Area Forecast Discussion
Issued by NWS Greer, SC

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852 FXUS62 KGSP 111055 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 655 AM EDT Fri Jul 11 2025 .SYNOPSIS... Active summertime weather will continue thru the weekend with numerous showers and thunderstorms each day. High temperatures will increase each day through Monday, trending back to around normal for the middle of next week behind a weak cold front. && .NEAR TERM /THROUGH TONIGHT/...
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As of 650 AM EDT Friday: Stout low stratus deck has overlaid the southern half of the CFWA. There are some areas of patchy dense fog, mainly near bodies of water and is too isolated for any dense fog product at this time. Any low stratus deck and lingering fog should scatter out quickly after daybreak as low-level mixing gets underway followed by summertime destabilization. Otherwise, the forecast remains on track with only minor tweaks made based on current observations and latest trends. Subtle mid-level trough will be in midst of slipping east of the region, while weak height rises push in from the south as a weak anticyclone slowly deepens over Florida and the Gulf. PWAT values between 1.50"-2.00", 2000-3000 J/kg of SBCAPE, and <20 kts of deep layer shear will set the stage for typical peak diurnal pulse convection. Slow moving storms may result in localized flooding as well with high rainfall rates. Convective initiation will start over the ridgetops across the southern Appalachians and the Blue Ridge Escarpment during the early afternoon hours, followed by downstream initiation with the presence of an inverted ridge on the lee of the Appalachians. Weak westerly flow aloft will help to induce drier mid-levels to go along with decent inverted-v low- levels, suggesting the threat for wet microbursts will be evident, with a few potentially producing strong to severe damaging wind gusts as DCAPE values range between 800-1200 J/kg. Associated outflow boundaries will help to carry convective initiation further east across the Piedmont zones later in the afternoon into the evenings hours, leading to a similar severe threat and weather pattern compared to the past few days. Most of the activity should gradually dissipate after sunset with the loss of peak diurnal heating. Lingering convective debris and tight dewpoint depressions will likely bring another round of low stratus and fog overnight Friday, especially if the convective debris clears out early on during the overnight period. Overnight lows will be similar to tonight with low 70s across the Piedmont and mid to upper 60s across the mountains and foothills.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of midnight Friday morning: Upper anticyclone to remain centered over the eastern Gulf Saturday. Meanwhile a broad shortwave will drift over the Mississippi Valley. As ridge builds, and with the approaching trough, a weak warm front appears to ride over the CWA from the SW. While PoPs mainly will be driven by diurnal instability, model QPF response suggests the front may lead to earlier than usual initiation over the mountains and GA/SC foothills. The warm front brings PWATs back a little above normal, with similar numbers persisting into Sunday. 0-6km shear remains weak, on the order of 10 kt. Despite the PWATs, sfc-midlevel delta-theta-e values are marginally favorable for severe downbursts. Pulse storms should be the preferred mode with seasonable threats of torrential rainfall and isolated instances of damaging wind. PoPs overall are a little above climo, mostly high chance for the Piedmont and likely over the mountains. The ridge effectively retrogrades slightly as the trough moves across the Great Lakes and lower OH Valley; low-level flow turns more northwesterly for Sunday and a more pronounced lee-trough QPF response is seen that afternoon compared to Sunday. Mountain PoPs trend a bit lower that day but remain similar in the lower Piedmont. Deep layer shear improves upstream near the base of the trough Sunday afternoon in KY and/or TN, although not especially strong at 25-30 kt in those areas. Not confident at this point there is sufficient flow and overnight instability to expect organized convection to reach the CWA Sunday night or early Monday. Temperatures will trend warmer with the building ridge, in the lower to mid 90s in the Piedmont and upper 80s in mountain valleys. Although some diurnal mixing will limit afternoon dewpoints, low-level moisture return will result in heat indices in the 100-105 range in warmer areas of the Piedmont each afternoon. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 130 AM Fri: There remains spread in timing among models as to the front. It looks questionable that the front will have induced meaningful airmass change Monday, with Monday night more likely. A signal for moisture pooling is seen on the GFS and EC Monday east of the Appalachians, so PoPs remain elevated and generally similar to Sunday. Shear and PWAT will be marginally better but the main difference compared to previous days is that PoPs have a better shot at continuing nocturnally given the frontal forcing tapering from west to east behind the front. Temps "cool" back to around climo Tue in the front`s wake. The trough and frontal boundary, or their remnants, meet the Bermuda High near the East Coast on Tuesday. The resulting convergence zone appears to be a focus for convective development then through Thursday. PoPs dip slightly Tuesday to about climo, then increase again diurnally Wed and Thu with easterly to southeasterly flow as the Bermuda High dominates, possibly bringing the convergence zone inland and nearer our CWA, or simply supporting more daily shower/storm development with the resultant moisture flux. Temps however remain near or even slightly below climo owing to increased cloud cover--but with muggy subtropical dewpoints. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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At KCLT and elsewhere: Widespread IFR/LIFR low stratus and vsbys have already overspread the terminals and will remain in place at least through daybreak. Went with prevailing IFR/LIFR with TEMPOs for the worst case scenario as much of the area remains locked in with a stout low stratus deck and ground fog. Any low stratus and/or fog will dissipate by mid-morning (14z or so) as daytime heating helps to scatter out and lift restrictions. Light southwesterly to variable winds will be in store through the morning hours and pick up in speed (4-8 kts) out of the southwest by peak heating. KAVL will maintain a north-northwesterly component through much of the period. SCT cu is likely to roam the skies through much of the afternoon and evening with another round of scattered to numerous showers and thunderstorms. Placed a PROB30 for TSRA and associated restrictions at all terminals as a result. Lingering convective debris after sunset will leave mid-to upper-level clouds across the area during the evening and early overnight hours. Another round of low stratus and fog restrictions will be possible overnight tonight through daybreak Saturday. Outlook: Typical summertime weather is expected into early next week, with scattered to numerous thunderstorms mainly in the afternoon/evening and fog and/or low stratus possible each morning.
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&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...Wimberley NEAR TERM...CAC SHORT TERM...Wimberley LONG TERM...Wimberley AVIATION...CAC