I feel NWS-GSP worded this spot on:
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 230 PM Monday: No major changes to the overall forecast from
the 12z guidance. If anything, they continue to trend a little
slower/delayed on the onset of precip, and also a little heavier in
QPF. The 12z ECMWF has come in more northerly/inland with the sfc
low track, and results in warmer thicknesses across the FA thru the
event. This allows a stronger warm nose, and perhaps, more of a
mixed bag of p-types, versus more ra/sn that previous runs
suggested. I opted to blend a little 12z ECMWF into the partial
thickness p-type nomogram tool for this forecast. Still get a lot of
snow in the mountains and the I-40 corridor with this solution, but
if the new ECMWF trend holds, these values will likely be a lot
lower, due to the sleet/frza mixing in. With all that said, it still
looks like a significant winter storm on tap for most of the
mountains and adjacent foothills in NC, while the Piedmont south of
I-40 is highly uncertain. Temps will start out below normal Friday,
as a reinforcing cold front pushes thru. Then classic cold air
damming sets up Friday night thru Sunday, as a strong sfc high
builds in across the Ohio Valley to the Mid-Atlantic. The heaviest
precip looks to be mainly Saturday night into early Sunday, but that
time may change slightly as we get closer to the event. Temps will
be tricky with the CAD. I stuck close to WPC, but these may be too
warm within the heart of the CAD wedge.