textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Precipitation amounts continue to trend lower for the mountains, with little to no precipitation outside of the mountains.

Overnight temperatures Friday and Saturday night are trending colder.

Updated aviation section for 18Z TAF issuance.

KEY MESSAGES

1. Precipitation chances increase Wednesday night and linger into Friday night across the mountains. Temperatures turn cold enough for snow, mainly across the higher elevations along the Tennessee border. 2. Gusty winds and colder temperatures linger behind a strong cold front Thursday through the weekend.

DISCUSSION

Key message 1: Precipitation chances increase Wednesday night and linger into Friday night across the mountains. Temperatures turn cold enough for snow, mainly across the higher elevations along the Tennessee border.

High pressure remains over the area through Wednesday before a pattern flip. High temperatures remain about 10 degrees above normal through Wednesday with lows tonight slightly warmer as moisture returns ahead of the approaching system.

The pattern change emerges as a ridge builds in 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 into Friday. Guidance has continued to bob and weave on the precise location of the low, but regardless of the exact spot, a cold front is anticipated to cross the area as it lifts northward. Model guidance has trended drier east of the mountains with <15% PoPs Thursday and Friday. Attention swings to the mountains as the coldest air of the season looks to be ushered in as a strong cP airmass plunges southward from Canada. 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, as the system draws closer, trends are not favorable for snow lovers as guidance decreases the overall snow accumulations. Current trends depict the probability of snow totals exceeding 2" from Thursday night into Friday night at 30-50%, with the highest chances likely in the Smoky Mountain National Park. One reason for this decrease in snow amounts is guidance on moisture lingering at the ridgetops. If there is more than models grasp, expect an uptick in snow amounts and if moisture is less, expect less snow. But, mechanical lifting over the mountains can sometimes surprise and lead to additional snow. Either way, forecaster confidence is medium and decreases the likelihood of issuing a Winter Weather Advisory at this time, should snow amounts remain under 2". This can change, depending on where the low sets up. Overall, locations along the NC/TN border could see snowflakes and a few areas may have a small amount of measurable snow.

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

The strong trough digging over the eastern CONUS keeps the CWA within a tighter gradient, keeping gusty winds throughout the area from Wednesday night through most of the weekend. At this time, guidance keeps winds 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 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.

Additionally, the strong area of high pressure spilling in from Canada brings the coldest temperatures so far this season. Trends are favoring slightly colder overnight temps Friday and Saturday night, increasing confidence for a widespread freeze. The coldest night looks to be Saturday night with guidance hinting at overnight lows in the very low 30s and 20s (NC Piedmont and mountains). 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 November 11 and no freeze products will be issued for any part of the CWA afterwards.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

At KCLT and elsewhere: VFR conditions prevail at all terminals through the TAF period. Winds through 12z become VRB and at times calm. KCLT should pick up out of the S/SW Wednesday afternoon. Intermittent SKC or FEW/SCT250 into the evening and overnight. Other than that, no vsby or cig restrictions.

Outlook: A cold front may bring precipitation and associated restrictions Wednesday night into Friday.

GSP WATCHES/WARNINGS/ADVISORIES

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