textproduct: Greenville-Spartanburg

SYNOPSIS

Dry 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 the weekend and into early next week.

NEAR TERM /THROUGH TUESDAY/

As of 1245 PM EST Monday...

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

Upper trough and associated surface wave will continue tracking across the GSP forecast area through the early evening hours before pushing east late this evening. This will keep snow chances around across the mountains through the late afternoon/early evening hours. Additional snowfall amounts of 1 to 2.5 inches can be expected for locations in the Winter Weather Advisory. Elevations above 3,500 feet outside the advisory can expect an additional 0.5 to 1 inch of snowfall. Highs across of the mountains will end up ~10-15 degrees below normal thanks to cloud cover sticking around.

Key Message 2: Cold rain will linger across the North Carolina mountain valleys, foothills, and Piedmont through late this afternoon with some sleet or snow may mixing in at times.

Dry conditions should continue across northeast Georgia and the South Carolina Upstate the rest of today. With temperatures expected to remain above freezing across the North Carolina mountain valleys, foothills, and Piedmont, the cold rain will continue through late this afternoon. Still have the chance to see some sleet and/or wet snow mix in at times across the North Carolina foothills and Piedmont, with snow possibly blowing down into the mountain valleys at times. However, only light (if any) accumulation is expected. Highs east of the mountains will also end up ~10-15 degrees below normal thanks to thick cloud cover.

Key Message 3: Drier conditions return this evening into tonight but slippery roads will be a concern through Tuesday morning for areas that received accumulating snowfall.

Surface high pressure gradually builds in from the north tonight bringing drier and colder conditions. With temps expected to fall (or remain) below freezing, slippery road conditions will be a concern for the evening and morning commutes across areas that received accumulating snowfall. An SPS may need be issued later this afternoon to account for possible hazardous road conditions this evening into early Monday morning. Cloud cover will gradually thin out through the overnight hours allowing temps to drop below freezing area-wide tonight. Lows will end up ~5-10 degrees below normal.

Key Message 4: Dry and cool conditions expected on Tuesday with gradually diminishing cloud cover.

Temperatures will rise above freezing by mid to late morning Tuesday for most locations allowing the concern for slippery roads to diminish. Surface high pressure will remain over the GSP forecast area keeping dry and cool conditions around for Tuesday. Although cloud cover will gradually thin out throughout the day (we will finally get to see sunshine), highs will remain ~10-15 degrees below normal area-wide. Highs will only reach into the upper 30s to upper 40s across the mountain valleys and east of the mountains. Highs across the higher elevations will range from the lower 30s to lower 40s.

SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/

Key Messages:

1) Winds pick up on Wednesday, especially over the mountains.

2) Mostly dry and near normal temps.

As of 1210 PM EST Monday: The short term looks mostly quiet with the exception of minimal precipitation chances and wind. A more typical winter pattern continues with a strong high off the west coast, creating NW flow aloft across the the eastern CONUS. On Wednesday, a strong area of low pressure churns over Canada as a second, weaker low spins off toward the south. Current guidance brings this low further south, increasing the chances for windy conditions. This tighter pressure gradient looks to go right over the CWA. A speed max embedded in the general flow, looks to maximize Wednesday into Wednesday night before exiting the area. At this time, guidance has a 40-50% chance of wind gusts greater than 45 mph at the higher elevations of the mountains. This would be right about Wind Advisory Criteria, so there is a possibility one would be needed. Confidence is increasing on wind gusts of 35 mph or greater as the chances also tick up into the 50-60% range across the NC mountains. Will continue to monitor. As for precipitation, the better news is guidance is coming in much drier as the persistent trough starts to recede northward, keeping the stints of advancing DPVA further north. So, the potential for a cold front is almost completely gone, meaning winter weather chances have also decreased. There is a slight chance (15-30%) that a brief burst of snow along the TN/NC border is possible Wednesday night, but confidence is low. IF anything falls, there is a 10-15% chance of snow amounts greater than 0.01 inch. Additionally, this means the colder temps that were in previous guidance has now pushed further into the next period. Temperatures Wednesday and Thursday look to be near normal.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

1) Snow chances over the NC mountains Thursday night into Friday are decreasing .

2) A potential colder period toward the end of the weekend with temperatures about 15 degrees below normal.

As of 1220 PM EST Monday: By Friday, the NW flow aloft remains locked in for the extended. However, guidance has changed and brings the better flow northward, keeping the CWA out of the main show. At the surface, the colder air looks to also be much slower breaking out of Canada and spilling into the U.S. This also keeps the temperatures near normal through at least Saturday, before dipping. As for any precipitation chances, this has also drastically changed. The highest PoPs are for the TN/NC border on Thursday and Friday nights and those are capped at slight (15-30%). If temperatures are cold enough and there is any surface moisture lingering, there could be a brief burst of snow at the highest elevations. Some of this may linger into Friday but confidence continues to increase that there won't be any impactful winter weather. Current probabilities for snow amounts greater than 0.01 inch are less than 20%, and this is mainly at the highest peaks. So, all in all, the winter weather chances are plummeting and a quieter period is starting to emerge. This still needs to be evaluated as any shift of the main flow aloft could be the difference between quiet weather and increasing precipitation chances.

AVIATION /18Z MONDAY THROUGH SATURDAY/

At KCLT and elsewhere: Restrictions are ranging from VFR to IFR across the western Carolinas as of 18Z. Restrictions are expected to stick around through much of the TAF period, with very little improvement through daybreak Tuesday. Restrictions will start to lift after sunrise on Tuesday with VFR returning across all terminals by the late morning or early afternoon hours. Patchy fog should develop around daybreak Tuesday before lifting by mid- morning. The SC terminals will see dry conditions continue through the 18Z TAF period, while precip chances linger across the NC terminals through late this afternoon. Some -SN could blow down the valley at KAVL but confidence is too low to mention at the terminal so went with -RA for now. KHKY has the best potential to see a -RASN mix this afternoon so have this accounted for at the terminal. -RA is expected at KCLT this afternoon. Wind direction will be NE east of the mountains through early Tuesday morning before winds gradually turn S/SSW mid-morning to early afternoon Tuesday. Winds at KAVL will be N'ly through tonight, toggling S'ly around daybreak Tuesday.

Outlook: Dry high pressure lingers through Wednesday. NW flow precip may develop along the NC/TN border Wednesday night and again Thursday night 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.