384
FXUS62 KGSP 220944
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
544 AM EDT FRI MAY 22 2026
WHAT HAS CHANGED
THE WET AND COOL FORECAST CONTINUES THROUGH THE MEMORIAL DAY HOLIDAY
WEEKEND. WET AND NEAR NORMAL THROUGH THE REST OF THE PERIOD.
KEY MESSAGES
1. DEVELOPING COLD AIR DAMMING WILL MAINTAIN DREARY CONDITIONS
FOR FRIDAY AND FRIDAY NIGHT, WITH WIDESPREAD CLOUDY AND RAINY
CONDITIONS. THE RISK OF SEVERE THUNDERSTORMS APPEARS QUITE
LOW. THE RISK OF FLOODING RAIN APPEARS LOW ALSO, BUT NONZERO,
WITH EXTREMELY ISOLATED ISSUES POSSIBLE GOING INTO FRIDAY NIGHT.
2. UNSETTLED WEATHER CONTINUES THROUGH MOST OF THE WEEK AS THE
LARGE-SCALE PATTERN USHERS GULF MOISTURE INTO THE CAROLINAS.
DISCUSSION
KEY MESSAGE 1: DEVELOPING COLD AIR DAMMING WILL MAINTAIN DREARY
CONDITIONS FOR FRIDAY AND FRIDAY NIGHT, WITH WIDESPREAD CLOUDY
AND RAINY CONDITIONS. THE RISK OF SEVERE THUNDERSTORMS APPEARS
QUITE LOW. THE RISK OF FLOODING RAIN APPEARS LOW ALSO, BUT NONZERO,
WITH EXTREMELY ISOLATED ISSUES POSSIBLE GOING INTO FRIDAY NIGHT.
SCATTERED SHOWERS CONTINUE ACROSS THE AREA IN RESPONSE TO ISENTROPIC
UPGLIDE ABOVE A SHALLOW WEDGE ASSOCIATED WITH COLD AIR DAMMING
BECOMING ESTABLISHED ACROSS THE AREA. RECENT MESOANALYSIS DEPICTS
PRECIOUS LITTLE REMAINING ELEVATED INSTABILITY, AND ACCORDINGLY A
DOWNTICK IN THUNDER HAS BEEN OBSERVED SINCE THE PREVIOUS FORECAST
UPDATE.
FOR TODAY, THE FORECAST REMAINS LARGELY UNCHANGED: PERIODS OF RAIN
AND EMBEDDED THUNDER ARE EXPECTED AS LOW-LEVEL ISENTROPIC ASCENT
PICKS UP STEAM OVER THE SOUTHERN PERIPHERY OF SURFACE HIGH PRESSURE
CENTERED OVER ONTARIO, AND A BONAFIDE CAD WEDGE TAKES SHAPE EAST OF
THE MOUNTAINS. 00Z HI-RES GUIDANCE DOESN'T HAVE A GREAT HANDLE ON
EXACTLY HOW RAIN WILL EVOLVE ON FRIDAY, BUT GENERALLY FALL INTO
TWO CAMPS: ONE SCENARIO IN WHICH COVERAGE LARGELY HITS A LULL
DURING THE MORNING HOURS (RECENT HRRR RUNS AND THE 00Z FV3), AND
ANOTHER IN WHICH A ROUND OF STRONGER UPGLIDE-INDUCED RAINFALL PICKS
UP STEAM THROUGH THE MORNING HOURS (00Z NAMNEST, ARW, AND RRFS).
DON'T HAVE A GREAT FEEL FOR WHICH CAMP WILL ULTIMATELY BE CORRECT.
EITHER WAY, WOULD EXPECT RAIN THROUGHOUT THE DAY AS WELL AS THE
STEADY DEVELOPMENT OF HYBRID CAD TO HAVE A SIGNIFICANT IMPACT ON
FRIDAY AFTERNOON HIGHS; THE NBM STILL APPEARS TO BE 1-3 DEGREES
TOO WARM...AND SO MODIFIED THE FORECAST ACCORDINGLY.
REGARDLESS, THE POTENTIAL FOR MORE WIDESPREAD RAIN AND EMBEDDED
(MAINLY ELEVATED) THUNDERSTORMS SHOULD INCREASE THROUGH FRIDAY
AFTERNOON, AS A SHORTWAVE AXIS MIGRATES FROM THE LOWER MISSISSIPPI
VALLEY NORTHEAST INTO GEORGIA. THE RESULTING INCREASE IN DPVA
SHOULD IMPROVE ELEVATED INSTABILITY, AND SO ALTHOUGH OPERATIONAL
GUIDANCE REMAINS IN GOOD AGREEMENT THAT THE CAD WEDGE WILL REMAIN
IN PLACE ALL DAY, THE CASE FOR WEDGE-TOP CONVECTION LOOKS BETTER
AND BETTER GOING INTO FRIDAY NIGHT. TONIGHT'S 00Z HREF PAINTS A
PRETTY CONVINCING PICTURE OF HEAVY RAINFALL DEVELOPING AFTER 00Z
SATURDAY, PARTICULARLY ACROSS THE UPPER SAVANNAH RIVER VALLEY AND
WESTERN UPSTATE, WHERE HI-RES GUIDANCE IS IN GOOD AGREEMENT THAT
THE COMBINED POTENTIAL FOR CONVECTIVE RATES AND TRAINING CELLS
WILL PRODUCE LOW-END HYDRO ISSUES. TO WIT, BOTH THE LATEST HREF
AND REFS OUTPUT INDICATE POTENTIAL FOR A CORRIDOR OF 3HR QPF
OF 1.5-2.5" ACROSS NORTHEAST GEORGIA AND THE WESTERN UPSTATE,
AND EXTREMELY ISOLATED POCKETS OF 2.5-3", MAINLY ALONG THE SC
BLUE RIDGE ESCARPMENT. DESPITE ONGOING D2-D3 DROUGHT CONDITIONS
ACROSS THE REGION, SUCH TOTALS ARE ENOUGH FOR AT LEAST ISOLATED
NUISANCE FLOODING.
