277
FXUS62 KGSP 311822
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
222 PM EDT FRI JUL 31 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES FOR THIS FORECAST UPDATE.
KEY MESSAGES
1. ANOTHER FRONTAL SYSTEM IS EXPECTED TO ARRIVE FROM THE WEST
THIS WEEKEND, PERHAPS BRIEFLY STALLING ACROSS OUR AREA EARLY NEXT
WEEK, BRINGING BACK HIGH RAIN CHANCES, BELOW-NORMAL TEMPERATURES,
AND SOME POTENTIAL FOR LOCALLY HEAVY RAINFALL.
2. A RETURN TO TYPICAL MID-SUMMER WEATHER IS EXPECTED TUESDAY,
CONTINUING THROUGH THE REMAINDER OF NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: ANOTHER FRONTAL SYSTEM IS EXPECTED TO ARRIVE FROM
THE WEST THIS WEEKEND, PERHAPS BRIEFLY STALLING ACROSS OUR AREA
EARLY NEXT WEEK, BRINGING BACK HIGH RAIN CHANCES, BELOW-NORMAL
TEMPERATURES, AND SOME POTENTIAL FOR LOCALLY HEAVY RAINFALL.
ONE MORE AFTERNOON/EVENING OF CONVECTION-FREE WEATHER IS AHEAD,
AS BELOW-NORMAL SURFACE DEWPOINTS ARE RESULTING IN VIRTUALLY NO
INSTABILITY ACROSS THE FORECAST AREA THIS AFTERNOON. HOWEVER, THIS
WILL BEGIN TO CHANGE TONIGHT, AS DEEP LAYER RIDGING MOVE OFF THE
EAST COAST, AND A SIGNIFICANT TROUGH/UPPER LOW APPROACHES THE OHIO
AND TN VALLEYS...RESULTING IN GRADUALLY INCREASING SOUTHERLY FLOW
AND INCREASING LOW LEVEL MOISTURE ACROSS OUR AREA. CONVECTION IS
EXPECTED TO DEVELOP TO OUR WEST WITHIN WARM CONVEYOR BELT REGIME
AHEAD OF FRONTAL SYSTEM ATTENDING THE HEIGHT FALLS, LIKELY MAKING
A RUN TOWARD OUR WESTERN AREAS BY THE END OF THE DAY. INCREASING
DEWPOINTS SHOULD ALLOW FOR AT LEAST MODEST DESTABILIZATION IN
THESE AREAS...AND THIS SHOULD ALLOW FOR CONVECTIVE ACTIVITY TO
MAKE SOME INROADS INTO THE AREA, AND GENERALLY 50-70 POPS ARE
ADVERTISED ACROSS THE WESTERN THIRD OR SO OF THE AREA.
WARM CONVEYOR BELT/DEEP MOISTURE PLUME CHARACTERIZED BY
PRECIPITABLE WATER VALUES OVER 2" WILL TRANSLATE INTO THE AREA
SATURDAY NIGHT, WITH SSW LOW LEVEL JET EXPECTED TO ACCELERATE TO
20-30 KTS. GENERALLY CONFLUENT LOW LEVEL FLOW UNDERNEATH DIFFLUENT
FLOW ALOFT WITHIN THE VERY MOIST AIR MASS WILL ALLOW CONVECTIVE
COVERAGE TO BLOSSOM SATURDAY NIGHT INTO EARLY SUNDAY. THE POTENTIAL
FOR TRAINING CELLS...ESPECIALLY AROUND TERRAIN FEATURES WITH A
SSW ASPECT WILL INCREASE DURING THIS TIME FRAME, INCREASING THE
POTENTIAL FOR EXCESSIVE RAINFALL. HAVING SAID THAT, THERE'S NOT A
STRONG SIGNAL IN QPF OUTPUT FROM CONVECTION-ALLOWING MODELS THAT
THIS THREAT WILL BE ANYTHING MORE THAN VERY LOCALIZED...AT LEAST
THROUGH SATURDAY NIGHT.
