823
FXUS62 KCAE 041826
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
226 PM EDT SAT JUL 4 2026
WHAT HAS CHANGED
A BIT MORE OF UNCERTAINTY IN TEMPERATURES SUNDAY DUE TO
CONVECTION. AVIATION DISCUSSION UPDATED FOR 18Z TAFS.
KEY MESSAGES
- 1. ABOVE NORMAL TEMPERATURES CONTINUE THIS WEEKEND INTO EARLY
NEXT WEEK. A HEAT ADVISORY IS IN EFFECT ALONG AND NORTH OF
I-20 UNTIL 8 PM THIS EVENING WITH HEAT INDICES UP TO 105
POSSIBLE.
- 2. CHANCES FOR SCATTERED DIURNAL SHOWERS AND THUNDERSTORMS
START SUNDAY, CONTINUING INTO NEXT WEEK. STRONG STORMS ARE
POSSIBLE EACH AFTERNOON AND EVENING.
DISCUSSION
KEY MESSAGE 1: ABOVE NORMAL TEMPERATURES CONTINUE THIS WEEKEND
INTO EARLY NEXT WEEK. A HEAT ADVISORY IS IN EFFECT ALONG AND
NORTH OF I-20 UNTIL 8 PM THIS EVENING WITH HEAT INDICES UP TO
105 POSSIBLE.
TEMPERATURES ARE ALREADY APPROACHING THE MID TO UPPER 90S EARLY
THIS 4TH OF JULY AFTERNOON WITH DEW POINTS BEING A BIT SLOW TO
MIX OUT (IN THE UPPER 60S TO LOW 70S RIGHT NOW), BRINGING HEAT
INDICES ALREADY NEAR 100-105F. SIGNS OF DEEPER MIXING BEGINNING
ARE SEEN IN SATELLITE IMAGERY/OBS WITH HIGHER BASED CUMULUS
DEVELOPING AND A SLIGHT LOWERING OF DEWPOINTS INTO THE PEE DEE
TOWARD THE MID TO UPPER 60S. THIS TREND SHOULD CONTINUE THE
REMAINDER OF THE AFTERNOON WITH TEMPERATURES TOPPING OUT IN THE
UPPER 90S TO NEAR 100F WITH HEAT INDICES PUSHING AS HIGH AS 105F
WITH SPOTS CLOSING IN ON 108F POSSIBLE. THE HEAT ADVISORY ALONG
AND NORTH OF I-20 WILL REMAIN IN EFFECT UNTIL 8 PM THIS EVENING
BUT KEEP IN MIND HEAT INDICES WILL LIKELY STILL BE IN THE 90S
AROUND THE TIME FOR THE VARIOUS FIREWORK DISPLAYS ACROSS THE FA.
AS HAS BEEN EMPHASIZED THE LAST COUPLE OF DAYS, BE DILIGENT TO
TAKE APPROPRIATE HEAT SAFETY MEASURES TODAY AS THE RISK FOR
HEAT-RELATED ILLNESS IS ELEVATED DUE TO THE AMOUNT OF OUTDOOR
ACTIVITIES AND PROLONGED HEAT EXPOSURE.
HEADING INTO SUNDAY, THE UPPER RIDGE IS EXPECTED TO GRADUALLY
WEAKEN TOWARD 590DM AND IT'S AXIS IS EXPECTED TO START SHIFTING
A BIT EASTWARD AS A SHORTWAVE TROUGH IMPINGES ON IT ACROSS THE
UPPER MIDWEST DOWN INTO THE TENNESSEE VALLEY. THIS WILL ALLOW
LOW LEVEL FLOW TO BECOME MORE SOUTHERLY TO SOUTHWESTERLY AND
BRING SURFACE DEWPOINTS BACK INTO THE UPPER 60S TO LOW 70S WITH
AFTERNOON HIGH TEMPERATURES INTO THE MID TO UPPER 90S. OVERALL,
INCREASED MOISTURE SHOULD AID IN BRINGING HEAT INDICES BACK
TOWARD 105F ACROSS THE FA DURING THE AFTERNOON. THE MAIN CAVEAT
TO THIS IS CONVECTIVE TEMPERATURES COULD BE QUICKLY ATTAINED
EARLY IN THE AFTERNOON, BRINGING SCATTERED CONVECTION (SEE KEY
MESSAGE #2 FOR MORE INFORMATION) A BIT EARLIER THAN CURRENTLY
DEPICTED IN THE LATEST HRRR RUNS FOR EXAMPLE. THIS WOULD NOT
ALLOW TEMPERATURES TO PEAK IN THE UPPER 90S AND WOULD KEEP HEAT
INDICES IN CHECK A BIT MORE. DUE TO THIS, HAVE HELD OFF FROM
ISSUING ANOTHER HEAT ADVISORY FOR NOW, BUT THIS WILL BE
EVALUATED FOR THE NEXT FORECAST PACKAGE. THIS TREND OF DIURNAL
CONVECTION COMPLICATING TEMPERATURE/HEAT INDICES FORECASTS IS
EXPECTED TO CONTINUE INTO NEXT WEEK AS DEEP MOISTURE MOVES IN
PLACE WITH TEMPERATURES NEAR TO ABOVE NORMAL. EVEN WITH THIS
COMPLICATION, HEAT INDICES LIKELY WILL EXCEED 100F THROUGH AT
LEAST WEDNESDAY (LREF PROBABILITIES ARE OVER 70% FOR THIS),
POSSIBLY NECESSITATING ADDITIONAL HEAT PRODUCTS.
