279
FXUS62 KGSP 130634
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
234 AM EDT THU AUG 13 2026
WHAT HAS CHANGED
A HEAT ADVISORY HAS BEEN ISSUED FOR THIS AFTERNOON FOR PARTS OF
NORTHEAST GA, UPSTATE SC, AND THE SOUTHERN PIEDMONT OF NC.
KEY MESSAGES
1. HEAT ADVISORY FOR PARTS OF THE UPSTATE/NORTHEAST GA/METRO CLT
THIS AFTERNOON. HOT AND HUMID WEATHER IS EXPECTED TO CONTINUE
WELL INTO NEXT WEEK WITH TRIPLE DIGIT HEAT INDEX VALUES EXPECTED
OUTSIDE THE MOUNTAINS.
2. ISOLATED/SCATTERED THUNDERSTORMS ARE POSSIBLE EACH
AFTERNOON/EVENING FOR THE NEXT SEVEN DAYS. A FEW COULD BECOME
SEVERE WITH DAMAGING WIND GUSTS AND LOCALIZED FLASH FLOODING ANY
GIVEN DAY.
DISCUSSION
KEY MESSAGE 1: HEAT ADVISORY FOR PARTS OF THE UPSTATE/NORTHEAST
GA/METRO CLT THIS AFTERNOON. HOT AND HUMID WEATHER IS EXPECTED TO
CONTINUE WELL INTO NEXT WEEK WITH TRIPLE DIGIT HEAT INDEX VALUES
EXPECTED OUTSIDE THE MOUNTAINS.
THE MODEL GUIDANCE SHOWS TODAY TO BE THE TRANSITION BETWEEN THE
WEST-NORTHWEST FLOW ALOFT THAT HAS KEPT OUR REGION IN THE MCS TRACK,
AND MORE OF AN INFLUENCE FROM A BUILDING UPPER ANTICYCLONE CENTERED
OVER THE NORTHERN GULF COAST. AS THIS HAPPENS, STORM COVERAGE WILL
AGAIN BE MORE SPARSE, WHICH WILL ALLOW MORE OF A WARMUP TODAY,
AND LESS MIXING OUT OF THE DEWPOINT. THE MODEL BLEND DEWPOINTS WERE
NUDGED DOWNWARD BY INCORPORATING SOME OF THE CAM GUIDANCE, BUT NOT
ENOUGH TO AVOID AFTERNOON HEAT INDEX VALUES CREEPING UP ABOVE 105
ACROSS THE LAKELANDS AND PARTS OF THE CLT METRO AREA. CONFIDENCE
IS HIGHER OVER THE LAKELANDS BECAUSE THAT AREA GOT ALMOST TO 105
YESTERDAY AND TODAY SHOULD BE SLIGHTLY HOTTER. CONFIDENCE IS LOWER
OVER METRO CLT, BUT IT STANDS TO REASON THAT URBAN HEAT ISLAND
EFFECTS WILL BE ENOUGH TO RAISE THE HEAT INDEX ABOVE 103 ACROSS
MOST OF THE METRO AREA. THIS ALSO AGREES WELL WITH THE ADVISORIES
ISSUED BY NEIGHBORING OFFICES.
AS WE GO INTO THE WEEKEND...GUIDANCE SHOWS THE UPPER ANTICYCLONE
COVERING MORE OF THE MS VALLEY/TN VALLEY AND SOUTHEAST REGIONS,
AND EXERTING MORE INFLUENCE OVER THE WESTERN CAROLINAS. CONFIDENCE
IS INCREASING THAT WE WILL NEED A HEAT ADVISORY OVER A LARGER AREA
EAST OF THE MTNS ON FRIDAY, UNLESS SOME UNEXPECTED CONVECTIVE
OUTFLOW MANAGES TO DROP IN. IT IS EASY TO IMAGINE DAILY HEAT
ADVISORIES ALL THE WAY OUT THRU NEXT THURSDAY EVEN AS THE UPPER
ANTICYCLONE AND RIDGE MIGHT RETROGRADE, BUT ESPECIALLY THROUGH THE
WEEKEND AS THE PATTERN SUPPORTS THE HOT TEMPERATURES RUNNING 5-10
DEGREES ABOVE NORMAL. DOG DAYS INDEED.
