textproduct: Greenville-Spartanburg

SYNOPSIS

A passing upper level disturbance will bring some light precipitation to the region today. High pressure will move in from the west through the middle part of the week. A series of two cold fronts will move across the region during the latter half of the week, ultimately bringing much cooler temperatures by the end of next weekend.

NEAR TERM /THROUGH TONIGHT/

As of 900 AM EST Monday...

Key Message 1: A Winter Weather Advisory remains in effect for Avery County as well as elevations above 3,500 feet in Yancey and Mitchell Counties until 1 AM Tuesday.

With temperatures near or below freezing above 3,500 ft in the NC mountains, snow will continue this morning. Still expect snow accumulations of 2 to 3 inches above 3,500 feet across the northern mountains with locally higher amounts up to 4 inches possible across the highest peaks. Thus, a Winter Weather Advisory remains in effect for Avery County as well as elevations above 3,500 ft in Yancey and Mitchell Counties until 1 AM Tuesday. The mountain valleys in Mitchell and Yancey Counties could see anywhere from a dusting to an inch of snow this morning/afternoon. Elevations above 3,500 ft in the southern/central NC mountains will get some snow, but it should remain below Advisory criteria. However, locations in the Smokies along the NC/TN border could see totals from 1 to 2 inches with locally higher amounts in isolated locations mostly above 3500 ft.

Key Message 2: A cold rain is expected elsewhere although some sleet or snow may mix in at times today, mainly across the North Carolina foothills and Piedmont.

Temperatures will be mostly above freezing across the rest of the mountain valleys and areas east of the mountains, so mainly a cold rain is expected for these locations. However, some light snow may blow down the valleys and/or some wet-bulbing may occur east of the mountains (mainly in the NC foothills/Piedmont along and north of I- 40) which could allow some brief snow/sleet to mix in with rain at times. It is not entirely out of the question for wet-bulbing to occur south of I-40 in the NC foothills/Piedmont as some of the CAMs continue to depict this scenario. However, with the cold air chasing the moisture east of the mountains, confidence on snow making it that far south remains low at this time. Regardless, no significant snow accumulations are expected east of the mtns if wet-bulbing does occur. With the persistent low cloud cover and precip today, highs should remain 10 to 15 degrees below normal across most of our CWA.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

Key Messages:

1) Breezy winds on Wednesday, especially over the ridgetops.

2) Some upslope snow showers possible along the TN border Wednesday night.

As of 1233 AM EST Monday: Not much change overall for the middle part of the week, which should be the relatively quiet part of the upcoming week. We will start out Tuesday with a cold high pressure air mass over the region. Temps should be about ten degrees below normal with variable clouds. But, the sfc high is still expected to move offshore Tuesday night followed by a nrn stream clipper moving over the Great Lakes on Wednesday. Still looking at breezy conditions on Wednesday as strong SW flow aloft ahead of the approaching short wave traverses the region during peak heating. The GFS shows the axis of a 40-50kt low level jet moving overhead in the afternoon, for example, and model fcst soundings show mixing well up above that layer. This suggests that momentum transfer could ultimately be sufficient to bring Advisory-level gusts down to the sfc over the mtns, especially the ridgetops. Thus, the model blend is more likely than not to be underdone with the wind gust potential. Fortunately, the WSW flow will help keep the RH in check, so Fire Wx is not as great a concern as it could be. Temps should rebound close to normal. After the short wave passes late in the day, the majority of the guidance shows some low level RH moving in from the WNW into the overnight period. Looks like a quick shot of NW Flow potential, though, with the better and deeper moisture moving past to the north. We will carry a small chance of snow showers on the TN border and a small accumulation in some spots. Lows will also be close to normal.

LONG TERM /THURSDAY THROUGH SUNDAY/

Key Messages

1) Low confidence in wintry precip near the TN border associated with period of northwest flow late in the week.

2) A potential colder period next weekend with temperatures running around 15 degrees below normal.

As of 1247 AM EST Monday: The model guidance has gradually trended toward a drier scenario for the late part of the week. After an initial boundary crosses the region, the bulk of Thursday looks fairly quiet with the upper trof axis overhead and weak sfc high pressure moving through. This will not be the boundary we want to tell you about. The brisk WNW flow aloft through Thursday and Friday will serve to keep temps merely on the order of five degrees below normal east of the mtns. There could be periodic surges of low level moisture Thursday night through Friday night that could bring brief periods of upslope snow shower activity to the TN border, but chances look minimal as some of the guidance is moisture-starved. Thus, confidence is low for any precip, but confidence is going up that areas outside the mtns will remain dry through the medium range. Still looks like a more significant cold front will ultimately move through over the first part of the weekend, ushering in a more arctic air mass for Sunday into Monday. The pattern looks like typical dead-of-winter-type stuff. That spells temps running around fifteen degrees below normal with highs in the low/mid 40s even with full sun.

AVIATION /14Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Expect IFR to periods of LIFR cigs to persist over the fcst area thru tonight with some amount of sct early Tuesday. Reduced visby will also be possible thru much of today, mostly in the MVFR range. An area of light rain is curren- tly moving over the our area from the west, but most of it should be east of our area by mid to late morning. Any lingering precip chances are handled with PROB30s. The latest guidance continues to suggest that the back edge of the precip may change over to a mix of RA/SN or all SN in the NW Piedmont of NC. Confidence remains high enough to keep a PROB30 at KHKY for -RASN into the early aftn. Some guidance even has a changeover as far south as KCLT. If this does happen, it would be occurring around midday with temps in the upper 30s to lower 40s. So the risk of impacts is low, but not zero. Otherwise, precip should taper off by the early afternoon outside of the mtns. Some of the latest guidance has cigs improving to MVFR by the late afternoon, but based on the overall trends, I think it's more likely that most terminals will remain IFR thru this evening. Winds are expected to pick up out of the NE later this morning.

Outlook: Drying high pressure returns Tuesday into Wednesday. NW flow precip may develop along the NC/TN border Wednesday night into Thursday but dry conditions should linger elsewhere.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...Winter Weather Advisory until 1 AM EST Tuesday for NCZ033-049- 050. SC...None.