURING THIS PERIOD, WITH A BIT OF A
TROUGH BUILDING ON THE EASTERN SIDE OF THIS. THUNDERSTORMS ARE
EXPECTED SUNDAY AFTERNOON AND EVENING AS A RESULT, WITH SOME
STRONG CONVECTION POSSIBLE. THE BEST CHANCE FOR THIS WILL BE IN
THE EASTERN/NORTHEASTERN PART OF THE FORECAST AREA WHERE THE
WEAK SHORTWAVE IS MOST LIKELY TO PASS NEAREST.
AS WE GET INTO EARLY NEXT WEEK, THE HIGH HEAT IS EXPECTED TO
CONTINUE BUT LOWER HUMIDITY IS LIKELY TO PUSH INTO SOME OF THE AREA
MONDAY AND ESPECIALLY TUESDAY/WEDNESDAY. CONVERGENCE ALOFT IN
THE NORTHEASTERN US SHOULD YIELD A WEAK SURFACE HIGH THAT WILL
RIDGE DOWN ALONG THE EASTERN SLOPES OF THE APPALACHIANS THROUGH
WEDNESDAY. LOWER MIXING RATIOS IN ASSOCIATION WITH THIS SURFACE
HIGH WILL LIKELY YIELD LOWER DEWPOINTS IN THE LOW 60S EACH
AFTERNOON, HELPING TO KEEP HEAT INDEX VALUES MORE MANAGEABLE.
HEAT RISK HAS ACTUALLY FALLEN BELOW MAJOR RISK FOR MUCH OF THE
EASTERN/NORTHERN FA BOTH MONDAY AND TUESDAY IN THE LATEST RUN,
WHICH MAKES SENSE GIVEN THE PATTERN SHOWING UP IN MODEL
GUIDANCE. MAJOR HEAT RISK STILL REMAINS ACROSS THE WESTERN
MIDLANDS AND CSRA BOTH DAYS, BUT THE MAGNITUDE AND INTENSITY OF
THE HEAT IS SOMEWHAT UNCERTAIN GIVEN THE RELATIVELY DRIER
AIRMASS EXPECTED TO PUSH IN BY TUESDAY. STILL, LREF ENSEMBLES
SHOW SOLID PROBABILITIES (>45%) OF MAX TEMPS >95F EACH DAY SUN-
WED, SO IT WILL STILL BE HOT. HEAT ADVISORIES MAY BE CONSIDERED
GIVEN THE DURATION OF THE HEAT, BUT WE WILL LIKELY NEED TO
EVALUATE THAT AS THE HEAT WAVE UNFOLDS INTO NEXT WEEK.
WEDNESDAY THROUGH THE END OF NEXT WEEK BEGINS TO LOOK OPPRESSIVE
AGAIN AS THE EARLY WEEK SURFACE HIGH SHIFTS OFF SHORE AND OUR
SURFACE FLOW RETURNS TO SOUTHWESTERLY AGAIN, BRINGING GULF
MOISTURE BACK INTO THE AREA.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD.
BROKEN TO SCATTERED CLOUDS AROUND 5-7KFT WILL REMAIN ACROSS THE
REGION THROUGH SUNSET THIS EVENING. WINDS HAVE MOSTLY BECOME
VARIABLE AROUND 5 KNOTS ACROSS THE REGION, AND THAT WILL
CONTINUE. WINDS THEN DIMINISH TO 3 KNOTS OR LESS AFTER SUNSET.
AN INCREASE OUT OF THE SOUTH SHOULD OCCUR BY MID-MORNING
THURSDAY AS MIXING BEGINS. ALTHOUGH VFR IS MAINLY EXPECTED
THROUGH THE PERIOD, THERE REMAINS A POSSIBILITY OF BRIEF
VISIBILITY RESTRICTIONS THURSDAY MORNING AS LOW LEVEL MOISTURE
RETURNS A BIT, ESPECIALLY AT AGS/OGB. CONFIDENCE STILL NOT HIGH
ENOUGH TO INCLUDE IN TAFS AT THIS TIME.
EXTENDED AVIATION OUTLOOK...INCREASING HEAT AND HUMIDITY
STARTING THURSDAY INTO THE WEEKEND SHOULD YIELD DAILY DIURNAL
CONVECTION AND POSSIBLE ASSOCIATED RESTRICTIONS.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...PL/TT
AVIATION...73
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