THIS ALL GOES TO SAY IT REMAINS LIKELY THAT A PROLONGED PERIOD
WITH HEAT INDICES ABOVE 100F WILL CONTINUE INTO AT LEAST THE MID
WEEK NEXT WEEK, SO HEAT SAFETY MEASURES SHOULD CONTINUE TO BE
TAKEN. THE DURATION OF THIS HEAT WILL CONTINUE TO MAKE THE
ELDERLY, YOUNG CHILDREN, PETS, AND THOSE WITHOUT INDOOR COOLING
AT PARTICULAR RISK SUNDAY AND INTO NEXT WEEK.
KEY MESSAGE 2: CHANCES FOR SCATTERED DIURNAL SHOWERS AND
THUNDERSTORMS START SUNDAY, CONTINUING INTO NEXT WEEK. STRONG
STORMS ARE POSSIBLE EACH AFTERNOON AND EVENING.
AS TEMPERATURES CONTINUE INTO THE UPPER 90S AND NEAR CONVECTIVE
TEMPS, AN ISOLATED SHOWER OR WEAK STORM CANNOT BE RULED OUT
THIS AFTERNOON AS SHOWN IN THE 12Z HREF SOLUTION AND LATEST HRRR
RUNS. A WEAK MID LEVEL PERTURBATION IS ALSO NOTED IN WV IMAGERY
ACROSS NORTHERN AL/GA, THUS CANNOT RULE OUT THIS FORCING
INITIATING A COUPLE SHOWERS OR STORMS MAINLY NEAR THE WESTERN
CSRA.
FOR SUNDAY, ROBUST SURFACE HEATING IS EXPECTED TO ALLOW
CONVECTIVE TEMPERATURES TO BE REACHED FAIRLY EARLY IN THE DAY
(BETWEEN 15-18Z), BRINGING SCATTERED SHOWERS AND STORMS ACROSS
THE FA. THIS IS FURTHER SUPPORTED IN THE MEAN HREF AND REFS
SOLUTIONS. WITH INCREASING MOISTURE FROM SOUTHERLY IVT
TRANSPORT, MUCAPE VALUES ARE EXPECTED TO NEAR 2000-2500 J/KG AND
DEEP MIXING SHOULD YIELD IMPRESSIVE DCAPE VALUES OVER 1000
J/KG. LINGERING SUBSIDENCE FROM THE WEAKENING RIDGE COULD KEEP
STORMS A BIT SHALLOW, BUT ANY MORE PERSISTENT UPDRAFT COULD
DEEPEN AND BRING THE RISK FOR A STRONG TO SEVERE STORM. THE MAIN
HAZARD FROM ANY STRONG STORM WOULD BE DAMAGING WINDS FROM
LOCALIZED DOWNBURSTS. THIS TYPE OF TYPICAL STRONG TO SEVERE
SUMMER PULSE ENVIRONMENT IS EXPECTED TO PERSIST INTO THE MID
WEEK NEXT WEEK. ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT THAT THE
SUPPRESSED AND EASTWARD MOVING RIDGE WILL ALLOW PIECES OF
SHORTWAVE ENERGY TO TRAVERSE THE REGION, BRINGING A BIT MORE
FORCING THAN THAT ON SUNDAY. SCATTERED CONVECTION IS EXPECTED
EACH DAY WITH THE MAIN THREAT CONTINUING TO BE DOWNBURST WINDS.
LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE AS PWAT'S RAISE TO
NEAR 2.0-2.20" EARLY IN THE WEEK.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD.
WINDS REMAINING LIGHT AND VARIABLE, THEY WILL BE TURNING MORE
SOUTHERLY AROUND 6 KNOTS THROUGH THE AFTERNOON. AFTER SUNSET
WINDS SHOULD RETURN TO MORE LIGHT AND VARIABLE FOR THE REMAINDER
OF THE PERIOD. ONLY CLOUD COVER FOR THE MAJORITY OF THE SITES
WILL BE SOME SCATTERED MID-LEVEL AFTERNOON CUMULUS. LATER
TONIGHT, WITH THERE BEING 4TH OF JULY CELEBRATIONS AND
FIREWORKS, THERE COULD BE SOME BRIEF VISIBILITY RESTRICTIONS
ASSOCIATED WITH SMOKE FROM THE FIREWORKS AT CAE/CUB/AGS/DNL.
EXTENDED AVIATION OUTLOOK...DAILY RAIN CHANCES AND POSSIBLE
RESTRICTIONS START TO INCREASE SUNDAY AFTERNOON INTO EARLY NEXT
WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SCZ016-018-
020>022-025>030-115-116.
GA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR GAZ040-063>065.
DISCUSSION...DH
AVIATION...73
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