textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No changes to Cold Wx Advisory at this issuance. We retain a Special Wx Statement for the entire forecast area to highlight widespread black ice and hazardous road conditions into Monday morning.

Updated overnight temp trends primarily based on latest NBM, which appears reasonably on track.

Updated aviation discussion for 00z TAFs.

KEY MESSAGES

1. Lingering snowpack combined with cold temperatures will lead to black ice as well as very cold wind chills through Monday morning. Black ice will lead to hazardous road conditions and very cold wind chills could result in hypothermia or frostbite if precautions are not taken. 2. Temperatures gradually warm through early week with dry conditions returning across the region. Precipitation chances return by mid week.

DISCUSSION

Key message 1: Lingering snowpack combined with cold temperatures will lead to black ice as well as very cold wind chills through Monday morning. Black ice will lead to hazardous road conditions and very cold wind chills could result in hypothermia or frostbite if precautions are not taken.

Dry high pressure lingers over the region through Monday night keeping dry and cold conditions around. Temperatures will remain below freezing across most locations through Monday morning before rising above freezing Monday afternoon. However, higher elevations in the North Carolina mountains will likely see temperatures remain below freezing through Monday night. Sunshine was effective in melting snow in many areas earlier this afternoon. However, once the sun sets, any moisture left behind will quickly refreeze onto roads, parking lots, sidewalks, driveways, bridges, and overpasses this evening into tonight leading to widespread black ice through Monday morning. Special Weather Statement highlights this possibility across the CWA. If traveling, be prepared for hazardous road conditions, especially on bridges and overpasses as well as on untreated roadways. Use extra caution when walking on sidewalks, driveways, and in parking lots.

Gusty winds still being reported in higher mountain elevations and at Asheville airport, but those gusts are expected to taper off gradually through the evening. Temps managed to warm more than expected in much of the CWA, even in the I-77 corridor where most places started the day with 8-12" of snow depth. With the diminishing winds, however, the combination of radiational cooling and the snowpack will result in a night similarly cold to last night, and likely 2-4 degrees colder east of the mountains where winds calm.Cold temperatures combined with lingering wind gusts will allow very cold wind chills of 5 to 12 degrees below zero to develop this evening into Monday morning across the northern and central North Carolina mountains, with most locations still seeing wind chill below -5 even after winds weaken late in the night. Thus, a Cold Weather Advisory still in effect for these zones from 6 PM this evening through 9 AM Monday. With temperatures expected to fall into the single digits to lower teens leading to wind chills as low as 5 degrees, a Cold Weather Advisory was also issued for the North Carolina foothills and Piedmont as well as the southern and eastern South Carolina Upstate from 6 PM this evening through 9 AM Monday. Wear appropriate clothing, a hat, and gloves. Make frequent checks on older family, friends, and neighbors. Ensure portable heaters are used correctly. Do not use generators or grills inside.

Key message 2: Temperatures gradually warm through early week with dry conditions returning across the region. Precipitation chances return by mid week.

Flat shortwave ridging will be translating across the Ohio Valley and the Appalachians by Tuesday morning while a piece of Pacific energy dives down the eastern flank of a tall west coast ridge. This will carve out a positively tilted trough over the Southern Plains with a broad zone of southwest flow extending from the Gulf states into the Carolinas. A surface cold front will also be dropping across the Midwest and into the Ohio Valley/Tennessee with a broad zone of precipitation ahead of the boundary. The leading edge of the precipitation encroaches on the mountains late Tuesday evening where rain chances are the highest. Guidance has come into better agreement with struggling to maintain much coverage of precipitation east of the mountains as the positive trough orientation and lack of stronger forcing and a well developed surface low will prove hostile to maintenance of the precipitation band. Guidance has also trended warmer with overnight temperatures with even fewer ensembles members cold enough for wintry weather east of the mountains, the majority of which remain dominated by the GEPS. Thus, will confine any rain/snow mix to the mountains with just rain elsewhere. A few members of guidance have hinted at the potential for a surface low to try and develop along the coastal baroclinic zone Wednesday night as the main trough axis crosses the region. There are also indications that an inverted surface trough may extend up I-26 from the coast. Guidance that favors this solution attempts to blossom another bout of anafrontal precipitation into cold air overnight into Thursday morning. This is a very low confidence scenario, so will keep the forecast to just rain and then drying. Temperatures make a run at returning to near seasonal average by late week.

AVIATION /00Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Dry and VFR through Monday evening. Gusts are on a decreasing trend over the NC mountains but saw fit to retain gusts at KAVL thru 05z. Some other sites had already dropped gusts as of the 00z TAF issuance time and some appear to already be decoupling with direction becoming erratic if not outright VRB. KCLT does look likely to remain light NW overnight, but at the remaining sites (other than KAVL) allowed VRB at some point. All sites except KAVL pick up from the SW by mid-morning Monday; with only 3-4 kt winds expected at KHKY let the VRB ride thru the end of the period there. A few cirrus will drift in overnight with some midlevel clouds at 070-090 also seen Monday; at KAVL a few lower VFR clouds also expected.

Outlook: Dry and VFR through Tuesday. A cold front brings precipitation and associated restrictions back Tuesday night into late Wednesday.

CLIMATE

RECORDS FOR 02-01

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 74 1950 22 1898 55 1950 4 1909 KCLT 76 1950 27 1900 55 1896 10 1900 KGSP 73 1957 30 1980 56 1969 9 1900 1936 1950 1916

RECORDS FOR 02-02

MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 76 1989 16 1908 52 1988 -2 1917 KCLT 80 1989 29 1908 61 1923 10 1917 KGSP 77 1989 28 1951 60 1923 9 1900

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...Cold Weather Advisory until 9 AM EST Monday for NCZ033-035>037- 049-050-053-056-057-065-068>072-082-501>510. SC...Cold Weather Advisory until 9 AM EST Monday for SCZ008-009- 011>014-019-103-106>109.