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Area Forecast Discussion
National Weather Service Blacksburg VA
802 PM EST Fri Dec 2 2016

High pressure will continue to build in from the southwest through
Saturday with seasonably cool temperatures. Weather pattern then
turns more active Sunday as a weak disturbance moves northeastward
from the Gulf Coast. A wetter storm system then moves in for Monday
night and Tuesday. A strong cold front trailing the second
system will usher in below normal temperatures through mid late
next week.


As of 336 PM EST Friday...A relatively cool afternoon with a
variable degree of cloud cover across the area. Conditions range
from clear skies across the southside of Virginia and the NC
piedmont/northwest NC mountains to persistent overcast
stratocumulus across the Alleghany Highlands, southeastern West
Virginia into northern Tazewell County VA. On the large scale, we
remain in confluent mid- level flow between an upper trough
extending from Quebec into IL/IN and building heights across the
Deep South...with northwesterly gradient flow across a large part
of the central Appalachians.

For tonight...925-700 mb cold advection in the northwesterly flow
stands to continue through tonight as the mid-level trough brushes
our southern Shenandoah Valley, with 850 mb temps falling to values
running from -2 to -6C by 12z Saturday. BUFKIT RH cross sections
from the 12z NAM and GFS suggest that the stratocu will remain
difficult to scour out in this regime, and probably will build
southward as the evening progresses. While northwesterly winds
should begin to diminish especially after midnight tonight, the
overall message is for a dry but rather chilly evening. Lows ranging
from the mid/upper 20s west of the Blue Ridge and around or a few
degrees above freezing east. With the northwest wind around for at
least the first part of the evening, definitely want to bring a coat
for any plans outdoors. 

For Saturday...Ridging continues to build both surface and aloft
into the area which should again maintain a dry forecast.
Lingering morning stratocu in western areas should erode through
mid-morning Saturday, giving way to increasing high clouds as mid
to high- level moisture advects in from the southwest. 850 mb
temps are generally a couple degrees either side of 0C. Highs
upper 30s to near 40 into western Virginia and southeast West
Virginia, the mid 40s for the NRV/Grayson Highlands and northwest
North Carolina mountains, and the upper 40s to low 50s from the
Roanoke Valley, southside Virginia and the Virginia/North Carolina


As of 336 PM EST Friday...A chilly high pressure system will
become centered over the Mid Atlantic region Saturday night and
Sunday. Meanwhile, a closed low over Mexico will send Gulf
moisture towards the area. This Gulf moisture will begin to
overrun the surface high sometime Saturday night. The air column
will slowly saturated, but precipitation is not expected into SW
VA until after midnight. If clouds invade the region by Saturday
evening, temperatures will remain warm to keep precipitation type
as mostly rain. However, the environment will be dry and the
initial precipitation could fall as snow or sleet. Any frozen
precipitation falling will be brief, maybe 5-10 minutes, with no
accumulations. Light rain will spread north through the day Sunday
while any measurable rainfall will primarily be along and south of
the VA/NC border. Isentropic lift and warm air advection continue
Sunday night to keep rain chances across the south while fog and
drizzle will be more common to the north. Rain chances continue to
decrease on Monday as a surface reflection across the Carolinas
develops. Even though the chance for measurable rain will be low,
thick low clouds and gray conditions will prevail through the day

Temperatures will be the coldest for the period Saturday night then
gradually warm through Monday. Sunday will be chilly with afternoon
temperatures in the 40s. Temperatures Sunday night will not fall
much but could make a rebound Monday into the low to mid 50s.


As of 336 PM EST Friday...A closed low will move out of Mexico
and into the Midwest Monday night. A surface wave will accompany
this low and track from the Tennessee Valley to the Ohio Valley
Monday night into Tuesday. Another surface reflection will track
from the Carolinas to off the Virginia outer banks. In between
these two systems will be a cool wedge and a very good chance for
rain. All these systems track north Tuesday as a cold front slides
across the region. Behind this front will be windy and very cold
conditions. High temperatures going into next weekend will be in
the 20s across the mountains and 30s east of the Blue Ridge.


As of 800 PM EST Friday...

Generally VFR for most of the TAFs except with MVFR stratocu
ceilings at BLF and LWB. Some of these MVFR ceilings may
occasionally affect BCB through 00z but should be predominantly
VFR. Stratocu should remain tough to scour out through the evening
but should begin to trend VFR all terminals during the day on
Saturday. Northwest winds should slacken overnight to 6-10 kts
before trending light northwest for Saturday.

Extended aviation discussion...

VFR conditions to prevail through Saturday night, though will
start to see moisture stream northeast from a low pressure system
moving across the Gulf Coast states Sunday into Monday with
increasing threat of mainly rain. Will likely see a period of sub-
VFR cigs and possibly vsbys at most sites Monday but confidence
still is low as to how far north MVFR or lower conditions will
advance. A strong cold front will likely bring more in the way of
widespread sub-VFR in rain and low cigs on Tuesday.


Record event report sent earlier today /WBCRERRNK/ for the warmest
fall season on record at Raonoke and Blacksburg.





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