529
FXUS62 KGSP 272353
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
753 PM EDT TUE MAY 27 2025
SYNOPSIS
COOL HIGH PRESSURE WILL MOVE OFF THE EAST COAST TONIGHT AND
WEDNESDAY RESULTING IN WARMER TEMPERATURES WEDNESDAY. LOW
PRESSURE MOVES ALONG A FRONT TOWARD OUR REGION CROSSING
OUR AREA THURSDAY NIGHT AND FRIDAY WITH MORE RAIN. A SLOW
MOVING WEAK COLD FRONT WILL DRIFT TOWARD THE CAROLINA COAST BY
FRIDAY NIGHT. DRIER WEATHER MOVES OVER OUR AREA FOR THE
WEEKEND AND INTO NEXT WEEK.
NEAR TERM /THROUGH WEDNESDAY/
AS OF 545 PM EDT TUESDAY: FORECAST LARGELY ON TRACK AT THIS
HOUR. POP MAXIMIZES THIS EVENING, AS BAND OF ELEVATED CONVECTION
CROSSES THE AREA. WEAKENED MCS ENTERING OUR FAR SW NC AND NE GA
ZONES ATTM; ELEVATED INSTABILITY IS WEAK AND EXPECT IT WILL FURTHER
DISORGANIZE, ALTHOUGH ISENTROPIC LIFT ISN'T GOING ANYWHERE SOON,
SO RETAINED A WAVE OF HIGH LIKELY TO CATEGORICAL POP ACROSS THE
MTNS/FOOTHILLS, WITH LIKELY VALUES FOR AREAS GENERALLY ALONG/SOUTH
OF I-85 (THESE VALUES UPDATED WITH CONSENSUS OF RECENT HRRR
RUNS, WHICH INITIALIZED THE MCS REASONABLY WELL). HIGHLY ISOLATED
LIGHTNING REMAINS POSSIBLE, SO KEPT A 15% PROB OF THUNDER WITH THE
PEAK POPS. THE POPS MOSTLY FALL BACK TO CHANCE BY THE WEE HOURS
OF THE MORNING; 850MB FLOW WILL HAVE VEERED BY THAT TIME WITH
ONLY SHALLOW UPGLIDE REMAINING THEN. NOT ENOUGH TO SCOUR OUT THE
WEDGE UNTIL AFTER DAYBREAK. QPF DOESN'T LOOK VERY HEAVY TONIGHT,
AND THE BEST RATES WILL BE LOCALIZED AND TRANSIENT ASSOCIATED WITH
CONVECTIVE CELLS THIS EVENING. FWIW, WPC DOES HAVE OUR AREA UNDER A
MARGINAL RISK FOR EXCESSIVE RAINFALL FOR TODAY/TONIGHT, REFLECTING
THE POTENTIAL FOR SOME TRAINING OF CELLS IN MODEST, UNIDIRECTIONAL
FLOW. UPDATED TEMP TRENDS PER RAW GUIDANCE, RESULTING IN SLIGHTLY
WARMER LOWS OVERNIGHT. NOTE, GSP SHOULD BREAK THE DAILY LOW-MAX
RECORD FOR TODAY, AS ANTICIPATED (SEE CLIMATE SECTION BELOW).
