Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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892 FXUS62 KGSP 100536 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 136 AM EDT Fri May 10 2024 .SYNOPSIS... A cold front will continue to push east of the area, before another system approaches Friday. Showers and thunderstorms are possible Friday afternoon, before dry high pressure builds in from the north through the weekend. && .NEAR TERM /THROUGH TODAY/... As of 135 AM: Widespread cirrus ahead of a thunderstorm complex to out SW will remain over the area early this morning. There will be some stratocu across the mountains and low stratus elsewhere. The copious high clouds should limit fog potential and will slow the previous cooling. Otherwise, mostly clear skies this evening should permit good radiational cooling for a time. Some dry advection will begin overnight as weak sfc low passes by to our north, pulling very weak sfc front through the area. This will promote just enough drying to maintain a dewpoint depression of a few degrees in the foothills and upper Piedmont, and furthermore some gradient wind is expected to persist. Thus, the likelihood of radiation fog/stratus looks small in those areas and mins will remain several degrees above normal. Mountain valleys are likely to see some fog, along with the SE CWA border where that weak front doesn`t reach and instead may serve to pool moisture. A couple hundred joules of CAPE may persist there thru daybreak. An MCV or other remnant of convection looks to round the base of the main trough in the morning and some guidance depicts a round of showers passing thru the Piedmont at that time. Partly cloudy skies will permit the return of warmer temps, again being a few degrees above normal. 700-500mb lapse rates will increase as main shortwave swings in, and isolated convective development is not out of the question over the mountains. For the aforementioned Piedmont areas, guidance members differ as to how soon low-level airmass change begins; GFS for example maintains poor low level lapse rates above the PBL and develops only small diurnal instability. The NAM depicts favorable lapse rates thru a deep layer and develops 1000 J/kg or more of CAPE in the afternoon. All models depict strong deep layer shear, perhaps 60+ kt, so if timing of the shortwave trends slightly slower or the low level lapse rates improve, we could see an isolated severe threat develop mainly southeast of I-85 or east of I-77. The setup warrants only a chance PoP in our south and east; FV3 and HRRR show short updraft helicity streaks from a lone cell. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... As of 1245 PM Thursday...An upper shortwave axis continues to swing east of the area Fri night as a cP air mass mixes into the lower levels. This airmass will slowly modify warmer over the weekend as a small scale ridge gives way to another diving Canadian h5 trof Sat afternoon. This trof looks to bring it/s own moisture and will probably produce some rain showers across the NC mtns Sat afternoon into the evening. No good chance of thunder during that time as sfc td/s drop into the 40s and potential instability remains nil or quite low. Drier conds with warming temps across the FA Sun as a broad sfc high builds over the area from the west. Generally, both days will be rather pleasant with highs a couple degrees below normal Sat, then back to normal levels on Sun. Mins will likely fall a couple degrees below normal each night. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 120 PM Thursday...A more springtime pattern returns during the ext range. The latest guidance contines to show a subs zone becoming displaced by waves of srn stream energy while a mlvl trof/low travseres the MS to OH valleys. The surface response indicates an opening GOM flow, which will supply a good amt of moisture to a broad frontal system each day. Onset precip timing Mon is suspect with the majority of models indicating a later timeframe than the moister insitu wedge pattern progged by the latest GFS. In any case, thunder probabilty remains low with non-conducive llvl thermal profiles. By Tue, expect a better chance of afternoon thunderstorms as a wavy cold approaches from the west and sfc dewps rise into the u50s to l60s. The pattern remains uncertain, yet possibly active into Wed as another round of srn stream energy may be pushing east across the GOM coastline by then. High Temps remain near normal Mon, then drop abt 5 degrees below normal Tue with the best chance of widespread precip and cloud cover. Highs rebound to normal values Wed. Lows begin the period near climo, then warm abv normal Tue/Wed nights. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: Copious high clouds will remain over the area this morning. Some VFR stratocu will also be seen at KAVl and KHKY. IFR to LIFR stratus is floating around over or near the rest of the sites. This could become BKN by daybreak into mid-morning. Any low cigs should scatter out or lift by noon. Guidance showing better chance of convection at KCLT than the rest of the sites, so have limited PROB30 to that location. W to SW wind this morning becomes gusty and more WSW for the afternoon. The gusty winds continue from the NW to N into the evening before diminishing. KAVL will see NNW wind throughout with very gusty conditions during the afternoon and evening. Outlook: Drier and likely VFR conditions can be expected this weekend. Moisture returns late Monday with active weather possible by Tuesday. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...SBK NEAR TERM...ARK/RWH/Wimberley SHORT TERM...SBK LONG TERM...SBK AVIATION...RWH