Southern stream shortwave over the Lower MS Valley Saturday evening
will eject east-northeast across the Southeast US through Sunday
night. At the surface, attendant sfc low traversing the Gulf Coast
States on Saturday will re-organize off the SE coast Sunday and
Sunday night before moving out to sea on Monday. Preceded by a
strong cold Arctic high that will build into the area from the north
Saturday and Saturday night, there is still high confidence that a
significant winter weather event will unfold across central NC late
Saturday night and Sunday, with the potential for some lingering
light precipitation Sunday night as the next shortwave trough
approaches the area from the west.
Forecast confidence in snow amounts are highest along and north of
the I-85, including the Triad, where the strong CAD High to our
north and associated diabatic cooling will keep the low-level cold
air locked in place and where the warm nose will be less prominent.
So after a potential brief mix at onset Saturday night, the
predominate p-type will be mostly snow through late Sunday afternoon
and evening, transitioning to a light freezing rain/drizzle, once we
loss saturation aloft and lift/forcing begins to weaken. Have kept
snowfall amounts in the 8 to 12 inches range, with the bulk of this
falling between 4 am to pm Sunday. An additional 0.10" of ice from
light freezing rain/drizzle on top of the snow is possible. Given,
this is the area where confidence is highest, will upgrade the
winter storm watch to a warning across the far NW Piedmont counties,
including Person County.
Just east of this heavy snow area(south and east of I-85) and west
of Interstate 95, given the potential for the warm nose aloft to
support multiple p-types throughout much of the event, forecast
confidence in snow amounts are much lower in this area, which would
greatly cut-back on snow accumulation. However, the latest 12 km NAM
has trended colder both in the low-levels and aloft across the
central/northern Piedmont, as well into the northern coastal Plain.
Given the colder thermal profiles, snow and sleet could now linger
into afternoon/early evening, before changing over to freezing
rain/drizzle with loss of saturation and lift aloft Sunday
evening/night. Have expanded the Winter Storm Watch east to include
areas west of I-95. Snowfall amounts of 3 to 6 inches are possible,
with expectations of a sharp cut-off along the eastern edge of these
area. IF the warm air aloft is indeed stronger than advertised, the
impacts across this area will still be great, with the potential for
ice accumulations from freezing rain of 0.10-0.20" possible.
Finally, for areas east of I-95 and across the far se counties, rain
Saturday night/Sunday morning could briefly mix with sleet and
freezing rain before changing over to rain. At this time, snow and
ice amounts are expected to be light. As such, will be omitted from
Temperatures: Lows Saturday night in the upper 20s NW to mid 30s,
with only a 2 to 3 degree recovery expected on Sunday. Lows Sunday
night very similar to Saturday night. Thus any snow and ice on roads
and surfaces will linger through Monday.