016
FXUS62 KGSP 080617
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
217 AM EDT THU MAY 8 2025
SYNOPSIS
STRONG TO SEVERE STORMS MAY BE CAPABLE OF PRODUCING DAMAGING
WIND GUSTS AND LARGE HAIL THIS AFTERNOON AND EVENING. A COLD
FRONT ARRIVES FRIDAY AND STALLS OVER THE SOUTHEAST THIS WEEKEND
INTO EARLY NEXT WEEK, KEEPING UNSETTLED WEATHER AROUND. HIGHS WILL
REMAIN ABOVE NORMAL TROUGH FRIDAY BEFORE DROPPING WELL BELOW NORMAL
THIS WEEKEND INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH TODAY/
AS OF 200 AM: AXIS OF WEAK SHORTWAVE NOW ALIGNED JUST EAST OF
THE APPALACHIANS, AND WILL PASS QUICKLY ACROSS MOST IF NOT ALL
OF THE CWA BEFORE DAWN. WARM FRONT REMAINS IN SIMILAR POSITION TO
WHERE IT WAS WEDNESDAY, ALTHOUGH FLOW OVER IT HAS TURNED SOMEWHAT
WESTERLY AND SO ISENTROPIC LIFT SEEMS JUST BARELY ENOUGH TO KEEP
LOW LEVEL CLOUD OVER IN PLACE IN THE WESTERN ZONES. A FEW SHOWERS
HAVE HOWEVER DEVELOPED ALONG THE SHORTWAVE AXIS AND MOST CAMS SHOW
THIS ACTIVITY TRACKING ACROSS THE UPSTATE AND NC BORDER AREA EARLY
THIS MORNING. SOME SHOWERS ARE ALSO POSSIBLE ALONG THE TN BORDER
SIMPLY AS A RESULT OF THE WARM FRONT. A LULL IN PRECIP CHANCES
IS EXPECTED BETWEEN SAY 12-16Z TODAY IN THE WAKE OF THE SHORTWAVE
AND WITH SUCH WEAK FORCING OTHERWISE.
HEIGHTS WILL BEGIN TO FALL OVER THE CWA BY LATE MORNING AS THE UPPER
LOW NOW OVER THE OZARKS GETS PICKED UP BY THE DIGGING LOW NEAR THE
EASTERN GREAT LAKES. LOW LEVEL WINDS REMAIN WEAK BUT THE APPROACH OF
THE COMBINED TROUGH APPEARS TO REACTIVATE THE WARM FRONT DURING THE
AFTERNOON. BY THAT TIME HOWEVER FAIRLY ROBUST DIURNAL INSTABILITY
LOOKS TO DEVELOP, WITH 1000-2000 J/KG OF SBCAPE; WE ARE FOR WANT
OF A SURFACE TRIGGER OTHER THAN RIDGETOP CONVERGENCE. IT IS NOT
TOO SURPRISING THAT CAMS PLUS THE NAM/GFS FIRE UP ACTIVITY ON THE
EAST-FACING BLUE RIDGE ESCARPMENT IN THE MID TO LATE AFTERNOON,
A LITTLE LATER THAN PEAK HEATING. THIS ACTIVITY WILL BE EXPOSED TO
30-40 KT OF WESTERLY DEEP LAYER SHEAR AND CAMS CONTINUE TO DEPICT
UPSCALE GROWTH ALONG COLD POOLS. THE SHEAR AND MEAN WIND SHOULD
CARRY CELLS MAINLY EAST INTO THE NC PIEDMONT, ALTHOUGH WITH SW'LY
NEAR-SFC FLOW, SOME INITIATION IS EXPECTED ALONG THE EDGE OF THE
COLD POOL THROUGH EVENING, WITH CONSENSUS SUGGESTING PROPAGATION
INTO THE SC/GA ZONES WILL OCCUR AT THAT TIME, SO PEAK POPS FOR THOSE
LOCATIONS IS WELL AFTER 00Z. SPC SLIGHT RISK PRIMARILY FOR WIND/HAIL
THREATS BUT ALSO WITH A 2% TORNADO CONTOUR SEEMS WELL PLACED.
SHORT TERM /TONIGHT THROUGH SATURDAY/
AS OF 200 PM EDT WEDNESDAY: CONVECTION, SOME POSSIBLY SEVERE, WILL
BE ONGOING AT THE START OF THE PERIOD. THE SEVERITY WILL DIMINISH BY
LATE EVENING WITH COVERAGE DIMINISHING OVERNIGHT. ANOTHER ROUND OF
SHOWERS AND SCATTERED STORMS DEVELOPS DURING THE DAY FRIDAY AS A
SHORT WAVE ROTATING AROUND AN UPPER LOW OVER THE MID ATLANTIC
CROSSES THE AREA AND A WAVE MOVES EAST ALONG THE FRONTAL BOUNDARY
STALLED TO OUR SOUTH. INSTABILITY AND SHEAR LOOK TO BE WEAKER THAN
THURSDAY, SO THE SEVERE CHANCE WILL BE MUCH LOWER, BUT NOT NON-
EXISTENT. CONVECTION DIMINISHES MUCH MORE QUICKLY FRIDAY EVENING.
