Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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532 FXUS62 KGSP 070604 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 204 AM EDT Sun Jul 7 2024 .SYNOPSIS... A weak front will move in from the north and become stationary near the southern portion of the forecast area today. This front will increase the chance for thunderstorm activity outside the mountains through Sunday. An active pattern of afternoon and evening showers and storms is expected to continue through next week. && .NEAR TERM /THROUGH TODAY/... As of 145 AM Sunday: Plenty of cloud cover expected thru the rest of the night, which combined with elevated dewpts will keep warm, muggy conditions thru daybreak. A few stray showers may develop, thanks to the very moist BL, but overall, expecting quiet conditions this morning. Otherwise...broad longwave troughing is currently draped across much of the CONUS from the Pacific Northwest to the Ohio Valley. Stout upper ridging remains centered over California along with a second ridge that has shifted off the east coast. A few showers may linger into the overnight as southeasterly flow returns to the area and the stalled boundary slowly lifts back north into the mountains. A widespread deck of low stratus clouds is expected to develop, which will further limit any cooling in the face of moisture return. This will keep overnight lows on the mild side with upper 60s to low 70s. By tomorrow, little change is expected with regards to the synoptic pattern. Coverage of showers and storms is expected to be greater, however, given the return of rich low-level moisture and ample instability. Showers will likely develop earlier in the afternoon with storms increasing in coverage as well, especially across the escarpment and I-85 corridor. Morning cloud cover and an early start to convection will not only keep temperatures in check, but will also limit instability with surface-based CAPE progged at 2000-2500 J/kg. As with any summertime convection, isolated damaging wet microburst cannot be ruled out, especially where multicell clusters/cell mergers occur. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... As of 145 AM Sunday...A moist and weakly forced atmos remains in place thru the short range. Upper heights vary little Mon as Atl moisture flux increases due to an eastward shift i Bermuda High ridging. Very hard to determine a main focusing zone as llvl bndrys remain ill defined. There is a decent signal for upslope precip/convec across the BR escarpment and further west into the NC mtns, however, and have the best PoPs there, pushing into the likely range, yet lower than the more deterministic NBM output. A solid chance precip will be maintained east of the mtns as PWATS remain quite high and subtle terrain lift could help instigate multicell outflow driven cells. Due to little changes in the overall synoptic pattern, will go with a persistence type fcst featuring high precip storms moving slowly northeast or east within the mean steering flow aloft. Thus, expect a chance of hydro issues, esp considering the increase in antecedent conds across localized areas. A few severe level storms will be possible as well with damaging outflow winds the main threat. More uncertainty on coverage and storm mode exists Tue as sfc troffing may develop from the west while the remnants of TC Beryl push up the MS Valley with differing timing solns seen on the op models. So, PoPs have been adj/d down a little yet still remain abv climo values. Max temps will hover near or arnd normal levels each day with no widespread HI issues expected. Mins will be held abv normal by a few degrees each morning. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 210 pm Saturday: The upper air pattern is expected to remain relatively static during the extended, with a central Conus trough expected to make only modest eastward progress, while the subtropical ridge/associated Bermuda high is forecast to strengthen across the western Atlantic. With such minimal changes in the overall patter expected, the environment over the southern Appalachians and vicinity is expected to remain more moist than is typical for early summer. This moisture could be enhanced further (albeit briefly) by the remnant circulation of T.C. Beryl, which is forecast to lift across the TN and OH Valleys during mid-week. Above-normal coverage of diurnal convection (60-70 PoPs across the mountains; 50-60 across the rest of the area) is therefore expected each day through the period. An excessive rainfall threat will continue...and may actually worsen a bit as antecedent conditions deteriorate locally. Temperatures are forecast to be within a degree or two of climo through the period. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: Despite plenty of high-based cigs, MVFR to LIFR clouds are beginning to form across the lower Piedmont, and should generally expand in coverage thru the pre-dawn hours, resulting likely IFR cigs at all the Piedmont sites by daybreak. The clouds will then be slow to lift to MVFR and finally scatter out to VFR by around midday. This may delay the diurnal convection, but with such moist air mass, expect scattered to numerous SHRA and TSRA starting in the mountains, then generally working east late aftn into the evening. Will go with a TEMPO at KAVL, where confidence and coverage warrants, while the other sites can still be handled with PROB30 groups. Convection should wane by late evening, leaving plenty of mid clouds around thru 06z. Areas of MVFR to LIFR cigs and patchy fog will likely form in the 06z-12z time frame again Monday morning. Winds will be light thru the period (except possible gusts and variable around convection). Outlook: An active summertime pattern continues for most of the upcoming week, leading to scattered to numerous showers/thunderstorms and possible restrictions each afternoon/evening. Fog or low stratus may develop each morning, especially over areas that received rain the previous day. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JDL NEAR TERM...ARK/CP/TW SHORT TERM...JDL LONG TERM...JDL AVIATION...ARK