538
FXUS62 KGSP 021411
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1011 AM EDT WED APR 2 2025
SYNOPSIS
COOLER TEMPERATURES AND RAIN CHANCES ARE IN STORE FOR MUCH OF
THE AREA TODAY, WITH THE RAIN CHANCES TAPERING OFF LATE THURSDAY.
FAIR AFTERNOON SKIES AND EXCEPTIONALLY WARM WEATHER END THE WEEK. A
COLD FRONT BRINGS SHOWER AND THUNDERSTORM CHANCES ON SUNDAY,
WITH DRIER AND COOLER CONDITIONS EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 1006 AM EDT WEDNESDAY: MODEL ANALYSES SUGGEST THAT ALTHOUGH
ISENTROPIC ASCENT IS STILL STRENGTHENING, IT'S NOT YET MATCHED
BY ENOUGH OF AN INCREASE IN MOISTURE TO PRODUCE WIDESPREAD RAIN.
PATCHY DRIZZLE IS LIKELY ONGOING IN MAY SPOTS ACROSS THE BLUE RIDGE
ESCARPMENT...BUT ISN'T SHOWING UP WELL ON RADAR. DEFINITELY SOCKED
INTO COLD AIR DAMMING AT THIS POINT, WITH REAL-TIME SOUNDINGS
DEPICTING A SURFACE WEDGE AND WIDESPREAD LOW CEILINGS ACROSS
THE AREA.
OTHERWISE...GUIDANCE IS IN PRETTY GOOD AGREEMENT THAT A LULL IN
SHOWER ACTIVITY IS EXPECTED THIS AFTN, WHICH MAY ALLOW THE WEDGE
TO START TO ERODE. CLOUD COVER AND SPOTTY LIGHT RAIN OR DRIZZLE
MAY PERSIST NEAR THE ESCARPMENT THRU THE DAY, BUT THE REST OF THE
AREA MAY SEE SOME BREAKS IN THE CLOUDS AND TEMPS WARM TO NORMAL OR
ABOVE. THERE IS SOME BUST POTENTIAL ON TEMPS, BUT WILL CONTINUE TO
FORECAST COOLER TEMPS IN THE WEDGE (STAYING IN THE LOW-MID 60S). MID
TO UPPER 70S POSSIBLE ALONG THE SOUTHEAST EDGE OF THE FORECAST
AREA FURTHEST AWAY FROM THE CENTER OF THE WEDGE. A WEDGE FRONT
WILL LIKELY SHARPEN BY LATE AFTN OR EARLY EVENING ROUGHLY ALONG
THE I-85 CORRIDOR, WITH SBCAPE EXPECTED SOUTH OF THE BOUNDARY. THE
MODELS ALL HAVE SURPRISINGLY DECENT INSTABILITY WITH HIGH CHANCES
OF ABOVE 1000 J/KG, AND POSSIBLY 1500-2000 J/KG. ISENTROPIC LIFT
REMAINS PERSISTENT AND MAY FORCE CONVECTION ALONG THE WEDGE FRONT
AND INTO THE WEDGE THIS EVENING. THE 00Z CAMS ALL AGREE ON THIS
ROUND OF ACTIVITY WITH SOME POSSIBLY PRODUCING THUNDER. SEVERE
CHANCES SHOULD REMAIN LOW WITH WEAK UPPER SUPPORT AND ABOUT 30 KT
OF 0-6 KM BULK SHEAR. QPF WILL BE SOMEWHAT VARIABLE DUE TO THE
SCATTERED NATURE OF THE CONVECTION, BUT PERSISTENT UPSLOPE SELY
FLOW COULD PRODUCE LOCALLY AN INCH OR MORE THRU TONIGHT. THE
CONVECTION WILL DECREASE OVERNIGHT, WITH SOME LINGERING LIGHT
SHOWERS OR DRIZZLE POSSIBLE NEAR THE ESCARPMENT. LOW CLOUDS SHOULD
THICKEN AND LOWER WITH DENSE FOG POSSIBLE ALONG THE ESCARPMENT AND
ADJACENT FOOTHILLS AS THE WEDGE ERODES. OUTSIDE OF THAT, MIXING
SHOULD LIMIT FOG DEVELOPMENT. LOWS WILL BE WELL ABOVE NORMAL,
