159 FXUS62 KGSP 130554 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 154 AM EDT Sun Jul 13 2025 .SYNOPSIS... Expect scattered thunderstorms and heavy downpours around the region each day of the coming week. A few storms could produce damaging wind gusts, particularly today and Monday. Daily high temperatures will be several degrees above normal at the beginning of the week but trend back to around normal Tuesday through Thursday. && .NEAR TERM /THROUGH TONIGHT/... As of 145 AM EDT Sunday: Lingering convective debris starting to scatter out of over the western half of the CFWA, helping to reveal major mountain valley low stratus and fog already developing. All precipitation has dissipated and leaving partly to mostly clear skies through the rest of the overnight period. Can`t rule out ground fog in locations that received heavier rainfall Saturday and near bodies of water. Expect overnight lows to run at or a few ticks above normal. Only very subtle changes to the synoptic pattern as a ridge over the Gulf noses further north in to the region, allowing for warmer and drier air to work into the vertical profiles. Positively-tilted trough over the central CONUS will gradually work eastward during the forecast period, dragging an attendant boundary with it. The actual frontal boundary will remain well northwest of the region. With more warmer and drier air aloft, expect the atmosphere to be slightly capped. Factor in a downward trend in PWAT values (1.25"-1.75") and convective coverage should shrink compared to the past few days. Still expect isolated convective initiation over the ridgetops and Blue Ridge Escarpment by the early afternoon and will shift east into the foothills and Piedmont by outflows and cold pool organization later into the afternoon and evening. The environment will still consist of 2000-3000 J/kg SBCAPE and <20 kts of deep layer shear, but with drier air entrainment within the profiles, storms that do develop will have a higher chance of becoming strong to severe compared to Saturday as DCAPE values will uptick to 800-1200 J/kg, with pockets of higher than 1200 J/kg. Wet microbursts will be the main threat, which is typical with summertime pulse convection. Hi-Res guidance have hinted at better convective coverage along and east of I-77 as a pool of higher PWAT values is evident and the lee trough shifting further away from the Appalachians. As a result, chance PoPs (25%-53%) are introduced for the CLT metro and I-77 corridor, while only slight chance (15%-24%) to unmentionable PoPs (<14%) for locations south of I-85 in the Upstate and Upper Savannah regions. With slightly higher heights and the lack of morning stratus, afternoon highs are forecasted to top out a few degrees above normal. Heat index values should reach triple digits in portions of the Piedmont zones, but will remain below Heat Advisory criteria. Most of the convection should gradually dissipate after sunset with the loss of peak diurnal heating. Lingering convective debris, available low-level moisture, and locations that receive heavy rainfall will be prone to another round of low stratus and fog overnight Sunday, 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. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 1230 AM Sunday: A weak upper anticyclone will be centered over the Gulf Coast region Monday, as a weak shortwave passes by to our north associated with a slowing cold front in the lower Ohio Valley. Inverted trough meanwhile will drift west invof the Bahamas. The result is nebulous upper forcing over our area but a broad zone of low to midlevel convergence centered over central NC/SC/GA and thus perhaps just to our east and south. Diurnal instability will be the main driver of showers/storms, with coverage enhanced above climo on account of the convergence and modestly high PWATs. Model QPF response has increased slightly in our CWA compared to runs from a day ago, and notably there appears a better chance of activity to continue after sunset; peak chances for Monday appear to be near 00z for our southeastern half. Temps look to be at or slightly above Sunday`s values, but dewpoints could be slightly higher so a few lower Piedmont spots briefly see heat index exceed 105. Shear is weak; despite moist profiles, very heavy downpours and water loading still maintain some wet microburst risk. As the northern shortwave moves further east the trailing front seems to finally stall just to our north. Partial thicknesses fall seemingly as a result of the inverted trough moving westward and replacing the upper ridge. Temps should trend cooler, back to around climo, even if the front technically stays to our north. Convergence still could be enhanced by the inverted trough. The cooler temps but similar if not higher dewpoints result in lower LCLs. CAPE and PoPs increase accordingly. Via the convergence zone another slow nocturnal decline is expected Tue night. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 115 AM Sunday: The inverted trough may have some enhancing influence Wednesday, but otherwise the dominant feature for the medium range looks to be the Bermuda High. Wednesday looks like the "coolest" day as partial thicknesses reach their nadir on most of the global models, possibly also owing to cloud cover with convective coverage near the trough axis. A gradual warming trend then occurs as the Bermuda High retrogrades over the Southeast Coast. Relatively high afternoon dewpoints will keep LCLs low and support above-climo PoPs again Thu. There is some spread among models, and between the GFS and EC ensemble members, as to how deep the Bermuda ridge ends up over our region. The next frontal system will pass the Great Lakes circa Thursday; GFS and GDPS suggest the ridge will hold off that system from our area until the associated shortwave is reinforced by a secondary trough digging into the northern Plains and western Great Lakes late Fri or early Sat. The EC brings the convergence zone into our area a bit sooner. The upshot of all this is that the GFS and GDPS solutions feature more typical PoPs (i.e., mainly over the mountains) whereas the EC maintains enhanced values reflecting less terrain influence. Given the timing differences confidence decreases Fri-Sat. Heat index still could peak at 100 to 105 in the warmer Piedmont areas Fri-Sat. Slow-moving cells producing heavy rainfall will remain a daily concern particularly where soils saturate following repeated rounds of showers/storms over the course of the week. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: Some lingering convective debris is evident across the western terminals, but signs of scattering has revealed mountain valley low stratus and fog. Any low stratus or fog outside of the mountain valleys will be sparse, which is shown in the latest TAF update. Kept the TEMPO for 1SM and OVC004 mention at KAVL for mountain valley influence and 5SM at KHKY due to elevated fog chances near bodies of water. Otherwise, fairly quiet through daybreak for the terminals. VFR conditions will prevail for the daytime period with isolated to scattered showers and thunderstorms expected, especially for the North Carolina TAF sites. Included a PROB30 for TSRA and associated restrictions at all terminals except KAND, where TSRA chances are the lowest. Light and variable winds through daybreak, will pick up out of the north-northwest by peak heating. Another round of low stratus and fog can`t be ruled out overnight Sunday, especially over the mountain valleys once again. Winds also go back to light and variable Sunday night. 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. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...Wimberley NEAR TERM...CAC SHORT TERM...Wimberley LONG TERM...Wimberley AVIATION...CAC