323
FXUS62 KGSP 271022
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
622 AM EDT MON APR 27 2026
WHAT HAS CHANGED
RAINFALL AMOUNTS TRENDING HIGHER FOR WEDNESDAY. TEMPERATURES
TRENDING COOLER FOR THE WEEKEND.
THE AVIATION FORECAST WAS UPDATED TO REFLECT THE IMPENDING 12Z
TAF ISSUANCE.
KEY MESSAGES
1. QUIET CONDITIONS CONTINUE FOR MOST OF MONDAY BEFORE A DECAYING
CONVECTIVE LINE CROSSES THE AREA TUESDAY MORNING.
2. TWO FRONTAL SYSTEMS BRING RAIN CHANCES WEDNESDAY AND AGAIN
EARLY IN THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: QUIET CONDITIONS CONTINUE FOR MOST OF MONDAY BEFORE
A DECAYING CONVECTIVE LINE CROSSES THE AREA TUESDAY MORNING.
SURFACE LOW PRESSURE OVER THE WESTERN ATLANTIC CONTINUES TO PULL
FARTHER OFFSHORE THIS MORNING, AND AS A RESULT LOW-LEVEL CAA ACROSS
THE WESTERN CAROLINAS HAS WEAKENED SIGNIFICANTLY. NONETHELESS,
ENOUGH MOISTURE HAS BEEN ADVECTED INTO THE REGION THAT A DECK OF
THICK STRATOCU REMAINS IN PLACE...BLANKETING THE PIEDMONT AND NC
MOUNTAINS, AND EVEN PENETRATING TO SOME EXTENT INTO THE UPSTATE.
AS A RESULT, TEMPS ACROSS MUCH OF THE AREA ARE INDEED RUNNING 1-3
DEGREES ABOVE FORECAST.
TODAY WILL BE A QUIET, TRANSITIONAL DAY FOR THE MOST PART.
STRATOCU SHOULD RETREAT QUICKLY AFTER SUNRISE, GIVING WAY TO
MOSTLY-CLEAR SKIES ALL DAY, WITH SOME CIRRUS AND PERHAPS A SHALLOW
AFTERNOON CU FIELD. NOT MUCH SUPPORT FOR AFTERNOON GUSTS , EVEN
IN SOME OF THE MORE AGGRESSIVE ENSEMBLE RUNS.
BY MONDAY NIGHT, A MATURE SURFACE LOW WILL BE LOCATED OVER
WISCONSIN, WITH ATTENDANT COLD FRONT EXTENDING ACROSS ILLINOIS AND
INTO THE OZARKS. MOST OF THE HI-RES MODELS - BOTH THE NEW HREF
MEMBERS AS WELL AS THE RECENT REFS ENSEMBLE GUIDANCE - DEPICT AN
MCS EJECTING OFF THIS BOUNDARY ON MONDAY EVENING AND TEARING ACROSS
THE TENNESSEE VALLEY THROUGH MONDAY NIGHT, AND MAKING A RUN AT OUR
NC MOUNTAIN ZONES THROUGH EARLY TUESDAY MORNING. BY DAWN TUESDAY,
DECAYING CONVECTION SHOULD BE ON OUR WESTERN DOORSTEP. GIVEN ITS
TIMING...ARRIVING NEAR THE DIURNAL MIN AND CROSSING THE CWA DURING
THE MORNING AND EARLY AFTERNOON HOURS ON TUESDAY...THE CONVECTIVE
ENVIRONMENT WON'T EXACTLY BE CONDUCIVE TO SEVERE WEATHER, AND THE
MOUNTAINS SHOULD BE ENOUGH TO DISRUPT ITS BALANCE AND KILL IT.
THIS IS WHAT MOST OF THE CAMS DEPICT. STILL, CAN'T ENTIRELY RULE
OUT A ROGUE DAMAGING WIND GUST SOMEWHERE AS THE REMNANTS CROSS
THE CWA EARLY TUESDAY.
KEY MESSAGE 2: TWO FRONTAL SYSTEMS BRING RAIN CHANCES WEDNESDAY AND
AGAIN EARLY IN THE WEEKEND.