WHILE EARLY DAY CONVECTION/WIDESPREAD THICK CLOUD COVER WILL
LIMIT DESTABILIZATION DURING THE DAYLIGHT HOURS SUNDAY, MODEST
INSTABILITY SHOULD BE REALIZED DURING THE AFTERNOON, ALLOWING
COVERAGE OF SHOWERS AND STORMS TO INCREASE...WITH 70-80 POPS
ADVERTISED ACROSS MUCH OF THE AREA. THE LOCALLY EXCESSIVE RAINFALL
POTENTIAL WILL CONTINUE AS THE FRONTAL BOUNDARY MOVES INTO THE AREA
BY AFTERNOON. WITH SHEAR PARAMETERS ALSO INCREASING ABOVE SEASONAL
NORMALS, CAN'T RULE OUT AN ORGANIZED STORM OR TWO PRODUCING DAMAGING
WIND GUSTS...ESPECIALLY ACROSS THE EASTERN HALF OF THE AREA. SHOWER
AND STORM COVERAGE WILL LIKELY CONTINUE INTO THE EARLY PART OF
SUNDAY NIGHT, BUT THE GLOBAL MODELS ARE IN GENERAL AGREEMENT
THAT THE DEEP MOISTURE PLUME WILL BEGIN TO SHIFT EAST OF THE CWA
SUNDAY NIGHT. THIS DOESN'T PRECLUDE ANOTHER ROUND OF SOLID, MAINLY
DIURNAL CONVECTIVE COVERAGE ON MONDAY, AS UPPER TROUGHING REMAINS
WEST OF THE AREA, AND LOW-LEVEL MOISTURE/DIURNAL DESTABILIZATION
ARE FORECAST TO BE MORE THAN ADEQUATE FOR INITIATION.
ONE MORE DAY OF NEAR-NORMAL MAX TEMPS IS EXPECTED SATURDAY, BUT
THIS WILL BE FOLLOWED BY A COUPLE OF DAYS WITH MAXES AROUND 5
DEGREES BELOW CLIMO UNDER PLENTY OF CLOUD COVER, NOT TO MENTION
ANOMALOUSLY LOW HEIGHTS. MIN TEMPS WILL BE RIGHT AROUND CLIMO IN
LIGHT OF THE INCREASINGLY HIGH HUMIDITY.
KEY MESSAGE 2: A RETURN TO TYPICAL MID-SUMMER WEATHER IS EXPECTED
TUESDAY, CONTINUING THROUGH THE REMAINDER OF NEXT WEEK.
AN UPPER LOW IS EXPECTED TO STEADILY TO STEADILY SPIN DOWN ACROSS
THE TN/OH VALLEYS EARLY NEXT WEEK, ALTHOUGH A RELATIVE WEAKNESS
IN THE SUBTROPICAL RIDGE IS LIKELY TO LINGER OVER OUR REGION
THROUGH THE END OF THE WEEK. A RETURN TO SEASONAL LEVELS OF HEAT
AND HUMIDITY IS EXPECTED BY MID-WEEK, SUPPORTING NEAR-NORMAL
TEMPERATURES AND TYPICAL SCATTERED (MOUNTAIN) TO ISOLATED
(ELSEWHERE) COVERAGE OF DIURNAL CONVECTION EACH DAY FROM TUESDAY
THROUGH FRIDAY.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: THE AIR MASS OVER THE TERMINAL FORECAST AREA
REMAINS RELATIVELY DRY THIS AFTERNOON, AND ANOTHER AFTERNOON/EVENING
THAT WILL BE FREE OF CONVECTION IS ANTICIPATED. GENERALLY LIGHT
SW WINDS ARE EXPECTED THIS AFTERNOON, BECOMING MORE S OR SE
TONIGHT. LOW LEVEL MOISTURE WILL THEREFORE BEGIN TO STEADILY
CLIMB SUCH THAT MOUNTAIN VALLEY FOG/LOW STRATUS MAY BE A BIT
MORE WIDESPREAD LATE TONIGHT/EARLY SATURDAY, BUT THIS IS FAR
FROM CERTAIN...ESPECIALLY FOR KAVL...SO A VFR FORECAST WILL BE
ADVERTISED FOR NOW. THE SSE WINDS ARE EXPECTED TO BEGIN INCREASING
AFTER SUNRISE SAT, LIKELY BECOMING GUSTY AFTER 18Z. INCREASING
MOISTURE AND INSTABILITY IS EXPECTED TO RESULT IN BETTER CHANCES
FOR DIURNAL CONVECTION SATURDAY, BUT THIS WILL BE MOST LIKELY
AFTER 18Z AT MOST SITES...AND ACTUALLY AFTER 00Z SUNDAY AT KCLT,
SO THERE'S NO NEED FOR ANY PROB30S AT THIS TIME.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES AND ASSOCIATED RESTRICTIONS
RETURN SATURDAY AFTERNOON/EVENING AND CONTINUE INTO EARLY NEXT WEEK.
WHILE CONVECTION WILL BE MOST ACTIVE DURING THE AFTERNOON/EVENING,
SOME DEGREE OF OVERNIGHT AND EARLY MORNING COVERAGE IS ANTICIPATED
SAT/EARLY SUNDAY. WIDESPREAD LOW CLOUDS AND FOG ARE POSSIBLE SUNDAY
MORNING AND AGAIN MONDAY MORNING. A RETURN TO MOSTLY DIURNAL
CONVECTION AND EARLY MORNING MOUNTAIN VALLEY FOG/STRATUS IS EXPECTED
DURING THE NEW WORK WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
JDL
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