The NWS actually mentions both scenarios. In other words they have no idea lol Intense isentropic lift atop the cold dome combined with anomalously moist air (PWATs of about 1"...in ~the 90th percentile of daily climatology)...followed by strong/focused ascent along a frontal boundary Sunday afternoon/evening will result in impressive storm total liquid equivalent precip...with 2-3 inches forecast across the mountains of southwest NC, SC, and northeast GA, and generally 1.5-2" elsewhere. Strong warm advection aloft will establish a warm nose that will eventually (a) support a transition from sleet to freezing rain from SW=>NE and ( allow for the valleys of far southwest NC...which will only be weakly affected by CAD...to warm above freezing. The first main forecast challenge is timing the transition to freezing rain. Forecast soundings become quite warm (+5C or more) aloft rather quickly tonight, suggesting a quick transition to FZRA. However, the cold layer at the surface is cold and deep enough to perhaps allow for some refreezing of hydrometeors before they hit the surface. However, this is far from a given...and it lends modest confidence to our ice/sleet accum forecast going forward. Nevertheless, most of the precip is expected to fall as freezing rain such that much of the CWA is expected to see storm total ice accums of 0.5-0.75." An exception on the higher end (0.75-1.0" with locally higher amounts) is forecast along the Blue Ridge escarpment...where the greatest alignment of persistent cold air and higher liquid equivalent is forecast. These amounts are expected to extend across the foothills of SC into the Greenville metro area as well. Widespread downed trees/lines and power outages are expected to be most concentrated in this area. On the lower end, a gradual transition to rain is expected along the southern and western periphery of the CWA during Sunday afternoon due to the synoptic pattern quickly becoming unfavorable for maintenance of cold air damming. This will occur as the upper flow pattern becomes phased...with a long wave trough being carved out over the eastern Conus and an upper ridge quickly building off the East Coast, resulting in cessation of confluent flow and allowing the weakening parent high to move far north into Quebec and become detached from the inverted ridge CAD ridge. The wind field responding to a developing coastal low will provide an additional erosion mechanism. As such, ice totals across the SC Lakelands and vicinity are expected to be in the 0.25-0.5" range, while the valleys beneath the Smokies may struggle to reach 0.25." In summation: forecast ice totals could be too low by 0.1-0.25" if the transition from sleet->freezing rain occurs significantly earlier than currently anticipated. Forecast totals could be too high along and south of the I-85 corridor if CAD erosion is more aggressive than currently forecast. Finally, locally excessive rainfall will be possible across mountainous areas where the transition to rain occurs Sunday afternoon...with the strong frontal band (where an isolated elevated thunderstorm cannot be ruled out) likely providing the tipping point to some minor runoff issues developing late afternoon/evening. .