759
FXUS62 KGSP 200614
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
214 AM EDT SUN SEP 20 2026
WHAT HAS CHANGED
SEVERE WEATHER CHANCES INCREASE MONDAY.
INCREASED CHANCES FOR PRECIPITATION ON TUESDAY AND WEDNESDAY.
KEY MESSAGES
1. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED EACH AFTERNOON
AND EVENING THROUGH MONDAY. A FEW OF THE STORMS MAY BECOME SEVERE,
WITH DAMAGING WIND GUSTS AND EXCESSIVE RAIN BEING THE MAIN THREATS.
2. A NOTABLE PATTERN CHANGE IS EXPECTED DURING THE MIDDLE OF THE
UPCOMING WEEK THAT SHOULD BRING COOLER TEMPERATURES TO OUR AREA.
DISCUSSION
KEY MESSAGE 1: SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED EACH
AFTERNOON AND EVENING THROUGH MONDAY. A FEW OF THE STORMS MAY BECOME
SEVERE, WITH DAMAGING WIND GUSTS AND EXCESSIVE RAIN BEING THE MAIN
THREATS.
CONDITIONS WILL REMAIN UNSETTLED OVER THE NEXT FEW DAYS AS FLAT UPPER
RIDGING CENTERED OVER THE SOUTHERN PLAINS INTERACTS WITH A WEAK UPPER
LOW OVER THE FLORIDA PENINSULA AND EASTERN GULF. THIS UPPER PATTERN
COUPLED WITH A VERY BROAD REGION OF LOW-LEVEL CONVERGENCE, WILL HELP
KEEP AMPLE DEEP-LAYER MOISTURE OVER THE SOUTHEAST AND FUEL DIURNAL
SHOWERS AND THUNDERSTORMS BOTH SUNDAY AND MONDAY. ACTIVITY IS EXPECTED
TO INITIATE OVER THE MTNS EACH DAY AND THEN SPREAD S/SE AS THE DAY/
EVENING PROGRESSES. OVERALL, IT'S LOOKING LIKE WE WILL SEE BETTER
COVERAGE ON MONDAY, ESPECIALLY OVER THE NC PIEDMONT AND EASTERN SC
UPSTATE. SOME OF THESE STORMS WILL LIKELY BECOME STRONG TO SEVERE,
WITH DAMAGING WIND GUSTS AND EXCESSIVE RAIN BEING THE MAIN THREATS.
IT'S STILL LOOKING LIKE STRONG TO SEVERE STORMS WILL BE MORE LIKELY
ON MONDAY THAN SUNDAY. AS SUCH, SPC KEEPS THEIR MARGINAL RISK AREA
JUST TO OUR NORTH ON SUNDAY, BUT PUTS A PORTION OF THE NC MOUNTAINS
IN A SLIGHT RISK FOR MONDAY. THIS APPEARS REASONABLE WITH GREATER
SFC-BASED CAPE EXPECTED ON MONDAY AND SUFFICIENT DCAPE EACH DAY. IN
ADDITION, THE RISK FOR EXCESSIVE RAIN ALSO INCREASES AS WARM CLOUD
DEPTH INCREASES AND STORM MOTIONS ARE LIKELY TO BE FAIRLY SLOW. AS
SUCH, WPC HAS THEIR MARGINAL RISK FOR EXCESSIVE RAINFALL EXPAND
ACROSS OUR AREA EACH DAY THRU TUESDAY. AS FOR TEMPERATURES, THEY
WILL REMAIN ABOVE NORMAL THRU AT LEAST MONDAY. VALUES WILL MODERATE
SOMEWHAT BY TUESDAY, ASSUMING INCREASED CLOUD COVER AND RAIN
COVERAGE, BUT HIGHS ARE STILL FCST TO BE A COUPLE DEGREES ABOVE
NORMAL FOR MID TO LATE SEPT.
KEY MESSAGE 2: A NOTABLE PATTERN CHANGE IS EXPECTED DURING THE MIDDLE
OF THE UPCOMING WEEK THAT SHOULD BRING COOLER TEMPERATURES TO OUR
AREA.
EARLY IN THE COMING WEEK, THE NORTHERN STREAM BECOMES MORE BLOCKY
OVER THE CENTRAL CONUS AS A MID/UPPER LOW SLIDES UNDERNEATH STOUT
UPPER RIDGING. THIS RESULTS IN A REX-TYPE BLOCKING PATTERN CENTERED
TO OUR NORTH BY MID-WEEK. THE UPPER LOW IS EXPECTED TO STRENGTHEN/
EXPAND TOWARDS THE END OF THE WEEK AND BEGIN TO MOVE OFFSHORE BY THE
WEEKEND. AT THE SURFACE, CYCLOGENESIS OFF THE MID-ATLANTIC COAST IS
EXPECTED TO BRING A BACK-DOOR COLD FRONT SOUTHWARD AND THRU OUR FCST
AREA ON TUESDAY. AT THE SAME TIME, VERY BROAD SFC HIGH PRESSURE WILL
PARK ITSELF TO OUR NORTH OVER ONTARIO AND QUEBEC HELPING TO ESTABLISH
A COLD-AIR DAMMING WEDGE ON WEDNESDAY THAT WILL LIKELY PERSIST THRU
THE END OF THE WEEK. THE RESULTING COOL NELY FLOW AND SHOWER POTENTIAL
WILL HELP KEEP TEMPERATURES ABOUT 8 TO 10 DEGREES BELOW NORMAL FOR THE
LATTER HALF OF THE WEEK. THE WEDGE WILL LIKELY WEAKEN BY FRIDAY AS THE
SURFACE LOW LIFTS FURTHER NE AND DRIER AIR WORKS ITS WAY INTO OUR AREA
FROM THE WEST. NONETHELESS, TEMPERATURES ARE EXPECTED TO REMAIN BELOW
NORMAL THRU NEXT WEEKEND WITH SHOWER CHANCES DIMINISHING EACH DAY.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: SHRA TAPERS OFF AT KHKY BY 07Z. WINDS REMAIN
LIGHT AND VRB THROUGH THE PERIOD ACROSS MOST TERMINALS. BR/FG LIKELY
AGAIN AT KAVL SO TEMPO 08Z-12Z. MVFR/IFR CIGS ARE SLOW TO IMPROVE
THIS MORNING AND LINGER INTO THE EARLY AFTERNOON AT ALL TERMINALS.
TSRA POSSIBLE AT A FEW SITES THIS AFTERNOON, PROMPTING ANOTHER
PROB30, EXCEPT AT KCLT/KAND WHERE CONFIDENCE IS LOWER. VFR CIGS AND
CALM WINDS RETURN AFTER 00Z.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES CONTINUE EACH AFTERNOON
THROUGH TUESDAY. MOUNTAIN VALLEY FOG AND LOW STRATUS POSSIBLE EACH
MORNING.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
CP/JPT
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