736
FXUS62 KGSP 261050
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
650 AM EDT FRI JUN 26 2026
WHAT HAS CHANGED
UPDATED THE AVIATION DISCUSSION FOR THE 12Z TAFS. UPDATED POPS TO
REFLECT RAIN CHANCES FOR THIS MORNING, MAINLY SOUTH OF I-85.
KEY MESSAGES
1. AFTERNOON/EVENING SHOWER AND THUNDERSTORM CHANCES RETURN
TOMORROW AND CONTINUE THROUGH THE WEEKEND, WITH ISOLATED SEVERE
STORMS POSSIBLE SATURDAY AND SUNDAY.
2. ELEVATED HEAT RISK IS FORECAST BY THE FIRST HALF OF NEXT WEEK,
WITH TRIPLE DIGIT HEAT INDICES POSSIBLE ACROSS MOST OF OUR LOWER
TERRAIN BY MID-WEEK.
DISCUSSION
KEY MESSAGE 1: AFTERNOON/EVENING SHOWER AND THUNDERSTORM CHANCES
RETURN TOMORROW AND CONTINUE THROUGH THE WEEKEND, WITH ISOLATED
SEVERE STORMS POSSIBLE SATURDAY AND SUNDAY.
QUASI-ZONAL FLOW ALOFT AND CONTINUED LOW-LEVEL SOUTH TO
SOUTHWESTERLY FLOW WILL PROVIDE WEAK MOISTURE ADVECTION AS A SUBTLE
SHORTWAVE SHIFTS ACROSS THE DEEP SOUTH AND SOUTHEAST THIS MORNING
AND THROUGH THE DAYTIME PERIOD. THIS HAS HELPED DEVELOP A FEW
SHOWERS SOUTH OF I-85 AND SHOULD CONTINUE TO PUSH NORTHEAST TOWARDS
THE CHARLOTTE AREA OVER THE NEXT COUPLE OF HOURS. WITH BETTER
MOISTURE ADVECTION, EXPECT FOR THE ATMOSPHERE TO DESTABILIZE MORE
COMPARED TO THE PAST COUPLE OF DAYS AND LEAD TO DIURNAL CONVECTION
ACROSS THE CWFA. BETTER POPS ARE FORECASTED TO BE EAST OF THE CWFA,
BUT ISOLATED COVERAGE WILL BECOME REALIZED ACROSS THE MOUNTAINS
AND PORTIONS OF THE PIEDMONT, WITH ANY LINGERING CONVECTION WANING
OFF SHORTLY AFTER SUNSET.
WEAK SHORTWAVE TROUGH TO THE NORTH AND THE PRESENCE OF A FRONTAL
BOUNDARY WILL SET THE STAGE FOR BETTER DIURNAL CONVECTIVE COVERAGE
ON SATURDAY. STRONG DESTABILIZATION WITH MORE ESTABLISHED MOISTURE
AND A SLIGHT INCREASE IN LOW-LEVEL SHEAR (0-3KM: ~20-25 KTS) SHOULD
HELP DEVELOP OUTFLOW DRIVEN CELL CLUSTERS THAT COULD PROMOTE A FEW
STRONG TO SEVERE STORMS, WITH THE BEST CHANCE BEING OVER WESTERN
NC DURING THE AFTERNOON AND EVENING HOURS.
THE FLOW ALOFT BECOMES MORE ANTICYCLONIC LATER SATURDAY AND SUNDAY
AS A DEEPENING ANTICYCLONE DEVELOPS OVER THE LOWER MS-VALLEY
AND TURNS THE FLOW ALOFT OVER THE CWFA NORTHWESTERLY. THIS IS A
TYPICAL "RING OF FIRE" SET UP WHERE STORMS DEVELOP UPSTREAM AND
MOVE DOWNSTREAM WITHIN THE MEAN FLOW AND SEND ONE OR MORE ROUNDS
OF POTENTIAL MCSS. CONFIDENCE IS RATHER LOW ON TIMING AND EXACT
LOCATION OF A POTENTIAL MCS, BUT THIS CAN BECOME INTERESTING,
ESPECIALLY IF ONE CAN TAKE ADVANTAGE OF MAX INSTABILITY DURING
DAYTIME HEATING, WHICH CAN'T BE RULED OUT ON SUNDAY AND WILL NEED
TO BE MONITORED. HOWEVER, TEMPERATURES WILL WARM UP TO 5 DEGREES
ABOVE NORMAL BY SUNDAY AS HIGHER HEIGHTS FILTER IN THANKS TO
THE DEEPENING UPPER/MID ANTICYCLONE, WITH HEAT INDICES GETTING
VERY CLOSE TO TRIPLE DIGITS, MAINLY IN THE SOUTHERN TIER OF THE
CWFA. ONE CAVEAT TO THIS FORECAST IS IF A MCS MOVES INTO THE CFWA
EARLIER IN THE DAY ON SUNDAY, LINGERING CONVECTIVE DEBRIS WILL
DISRUPT MAX TEMPERATURES FROM REACHING THEIR FULL POTENTIAL AND
WILL LOWER POPS IN REGARDS TO THE DIURNAL CONVECTIVE COVERAGE AS
WELL WITH LESS DESTABILIZATION.
