textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Aviation discussion updated to reflect latest 18z TAF issuance.

No changes to any of the Wind or Cold headlines at this hour. Increased Fire Danger statement still in effect for NE Georgia today, 11 AM to 7 PM EST.

Minor changes were made to the forecast Wednesday and beyond, but the general trend toward wetter conditions through the end of the week remains the same.

KEY MESSAGES

1. The High Wind Warning/Wind Advisories remain in effect till 7 PM this evening. Damaging wind gust potential remains high early this afternoon, but will gradually taper off through the mid/late afternoon. Thee conditions may knock down tree limbs and cause power outages. 2. A Cold Weather Advisory remains in effect for portions of the North Carolina mountains through early Sunday morning as dangerously cold wind chills could result in hypothermia or frostbite if precautions are not taken. 3. This week starts off warm as a moisture-rich air mass settles in from the south. Rain chances arrive by Wednesday and continue through the end of the week.

DISCUSSION

Key message 1: The High Wind Warning/Wind Advisories remain in effect till 7 PM this evening. Damaging wind gust potential remains high early this afternoon, but will gradually taper off through the mid/late afternoon. Thee conditions may knock down tree limbs and cause power outages.

The latest HRRR suggests that we are past the worst of the wind gust potential as of 16Z, but observations continue to show several places where Advisory-criteria gusts were lingering. The 850mb flow should continue to diminish through the afternoon, but deep enough mixing will keep the afternoon blustery. Because of the lingering threat, the Warning/Advisory will be allowed to continue for the time being, though it appears it could probably be cancelled by late afternoon.

Key message 2: A Cold Weather Advisory remains in effect for portions of the North Carolina mountains through early Sunday morning as dangerously cold wind chills could result in hypothermia or frostbite if precautions are not taken.

High pressure is still expected to settle down over the central Appalachians and upper Ohio Valley tonight, while a NW flow aloft gradually weakens. Another shot of stronger mid-level flow late tonight and weak DPVA will bring some mid-level cloudiness across the region after midnight that will help to hold in some heat, so low temps tonight have trended back up a bit, though still plenty cold and on the order of 15 degrees below normal. Because of the upward trend, it looks like less of the mountains will reach Cold Weather Advisory criteria wind chill, so really only elevations above 5000 feet are at risk. Nevertheless, the Advisory is already out there, so we might just as well let it ride in the event that clouds thin out and lows drop below forecast. This looks like the last really cold night for the next week or so.

We would be remiss if we didn't mention that the passage of the aforementioned mid-level forcing might allow some light snow activity to break containment over southwest VA/northwest NC and then brush past the NW Piedmont zones Sunday morning. A slight chance of light snow was added mainly to Davie County, with flurries elsewhere to the NW Piedmont and areas N and NE of metro Charlotte. After the last few events, this should not be a big deal, if any flakes even manage to make it through the very dry boundary layer to reach the ground.

Key message 3: This week starts off warm as a moisture-rich air mass settles in from the south. Rain chances arrive by Wednesday and continue through the end of the week.

Still expecting above-normal temperatures to continue through the first half of the new workweek, as the intrusion of higher-theta-e air from the Gulf Coast results in anomalously high thicknesses and an increase in moisture across the region. Deterministic guidance depicts sustained but mostly weak low-level moist WAA persisting Monday through Wednesday beneath dry northwest flow in the mid- to upper-levels. The result will be increasingly thick low-level clouds by Monday night and early Tuesday, and more to the point, temperatures several categories above climo...with highs reaching the mid-60s on Tuesday, and potentially even the upper 60s by Wednesday.

Rain chances will begin to increase on Wednesday as a compact upper trough interacts with low-level moisture across the region and spurs at least scattered light showers for much of the forecast area. Models depict a boundary layout out somewhere to our south and remaining stagnant there through the end of the week. Meanwhile, a stout surface high will migrate out of the Great Lakes into the Upper Ohio Valley. It won't quite be positioned properly for a true cold-air damming event, and will instead drive a weak reinforcing backdoor-ish cold front across the area through Thursday, further drying the boundary layer while low-level flow becomes increasingly nebulous.

Ensembles depict one or two more weak embedded shortwaves diving out of the Ohio Valley and into the Carolinas through next Saturday, resulting in periods of activation along the remnant boundary to our south, accompanied by periods of mostly light rain across the region. From a pattern-recognition standpoint, there could be some potential for visibility issues and low cloud cover during this period, but model profiles keep the low-levels unusually dry for this type of setup. By Friday night, long-range ensembles favor the high becoming centered somewhere between eastern Ohio and the Long Island coast, making for a marginally-better CAD setup and helping to further drop temperatures toward the end of the week. If there's enough surface CAA within the developing surface ridge, we could wind up with potential for frozen p-types again Friday night into Saturday morning for parts of the forecast area...but at this point in time, model consensus barely exists, and confidence is extremely low.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

At KCLT and elsewhere: VFR expected at all terminals through the period, but with frequent strong wind gusts from the NW to N lingering through the afternoon. After sunset, we should lose the gusts altogether as high pressure builds in. Wind may go light NE this evening before becoming light/variable at most terminals overnight. A passing wave should bring a mid-level cloud deck overhead late tonight and Sunday morning. There is an outside chance of some brief snow flurries at KHKY and KCLT, but indications are that any light snow that reaches the ground will probably miss both terminals and remain confined to the northwest Piedmont or Triad.

Outlook: Dry, VFR conditions are expected through Monday. Moisture will return during the middle part of the week, which could result in some ceiling restrictions.

GSP WATCHES/WARNINGS/ADVISORIES

GA...Wind Advisory until 7 PM EST this evening for GAZ010-017. INCREASED FIRE DANGER until 7 PM EST this evening for GAZ010- 017-018-026-028-029. NC...Wind Advisory until 7 PM EST this evening for NCZ035>037-048- 051-052-056>059-062-068>072-502-504-506-508-510. High Wind Warning until 7 PM EST this evening for NCZ033-049- 050-053-063>065-501-503-505-507-509. Cold Weather Advisory until 7 AM EST Sunday for NCZ033-048>052- 059. SC...Wind Advisory until 7 PM EST this evening for SCZ008-101>106- 108-109.