MODEL GUIDANCE NO COALESCING AROUND A SOLUTION SHOWING TWO FRONTAL
SYSTEMS BRINGING RAIN CHANCES TO THE AREA WEDNESDAY AND AGAIN LATE
FRIDAY INTO SATURDAY. A COLD FRONT MOVES INTO THE AREA WEDNESDAY. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT AS IT MOVES THROUGH. THIS
ALONG WITH AN ASSOCIATED SHORTWAVE WILL PROVIDE PLENTY OF FORCING
FOR PRECIPITATION. WEAK INSTABILITY ALSO DEVELOPS WITH SCATTERED
THUNDERSTORMS EXPECTED ALONG WITH THE WIDESPREAD SHOWERS. A MODERATE
AMOUNT OF BULK SHEAR ALSO DEVELOPS. SCATTERED THUNDERSTORMS ARE
EXPECTED ALONG WITH THE WIDESPREAD SHOWERS. IT IS STILL UNCERTAIN
WHETHER THE COMBINATION OF THESE FEATURES WILL BE ENOUGH FOR ANY
SEVERE STORMS TO FORM, BUT THE POTENTIAL IS THERE. DEEP MOISTURE
ALSO MOVES IN AHEAD OF THIS SYSTEM WITH PW VALUES APPROACHING 200
PERCENT OF NORMAL. THIS COMBINED WITH PLENTY OF FORCING COULD LEAD
TO SOME HEAVY RAINFALL, MAINLY ACROSS THE MOUNTAINS. THE OVERALL
FLOOD THREAT IS LOW GIVEN THE RECENT DROUGHT CONDITIONS AND QUICK
MOVEMENT OF THIS SYSTEM, BUT IT BEARS WATCHING.
DRY CONDITIONS EXPECTED THURSDAY AS THE FRONT MOVES SOUTH OF THE
AREA, BUT THE NEXT WEATHER MAKER DEVELOPS IN THE FORM OF A GULF
COAST LOW PRESSURE SYSTEM WHICH MOVES BY TO OUR SOUTH ON SATURDAY.
MOISTURE AND PRECIP CHANCES BEGIN RAMPING UP LATE ON FRIDAY AND
SPREADING ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY. THE GUIDANCE
DOES DIFFER ON THE EXACT TRACK OF THE LOW PRESSURE, SO POP IS
CURRENTLY IN THE CHANCE RANGE AND QPF IS MODERATE AT BEST. THIS
COULD CHANGE IN EITHER DIRECTION DEPENDING ON THE ACTUAL TRACK OF
THE LOW. DRY HIGH PRESSURE RETURNS FOR SUNDAY. THE AIRMASS
ASSOCIATED WITH THE HIGH WILL BE ON THE COOL SIDE AND FROST/FREEZE
CONDITIONS COULD BECOME A CONCERN ACROSS THE MOUNTAINS SATURDAY
NIGHT.
AVIATION /12Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: AN EXTENSIVE STRATOCU DECK REMAINS IN PLACE
ACROSS MOST OF THE TERMINAL FORECAST AREA, HAVING MADE DEEPER
INROADS INTO THE UPSTATE THAN ANTICIPATED. NOW CARRYING TEMPOS
FOR MVFR AT ALL SITES THROUGH 13Z; THEREAFTER, STILL THINK LOW
CLOUDS SHOULD SCATTER OUT FAIRLY QUICKLY. EXPECT MOSTLY JUST
CIRRUS AND CONTINUED S/SSE WINDS FOR MOST OF THE DAY TODAY.
A DECAYING CONVECTIVE SYSTEM WILL APPROACH THE WESTERN FRINGE
OF THE TERMINAL FORECAST AREA TONIGHT, AND SHOULD PUSH INTO THE
NC MOUNTAINS BY 12Z TUESDAY. HI-RES GUIDANCE IS IN PRETTY GOOD
AGREEMENT THAT THE SYSTEM WILL BEGIN TO BREAK DOWN EAST OF THE
MOUNTAINS...AND CONFIDENCE IS LIMITED ON HOW FAR EAST ITS REMNANTS
WILL MAKE IT. THINK AT LEAST SCATTERED SHRA SHOULD MAKE IT INTO
THE I-77 CORRIDOR THROUGH LATE MORNING TUESDAY...SO NOW CARRYING
PROB30S AT MOST SITES NEAR THE END OF THE PERIOD.
OUTLOOK: ACTIVE WEATHER WILL CONTINUE INTO MID-WEEK, WITH ANOTHER
DISTURBANCE EXPECTED ON WEDNESDAY/WEDNESDAY NIGHT. FURTHER RAINFALL
IS POSSIBLE BY THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
MPR/RWH
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