321
FXUS62 KGSP 012321
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
721 PM EDT SAT AUG 1 2026
WHAT HAS CHANGED
UPDATED THE AVIATION DISCUSSION FOR THE 00Z TAFS.
KEY MESSAGES
1. A STALLED FRONTAL BOUNDARY TO OUR WEST PRODUCES MULTIPLE
ROUNDS OF SHOWERS AND THUNDERSTORMS CAPABLE OF PRODUCING HEAVY
DOWNPOURS AND ISOLATED FLASH FLOODING. A LOW-END SEVERE WEATHER
RISK IS ALSO IN STORE FOR SUNDAY.
2. TYPICAL SUMMERTIME WEATHER RETURNS NEXT WEEK, WITH HOT AND
MUGGY CONDITIONS AND AFTERNOON SHOWERS AND THUNDERSTORMS.
DISCUSSION
KEY MESSAGE 1: A STALLED FRONTAL BOUNDARY TO OUR WEST PRODUCES
MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS CAPABLE OF PRODUCING
HEAVY DOWNPOURS AND ISOLATED FLASH FLOODING. A LOW-END SEVERE
WEATHER RISK IS ALSO IN STORE FOR SUNDAY.
SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS THE
EASTERN HALF OF THE FORECAST AREA THIS EVENING. ACTIVITY SHOULD
CONTINUE TO BLOSSOM AS AN OUTFLOW BOUNDARY PUSHES WESTWARD AHEAD OF
THIS ACTIVITY. THE SEVERE THREAT WILL REMAIN VERY LOW BUT ADDITIONAL
STRONG, SUB-SEVERE STORMS ARE POSSIBLE. THE BIGGER THREAT STILL
APPEARS TO BE HEAVY RAINFALL, WITH PWATS AS HIGH AS 1.9-2.1" THROUGH
TONIGHT AS A 20-30KT LLJ ADVECTS MORE AND MORE MOISTURE INTO THE
REGION. THIS IS NEAR THE HIGH END OF CLIMATOLOGY, AND MORE THAN
ENOUGH FOR EFFICIENT RAINFALL PRODUCTION BY ANY BETTER STORM
DEVELOPING IN THIS ENVIRONMENT.
SOME OF THE HI-RES GUIDANCE STILL HINTS AT A ROUND OF SHOWERS
REDEVELOPING IN THE PREDAWN HOURS SUNDAY. BY FAR THE BIGGER STORY,
HOWEVER, WILL BE THE AFTERNOON SUNDAY. BY THIS POINT IN TIME,
THE UPPER TROUGH (OR LOW, DEPENDING ON YOUR CHOICE OF MODEL) SHOULD
HAVE DRAWN CLOSE ENOUGH THAT MORE APPRECIABLE SYNOPTIC FORCING AS
WELL AS STRONG UPPER FLOW IN GENERAL WILL COVER THE AREA. AS A
RESULT, MUCH BETTER DEEP-LAYER SHEAR, ON THE ORDER OF 20-30KTS,
SHOULD BE IN PLACE OVER MUCH OF THE AREA. AS MUCH AS 2500 J/KG
SBCAPE CAN BE EXPECTED ACROSS MUCH OF THE AREA. THE HI-RES
GUIDANCE DOESN'T QUITE HAVE A HANDLE ON THE EVOLUTION OF SUNDAY'S
CONVECTION...BUT PATTERN RECOGNITION ALONE SAYS WE CAN EXPECT MORE
WIDESPREAD ACTIVITY AND SOME DEGREE OF ORGANIZATION LENDING ITSELF
TO A LOW-END DAMAGING WIND THREAT. STILL, AS MOIST AS PROFILES
ARE, THINK ANY ACTUAL SEVERE WILL BE ISOLATED, AND THE GREATER
POTENTIAL WILL ONCE AGAIN BE FOR TRAINING CELLS ACROSS THE AREA,
AND RESULTANT ISOLATED FLASH FLOODING.
KEY MESSAGE 2: TYPICAL SUMMERTIME WEATHER RETURNS NEXT WEEK, WITH HOT
AND MUGGY CONDITIONS AND AFTERNOON SHOWERS AND THUNDERSTORMS.
LONG-RANGE ENSEMBLES CONTINUE TO FEATURE EITHER A CLOSED UPPER LOW
OR A WEAKENING UPPER TROUGH SANDWICHED BETWEEN RIDGES OVER THE
WESTERN ATLANTIC AND CENTRAL CONUS, RESULTING IN SOME LEVEL OF
MOISTURE RETURN PERSISTING THROUGH THE WEEK. WITHOUT ANY CLARITY ON
THE SYNOPTIC PATTERN, IT'S TOUGH TO SAY WHAT THIS WILL MEAN FOR THE
CONVECTIVE FORECAST; RIGHT NOW IT WOULD LOOK LIKE A RETURN TO
DIURNAL SHOWERS AND STORMS IS LIKELY, BUT IF A TRUE CLOSED LOW
PERSISTS FOR DAYS, WE COULD BE UNDER THE GUN FOR MORE WIDESPREAD
COVERAGE THAN NORMAL BY DAY, AND SOME PERSISTENCE OF POPS INTO THE
OVERNIGHT.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: MESSY 00Z TAF PERIOD AS SCATTERED SHRA/TSRA
CHANCES SHOULD CONTINUE INTO LATE TONIGHT. THUS, WENT WITH TEMPOS
FOR TSRA AND ASSOCIATED RESTRICTIONS THIS EVENING INTO LATE TONIGHT
ACROSS THE TERMINALS. THE SC UPSTATE TERMINALS AND KAVL WILL HAVE
THE BEST POTENTIAL TO SEE SHRA, POSSIBLY EVEN TSRA, DEVELOP
OVERNIGHT INTO DAYBREAK SUNDAY BUT CONFIDENCE IS LOW SO WENT WITH
PROB30S. TSRA WILL RETURN AGAIN SUNDAY AFTERNOON/EVENING SO HAVE
PROB30S ACROSS ALL TERMINALS TOWARDS THE END OF THE TAF PERIOD.
OVERNIGHT CIGS SHOULD DROP TO IFR/LIFR WHILE VSBYS DROP TO MVFR/IFR.
BRIEF IMPROVEMENT IS EXPECTED WITH BOTH CIGS AND VSBYS WHERE ANY
SHRA/TSRA DEVELOP OVERNIGHT. RESTRICTIONS WILL BE SLOW TO LIFT
SUNDAY MORNING. VSBYS SHOULD RETURN TO VFR BY LATE SUNDAY MORNING OR
EARLY SUNDAY AFTERNOON BUT CIGS LIKELY WILL NOT LIFT TO VFR UNTIL
LATE AFTERNOON SUNDAY. WINDS WILL BE SE/S THROUGH THE PERIOD WITH
LOW-END GUSTS POSSIBLE STARTING SUNDAY AFTERNOON.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES, ALONG WITH ASSOCIATED
FLIGHT RESTRICTIONS, ARE EXPECTED TO LINGER THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK. PATCHY FOG AND LOW STRATUS WILL BE POSSIBLE IN
THE MOUNTAIN VALLEYS EACH MORNING, AND WHEREVER HEAVIER RAINFALL
FELL THE PREVIOUS EVENING.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
AR/MPR
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