WEDNESDAY, SFC HIGH PRESSURE WILL SLIDE OFF THE EAST COAST,
WHILE A WEAK LOW PRESSURE SYSTEM DEVELOPS NEAR THE TIDEWATER
AREA. MEANWHILE, 850 MB FLOW VEERS TO WESTERLY AND HELPS SCOUR OUT
THE CAD WEDGE. SO A PRONOUNCED REBOUND IN TEMPS WITH SCATTERING
OUT OF THE LOW CLOUDS IS EXPECTED ACROSS THE ENTIRE AREA. THERE
WILL BE SOME SBCAPE MATERIALIZE, BUT CONVECTION IS EXPECTED TO
LACK A GOOD TRIGGER. ISOLATED TO WIDELY SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS IS EXPECTED LATE AFTN INTO EARLY EVENING,
HIGHEST IN THE MOUNTAINS. HIGHS WILL BE BACK INTO THE UPPER 70S
TO LOWER 80S IN THE LOWER VALLEYS AND PIEDMONT.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/
KEY MESSAGES:
1) SHOWER CHANCES INCREASE THURSDAY
2) SHOWERS AND THUNDERSTORMS POSSIBLE FRIDAY WITH A COLD FRONT
3) TEMPERATURES REBOUND TO NORMAL
AS OF 140 PM TUESDAY: PICKING UP WEDNESDAY NIGHT, THE PATTERN
BECOMES MORE UNSETTLED THROUGH THE SHORT TERM. SYNOPTICALLY, BROAD
SW FLOW OVER THE SOUTHEAST TO START WITH EMBEDDED SHORTWAVES MOVING
THROUGH INTO THURSDAY NIGHT. THIS ADDITIONAL UPPER FORCING SUPPORT
INCREASES RAIN CHANCES ACROSS THE CWA. CAPPING POPS AT CHANCE (45-
60%). CURRENT GUIDANCE SHOWS MINIMAL INSTABILITY DURING THE
AFTERNOON HOURS, KEEPING THUNDERSTORM CHANCES LOW. CANNOT RULE OUT A
RUMBLE OF THUNDER. FOR FRIDAY, THE PATTERN REMAINS UNSETTLED AS
GUIDANCE SHOWS A TROUGH AND UPPER LOW SWINGING SOUTHWARD, BRINGING A
COLD FRONT ACROSS THE CWA. AT THIS TIME, THE FROPA LOOKS TO SWEEP
THROUGH FRIDAY, REACHING EAST OF THE MOUNTAINS AROUND PEAK HEATING.
CURRENT MODELS ARE NOT AS EXCITED WITH RELATIVELY MODERATE BULK
SHEAR OF 25-30KTS AND A FEW HUNDRED JOULES OF SBCAPE. MODELED
SOUNDINGS FROM THE GFS, FOR WHAT IT'S WORTH, SHOW A PROFILE THAT
COULD SUPPORT A FEW STRONG THUNDERSTORMS, BUT SEVERE IS LIMITED AT
THIS TIME. HOWEVER, DEPENDING ON WHERE THIS FRONT PASSES THROUGH AND
WHEN IT OCCURS WILL PLAY A ROLE IN HOW THESE STORMS EVOLVE.
CURRENTLY, SPC HAS HIGHLIGHTED AN AREA JUST ON THE EASTERN FRINGE OF
THE CWA, SO WILL CONTINUE TO MONITOR AS THINGS WILL CHANGE. POPS
REMAIN HIGH (70-80%) RANGE AS THERE IS DECENT WIDESPREAD QPF
RESPONSE WITH THIS SYSTEM. TEMPERATURES SHOULD REBOUND CLOSER TO
NORMAL.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
KEY MESSAGES
1) RAIN CHANCES INCREASE SUNDAY ACROSS THE NC MOUNTAINS
2) HIGH PRESSURE BUILDS IN TO START THE WEEK AND MOSTLY DRY
CONDITIONS RETURN
3) TEMPERATURES GRADUALLY WARM THROUGH THE PERIOD
AS OF 200 PM TUESDAY: BY FRIDAY NIGHT, THE UPPER LOW BEGINS TO LIFT
NE, DRAGGING THE REMNANT COLD FRONT OUT OF THE AREA. BEHIND THE
FRONT, MUCH DRIER AIR FILTERS IN AS NW FLOW BRINGS IN THE LESS MUGGY
AIR INTO THE REGION. THROUGH THE WEEKEND, THE TROUGH REMAINS
STEADILY OVERHEAD AS A RIDGE BUILDS IN OUT WEST. THIS SHOULD HELP TO
KEEP RAIN CHANCES DOWN ON SATURDAY FOR A PORTION OF THE CWA.
GUIDANCE AT THIS TIME SETS UP A PERSISTENT NW FLOW OVER THE NC
MOUNTAINS, WITH LINGERING SURFACE MOISTURE. CANNOT RULE OUT A FEW
LIGHT SHOWERS BUT POPS REMAIN AT SLIGHT CHANCE (15-30%) AT BEST.
