933
FXUS62 KCAE 021758
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
158 PM EDT THU JUL 2 2026
WHAT HAS CHANGED
ISSUED A HEAT ADVISORY FOR COUNTIES ALONG AND NORTH OF THE I-20
CORRIDOR TOMORROW. AVIATION DISCUSSION UPDATED FOR 18Z TAF'S.
KEY MESSAGES
- 1. ABOVE NORMAL TEMPERATURES CONTINUE, PEAKING DURING THE
INDEPENDENCE DAY WEEKEND. A HEAT ADVISORY WILL BE IN EFFECT
ALONG AND NORTH OF I-20 FROM 12PM-8PM FRIDAY WITH HEAT INDICES
BETWEEN 105-108F POSSIBLE.
- 2. AN ISOLATED STRONG TO MARGINALLY SEVERE STORM COULD SNEAK
INTO THE NORTHERN FA LATE THIS AFTERNOON. INCREASING CHANCES
FOR SHOWERS AND THUNDERSTORMS LATE THIS WEEKEND INTO NEXT
WEEK.
DISCUSSION
KEY MESSAGE 1: ABOVE NORMAL TEMPERATURES CONTINUE, PEAKING
DURING THE INDEPENDENCE DAY WEEKEND. A HEAT ADVISORY WILL BE IN
EFFECT ALONG AND NORTH OF I-20 FROM 12PM-8PM FRIDAY WITH HEAT
INDICES BETWEEN 105-108F POSSIBLE.
THERE HAS NOT BEEN A SIGNIFICANT CHANGE TO THE FORECAST THE
COMING DAYS WITH HOT/HUMID CONDITIONS PERSISTING. TEMPERATURES
THIS AFTERNOON ARE ALREADY REACHING THE LOW TO MID 90S AND
SHOULD TOP OUT IN THE MID TO UPPER 90S WITH HEAT INDICES
APPROACHING 105F, THOUGH SOME SPOTS MAINLY IN LANCASTER COUNTY
COULD REACH 108-110F, THUS THE HEAT ADVISORY REMAINS IN EFFECT
THROUGH 8PM THIS EVENING HERE.
HEADING INTO FRIDAY AND THE INDEPENDENCE DAY WEEKEND, THE
ROBUST UPPER RIDGE (NEAR THE NAEFS 99.5TH PERCENTILE) IS PROGGED
TO MOVE OVERHEAD IN THE CAROLINAS AS 850MB TEMPERATURES WARM
FURTHER TOWARD 20-22C, KEEPING AFTERNOON HIGHS IN UPPER 90S TO
NEAR 100F EACH DAY. SLIGHTLY DRIER AIR IS SHOWN IN MODEL
GUIDANCE SHIFTING IN THIS WEEKEND WITH THE CENTER OF THE HIGH
(PWAT'S LESS THAN 1.50"), BUT SURFACE DEWPOINTS SHOULD REMAIN IN
THE UPPER 60S TO LOW 70S, POSSIBLY MIXING OUT INTO THE LOW TO
MID 60S MAINLY SATURDAY WHEN THE DEEPEST MIXING IS EXPECTED. DUE
TO THESE HOT/HUMID CONDITIONS, HEAT INDICES COULD NEAR 105-108F
FRIDAY AFTERNOON, WHICH IS MARGINAL FOR HEAT ADVISORY CRITERIA,
BUT WITH EXTENSIVE OUTDOOR ACTIVITIES FOR THE START OF THE
HOLIDAY WEEKEND, AN INCREASED NUMBER OF INDIVIDUALS WILL LIKELY
BE EXPOSED TO THE PROLONGED HEAT. DUE TO THE POTENTIAL IMPACTS
FROM THIS HEAT, HAVE DECIDED TO ISSUE A HEAT ADVISORY FOR
COUNTIES ALONG AND NORTH OF THE I-20 CORRIDOR, RUNNING FROM 12PM
TO 8PM FRIDAY. DECIDED TO HOLD OFF FURTHER SOUTH AS THE AXIS OF
925-850MB DEWPOINTS GREATER THAN 18C IS EXPECTED TO REMAIN
NEAR/NORTH OF THE I-20 CORRIDOR WITH MORE MIXING OUT OF
DEWPOINTS EXPECTED SOUTH OF HERE, LEADING TO SLIGHTLY LOWER HEAT
INDICES.
FORECAST SOUNDINGS INDICATE DEEP MIXING ON INDEPENDENCE DAY,
WHICH COULD BRING SURFACE DEWPOINTS TOWARD THE LOW TO MID 60S,
BUT HEAT INDICES SHOULD STILL APPROACH 100-105F. THE POTENTIAL
NEED FOR ANOTHER MORE SO IMPACT BASED HEAT ADVISORY WILL
CONTINUE TO BE EVALUATED IN COMING FORECAST PACKAGES, BUT
CONFIDENCE IN NEEDING THIS IS LOW AS HEAT INDICES SHOULD BE EVEN
MORE MARGINAL THAN FRIDAY. MOISTURE IS EXPECTED TO UPTICK
SLIGHTLY SUNDAY AND INTO THE EARLY WEEK AS LOW LEVEL FLOW
BECOMES INCREASINGLY SOUTHERLY, BRINGING MULTIPLE DAYS WITH HEAT
INDICES ABOVE 100F AND THE POSSIBLE NEED FOR MORE HEAT
PRODUCTS.
