Raleigh NWS has a great discussion. Still saying it's too early to know anything for certain yet.
LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 455 PM Saturday...
* Forecast confidence remains high for a continuation of well below
average temperatures this period, maximized with departures from
normal of 15-25 F mid-week.
* Forecast confidence is low regarding the northern extent of
(wintry) precipitation across cntl-ern NC, as generally
flat/suppressed/weak low pressure tracks from the Gulf of Mexico to
well offshore the South and southern Middle Atlantic coasts Tue-
early Wed.
A highly amplified mid/upr-level pattern will be characterized by a
ridge over the ern Pacific and mean troughs that will pivot across
the cntl-ern US. The first of those troughs, and most influential
for the threat of wintry precipitation (snow) into cntl NC, will be
a positively-tilted and at least partially phased trough that will
extend from the upr Great Lakes to the Southwest at 12Z Tue and
pivot across and offshore the South and srn Middle Atlantic through
Wed. It should be noted that the most-basal of those shortwave
perturbations just entered the North American RAOB network near
Annette Island and Yakutat, Alaska this morning. Further sampling of
this feature across wrn British Columbia and the Pacific Northwest
through 12Z Sunday may better resolve its presence and downstream
synoptic influence and ultimately decrease above average model
spread in solutions of its impact to srn US wintry weather Tue-Tue
night. The other shortwave perturbations forecast to comprise the
positive-tilt trough should also become better-resolved for model
initial conditions, as they dig sharply ssewd from the Northwest
Territories and Yukon to the cntl Canadian Prairies. Low amplitude
shortwave ridging will then progress across and offshore the Middle
and South Atlantic later Wed-Wed night, downstream of a trough that
will reload and pivot from the Great Plains and MS Valley to the
East Coast through Sat.
At the surface, Arctic high pressure will initially sprawl from the
cntl Great Basin to the Middle Atlantic, then gradually weaken as it
migrates ewd and becomes centered over the Middle Atlantic through
the end of the week. A frontal zone will be suppressed well-
southward across the sub-tropics, from the Gulf of Mexico to the
swrn N. Atlantic, along the srn/equatorward drape of the expansive
Arctic high and airmass through mid-week; and model agreement is
relatively high regarding only weak/flat frontal wave development
along that frontal zone from the Gulf of Mexico to offshore the
South Atlantic coast Tue-Tue night. While some models depict more
substantial deepening of the low as it tracks between Cape Hatteras
and Bermuda, any such development and deepening would be too late
and inconsequential for significant impacts to cntl NC. The
aforementioned re-loading of the trough aloft initially into the
cntl US may allow the surface frontal zone and subsequent
cyclogenesis to buckle poleward and nearer the Middle Atlantic and
srn New England coasts later in the week, with possible additional,
low confidence precipitation impacts into cntl NC.
The previously very wet solutions on the extreme nwrn edge of the
guidance envelope, led by the GEM and GEPS, have trended southward
and drier and now form a strong consensus cluster of guidance with
EPS solutions of the past couple of days. While this cluster
appears to be a favored and reasonable solution for measurable snow
and low to moderate impacts across e-cntl NC, the much drier and swd-
suppressed GFS and GEFS solutions have support of the EC-AIFS and
produce very little snow into cntl and even sern NC. Forecast
confidence consequently remains below average at this time.