LOOKING AHEAD INTO SUNDAY, LONG RANGE GUIDANCE FROM THE GFS/EURO
WANT TO SEND A VORTICITY LOBE SCREAMING DOWN THE WESTERN SIDE OF THE
TROUGH. THIS MEANS BRINGING A HICCUP IN THE UPPER FLOW AND
ADDITIONAL FORCING, THAT COULD CONTRIBUTE TO INCREASING PRECIP
CHANCES. THIS IS STILL 5-6 DAYS OUT, SO WON'T LOCK ANYTHING IN AT
THIS TIME. HOWEVER, SHOWER CHANCES INCREASE SLIGHTLY, MOSTLY OVER
THE MOUNTAINS (30-40%). LOOKING EVEN FURTHER INTO THE FORECAST, THE
SYNOPTIC PATTERN STARTS TO TURN DRIER AS A QUASI-OMEGA BLOCKING
PATTERN ATTEMPTS TO EMERGE AT THE BEGINNING OF NEXT WEEK. THIS TIME,
THE RIDGE AXIS LOOKS TO PUSH FURTHER EASTWARD AND BRING MUCH DRIER
WEATHER FOR THE AREA AS WHOLE, BUT TYPICAL DIURNALLY DRIVEN POP UP
SHOWERS EMERGE. ALL IN ALL, THE EXTENDED LOOKS TO HAVE A MIX OF
MOSTLY DRY WEATHER AND A FEW SHOWERS. TEMPERATURES LOOK TO GRADUALLY
INCREASE THROUGHOUT THE PERIOD AND REMAIN AT OR JUST ABOVE NORMAL BY
THE END OF THE PERIOD.
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: COLD-AIR DAMMING WEDGE STILL IN PLACE ACROSS
THE REGION. CIGS HELD ON AT 010-015 IN MANY AREAS LATE AFTERNOON
BUT APPEAR TO HAVE FALLEN SLOWLY TO IFR IN THE 30 MIN OR SO PRIOR TO
ISSUANCE TIME; THIS TREND IS EXPECTED TO CONTINUE. BAND OF SHRA ON
TRACK TO PASS KAVL/KGSP/KGMU AT THE VERY BEGINNING OF THE PERIOD,
AND PASSING THRU KHKY/KCLT AROUND 02Z. TS CHANCE TOO SMALL TO
MENTION BUT CAN'T BE RULED COMPLETELY OUT. BRIEF IFR VSBY LIKELY
ALTHOUGH CIGS MAY IMPROVE FOR A SHORT TIME; IN THE SUBSIDENCE
BEHIND THE LINE, CIGS LOOK TO LOWER AND MAY NOT RECOVER THE REST
OF THE NIGHT. -DZ AND SCATTERED SHRA WILL PERSIST FOR SEVERAL
MORE HOURS. VSBY WILL PROBABLY FALL TO IFR AROUND DAYBREAK IF
NOT SOONER. CAD EROSION PROCESS WILL BEGIN BY MID MORNING WED AS
WINDS VEER AND LOW-LEVEL UPGLIDE DIMINISHES, ALTHOUGH HAVE LEANED
PESSIMISTIC AND HELD ONTO IFR THRU ABOUT MIDDAY. SCT CLOUDS BELOW
045 IN THE AFTERNOON WITH PARTIAL CLEARING BY EVENING. WINDS WILL
REMAIN LIGHT NE TONIGHT ALTHOUGH COULD BRIEFLY TURN SW'LY BEHIND
THE LINE OF SHRA; WITH SCATTERING CLOUDS THEY SHOULD COME UP FROM
THE SW.
OUTLOOK: SHOWER AND THUNDERSTORM CHANCES AND ASSOCIATED RESTRICTIONS
CONTINUE THRU THE REMAINDER OF THE WORK WEEK WITH DRIER CONDITIONS
EXPECTED BY THE START OF THE WEEKEND.
CLIMATE
RECORDS FOR 05-27
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 93 1890 55 1961 68 1991 36 1961
KCLT 96 1916 60 1901 77 1916 41 1961
KGSP 98 1916 65 1963 72 1991 43 1961
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...ARK/WIMBERLEY
SHORT TERM...CP
LONG TERM...CP
AVIATION...WIMBERLEY
CLIMATE...ARK
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