MAINLY IN THE UPPER 50S TO MID 60S.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
AS OF 200 AM WED: LITTLE CHANGE IN THE OVERALL PATTERN FOR THURSDAY,
EITHER FROM YESTERDAY MORNING'S FORECAST CYCLE OR COMPARED TO
WEDNESDAY. CONFIDENCE HOWEVER IS LOWER IN THE FORECAST FOR THURSDAY
COMPARED TO WEDNESDAY, AS IT WILL DEPEND ON THE STATUS OF CAD. IN THE
"AGAINST" COLUMN FOR CAD, THE PARENT HIGH WILL BE PRETTY MUCH
OFFSHORE BY THU MORNING. THE NECESSARY UPPER CONFLUENCE WILL BE AS
WELL, AS RIDGE AXIS WILL BE ALIGNED ALONG THE NORTHEAST COAST. IN
TURN, NEAR-SFC FLOW IS LIKELY TO HAVE VEERED TO SOUTH-SOUTHWESTERLY,
LESS FAVORABLE FOR KEEPING A WEDGE LOCKED IN. ON THE OTHER HAND, IN
THE "FOR" COLUMN, THAT FLOW SHOULD BE ENOUGH TO KEEP A SATURATED
SFC-BASED LAYER THROUGH MORNING, AND THERE WON'T BE MUCH TO ERODE IT
ASIDE FROM INSOLATION ATOP THE CLOUD DECK. DRYING/SUBSIDENCE DO
CONTINUE ALOFT AND THE SATURATED LAYER BECOMES INCREASINGLY SHALLOW
WITH TIME. BREAKS IN THE CLOUD COVER ARE LIKELY TO DEVELOP; WHERE THE
CLOUDS ERODE THE WEDGE PROBABLY WILL TOO. AN INVERSION DOES PERSIST
MOST IF NOT ALL OF THE AFTERNOON, AND DRY AIR ALOFT WOULD BE HARD FOR
RISING PARCELS TO OVERCOME. NEVERTHELESS THE GFS, GDPS AND ECMWF ALL
RESPOND WITH SOME QPF ALONG AN APPARENT DIFFERENTIAL HEATING BOUNDARY
THU AFTERNOON, AND GIVEN THE CONSENSUS, A SLIGHT-CHANCE PRECIP
MENTION IS MADE ACROSS PART OF THE I-85 CORRIDOR. MOST GUIDANCE HAS
TRENDED COOLER FOR THURSDAY REFLECTING THE LIKELIHOOD OF THE WEDGE
LINGERING AT LEAST PART OF THE DAY, BUT HIGHS IN THE LOWER 80S STILL
ARE EXPECTED SOUTHEAST OF I-85 AND ALONG/EAST OF I-77.
SFC/UPPER LOW WILL CONTINUE TO PASS THRU EASTERN CANADA THU NIGHT
WHILE ALMOST-CUTOFF UPPER LOW TOO WILL PROGRESS EAST ACROSS THE
DESERT SOUTHWEST. SE RIDGE/ANTICYCLONE WILL BEGIN TO RETROGRADE AND
THE OHIO VALLEY FRONT WILL BE PUSHED NORTHWARD A BIT. 925-850MB
MOISTURE IS PROGGED TO DIMINISH THU NIGHT AS WINDS VEER FURTHER SW IN
RESPONSE TO THE ABOVE. THE CLOUDS ASSOCIATED WITH THE WEDGE SHOULD
THIN/SCATTER ALTHOUGH STRATUS COULD DEVELOP AND ADVECT INTO THE
SOUTHERN ZONES, AT LEAST. THESE SHOULD BE ABLE TO SCATTER FRI
MORNING. CAPPING INVERSION AND STILL VERY DRY AIR ALOFT SHOULD
PRECLUDE ANY SHOWER ACTIVITY, POSSIBLY EXCEPTING MOUNTAIN RIDGETOPS;
SMALL DIURNAL PRECIP CHANCES RETURN THERE. THICKNESSES TREND UPWARD
AND WITH HEIGHTS UNDER THE ANTICYCLONE STILL SHOWN AT NEARLY +3 SD
EAST OF FLORIDA, MAX TEMPS FLIRT WITH THE DAILY RECORDS AT
CLT/GSP/AVL.