GUIDANCE AGREES ON THE MID ATLANTIC UPPER LOW MOVING EAST ON
SATURDAY AS ANOTHER UPPER LOW DEVELOPS OVER THE LOWER MS RIVER
VALLEY. THEY ALSO AGREE ON HIGH PRESSURE BUILDING INTO THE AREA FROM
THE NORTH WITH SOME AMOUNT OF LOW LEVEL DRY AIR FILTERING IN. THEY
ALSO AGREE ON A WEAK, MOIST SOUTHERLY FLOW DEVELOPING OVER PART OF
THE AREA. THEY DISAGREE ON WHERE THE BOUNDARY BETWEEN THE DRIER AND
MOISTER AIR SETS UP. THEREFORE, HAVE GONE WITH THE MODEL BLEND FOR
POP, WITH HIGHER VALUES OVER THE UPSTATE, NE GA, AND THE MOUNTAINS
WEST OF ASHEVILLE. LITTLE TO NO INSTABILITY IS EXPECTED MINIMIZING
THUNDER CHANCES. THERE WILL BE SOME BRIEF, HEAVY RAINFALL IN THE
STORMS THURSDAY EVENING, BUT LIGHT TO MAYBE MODERATE QPF EXPECTED
THROUGH THE REST OF THE PERIOD. TEMPS NEAR TO A LITTLE ABOVE NORMAL
FRIDAY DROP TO AS MUCH AS 10 DEGREES BELOW NORMAL SATURDAY, WITH THE
COOLER READINGS WHERE PRECIP CHANCES ARE HIGHER.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
AS OF 230 PM EDT WEDNESDAY: GUIDANCE REMAINS IN AGREEMENT ON THE
OVERALL PATTERN WITH SOME DISAGREEMENT ON THE DETAILS. THE UPPER LOW
OVER THE LOWER MS RIVER VALLEY WILL DOMINATE OUR EXPECTED WEATHER AS
IT SPINS IN PLACE SUNDAY, THEN BEGINS A SLOW EASTWARD TREK THROUGH
WEDNESDAY. IF SATURDAY ENDS UP DRIER, THEN THE HYBRID CAD WAITS
UNTIL SUNDAY TO DEVELOP WHEN A BETTER LOW LEVEL MOIST SOUTHERLY FLOW
DEVELOPS BRINGING SHOWERS BACK INTO THE AREA. THE CAD HOLDS ON
MONDAY WITH A CONTINUED MOIST SOUTHERLY LOW LEVEL FLOW AND
WIDESPREAD SHOWERS. THAT SAID, THERE MAY BE SOME EROSION OF THE CAD
SOUTH OF I-85 WHICH COULD SET UP A WARM FRONTAL BOUNDARY AND SOME
THUNDERSTORMS. THE UPPER AND SURFACE LOWS REALLY START MOVING
TUESDAY KEEPING THE MOIST SOUTHERLY LOW LEVEL FLOW OVER THE AREA BUT
HELPING ERODE THE CAD AS THEY MOVE IN. WIDESPREAD SHOWERS AND SOME
THUNDERSTORMS EXPECTED AGAIN. PRECIP FINALLY COMES TO AN END FROM
WEST TO EAST TUESDAY NIGHT AS THE LOWS MOVE EAST OF THE AREA.
HOWEVER, SCATTERED SHOWERS, ESPECIALLY OVER NC, WILL BE POSSIBLE
WEDNESDAY WITH LINGERING MOISTURE. TEMPS REMAIN BELOW NORMAL SUNDAY
AND MONDAY THEN RISE A LITTLE ABOVE NORMAL BY WEDNESDAY.
AVIATION /06Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: A WEAK AND SOMEWHAT ILL-DEFINED FRONTAL ZONE
REMAINS OVER THE TERMINAL AREA AND IS RESPONSIBLE FOR SPOTTY LOW
VFR TO MVFR CLOUDS NEAR THE SC SITES AND KAVL. A COUPLE OF SHRA
MAY PASS OVER KAND/KGMU/KGSP PRIOR TO 12Z THIS MORNING BRINGING
MVFR IMPACTS. KAND STILL LOOKS LIKELY TO GO TO IFR CIG NEAR/AFTER
DAYBREAK. OTHERWISE, MAINLY MIDLEVEL CLOUDS AND CIRRUS AROUND THE
AREA UNTIL DIURNAL CU DEVELOP LATE MORNING TO MIDDAY. UNSTABLE
PROFILES THIS AFTN WITH LITTLE TO NO TRIGGER DURING PEAK HEATING
ASIDE FROM RIDGETOP CONVERGENCE. SHRA/TSRA LOOK TO FIRE OVER THE
MOUNTAINS A BIT LATER THAN THE TYPICAL TIME NEAR AND NE OF KAVL,
THEN PROPAGATE EAST AND SOUTH THRU THE EVENING. HENCE PROB30
INCLUDED AT ALL SITES FOR TSRA, BEGINNING AT 20Z AT KAVL AND
PROGRESSIVELY LATER EAST AND SOUTH. STRONG WIND GUSTS WILL BE
POSSIBLE WITH ANY TSRA AND POSSIBLY HAIL BIG ENOUGH TO CAUSE MINOR
DAMAGE. RESTRICTIONS LIKELY ACROSS MUCH OF THE AREA AFTER 06Z FRI,
PARTICULARLY WHERE HEAVY RAIN FALLS TONIGHT.
OUTLOOK: AN UNSETTLED PATTERN WILL LINGER INTO EARLY NEXT WEEK
KEEPING CHANCES FOR SHOWERS AND THUNDERSTORMS AROUND AS WELL AS
ASSOCIATED RESTRICTIONS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
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