KEY MESSAGE 2: UNSETTLED WEATHER CONTINUES THROUGH MOST OF THE WEEK
AS THE LARGE-SCALE PATTERN USHERS GULF MOISTURE INTO THE CAROLINAS.
SYNOPTIC GUIDANCE CONTINUES TO INDICATE THAT BROAD TROUGHING
WILL REMAIN IN PLACE ACROSS THE CENTRAL CONUS WHILE UPPER RIDGING
WILL STAY CENTERED OVER THE WESTERN ATLANTIC FROM SUNDAY THROUGH
AT LEAST MID-WEEK. THIS CONFIGURATION IS FAVORABLE FOR STEADY
MOISTURE FLUX OFF THE GULF, MEANING PERIODS OF WIDESPREAD RAIN
SHOULD CONTINUE ON SUNDAY AND THE FIRST SEVERAL DAYS OF NEXT WEEK.
OPERATIONAL MODELS DEPICT ANOTHER LOW-AMPLITUDE SHORTWAVE LIFTING
ACROSS THE CAROLINAS ON SUNDAY NIGHT, AND ACCORDINGLY ANOTHER
INCREASE IN QPF DURING THAT PERIOD. CONFIDENCE IS LOW ON ANY
IMPACTS, BUT AT THIS TIME SUNDAY NIGHT APPEARS TO BE THE NEXT
POINT OF INTEREST FOR MORE WIDESPREAD SIGNIFICANT RAINFALL.
UNSETTLED WEATHER AND ABOVE-NORMAL RAINFALL CHANCES LOOK TO CONTINUE
THROUGH AT LEAST MIDWEEK. DEPENDING ON HOW THE NEXT FEW DAYS PAN
OUT, IT'S STILL WITHIN REASON THAT WE COULD BE LOOKING AT A NONZERO
HEAVY RAIN / FLASH FLOOD THREAT BY MIDWEEK...AND IT'S SOMEWHAT
MORE LIKELY THAT WE SHOULD PUT A SERIOUS DENT IN ONGOING DROUGHT
CONDITIONS. STILL...BEST NOT TO COUNT OUR EGGS BEFORE THEY HATCH.
THERE'S A LOT THAT CAN GO RIGHT (OR WRONG) FOR THINGS TO PROCEED
AS ANTICIPATED.
AVIATION /09Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: AS WE APPROACH 06Z, CONVECTION SEEMS TO HAVE
GAINED A SECOND WIND, WITH SCATTERED SHOWERS REDEVELOPING ACROSS
MUCH OF THE NC PIEDMONT AND, AT THE TIME OF THE THIS WRITING, TO
SOME EXTENT ACROSS THE SOUTHERN APPALACHIANS AS WELL. GENERALLY
THINK THAT THIS WILL BE MAINLY SHOWERY, WITH INSTABILITY FAIRLY
LIMITED AT THIS POINT, AND THE ATMOSPHERE NOT QUITE "JUICED UP"
ENOUGH FOR WIDESPREAD TSRA. STILL, COULD CERTAINLY SEE A RUMBLE OF
THUNDER HERE AND THERE. DURING THE WEE HOURS OF FRIDAY MORNING,
STILL EXPECT A LULL IN COVERAGE, SUPPORTED BY MOST OF THE 00Z
GUIDANCE. THE LATTER HALF OF TONIGHT WILL INSTEAD BE MARKED
BY A QUICK EXPANSION OF MVFR TO IFR CEILINGS - ALREADY IN PLACE
ACROSS PARTS OF THE I-77 CORRIDOR - ACROSS MUCH OR ALL OF THE AREA.
AT LEAST WIDELY SCATTERED SHOWERS WILL CONTINUE ACROSS THE TERMINAL
FORECAST AREA THROUGH EARLY AFTERNOON FRIDAY, AFTER WHICH AN
INCREASE IN ELEVATED INSTABILITY SHOULD RESULT IN MORE WIDESPREAD
SHRA AND A GREATER CHANCE FOR TSRA, ESPECIALLY DURING THE LATE
AFTERNOON AND EVENING HOURS. COLD AIR DAMMING IS STILL EXPECTED TO
PERSIST FOR MOST OR ALL OF FRIDAY, WITH IFR RESTRICTIONS UNLIKELY
TO RELIABLY LIFT ALL DAY. MORE INTENSE SHRA SHOULD REDEVELOP
AFTER 00Z SATURDAY, PARTICULARLY ACROSS THE WESTERN SC UPSTATE.
OUTLOOK: COLD-AIR DAMMING PERSISTS THRU SATURDAY. THE CAD WILL
LIKELY PRODUCE WIDESPREAD MVFR TO IFR CEILINGS INTO SATURDAY.
PERIODS OF MAINLY DIURNAL CONVECTION WILL ALSO CONTINUE ATOP
THE CAD WEDGE AND INTO NEXT WEEK, EVEN AS THE CAD ERODES. THE
POTENTIAL FOR OVERNIGHT FOG/LOW CLOUDS WILL INCREASE THROUGH THE
PERIOD AS WELL. ACTIVE DIURNAL CONVECTION EXPECTED TO CONTINUE
THRU THE FIRST HALF OF NEXT WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
MPR
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