textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated Aviation Discussion.

KEY MESSAGES

1. Much cooler today with scattered showers and isolated mountain thunderstorms. 2. Dry/convection-free weather with a warming trend Wednesday through the end of the week.

DISCUSSION

Key message 1: Much cooler today with scattered showers and isolated mountain thunderstorms.

The latest water vapor imagery depicts a broad long wave trough centered just off the East Coast, with a short wave trough digging south into the central Appalachians. Surface analysis depicts light NE flow across our forecast area, with drier air gradually filtering into the Piedmont. In the wake of the short wave, broad high pressure will build southeast from the Great Lakes, sharpening an inverted ridge down Virginia and Carolina Piedmont as statically stable air spills east of the central Appalachians. In conjunction with this, an inverted trough will sharpen across east TN and far western NC, and this will provide the primary impetus for precip chances later today...with chances enhanced by the approaching short wave. PoPs will therefore be highest (likely) across far southwest NC, while 20-40 PoPs are advertised for much of the remaining area west of roughly Highway 321. Mostly showers are anticipated, although an isolated thunderstorm is possible across the Smokies and vicinity. ENE low level flow along with mid-level cloud cover is expected to result in temps around 10 degrees below normal in most locations through tonight.

Key message 2: Dry/convection-free weather with a warming trend Wednesday through the end of the week.

Heights will begin to rise Wed, as a long wave trough progresses away from the East Coast, and a highly amplified ridge/associated anticyclone builds into the Southeast from the central Conus. A warming trend commences Wednesday, with temps steadily warming each day...reaching normal levels by Friday and likely remaining within a degree or two of climo through early next week as the ridge begins to break down. The upper air pattern will favor some degree of surface ridging across the southern Appalachians and vicinity through much of the week, with little-to-no moisture transport expected off the Gulf of western Atlantic. As such, chances for convection are virtually nil until at least Sunday, when the air mass may modify sufficiently to allow for spotty diurnal showers/perhaps a storm over the high terrain. Chances for convection improve a bit into the early part of the new work week, when global models generally agree in falling eastern heights and improving moisture/instability profiles.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

At KCLT and elsewhere: VFR is expected to prevail through the period, as an inverted surface ridge gradually strengthens through the morning, resulting in steadily increasing NE winds and allowing drier low level air to filter through the Terminal Forecast Area. Meanwhile, areas of BKN/OVC mid-level clouds in the 070-100 range are expected through the daylight hours, with SKC conditions developing overnight. Scattered showers are expected to develop across upstate SC and the mountains this afternoon, with VCSH carried at the TAF sites in those areas. NE winds of around 10 kts will develop at all sites except KAVL by late morning...continuing through the daylight hours before diminishing this evening.

Outlook: Convection-free weather is expected through at least Saturday. VFR will predominate, but some potential for morning mountain valley fog/low clouds will develop by the end of the week.

GSP WATCHES/WARNINGS/ADVISORIES

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