textproduct: Greenville-Spartanburg

SYNOPSIS

Below normal high temperatures stick around through next week. Dry and cold high pressure remains in control through Saturday before a cold front brings precipitation chances Sunday. Drier conditions develop briefly Monday before a low pressure system brings better precipitation chances Tuesday. Dry high pressure returns Wednesday into Thursday.

NEAR TERM /THROUGH TONIGHT/

As of 1151 PM EST Thursday...

Key Messages:

1) Clear and chilly today with sporadic wind gusts most of the afternoon.

2) Dry and breezy afternoon conditions warrant a Fire Danger Statement for NE Georgia.

3) Frigid temperatures tonight with lows in the 20s.

Deep upper trough still evident on satellite imagery tonight, with very dry profiles depicted in this evening's soundings. Surface high pressure extending well north and west of the Carolinas continues to spill into the area, advecting much drier and colder air along with it. Expect a steady 3-5kt northwest wind to continue overnight tonight across the low terrain, with some potential for stronger winds at high elevations. This should disrupt radiative cooling for the entire region, but temperatures will be bitterly cold nonetheless, by virtue of strong CAA. Expect lows in the 20s for most of the Upstate and Piedmont, while many locations in the Appalachians will drop into the teens.

Big story for Friday will again be low-end fire weather concerns. GFS and NAM profiles depict afternoon mixing to at least the 850mb level, tapping into some very dry air aloft and helping dewpoints drop significantly for much of the day. Most of the Upstate will see afternoon RHs fall into the 20-25% range, possibly lower in isolated locations. There'll be fairly limited overlap of remaining gusty winds and low RHs...so most of the area should skate by without needing any fire danger products...the exception being NE Georgia, for which a Fire Danger Statement has been issued for the afternoon hours. High temps should only climb into the mid-40s or lower 50s across the Piedmont and Upstate.

Cirrus will begin to increase Friday night as moisture arrives ahead of a developing upper trough dipping into the central Great Plains. As winds become light to calm, the increase in cirrus will barely offset radiative cooling...and temperatures should dip into the lower 20s outside the mountains...except in the Savannah River Valley, where they'll remain in the mid- to upper-20s.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

As of midnight Friday morning:

Key message 1: Dry high pressure Saturday.

A 1030+ mb surface high will migrate across the Eastern Seaboard Saturday, centering off the Atlantic coast Saturday night. Following a chilly start, weak low-level CAA will continue for part of the day before SW flow develops. High clouds may filter sunshine to some degree although skies will be mostly sunny during the afternoon. Some mountain valleys may see a rebound of a few degrees vice Friday, but most of the Piedmont will see max temps similar if not a bit cooler. Maxes 10-15 below normal all around.

Key message 2: Brief period of wintry precip possible in portions of the mountains and NW NC Piedmont late Saturday night or Sunday morning ahead of a weak cold front.

A deep low will track thru the mid-Mississippi Valley toward the Great Lakes Saturday, helping drive the SW flow in the afternoon which will continue aloft overnight. A 40-50 kt LLJ will lead to strong/gusty winds at high elevations although as typical in southerly flow gusts should be limited to below advisory criteria. The LLJ will however promote moisture return near the surface, with a resultant chance of precip beginning in the late overnight hours, mainly over the mountains and along the south-facing Blue Ridge Escarpment. Below the moist layer associated with the LLJ, a dry surface layer will exist for a time, and some diabatic cooling is possible in some of the mountain valleys, particularly below the Escarpment, and in parts of the I-40 corridor of the NC Piedmont. The surface high appears too distant to support true in-situ CAD, so by the time precip becomes more likely during the day Sunday, temps in most areas should be able to warm above freezing, leaving an all-rain forecast except for a few spots that could see NW flow snowfall Sunday evening behind the cold front, although that too looks brief as deep drying occurs rapidly behind it. Mins remain a few degrees below normal Sunday night.

LONG TERM /MONDAY THROUGH THURSDAY/

As of 1245 AM Fri:

Key message 1: Precip could redevelop as soon as Monday evening, but more likely early Tuesday, as cyclone develops on the Coastal Plain south and east of the area. This offers another chance for accumulating wintry precip for the NC mountains and NW NC Piedmont, and a cold rain elsewhere.

Cold front looks to stall south of the CWA Sunday night, with some spread among the major models as to just how far south, but general consensus south of I-20. Shortwave moving across the southern Rockies and Plains looks to induce cyclogenesis near the western Gulf Coast in a Miller-A pattern. Surface high is in a somewhat more favorable position for CAD this time; temps will trend slightly cooler for Monday with winds remaining NE'ly over most of the area thru the day. Small chances for PoPs develop from south to north Monday afternoon and evening, with likely to categorical values after midnight. Areas of the mountains northeast of the French Broad, and parts of the foothill/Piedmont I-40 corridor again look likely to experience a period of wintry mix late Monday night and/or Tuesday morning. The 28/00z cycle of guidance appears to have come into better agreement on the depth of moisture and general extent of wintry precip. For now have gone with a mainly FZRA/PL mix given confidence in the strength of the warm nose. Even the colder GDPS suggests a transition to all rain by late morning Tuesday.

Key message 2: A brief period of NW flow snow is possible late Tuesday, but otherwise dry high pressure should return by late Tuesday night, with daytime temps trending warmer Wed and Thu.

Cooling temps late afternoon Tuesday along the TN border will support a transition to snow showers there on the back side of the system. Most of the precip pulls away during the afternoon and evening and ends as rain in other areas. Mins fall back several degrees below normal again Tue night, but deep drying and height rises will allow sunny skies and warmer temps Wednesday, though still 5-8 degrees below normal. Under quasi-zonal upper flow, a fast-moving disturbance could affect the area with some clouds by Thursday, although temps most likely will trend warmer again, almost back to normal.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

At KCLT and elsewhere: VFR on tap for the 06z TAFs. A steady NW breeze will continue overnight with some occasional gusts at mountain terminals. Gusts will become more frequent after daybreak, and will occur at least intermittently at the Upstate and Piedmont terminals as well...before gradually tapering off into Friday afternoon and evening. SKC is expected until late Friday afternoon, when cirrus will begin to push in from the west, gradually thickening through the end of the period Saturday morning. Some isolated altocu may develop overnight, but with too little coverage for a mention at any of the TAF sites.

Outlook: Dry and VFR conditions will continue through Saturday. Rain chances return Sunday, bringing the next chance for flight restrictions. Drier conditions will return briefly Monday before rain chances and associated flight restrictions, return Tuesday. Drier conditions will return Wednesday into Thursday.

GSP WATCHES/WARNINGS/ADVISORIES

GA...Increased Fire Danger from 11 AM EST this morning through this evening for GAZ010-017-018-026-028-029. NC...None. SC...None.