Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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174 FXUS62 KGSP 230618 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 218 AM EDT Sun Jun 23 2024 .SYNOPSIS... Hot temperatures will linger through next week, with humidity increasing east of the mountains starting Wednesday. A cold front will track across the area overnight tonight into daybreak Monday bringing a weak line of showers and isolated thunderstorms to the area. Drier conditions return the rest of the day Monday, lingering into the first half of Wednesday. Another cold front will push across the area Wednesday night into Thursday, potentially bringing better shower and thunderstorm chances to the area mid to late week. && .NEAR TERM /THROUGH TONIGHT/... As of 150 AM: Upper anticyclone now centered over Texas, and upper low off the Carolina/Georgia coast. Thus we are currently in a relatively neutral pattern without much forcing, but also with less suppression. Low-level flow is solidly out of the SW. Some degree of low-level convergence persists across our area between the maritime airmass and the dry air associated with the anticyclone. A few patches of clouds persist as a result but otherwise skies are clear; the convergence seems to be the cause for spotty QPF response early this morning, but all depictions thereof, going back to last night, have proven overdone, so we retain a dry fcst this morning. Low levels remain fairly mixed, and with light wind continuing radiation fog/stratus is not much of a concern despite moist sfc conditions. The anticyclone will continue to retrograde slowly today, and a shortwave crossing the Great Lakes eventually will promote height falls across the Eastern Seaboard. This mainly occurs in the late afternoon and evening, thus a little late to coincide with peak heating. Lapse rates are good in the low levels and modest above about 600 mb, but model progs still depict a warm layer around there, and neutral to downward vertical motion above that layer, much like they did yesterday. CAM response is also similarly paltry like it was the past couple of days, when we had little to no deep convection. PoPs this aftn and early evening have been limited to a low slight-chance mainly in the NC Foothills and Piedmont. Some of the models kick off their convection around 00z in that area, presumably in response to the height falls, so the small chances tick upward a little then, to scattered/chance wording in some spots. The trough also will bring a weak cold front across the Appalachians overnight, which will bring the best chance of the period for the NC mountains and GA/SC Piedmont, but still no better than scattered coverage. && .SHORT TERM /MONDAY THROUGH TUESDAY/... As of 120 PM Sat...Canadian high pressure mixes in thru the day Monday and winds become n/ly to nw/ly. However, this airmass will be rather warm so little CAA, if any, can be expected and temps shud have no problem rising to the m90s east of the mtns and u80s mtn valleys. Will be close to heat indices reaching 105 F across NE GA and the western Upstate Lakeland region as sfc dewpts will mix out the least compared to other areas. A Heat Adv may be needed for Mon. The pattern remains quite warm and supressive Mon night into Tue as upper heights continue to rise while a subTrop high becomes more dominant. Soundings show parcels possibly breaking the cap across the mtn ridges Tue afternoon for brief -shra/tstms, but most areas will remain dry. Still, another hot day in store with temps similar to Mon yet a little better dewp mixing may hold heat index values shy of advisory criteria across the FA. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 155 PM Sat...No major changes were made to the ext range fcst. The latest guidance is still at odds with the development and evolution of an upstream trof / frontal system Tue night thru Thu. The GFS is a moist outlier with better h92-h85 moist adv off the wrn GOM and is much faster and energized than the other op models. The GFS dProg/dt trends have been holding consistent however, so the latest run has been given good weight in the fcst. The ECMWF on the other hand is slower and only develops isol precip across the NC mtns Wed and reluctantly develops more widespread activity on Thu as the sfc front likely stalls. So, backed off the NBM PoPs east of the mtns for Wed and Thu, yet still have low likely chances across the mtns and mid chance PoPs east each afternoon. The upper levels remain quite warm thru the period and with limited shear or forcing, most storms shud remain below severe criteria. Wednesday will be another hot one before temps cool a little Thu and Fri. Could need a heat advisory Wed for the srn zones as higher dewpts are pooled north ahead of the Tue night cold front. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR expected thru the period aside from the possibility of MVFR level stratus developing near daybreak at KCLT on moist southerly flow, or from very brief MVFR cigs from diurnal cu at their onset in the late morning, before they mix up to VFR level. Retained TEMPO for KCLT to this effect. A light S`ly breeze will continue thru daybreak, veering to SW late morning and picking up slightly this aftn. Some instability will develop again today with profiles similar in nature to the previous two days; again forcing will be very weak and profiles dry aloft, so expect no better than very isolated coverage of SHRA this aftn. Trough exiting the Midwest however could realize some elevated instability this evening, so SHRA or a stray TSRA becomes more likely then primarily near the NC sites. That said, chance is too low to mention. Associated front should promote drying early Monday, with light winds continuing, making radiation fog/stratus unlikely, although KAVL could see low clouds develop via upslope lift after 06z. Outlook: Drying trend now expected to continue Mon-Tue with little to no diurnal convection. Summertime humidity return Wed-Thu with SHRA/TSRA chances also returning. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...AR NEAR TERM...Wimberley SHORT TERM...SBK LONG TERM...SBK AVIATION...Wimberley