KEY MESSAGE 2: ISOLATED/SCATTERED THUNDERSTORMS ARE POSSIBLE EACH
AFTERNOON/EVENING FOR THE NEXT SEVEN DAYS. A FEW COULD BECOME SEVERE
WITH DAMAGING WIND GUSTS AND LOCALIZED FLASH FLOODING ANY GIVEN DAY.
FOR TODAY, SOME OF THE CAMS ONCE AGAIN SUGGEST SOME POSSIBLE
CONVECTIVE DEVELOPMENT ALONG A REMNANT OUTFLOW FROM CONVECTION TO
THE WEST. THE ENVIRONMENT SHOULD BECOME REASONABLY UNSTABLE WITH
THE RAP SHOWING POCKETS OF SFC-BASED CAPE IN THE 3000-4000 J/KG
RANGE, SO PLENTY OF FUEL IF WE CAN GET A TRIGGER LIKE AN OUTFLOW
BOUNDARY. THE PRECIP PROBS WILL BE RAISED SLIGHTLY ABOVE THE
MODEL BLEND BECAUSE OF THIS POTENTIAL. OTHERWISE, THE BUILDING
UPPER ANTICYCLONE OVER THE SOUTHEAST/TN VALLEY REGIONS SHOULD
SHUNT THE MCS TRACK MORE NORTHWARD STARTING TODAY, WHICH WILL CUT
DOWN ON OUR CHANCES FOR THE MORE ORGANIZED CONVECTION ON FRIDAY
AND THROUGH THE WEEKEND. DIURNAL THUNDERSTORMS WILL CONTINUE WITH
PROBABILITY HIGHEST OVER THE MTNS. ANY GIVEN AFTERNOON/EVE WILL HAVE
THE POTENTIAL FOR A FEW SEVERE WIND PRODUCING STORMS AND LOCALIZED
FLASH FLOODING. TYPICAL SUMMERTIME STUFF. AS THE UPPER ANTICYCLONE
STARTS TO WEAKEN EARLY NEXT WEEK, THE MCS TRACK COULD DROP TO THE
SOUTH AGAIN, BUT THAT IS LESS CERTAIN THAN THIS PAST WEEK WAS.
AVIATION /06Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: WATCHING A REMNANT BLOB OF SHOWERS MAKING
THEIR WAY OVER THE NRN MOUNTAINS AT ISSUANCE TIME, WAITING TO SEE
IF ANY STORMS WILL REGENERATE ON THE EAST SIDE. THERE REMAINS
SOME LINGERING INSTABILITY, SO IT IS POSSIBLE, BUT FOR NOW THE
MAIN IMPACT WILL BE TO KHKY. THE DOWNWARD TREND SUGGESTS KEEPING
THEM VFR IN LIGHT RAIN, BUT THEN PERHAPS INCLUDING AN MVFR VIS
RESTRICTION TOWARD DAYBREAK WITH THE RAIN-COOLED AIR. KAVL IS
A TOSSUP WITH THE LOW CLOUD FORMATION BECAUSE OF THE HIGH LEVEL
CONVECTIVE DEBRIS MOVING OVERHEAD. FOR NOW I HAVE INCLUDED AN MVFR
RESTRICTION PREVAILING AFTER 08Z, BUT THIS COULD EASILY GO EITHER
WAY. THE RESTRICTIONS SHOULD END SHORTLY AFTER 12Z. THEREAFTER,
PREVAILING VFR AT ALL TERMINALS. ONCE AGAIN, THE CAMS SHOW LITTLE
IN THE WAY OF CONVECTION, BUT WITH THE ENVIRONMENT WE HAVE, WE
PREFER TO INCLUDE PROB30S AT MOST TERMINALS AS A PLACEHOLDER FOR
THUNDERSTORM ACTIVITY. LATER TAFS WILL RE-EVALUATE. WIND LIGHT
WSW AWAY FROM STORM OUTFLOWS.
OUTLOOK: A FEW SHOWERS OR THUNDERSTORMS POSSIBLE EACH AFTERNOON WITH
FLIGHT RESTRICTIONS POSSIBLE FOR LOW STRATUS AND FOG EACH MORNING.
GSP WATCHES/WARNINGS/ADVISORIES
GA...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
GAZ026-028-029.
NC...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
NCZ071-072-082.
SC...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
SCZ009-011-014-019.
PM
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