482
FXUS62 KGSP 191042
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
642 AM EDT SUN JUL 19 2026
WHAT HAS CHANGED
UPDATED THE AVIATION DISCUSSION FOR THE 12Z TAFS.
KEY MESSAGES
1. HOT AND HUMID CONDITIONS WITH HEAT INDEX VALUES RANGING FROM
100 TO 105 DEGREES THIS AFTERNOON. ELEVATED HEAT INDEX VALUES
CONTINUE THROUGH WEDNESDAY. COOLER TEMPERATURES LATER IN THE WEEK
SHOULD KEEP HEAT INDICES BELOW 100 DEGREES.
2. INCREASED CONVECTIVE COVERAGE EXPECTED TODAY WITH SOME
SEVERE THUNDERSTORMS. DAMAGING WINDS ARE LIKELY TO BE THE MAIN
HAZARD. ELEVATED CONVECTIVE COVERAGE CONTINUES MONDAY WITH A FEW
SEVERE STORMS. TYPICAL DIURNAL SHOWER AND THUNDERSTORM CHANCES
TUESDAY, BEFORE A COLD FRONT BRINGS INCREASED COVERAGE AND THE
POTENTIAL FOR MORE SEVERE WEATHER ON WEDNESDAY.
DISCUSSION
KEY MESSAGE 1: HOT AND HUMID CONDITIONS WITH HEAT INDEX VALUES RANGING
FROM 100 TO 105 DEGREES THIS AFTERNOON. ELEVATED HEAT INDEX VALUES
CONTINUE THROUGH WEDNESDAY. COOLER TEMPERATURES LATER IN THE WEEK
SHOULD KEEP HEAT INDICES BELOW 100 DEGREES.
DESPITE BETTER CONVECTIVE COVERAGE AND ASSOCIATED CLOUD DEBRIS,
ALONG WITH LOWER THICKNESS VALUES, HIGHS WILL REACH THE LOW TO MID
90 TODAY. WITH ELEVATED DEWPOINTS, HEAT INDEX VALUES OVER 100 ARE
EXPECTED FOR MUCH OF THE AREA. A FEW LOCATIONS MAY BRIEFLY REACH
105, BUT SHOULD BE ISOLATED ENOUGH TO PRECLUDE A HEAT ADVISORY.
HIGHS COOL FURTHER ON MONDAY BUT SPIKE BACK UP A FEW DEGREES TUESDAY
AND WEDNESDAY. HEAT INDEX VALUES WILL MOSTLY BE 100 OR LESS MONDAY,
BUT WITH THE INCREASED TEMPS AND LINGERING ELEVATED DEWPOINTS
TUESDAY AND WEDNESDAY, HEAT INDEX INCREASES BACK OVER 100 FOR MANY
LOCATIONS ALONG AND SOUTH OF THE I-85 CORRIDOR. SPOTTY 105 VALUES
ARE POSSIBLE TUESDAY, BUT THE PROBABILITY OF NEEDING A HEAT ADVISORY
LOOKS LOW AT THIS TIME. THE HEAT AND HUMIDITY FINALLY BREAK BY
THURSDAY WITH AN AIR MASS CHANCE BEHIND A COLD FRONT. UNTIL THEN,
STAY HYDRATED, TAKE FREQUENT BREAKS IN AIR-CONDITIONED OR SHADED
AREAS, AND NEVER LEAVE CHILDREN OR PETS UNATTENDED IN VEHICLES.
KEY MESSAGE 2: INCREASED CONVECTIVE COVERAGE EXPECTED TODAY
WITH SOME SEVERE THUNDERSTORMS. DAMAGING WINDS ARE LIKELY TO BE THE
MAIN HAZARD. ELEVATED CONVECTIVE COVERAGE CONTINUES MONDAY WITH A
FEW SEVERE STORMS. TYPICAL DIURNAL SHOWER AND THUNDERSTORM CHANCES
TUESDAY, BEFORE A COLD FRONT BRINGS INCREASED COVERAGE AND THE
POTENTIAL FOR MORE SEVERE WEATHER ON WEDNESDAY.
AN UPPER TROF DIGGING INTO THE NORTHEAST WILL PUSH A WEAK FRONT INTO
THE AREA FROM THE NORTH. THE ATMOSPHERE WILL AGAIN BECOME VERY
UNSTABLE WITH AN INCREASE IN BULK SHEAR DUE TO THE TROF AND FRONT.
HIGH PW VALUES AND STEEP LOW LEVEL LAPSE RATES WILL CREATE THE
THREAT FOR DAMAGING DOWNBURSTS. THE INCREASE IN SHEAR COULD BRING
SOME ORGANIZATION TO THE CONVECTION WHICH COULD INCREASE THE SEVERE
STORM POTENTIAL. SPC HAS INTRODUCED A SLIGHT RISE OF SEVERE STORMS
AS A RESULT. THE FRONT STALLS OVER THE AREA MONDAY, BUT THE SHEAR
WEAKENS. HOWEVER, THE ATMOS REMAINS VERY UNSTABLE WITH HIGH PW
VALUES AND STEEP LOW LEVEL LAPSE RATES. SPC HAS A MARGINAL RISK FOR
MUCH OF THE AREA.
DIURNAL CONVECTIVE CHANCES LINGER TUESDAY BUT OVERALL COVERAGE
SHOULD BE LOWER. THE CHANCE RAMPS BACK UP WEDNESDAY AS ANOTHER TROF
DIGS INTO THE EASTERN CONUS PUSHING YET ANOTHER FRONT INTO THE AREA.
THE CHANCE OF STRONG TO SEVERE STORMS MAY RAMP BACK UP AS WELL WITH
A MOIST AND UNSTABLE AIR MASS AND SOME ORGANIZATION POSSIBLE. MORE
TYPICAL DIURNAL CONVECTIVE TRENDS RETURN THROUGH THE REST OF THE
FORECAST PERIOD.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: MOUNTAIN VALLEY FOG/STRATUS HAS FLOATED
AROUND KAVL THIS MORNING. HAVE A SHORT TEMPO IN PLACE FOR THIS.
DIURNAL CUMULUS MAY FORM AT MVFR TO LOW VFR LEVEL IN THE MORNING
BEFORE LIFTING, BUT CHANCE TOO LOW FOR ANY CIGS IN THE TAF FOR NOW.
SIMILAR COVERAGE OF SHOWERS/STORMS EXPECTED THIS AFTERNOON, AND ALL
SITES GET A PROB30 FOR DIURNAL SHRA/TSRA. MOUNTAIN VALLEY FOG
EXPECTED ONCE AGAIN OVERNIGHT. LIGHT SW WIND PICKS UP SPEED BY
AFTERNOON. KAVL SEES NW WIND.
OUTLOOK: GOOD COVERAGE OF AFTERNOON/EVENING SHRA/TSRA CONTINUES
MONDAY WITH LESS COVERAGE EXPECTED ON TUESDAY BEFORE INCREASING
AGAIN ON WEDNESDAY THEN LOWERING AGAIN THURSDAY. LOW STRATUS AND/OR
FOG WILL BE POSSIBLE EACH MORNING, MAINLY IN THE MTN VALLEYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
RWH
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