067
FXUS62 KGSP 190535
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
135 AM EDT WED AUG 19 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES TO THE GENERAL FORECAST.
THE AVIATION FORECAST WAS UPDATED TO REFLECT THE RECENT 06Z TAF
ISSUANCE.
KEY MESSAGES
1. HOT AND MUGGY CONDITIONS PERSIST THROUGH THE END OF THE
WEEK. SOME RELIEF ARRIVES THIS WEEKEND.
2. DIURNAL SHOWERS AND STORMS RETURN THURSDAY, AND PERSIST THROUGH
THE END OF THE WEEK. DRIER CONDITIONS ARRIVE AGAIN BY SUNDAY.
DISCUSSION
KEY MESSAGE 1: HOT AND MUGGY CONDITIONS PERSIST THROUGH THE END OF
THE WEEK. SOME RELIEF ARRIVES THIS WEEKEND.
A WEAKNESS IN THE SUBTROPICAL RIDGE REMAINS IN PLACE OVER THE
SOUTHEAST TONIGHT, ON THE PERIPHERY OF A MUCH DEEPER UPPER LOW
CENTERED OVER EASTERN CANADA. STILL DON'T EXPECT MUCH CHANGE
TO THIS CONFIGURATION OVER THE NEXT FEW DAYS; AT THE SURFACE,
WEAK N/NE FLOW WILL CONTINUE BEHIND MONDAY NIGHT'S COLD FRONT,
KEEPING DEWPOINTS CONSTRAINED AND RESULTING IN UPPER-90S TO
LOWER-100S HEAT INDEX VALUES THIS AFTERNOON, AND AGAIN THURSDAY
AND FRIDAY AFTERNOONS. STILL UNPLEASANTLY HOT AND MUGGY, BUT NOT
QUITE INTO THE DANGER-ZONE THAT WOULD PROMPT A HEAT ADVISORY.
GUIDANCE CONTINUES TO DEPICT ANOTHER COLD FRONT ARRIVING ON
SATURDAY NIGHT OR SUNDAY, BUT TRUE TO FORM, DETERMINISTIC MODELS
HAVE WAFFLED ONCE AGAIN, TOWARD A STALLING FRONT IN OR SOUTH OF
THE GSP FORECAST AREA. LONG-RANGE ENSEMBLES STILL FEATURE A MIX
OF BOTH THIS SCENARIO AND THE PREVIOUSLY-FAVORED SCENARIO IN WHICH
THE FRONT MAKES A COMPLETE PASSAGE, DRYING US OUT SUNDAY AFTERNOON
INTO MONDAY. EITHER WAY, MUCH OF THE REGION COULD SEE SOME RELIEF
FROM THE HEAT OVER THE WEEKEND AS THE FRONT ARRIVES AND USHERS IN
SOMEWHAT A SOMEWHAT COOLER AND DRIER AIR MASS.
KEY MESSAGE 2: DIURNAL SHOWERS AND STORMS RETURN THURSDAY, AND
PERSIST THROUGH THE END OF THE WEEK. DRIER CONDITIONS ARRIVE
AGAIN BY SUNDAY.
A CLOSED H50 LOW WILL MEANDER FROM THE HUDSON BAY EASTWARD ACROSS
QUEBEC AND INTO THE NORTHWESTERN ATLANTIC THROUGH THE END OF
THIS WEEK. A SERIES OF EMBEDDED VORT LOBES WILL ROTATE AROUND IT;
THEY'LL GENERALLY STAY TO OUR NORTH BUT SHOULD NONETHELESS ACT TO
REINFORCE THE TROUGHINESS ALREADY IN PLACE ACROSS THE CAROLINAS.
A COLD FRONT, MEANWHILE, WILL SETTLE ACROSS THE OHIO VALLEY BY
LATE WEDNESDAY, PROVIDING THE IMPETUS FOR ORGANIZED CONVECTION
WELL UPSTREAM. THE 00Z SUITE OF HI-RES GUIDANCE ALMOST UNIVERSALLY
DEPICTS A DECAYING MCS SLIDING ACROSS KENTUCKY AND EASTERN TENNESSEE
EARLY THURSDAY MORNING, AND MAKING A RUN AT THE TENNESSEE BORDER;
CONFIDENCE REMAINS LOW ON HOW MUCH OF A SEVERE THREAT THIS WILL
POSE, AS GIVEN THE CURRENTLY-FORECAST ARRIVAL TIME NEAR THE DIURNAL
MIN, CONDITIONS WON'T BE FAVORABLE FOR IT TO MAINTAIN ITS INTEGRITY
CROSSING THE APPALACHIANS.
THEREAFTER, EXPECT A RETURN TO MORE SEASONABLE DIURNAL CONVECTION
ON THURSDAY AND FRIDAY AFTERNOONS. BOTH AFTERNOONS, BUT ESPECIALLY
FRIDAY, WILL FEATURE SOME DEGREE OF NON-NEGLIGIBLE SHEAR AS THE
COLD FRONT AND ASSOCIATED H50 WESTERLIES DRAW CLOSER TO THE AREA
(PERHAPS EVEN SETTLING INTO THE MOUNTAINS BY FRIDAY AFTERNOON OR
EVENING), SO STILL THINK SOME DEGREE OF WEAKLY-ORGANIZED CONVECTION
WILL BE POSSIBLE, INSTEAD OF THE COMPLETELY DISORGANIZED PULSE
CONVECTION WE'D SEE IN A LESS-DYNAMIC ENVIRONMENT. SO, WILL NEED
TO CONTINUE MONITORING THE SEVERE THREAT LATE THIS WEEK.
TIMING INCONSISTENCIES CONTINUE TO PLAGUE THE 00Z LONG-RANGE
ENSEMBLES; IT REMAINS QUESTIONABLE WHERE THE FRONT WILL BE
BY SATURDAY AFTERNOON. WHETHER IT HAS SHIFTED TO OUR EAST, OR
REMAINS IN OUR AREA, WILL MODERATE CONVECTION CHANCES FOR SATURDAY.
CONFIDENCE IS HIGHER THAT BY SUNDAY AND MONDAY, WE'LL START TO SEE
AN INFLUX OF DRIER POSTFRONTAL AIR, RESULTING IN A COOLDOWN AND
SUPPRESSED AFTERNOON CONVECTION SUNDAY AND MONDAY. DETAILS REMAIN
A LITTLE MURKY, HOWEVER...SO STAY TUNED.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: VFR ON TAP FOR THE 06Z TAF PERIOD. OTHER
THAN THE POTENTIAL ONCE AGAIN FOR SOME IFR TO LIFR VALLEY FOG AND
LOW STRATUS ACROSS THE NORTH CAROLINA MOUNTAINS, WHICH SHOULD ONLY
IMPACT KAVL FOR A FEW HOURS BEFORE DAWN...IF AT ALL...THE TAFS ARE
VFR, FEATURING FEW CIRRUS, PERHAPS A BRIEF AFTERNOON CU FIELD ON
WEDNESDAY, AND A STEADY 4-8KT N WIND THROUGH THE PERIOD.
OUTLOOK: SCATTERED DIURNAL CONVECTION IS EXPECTED TO RETURN ON
THURSDAY, WITH AFTERNOON SHOWERS AND STORMS POSSIBLE EACH DAY
THROUGH SATURDAY. LOW STRATUS AND FOG WILL BE POSSIBLE EACH
MORNING, MAINLY IN THE MOUNTAIN VALLEYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
MPR
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