KEY MESSAGE 2: ELEVATED HEAT RISK IS FORECAST BY THE FIRST HALF OF
NEXT WEEK, WITH TRIPLE DIGIT HEAT INDICES POSSIBLE ACROSS MOST OF
OUR LOWER TERRAIN BY MID-WEEK.
A STRONG UPPER/MID-LEVEL ANTICYCLONE WILL SET UP SHOP OVER THE MS
VALLEY LATE SUNDAY AND MONDAY, WHILE GRADUALLY PROPAGATING EASTWARD
DURING THE NEW WORKWEEK AND WILL ENGULF MOST OF THE EASTERN CONUS,
ESPECIALLY BY TUESDAY AND BEYOND. AFTERNOON HIGHS WILL REACH 4-8
DEGREES ABOVE NORMAL EACH DAY STARTING MONDAY AS THE HEAT REALLY
CRANKS UP BY WEDNESDAY AND THURSDAY. DRIER AIR ALOFT WILL HELP
TO SUPPRESS THE ATMOSPHERE, LEADING TO LESS DIURNAL CONVECTION
AND MORE IN THE WAY OF MIXING SURFACE DEWPOINTS WITH BETTER
LOW-LEVEL SUBSIDENCE. IN THIS CASE, HEAT INDICES WILL APPROACH
100 DEGREES DURING PEAK HEATING, BUT CONFIDENCE FOR ADVISORY
CRITERIA IS RELATIVELY LOW AT THIS TIME, BUT BEST CHANCES WOULD
BE IN THE LAKELANDS AND CHARLOTTE METRO. CAN'T RULE OUT DAILY
ISOLATED AFTERNOON SHOWERS AND STORMS OVER THE HIGH TERRAIN, BUT
ANY MENTIONABLE POP (15-30%) WILL REMAIN CONFINED TO THE MOUNTAINS
THROUGH THE END OF THE FORECAST PERIOD.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS WILL PREVAIL THROUGH
THE FORECAST PERIOD. CAN'T RULE OUT MOUNTAIN VALLEY FOG, BUT NOT
EXPECTED TO IMPACT KAVL THROUGH DAYBREAK. LIGHT AND VARIABLE WINDS
WILL PICK UP OUT OF THE SOUTH TO SOUTHWEST AT 4-8 KTS LATER THIS
MORNING AND INTO THE AFTERNOON. EXPECT AN INCREASE IN VFR-LEVEL
STRATOCU OR MID CLOUDS BEFORE DAYBREAK, ESPECIALLY FOR THE UPSTATE
AND CLT. A FEW SHOWERS CONTINUE TO PUSH SOUTH OF I-85, BUT CURRENT
TRENDS HAS THIS AREA OF SHOWERS MOVING TOWARD CLT, SO PLACED A VCSH
IN THE PREVAILING LINE AND KEEP IT THROUGH 15Z. DIURNAL CONVECTION
IS EXPECTED FOR THIS AFTERNOON AND EARLY EVENING, WITH THE BEST
CHANCES BEING IN KAVL AND KCLT, WHERE A PROB30 IS IN PLACE FOR TSRA
AND ASSOCIATED RESTRICTIONS. DECIDED TO GO WITH VCTS DURING PEAK
HEATING FOR THE UPSTATE SITES AS CONFIDENCE IS TOO LOW IN REGARDS TO
THUNDERSTORM COVERAGE FOR ANYTHING MORE THAN THAT, BUT WILL NEED TO
BE REEVALUATED THROUGH THE MORNING. ANY SHRA OR TSRA THAT DEVELOPS
SHOULD DISSIPATE OR MOVE AWAY FROM ALL TERMINALS BY 00Z SATURDAY.
LINGERING CONVECTIVE DEBRIS AND AN INCREASE IN OVERALL CLOUD COVER
SHOULD STICK AROUND INTO THE OVERNIGHT PERIOD.
OUTLOOK: AFTERNOON/EVENING SHOWER AND THUNDERSTORM CHANCES AND
ASSOCIATED RESTRICTIONS CONTINUE THROUGH THE WEEKEND. DIURNAL
CONVECTIVE CHANCES DIMINISH A BIT EARLY IN THE NEW WORK WEEK,
AS UPPER LEVEL HIGH PRESSURE STRENGTHENS OVER THE REGION. EARLY
MORNING FOG/LOW STRATUS IS POSSIBLE EACH DAY, ESPECIALLY IN THE
MOUNTAIN VALLEYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
CAC
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