


Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
455 FXUS62 KGSP 140549 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 149 AM EDT Mon Jul 14 2025 .SYNOPSIS... A typically active mid-summer week is ahead as daily thunderstorm chances continue. A few storms could produce damaging wind gusts and localized flash flooding may develop following heavy rainfall. Daily high temperatures will be several degrees above normal today, trend back to around normal Tuesday through Thursday, then trend warmer again. && .NEAR TERM /THROUGH TONIGHT/... As of 145 AM EDT Monday: Lingering convection across the western Piedmont of North Carolina has dissipated, leaving convective debris in the area. Otherwise, another muggy night is in store with mountain valley fog expected once again. The mid- to upper-level ridge over the southeastern CONUS will flatten out as a weak shortwave slips north of the CFWA during the daytime period. Expect the coverage in convection to uptick compared to Sunday with initiation likely to start across the mountains and spread east into the foothills and Piedmont later in the afternoon and evening. CAMS support the idea of outflow/cold pool driven organization as the activity gets going with an environment of 2000- 3000 J/kg of SBCAPE, 800-1200 J/kg of DCAPE, and <20 kts of deep layer shear. This suggest that strong to severe storms are still present with wet microbursts as the primary threat, to go along with a localized flash flood threat as a PWAT values remain high (1.50"- 2.00"). There is some speculation that convection won`t have a typical diurnal trend and may linger late in the evening into the early portions of the overnight. Afternoon highs will remain a few ticks above normal, but dewpoints should mix out enough to keep heat index values just below Advisory criteria. Lingering convection and debris will be evident to start out the overnight period with a gradual dissipation. Another muggy night with overnight lows running a few ticks above normal, while areas of low stratus and fog can`t be ruled out, especially in the major mountain valleys. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 1215 AM Mon: Shortwave associated with Canadian system, with trailing weak cold front, will move off the East Coast Tuesday. Meanwhile, a baggy trough in the mid-MS Valley, formerly a cutoff low, will drift northeast and stall and/or reverse the frontal boundary. This looks to prevent us from experiencing true airmass change via the front. Inverted trough however tracking across Florida will reinforce southeasterly low-level flow. Some semblance of a convergence axis could result with the trough, but a clear signal is seen among models for sea-breeze front to advect into the CWA in the late afternoon or evening. Although temps trend slightly cooler under reduced thicknesses, muggy dewpoints will maintain relatively low LCLs; in addition to the usual diurnal forcing, the potential for enhanced convergence suggests above-climo PoPs once again, declining slowly Tuesday night given the potential for lingering sea breeze activity. The pattern really doesn`t change much for Wednesday, although the GFS and EC veer low-level flow slightly more toward the SW, which could suggest more typical/climatological PoP trends. However, the NAM and GDPS maintain an easterly component to very low level winds and accordingly suggest a second day of sea breeze convection. Thicknesses trend slightly lower Wednesday for max temps a wee bit cooler but still about normal. Both days, dewpoints will remain a bit higher than normal and heat index should push past 100 in areas of the Piedmont, but below Heat Advisory criteria. Thunderstorms appear to pose seasonable, generally localized threats of wet microbursts and torrential rainfall, which could result in a few instances of wind damage and flash flooding each day. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 115 AM Mon: A weakness persists in the upper pattern over the Gulf Coast region as the weak trough continues to drift west. A fair number of members of each global ensemble depict formation of a surface low in the Gulf, which generally is shown to drift onshore invof Louisiana Thursday or early Friday. Hence no direct impact of any such low is expected here. More or less typical diurnal PoPs are expected Thursday although coverage may still be a bit higher than climo owing to elevated dewpoints. A gradual warming trend is expected for the CWA Thursday thru Saturday as the Bermuda High retrogrades over the Southeast Coast, but the lower heights surrounding the low may mitigate the warming to some extent. A broad shortwave trough associated with the next frontal system should pass the central and northern Appalachian chain circa Friday, which could bring the front as far south as NC. As ridge builds to our west or southwest behind the dissipating Gulf trough/low, the front may pivot and could effectively stall over the CWA into next weekend. As a result PoPs trend slightly higher again for Fri-Sun with a slower than usual nocturnal decline Sat and Sun nights. Shear does not increase appreciably; weak steering flow will continue and could orient parallel to the front, so heavy rainfall and localized flash flooding probably will be a daily concern particularly where soils saturate following repeated rounds of showers/storms over the course of the week. Heat index still is forecast to peak at 100 to 105 in the warmer Piedmont areas Fri-Sun. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... At KCLT and elsewhere: Lingering convective debris should gradually scatter out over the next couple of hours as any showers and thunderstorms have dissipated. Already seeing mountain valley low stratus/fog with a few instances near KAVL. As a result, placed a TEMPO through daybreak for LIFR vsby and cig. KHKY received heavy rainfall with fog already developing upstream over the nearby river basin, so decided to place a TEMPO for LIFR vsby and cig through daybreak as well. VFR conditions at KCLT and the Upstate sites through the morning hours. Another round of afternoon and evening showers and thunderstorms are expected across the area. PROB30 has been placed at all TAF sites with associated restrictions. Otherwise, another round of low stratus and fog will be possible across the terminals overnight, with the best chance at KAVL and KHKY once again. Winds will be light and variable through much of the forecast period, but will favor a northwesterly direction. 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