LONG TERM /SATURDAY THROUGH TUESDAY/
AS OF 300 AM WED: THE UPPER RIDGE OFF THE SE COAST WILL BEGIN TO
DRIFT EAST SATURDAY AND BE SLIGHTLY SUPPRESSED AS DEEP NORTHERN AND
SOUTHERN STREAM TROUGHS PHASE OVER THE PLAINS, FINALLY BUDGING THE
STALLED FRONTAL BOUNDARY IN THE OHIO VALLEY. WEAK CYCLOGENESIS WILL
OCCUR AHEAD OF THE SOUTHERN SHORTWAVE INVOF ARKANSAS LATE SATURDAY;
THAT LOW LOOKS TO TRACK TOWARD THE CHESAPEAKE BAY REGION FROM THEN
THRU SUN NIGHT, EVENTUALLY PULLING THE COLD FRONT ACROSS OUR AREA.
UNDER THE RIDGE SATURDAY, EXPECT ANOTHER HOT DAY WITH TEMPS NEAR OR
SLIGHTLY ABOVE DAILY RECORDS. SOME CUMULUS CLOUD COVER MAY BE SEEN
WITH A SHALLOW MOIST LAYER TRAPPED UNDER SUBSIDENCE INVERSION. NBM
HAS TRENDED SLIGHTLY COOLER AND WITH THE POTENTIAL FOR A LITTLE CLOUD
COVER, NOT SEEING REASON TO GO ABOVE NBM AT THIS TIME.
MOISTENING ALOFT IS SHOWN TO OCCUR RAPIDLY OVERNIGHT INTO SUNDAY
MORNING AS THE TROUGH APPROACHES, AND LIKELY TO CATEGORICAL POPS ARE
FORECAST SUNDAY, PEAKING DURING THE DAY OVER THE WESTERN HALF OF THE
CWA AND SUNDAY EVENING IN THE EASTERN HALF. WITH THE BASE OF THE
500MB TROUGH STILL OVER THE ARKLATEX AT THAT TIME, DYNAMIC FORCING
ACROSS OUR AREA IS PRIMARILY FROM RR QUAD OF UPPER JET. PROGGED PWATS
RISE TO NEAR 1.5-1.75 INCHES, UNUSUALLY HIGH FOR THIS TIME OF YEAR.
FLOW WILL BE MOSTLY UNIDIRECTIONAL AND SOUTHWESTERLY AHEAD OF THE
FRONT, SO MOISTURE RETURN IS NOT QUITE IDEAL FOR A WIDESPREAD HEAVY
RAIN EVENT. COUPLED WITH THE LACK OF LOWER LEVEL FORCING AND SMALL
CAPE OWING TO THE WARM (AND DRY) AIRMASS, THESE SEEM TO BE LIMITING
FACTORS: ENSEMBLE PROBABILITIES OF EVEN 1" IN 24 HOURS ARE
SURPRISINGLY LOW EAST OF THE MOUNTAINS. THE UNIDIRECTIONAL FLOW DOES
APPEAR FAIRLY WELL ALIGNED WITH THE DEPICTED FRONT, SO SOME TRAINING
COULD LOCALLY ENHANCE AMOUNTS. PEEKING AT INDIVIDUAL ENSEMBLE MEMBERS
A NARROW FRONTOGENETIC BAND MAY ALSO DEVELOP, THE EXACT LOCATION
LOOKING MORE LIKELY TO BE OVER TN/AL/GA BUT WITHIN OUR CWA IN SOME.
FOR NOW WPC IS EXPECTED TO MAINTAIN A MARGINAL RISK ERO. INSTABILITY
ALSO WILL BE A LIMITING FACTOR FOR SEVERE THREAT, WHICH OTHERWISE
MIGHT BE APPRECIABLE GIVEN THE STRONG 0-3 AND 0-6 KM SHEAR.
ANY FLOOD/SEVERE THREAT SHOULD TAPER OFF BY EARLY MONDAY MORNING.
