textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No major changes.

KEY MESSAGES

1. Quiet weather through tonight. 2. Relatively dry and warm temps through midweek. Temps increase for the second half of the week, with a return of daily chances of showers and thunderstorms.

DISCUSSION

Key message 1: Quiet weather through tonight.

Well defined upper trough is present off the Atlantic coast while a deep upper ridge is centered in the Plains. At the surface, high pressure centered over the Great Lakes this afternoon extends down the Eastern Seaboard in wedge-like fashion. Expecting mostly clear skies tonight aside from the possibility of some mountain valley fog/stratus, or upslope clouds near the Escarpment with continuing easterly flow.

Key message 2: Relatively dry and warm temps through midweek. Temps increase for the second half of the week, with a return of daily chances for showers and thunderstorms.

The axis of the deep upper ridge pivots eastward Tuesday, as a trough moves across the northern Plains and Prairie Provinces, leaving a broad anticyclone across the southern half of the CONUS by midweek. The surface high shifts off the East Coast in response. Though onshore low-level flow may result in a bit of cloud cover late tonight or late Tuesday night, profiles will be subsident and dry and precip chances very low through Wednesday. Under mainly sunny daytime skies the airmass will modify such that temps return to about normal Tuesday, and slightly above normal Wednesday as light southwest flow is reestablished.

Subtle upper height falls do look to begin Wednesday night into Thursday as the axis of the Canadian trough reaches the Great Lakes and upper MS Valley. Diurnal convection again looks plausible, at least over the mountains, as temperatures and humidity trend still higher. A few ensemble members still show some diurnal showers/storms developing Thursday afternoon/evening in the Deep South, primarily to our southwest; the signal for the trough to interact with the old frontal boundary appears weaker, and accordingly PoPs have trended lower Thu for our southern zones. There does appear consensus for the front to stretch out in a zonal orientation across the southern Appalachians and Mid-Atlantic circa Friday, as the parent trough progresses across New England and offshore. The best overall chance of showers/storms appears that day. Another trailing weak shortwave does appear in most model output, which may result in a wave developing along the front near or west of the CWA. Thus it looks like the front more or less stalls for the weekend and airmass change appears unlikely. Hot and muggy conditions, and above-average convective coverage, persist Friday through Sunday. Temperatures should run a few degrees above normal. A few lower Piedmont locations Friday may see heat index top out near 100, with HI in the upper 90s otherwise likely along and south of I-85 then through Sunday.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

At KCLT and elsewhere: Mostly VFR conditions expected through the TAF period. Overnight, valley fog could bring KAVL down to IFR fo 3/4SM vsby and low stratus, so a TEMPO in effect 10z-14z. Winds remain light out of the NE/E at all sites. KHKY/KCLT could become VRB, but still light. Cigs remain SKC to SCT/FEW250.

Outlook: Dry and VFR through Wed outside of morning mountain valley fog and low stratus. Restrictions could return by Thursday.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.