textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Snowfall amounts for the mountain areas along the Tennessee border is trending slightly higher.

KEY MESSAGES

1. NW snowfall possible Thursday morning and lingers into early Saturday across the highest elevations along the Tennessee border. 2. Expect gusty winds and colder temperatures behind a strong cold front Thursday through the weekend.

DISCUSSION

Key message 1: NW snowfall possible Thursday morning and lingers into early Saturday across the highest elevations along the Tennessee border.

A distinct pattern change emerges today through most of the weekend as a ridge builds out west and develops a strong trough downstream over the eastern portion of the CONUS. Meanwhile, a surface low forms across the Ohio/TN Valley and lifts northeast Thursday night. Trailing behind the low, a cold front is anticipated to cross the area and usher in the coldest air of the season. Model guidance is trending slightly higher in terms of potential NW flow snow at the NC/TN border. Though the majority of moisture should be mixed out with the addition of drier air, NW flow winds and lingering moisture at the NC/TN border increases the chances for the season's first snow. However, there are a few caveats. Soundings from a slew of model guidance depicts some instability within the snow growth zone aloft at the highest elevations over the mountains. What this means is the potential for increases snowfall rates as air is mechanically lifted over the peaks. Should any of this align, an uptick in snowfall amounts is possible. If there is no instability that materializes, snowfall rates would be much lower. Given the warmer temps leading up to the event, small amounts of snow could melt away before more falls, leading to minor accumulations. Currently, snowfall totals for the highest elevations along the NC/TN border are between 0.1"-3" from Thursday night into Friday night. The highest amounts remain likely in the Smoky Mountain National Park. Forecaster confidence remains medium given the few caveats discussed. At this time, a Winter Weather Advisory will not be issued given the very few locations where the majority of snowfall amounts remain under 2". This can change and there is still time to issue a product IF one is needed.

Key message 2: Expect gusty winds and colder temperatures behind a strong cold front Thursday through the weekend.

The strong upper trough remains over the eastern portion of the CONUS from early Thursday before breaking down by Saturday night. At the surface, a stout cP airmass eventually spills in and expands across the eastern portion of the country. Long range guidance does keep this area of high pressure locked into the area through Day 7. What this means for the southeast is shunted precip chances and cooler temps. Trends continue to favor cold overnight temps Friday and Saturday night, increasing confidence for a widespread freeze. The coldest night looks to be Saturday night with temps dipping into the very low 30s and 20s (NC Piedmont and mountains). Though slightly warmer, the general trend for overnight temps for the remainder of the forecast period remains cold. Daytime highs are trending at or just below normal through the remainder of the forecast period. As a reminder, the growing season is considered done after today, November 11 and no freeze products will be issued for any part of the CWA afterwards.

Additionally, the strong trough digging over the eastern CONUS churns over the CWA, keeping gusty winds throughout the area starting tonight through most of the weekend. At this time, guidance still keeps wind gusts over the mountains below Wind Advisory criteria of 46 mph. However, this could change depending on how far south the trough dips and where the most narrow wind gradient sets up. Should the gradient become tighter, wind speeds could increase. Ridgetops have a better chance of seeing 40-50 mph winds, but elsewhere, confidence decreases.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

At KCLT and elsewhere: VFR conditions prevail through the TAF period at all terminals. Winds become light and VRB this afternoon and overnight. Winds should pickup out of the SW after 12z with gusts of 15-25kts for Thursday as a front moves in. Winds turn W/NW toward the end of the period. VFR cigs remain with KAVL dipping to low VFR by Thursday morning. No other restrictions anticipated.

Outlook: A cold front may bring precipitation and associated restrictions Thursday night into Friday, mainly over the mountains.

GSP WATCHES/WARNINGS/ADVISORIES

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