Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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873 FXUS62 KGSP 011755 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 155 PM EDT Sat Jun 1 2024 .SYNOPSIS... Dry high pressure moves off the Carolina coast on Sunday with warming temperatures and increasing moisture. A typical summer pattern will return during the first half of the week with daily afternoon thunderstorm chances. Showers and thunderstorms will likely increase in coverage for Wednesday and Thursday as a cold front approaches our area. && .NEAR TERM /THROUGH TONIGHT/... As of 9:55 AM Saturday...The better cirrus coverage is currently moving east of the I-77 corridor as a much broader cloud shield and associated showers gradually approach the western Carolinas from the west. Based on the latest near-term guidance and linger- ing cirrus coverage, I lowered high temps a bit for today. Otherwise, upper level ridging will shift east today as a shortwave upper trof advances east overnight. Still expect mainly upper clouds thru the day today, which will have an impact on lowering sfc temps even as the sfc flow picks pick a more s/ly component. Highs will likely hold a cat or so below normal levels. Still a dry sfc layer as upper subs will be slow to erode, thus expect low RH thru the afternoon period. Forcing ahead of the upper s/w reaches the NC mtns late afternoon, yet moisture advect off the Atl will take some time for the low levels to saturate across the FA. The latest op models show the best timing of llvl moist transport aft midnight, however, sct showers are probable across the NC mtns before that. More widespread precip will occur overnight, but with limited instability and meager mlvl LRs, deeper cells with high rainfall rates will be hard to develop. The upslope regions of the NC mtns will receive the higher precip amts with arnd three quarters of an inch or so, while anticipate only arnd a quarter inch east thru daybreak Sun. Mins Sat night will be held right arnd normal due to reduced heating during the daytime Sat and increasing column moisture. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 227 AM Saturday: Surface high pressure shifting offshore will allow for winds to shift to out of the south/southeast with onshore flow ushering moisture back into the region. At the same time, a shortwave trough will be lifting through the Ohio Valley and into the Appalachians. Showers will likely already be ongoing Sunday morning across the mountains with this activity expected to expand east across the Upstate and into the Foothills/Piedmont through the day. A few thunderstorms will also be possible during the afternoon to early evening hours. Cloud cover and coverage of precipitation will likely keep temperatures below average for another day with afternoon highs generally in the low to upper 70s. By Monday, the upper trough will have lifted across New England leaving behind a nebulously forced pattern. Weak westerlies will extend from the Southern Plains into the southeast states with a couple weak embedded shortwave perturbations. This will foster diurnally driven scattered afternoon showers and thunderstorms with afternoon high temperatures rebounding into the low to mid 80s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 234 AM Saturday: A weakly forced summer pattern will continue Tuesday as temperatures continue to warm with another round of scattered diurnal convection. Heading into mid week, an intense Pacific jet over British Columbia and Washington state will help carve out a potent negatively tilted trough over the Northern Plains into the Great Lakes region. While the strongest large scale height falls will remain displaced north of the area, some degree of increased forcing will likely exist across the Southern Appalachians Wednesday into Thursday. This will result in a noticeable uptick in coverage of showers and thunderstorms on Wednesday across much of the area. An associated cold front will also approach the area Thursday into Friday. Severe weather chances still appear low through the period given poor thermodynamic profiles with tall/skinny CAPE profiles and near moist adiabatic lapse rates. Guidance beings to diverge, however, with exact timing of the front and evolution of the synoptic wave. Most solutions close off a large upper low, but show considerable spread as to when/where this occurs. Regardless, another seasonably dry and cool airmass will eventually spill into the area by next weekend. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... At KCLT and elsewhere: Expect VFR conditions to continue thru the 18z period at all taf sites except at KAVL and KAND, where cigs are expected to drop below VFR towards the end of the period late tomorrow morning. The other terminals could see some lower cigs by that time, but more than likely they will remain low-end VFR thru the period. Otherwise, VFR clouds will gradually lower tonight and early Sunday with sct showers approaching the area by that time. I have PROB30s for shra at all sites beginning Sunday morning and PROB30s for tsra by the early afternoon once some in- stability is present. Winds should continue to favor a SLY to SELY direction thru the period, becoming weaker later tonight and then picking back up moderately by the early afternoon tomorrow. Outlook: Diurnal shower and thunderstorm chances will linger thru the middle of next week. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...TW NEAR TERM...JPT/SBK SHORT TERM...TW LONG TERM...TW AVIATION...JPT