textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No significant changes for this forecast.

KEY MESSAGES

1. NW snowfall is expected to begin later tonight and continue into Saturday morning across the higher elevations along the Tennessee border. 2. Expect gusty winds and colder temperatures behind a strong cold front beginning today and lingering through the weekend.

DISCUSSION

Key message 1: NW snowfall is expected to begin later tonight and continue into Saturday morning across the higher elevations along the Tennessee border.

A significant, large-scale pattern change will begin today and persist thru the weekend as steep upper ridging builds over the western CONUS and broad/deep upper trofing develops downstream over the eastern CONUS. At the same time, a sfc low develops over the Ohio/TN Valley and tracks NE today/tonight. An associated cold front is expected to cross our fcst area and bring the coldest air of the season in its wake. Although the majority of the moisture will mostly mix out with the addition of the drier air, NW flow winds and lingering low-level moisture along the NC/TN border in- creases the chances for the season's first snow. The bulk of the latest model guidance doesn't appear to have changed significantly wrt QPF and/or snow amounts over the impacted areas. Nonetheless, some amount of instability within the snow growth zone is possible over the higher elevations along the NC/TN border region. If this materializes, those areas can expect increased snowfall rates as the cold air is mechanically lifted over the terrain. However, given the warmer temperatures leading up to this event, some of the snow could melt early on leading to less accumulations. At present, expected snowfall totals along the NC/TN border are still in the 0.1" to 3" range for most locations, with isolated higher amounts. The highest amounts still appear most likely over portions of Smoky Mountain National Park. The issuance of a Winter Weather Advisory is not expected as most locations should receive less than 2" of snow.

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

A broad/deep upper trof will remain over the eastern CONUS over the next few days. At the sfc, a robust cP airmass steadily spreads over our area bringing the coldest air so far this fall. This airmass will keep most of the southeast dry and considerably cooler/colder. Trends continue to favor cold overnight temperatures Friday and Saturday night, increasing the likelihood for a widespread freeze across our fcst area. The coldest night is still expected to be Saturday night with temps dipping into the 20s to low 30s across our CWA. Although some warming is expected, the general trend for temperatures for the remainder of the fcst period remains below normal for mid-November. As a reminder, the growing season is considered over as of November 11 and no freeze products will be issued for any part of our CWA going forward.

In addition, the above-mentioned robust upper trof digging over the eastern CONUS will keep gusty winds over our area thru most of the weekend. At this time, the latest guidance still keeps wind gusts below Wind Advisory criteria across our area. However, this could change depending on how far south the trof reaches and where the stronger wind/pressure gradient sets up. Should the gradient become tighter, wind speeds could increase. Higher peaks and ridgetops have a better chance of seeing 40 to 50 mph wind gusts. Elsewhere, gusts should be weaker.

AVIATION /06Z THURSDAY THROUGH MONDAY/

At KCLT and elsewhere: VFR conditions should prevail at all terminals through the TAF period. That being said, we are watching a band of rain with a few embedded thunderstorms moving east across the TN Valley at issuance time. The model consensus and radar trend supports the idea that the precip would gradually weaken as it moves east quickly across our region through the pre-dawn hours. Some brief MVFR vis restrictions have been seen where precip was heaviest, but the lowest clouds have generally been just above the MVFR threshold. Will include a brief PROB30 at most terminals to account for this, but with no MVFR restrictions yet. Will amend from there if it looks like precip is more likely to impact a terminal or if restrictions are more likely. After this pre-frontal wave passes, wind remains SW and the mostly mid-level ceilings will scatter out. With some daytime heating, expect frequent gusts from mid-morning onward ahead of the cold front. The front is expected to move across the region during the late morning and early afternoon with a gradual wind shift to WNW while frequent gusts continue. The gusts should diminish with sunset in most places. At KAVL, low clouds forced by the NW flow on the TN side of the mtns will eventually move up the valley to form a VFR-level broken ceiling, probably by late afternoon. Expect that as the NW flow gets more productive after midnight, an MVFR restriction will be seen toward daybreak on Friday, which is still outside this TAF period but will be considered for the next issuance.

Outlook: Lingering northwest flow showers and snow showers will impact the mountains behind the front from daybreak Friday through Saturday morning, but should remain confined to the Tennessee border with no impacts expected at KAVL.

GSP WATCHES/WARNINGS/ADVISORIES

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