EXERCISE CAUTION THIS HOLIDAY WEEKEND WHEN SPENDING AN EXTENDED
PERIOD OF TIME OUTDOORS AND MAKE SURE TO TAKE APPROPRIATE HEAT
SAFETY MEASURES. THE ELDERLY, YOUNG CHILDREN, PETS, AND THOSE
WITHOUT INDOOR COOLING WILL BE AT PARTICULAR RISK THIS WEEKEND
AND OVER THE COMING WEEK.
KEY MESSAGE 2: AN ISOLATED STRONG TO MARGINALLY SEVERE STORM
COULD SNEAK INTO THE NORTHERN FA LATE THIS AFTERNOON. INCREASING
CHANCES FOR SHOWERS AND THUNDERSTORMS LATE THIS WEEKEND INTO
NEXT WEEK.
A MOISTURE AXIS ON THE EASTERN SIDE OF MID LEVEL RIDGE IS SEEN
INTO THE UPSTATE AND TOWARD THE FAR NORTHERN MIDLANDS WITH
SURFACE DEW POINTS IN THE LOW TO MID 70S. A THERMALLY INDUCED
SURFACE TROUGH AXIS IS SEEN HERE AS WELL AND THIS REGION IS
WHERE ISOLATED CONVECTION IS EXPECTED TO DEVELOP THIS AFTERNOON
INTO THE EARLY EVENING. MLCAPE IS ALREADY APPROACHING 2000 J/KG
NORTH OF A LINE THROUGH MCCORMICK TO NEWBERRY TO LANCASTER WITH
DCAPE VALUES EXCEEDING 1000 J/KG THANKS TO GENEROUS MIXING.
CAM'S CONTINUE TO SHOW ISOLATED CONVECTION DEVELOPING LATER THIS
AFTERNOON NEAR THE UPSTATE AND CHARLOTTE THAT COULD CLIP THE
NORTHERN MIDLANDS. A STRONG TO MARGINALLY SEVERE STORM CANNOT BE
RULED OUT WITH THE THREAT OF DAMAGING WIND GUSTS THANKS TO
ROBUST DOWNDRAFTS, BUT WIDESPREAD IMPACTS HERE ARE NOT LIKELY.
THE SIGNAL PERSISTS ACROSS ENSEMBLE AND GLOBAL MODELS THAT THE
UPPER RIDGE WILL BECOME INCREASINGLY SUPPRESSED SUNDAY INTO NEXT
WEEK AS A SHORTWAVE TROUGH WORKS INTO THE GREAT LAKES REGION.
THIS WILL ALLOW FOR SOME WEAK HEIGHT FALLS AND SHORTWAVE ENERGY
TO MOVE INTO THE REGION EARLY IN THE WEEK WITH PWAT'S TICKING
BACK UP NEAR 2". WITH THE CONTINUED HEAT AND NOW INCREASED
MOISTURE EARLY NEXT WEEK, SEASONABLE TO STRONG DIURNAL
INSTABILITY COULD DEVELOP WITH DAILY SHOWERS AND STORMS
POSSIBLE. SOME STRONG TO SEVERE STORMS CANNOT BE RULED OUT AS
HIGHLIGHTED IN CSU ML GUIDANCE AND NCAR AI GUIDANCE.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
VFR CONDITIONS GENERALLY EXPECTED THROUGH THE TAF PERIOD.
DRY AND HOT CONDITIONS PERSIST UNDER THE INFLUENCE OF A STRONG
UPPER RIDGE. SOUTHEASTERLY WINDS 5 TO 10 KNOTS EXPECTED THIS
AFTERNOON WHICH SHOULD THEN DIMINISH TO LIGHT AND VARIABLE TO
CALM OVERNIGHT. WINDS WILL GRADUALLY PICK UP BY LATE MORNING
AGAIN FROM THE EAST SOUTHEAST. SOME BRIEF RIVER FOG MAY BE
POSSIBLE AT PRONE AGS/OGB LOCATIONS 09Z-12Z TIME FRAME BUT
CONFIDENCE IS LOW SO ONLY IN A TEMPO GROUP. SCATTERED DIURNAL
CUMULUS CLOUDS DEVELOPING NOW AND LIKELY TO PERSIST UNTIL SUNSET
THEN CLEARING SKIES OVERNIGHT.
EXTENDED AVIATION OUTLOOK...RAINFALL UNLIKELY THROUGH SATURDAY
AS RIDGING BUILDS OVERHEAD. BRIEF EARLY MORNING VSBY
RESTRICTIONS POSSIBLE. RAIN CHANCES AND POSSIBLE RESTRICTIONS
START TO INCREASE SUNDAY INTO EARLY NEXT WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...HEAT ADVISORY FROM NOON TO 8 PM EDT FRIDAY FOR SCZ016-018-
020>022-025>028-030-115-116.
HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SCZ115-116.
GA...HEAT ADVISORY FROM NOON TO 8 PM EDT FRIDAY FOR GAZ040-063>065.
DISCUSSION...DH
AVIATION...23
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