248
FXUS62 KGSP 010013
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
813 PM EDT FRI JUL 31 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES FOR THIS FORECAST UPDATE.
AVIATION DISCUSSION WAS UPDATED FOR THE 00Z TAFS.
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 /00Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS TO START THE 00Z TAF
PERIOD, BUT GUIDANCE HAS RECENTLY TRENDED IN DEPICTING SOME
LOW STRATUS FORMING BEFORE SUNRISE ACROSS THE MIDLANDS AND
EXPAND NORTH/NORTHWEST WITHIN INCREASING SOUTHEASTERLY LOW-LEVEL
FLOW. CONFIDENCE REMAINS LOW, SO ONLY FEW IFR TO LOW-MVFR CLOUDS
WILL BE ADDED TO THE PIEDMONT TAF SITES WITH THE 00Z TAFS. MOUNTAIN
VALLEY FOG IS EXPECTED TO FORM AGAIN AS WELL, BUT WITH INCREASING
HIGH CLOUDS SPREADING IN FROM THE WEST AND LINGERING DRY AIR IN
PLACE, CONFIDENCE REMAINS TOO LOW TO LOWER VSBY BELOW 6SM AT KAVL
FOR NOW.
WHATEVER LOW CLOUDS AND/OR FOG THAT MAY FORM SHOULD LIFT/SCATTER
OUT TO VFR BY LATE MORNING. THE SSE WINDS WILL INCREASE SOMEWHAT
SATURDAY AFTN, WITH LOW-END GUSTS EXPECTED AT KCLT. WITH MOISTURE
RETURNING QUICKLY, EXPECT SCATTERED DIURNAL CONVECTION ACROSS
THE MOUNTAINS AND UPSTATE SITES IN THE AFTN, GRADUALLY SPREADING
EAST TO KHKY AND KCLT IN THE EVENING. WILL GO WITH PROB30S FOR
TSRA AT ALL SITES, WITH PREVAILING SHRA AT KAND, DUE TO HIGHER
CONVECTIVE COVERAGE.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES AND ASSOCIATED RESTRICTIONS
EXPECTED TO CONTINUE THRU AT LEAST THE MIDDLE OF NEXT WEEK.
WHILE CONVECTION WILL BE MOST ACTIVE DURING THE AFTERNOON/EVENING,
SOME DEGREE OF OVERNIGHT AND EARLY MORNING COVERAGE IS ANTICIPATED
SATURDAY NIGHT/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.
ARK/JDL
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