textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated for new Aviation Discussion.

KEY MESSAGES

1. Mainly dry cold air damming continues through Tuesday. Spotty light rain possible possible across mainly North Carolina this evening. Patchy drizzle possible any location overnight and Tuesday morning. 2. Cold air damming finally erodes on Wednesday allowing much warmer and well above normal temperatures to return for the rest of the week. Trending drier through Friday before shower and thunderstorm chances return this weekend, but confidence is low.

DISCUSSION

Key message 1: Mainly dry cold air damming continues through Tuesday. Spotty light rain possible possible across mainly North Carolina this evening. Patchy drizzle possible any location overnight and Tuesday morning.

A mainly dry cold air damming event continues across the area. Lower clouds have been more spotty as well given the drier onset. There has been some spotty light rain across the NC mountains, and more may return through the evening for mainly our North Carolina locations. Generally dry for the Upstate and NE GA. That said, patchy drizzle is possible at any location overnight and Tuesday morning with continued influx of low level moisture and weak isentropic lift. Despite some breaks in the clouds early, expect low clouds to spread back across the area as well. Patchy fog is possible, but less likely than during a wetter CAD event. Lows tonight will be around 5 degrees above normal, with no freezing precipitation expected.

The CAD should linger well into Tuesday, but clouds may scatter out during the late afternoon with little to no precip to lock it in place. Still, given the cloudy skies expected for the bulk of the day, undercut the guidance blend for highs, but not nearly as much as if there were precip falling. The highs are only slightly below normal outside of the mountains and a few degrees above normal across the mountains.

Key message 2: Cold air damming finally erodes on Wednesday allowing much warmer and well above normal temperatures to return for the rest of the week. Trending drier through Friday before shower and thunderstorm chances return this weekend, but confidence is low.

In-situ cold air damming lingers through Wednesday morning before finally eroding Wednesday afternoon. Upper ridging will build across the Southeast while the southwestern periphery of a surface high centered over the western Atlantic remains extended over the region through the weekend. This will allow low-level southwest flow to develop, leading to an influx of moisture from the gulf through the period. Thus, much warmer and well above normal temperatures can be expected mid to late week. The NBM is trending warmer for highs each afternoon, allowing for higher probabilities of temperatures reaching the 80 degree mark east of the mountains Thursday into the weekend. The NBM now shows a 20 to 35 percent chance of highs exceeding 79 degrees for most locations east of the mountains on Thursday, increasing to 50 to 80 percent Friday into the weekend. Shower and thunderstorm chances will return as well, mainly this weekend, as the latest NBM is trending drier for Thursday and Friday. However, the NBM is also trending lower regarding PoPs this weekend, so confidence on diurnal convection over the weekend remains low.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

At KCLT and elsewhere: We are still dealing with a dry cold air damming wedge across most of the region early this evening, with patches of light precip falling out of a mid-level ceiling but not reaching the ground. Guidance continues to show the redevelopment of a low cloud ceiling restriction during the middle to late evening as the easterly flow at low levels becomes more productive. Whether or not this will take the form of a cloud deck over the Coastal Plain moving in from the east or new development right overhead remains to be seen, but all terminals get a prevailing MVFR by around 05Z. At the moment, the guidance only drops the ceiling into the lower part of MVFR, possibly because extensive precip is not expected. Will not include any IFR-level restrictions, but it is within the realm of possibilities and will be evaluated for future amendments. If more precip develops than expected, it would result in a higher chance of IFR. Wind will be NE across the region thru most of the overnight hours. The ceiling restriction will be with us through the early to middle part of the afternoon on Tuesday and will finally start to break up as sfc winds veer around to ESE or S by late afternoon.

Outlook: VFR is expected to return on Wednesday, while another cold front may bring showers and associated restrictions for the weekend.

GSP WATCHES/WARNINGS/ADVISORIES

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