SMALL POPS PERSIST OVER MUCH OF THE AREA MONDAY AS UPPER TROUGH AXIS
PASSES. TEMPS FALL BACK TO ABOUT CLIMO THAT DAY. POPS END BEFORE
TEMPERATURES TURN COLDER MON NIGHT SO ALL PRECIP ENDS AS LIQUID; A
HIGH ELEVATION FREEZE IS POSSIBLE THEN. BELOW CLIMO TEMPS UNDER
MOSTLY CLEAR SKIES TUE AND TUE NIGHT. THE SPRING FROST-FREEZE PROGRAM
WILL NOT YET HAVE BEGUN IN AREAS WHERE TEMPS WOULD SUPPORT FROST, BUT
DRY DEWPOINTS MAY PRECLUDE FROST ANYWAY.
AVIATION /14Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: MVFR TO IFR CIGS HAVE FORMED, AS EXPECTED,
AS MOIST SELY FLOW INCREASES ATOP THE AREA. SCATTERED LIGHT
SHOWERS ARE BEGINNING TO DEVELOP AND WILL CONTINUE TO EXPAND IN
COVERAGE THRU MID-MORNING, AND CONTINUE TO AFFECT THE AREA INTO THE
AFTN. THE CLOUDS AND SHOWERS WILL HELP LOCK IN A WEAK WEDGE. FROM
THERE, CONFIDENCE IS MODERATE AT BEST, ON HOW THE CIGS WILL
BEHAVE. OVERALL, GUIDANCE HAS TRENDED MORE OPTIMISTIC ON THE EDGES
OF THE CLOUD DECK SCATTERING OUT TO VFR BY MID-AFTN, WITH IFR CIGS
IMPROVING TO MVFR WITHIN THE WEDGE. WINDS WILL BE GENERALLY FAVOR
AN ESE TO SE DIRECTION AT KCLT. GUIDANCE HAS TRENDED LESS BULLISH
ON ANOTHER ROUND OF SHOWERS THIS EVENING, BUT STILL SHOULD SEE SOME
SHOWERS AND POSSIBLY TS DEVELOP ACROSS THE UPSTATE. WILL MENTION
PROB30 FOR TSRA AT THE UPSTATE SITES, BUT KEEP SHRA ELSEWHERE,
DUE TO LESS INSTABILITY. THE WEDGE IS EXPECTED TO START TO ERODE
AND BRING WINDS OUT OF THE S/SE AT ALL SITES OVERNIGHT. THE WEDGE
EROSION WILL LIKELY RESULT IN CIGS LOWERING TO LIFR.
OUTLOOK: SCATTERED SHOWERS AS WELL AS CIG RESTRICTIONS MAY LINGER
INTO THURSDAY. VSBY RESTRICTIONS WILL LINGER THROUGH DAYBREAK
THURSDAY. IFR TO MVFR CIGS MAY RETURN AGAIN LATE THURSDAY NIGHT
INTO FRIDAY MORNING. DRIER CONDITIONS RETURN THURSDAY NIGHT
INTO SATURDAY NIGHT BEFORE ANOTHER COLD FRONT BRINGS SHOWER AND
THUNDERSTORM CHANCES, AND ASSOCIATED RESTRICTIONS, BACK ON SUNDAY.
CLIMATE
RECORDS FOR 04-03
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 88 1963 31 1936 64 1946 23 1936
KCLT 90 1946 42 1915 62 1986 26 2021
1946
KGSP 87 1967 44 1901 62 2014 27 2021
1963 1993
1946 1902
RECORDS FOR 04-04
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 83 1999 33 1891 61 1893 22 1936
1978
KCLT 87 1999 43 1911 63 1986 29 1936
1899 1945
1934
KGSP 88 1963 44 1936 62 1999 25 1975
1934
RECORDS FOR 04-05
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 86 1909 30 1891 60 2023 20 1944
1910
KCLT 88 1942 38 1891 62 1910 26 1891
KGSP 90 1934 43 1899 60 2023 25 1904
1888
RECORDS FOR 04-06
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 88 1967 36 1950 64 2023 22 1898
KCLT 90 2010 43 1931 67 2023 28 1891
1929
KGSP 88 2010 47 1950 65 2023 26 1904
1945
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...ARK/MPR
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...ARK
CLIMATE...GSP
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