Sunrise 6:10 AM   Sunset 8:37 PM Moonrise 1:55 AM   Moonset 2:27 PM

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FXUS62 KGSP 011032 AFDGSP

Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 632 AM EDT Sat Jun 1 2024

SYNOPSIS
Dry high pressure centered over the region will keep temperatures slightly below normal, with dry weather persisting through today.
High pressure shifts offshore Sunday with warming temperatures and increasing moisture. A typical summer pattern will return early next week with daily afternoon thunderstorm chances. Showers and thunderstorms will likely increase in coverage Wednesday into Thursday as a cold front approaches the area.

NEAR TERM /THROUGH TONIGHT/
630 AM Update...Isolated spots of fairly dense ground fog has formed across the NC mtn valleys and east near Rock Hill. Not expecting expanding coverage this morning and the existing fog will dissipate over the next couple hours with daytime heating.

Upper level ridging will shift east today as a s/w 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 FRIDAY/
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 /12Z SATURDAY THROUGH WEDNESDAY/
At KCLT and elsewhere: VFR conds continue thru the 06z TAF period.
Upper clouds dominate as stg ulvl ridging slowly shifts east in advance of a s/w trof progged to cross the region Sat night. Expect lowering clouds by the late period with MVFR CIGS possible at KAVL aft 00z. Winds remain south to se/ly all sites as sfc high becomes situated off the Atl coast. No great gust potential as the mixed layer remains weakly energized, but there could be isol low-end gusts this afternoon and again very late period as the atmos becomes a little more dynamic.

Outlook: Shower and thunderstorm chances return Saturday night into Sunday and will linger into next week.

GSP WATCHES/WARNINGS/ADVISORIES
GA...None.
NC...None.
SC...None.

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