Scientific Forecaster Discussion
fxus61 krnk 181904
Area forecast discussion
National Weather Service Blacksburg Virginia
304 PM EDT Fri Oct 18 2019
high pressure moves overhead this evening into tonight, then heads
offshore Saturday. A tropical system will track across the southeast
states this weekend bringing a good threat of rain. A cold front
will cross the mid- Atlantic region Monday night into Tuesday,
providing yet another opportunity for rain.
Near term /through Saturday/...
as of 153 PM EDT Friday...
High pressure over the Ohio Valley this afternoon will move east
tonight and push off the Atlantic coast Saturday. It will be
another good radiational cooling night, with only increasing
high thin clouds expected. Areas of frost will develop overnight
into Saturday morning. A frost advisory has been posted for our
mountains, and the Alleghany Highlands, east to the Piedmont
north of the Roanoke River for tonight. Pockets of frost in low
lying areas are not out of the question over the southern
Virginia Piedmont into NC, but coverage seems too isolated for
High clouds will push north ahead of tropical storm Nestor
moving across the Gulf of Mexico, and into the Florida
Panhandle overnight. Please refer to the latest NHC advisory on
nester and its path. At 2 PM, the center of tropical storm
Nestor was located near latitude 26.3 north, longitude 89.5
west. Nestor is moving toward the northeast near 22 mph, and
this general motion is expected to continue through Sunday.
Temperatures will drop fast after sunset, reaching lows in the
mid to around 40 degrees, with some freezing temperatures in
deeper sheltered valleys. As the flow turns more south and
increases toward dawn Saturday, temperatures may steady out or
rise across the higher terrain of the southwest forecast area.
The high center will slide east on Saturday as low pressure
pushes north in the Georgia by Saturday evening. Clouds will
increase and lower Saturday as as the tropical storm Nestor
progresses across the southeastern states. Tropical moisture
will advect north Saturday with rain chances increasing after
18z on Saturday afternoon. High temperatures Saturday will range
from the mid 50s in the mountains to the mid 60s in the
Forecast confidence is medium to high for near term period.
Short term /Saturday night through Tuesday night/...
as of 300 PM EDT Friday...
The remnants of Nestor will be moving rapidly through the
southeastern US to the North Carolina coast by daybreak Sunday.
Latest guidance favors a more eastward track, but the
circulation will still be close enough to spread robust
isentropic lift and excellent synoptic forcing into the region
with associated widespread rainfall Saturday night. The bulk of
the rainfall will remain close to the center of circulation that
will be passing by to the southeast, but Southside Virginia will be
close enough to receive a good soaking rainfall with totals of
roughly 1.0 to 1.5 inches extending down to the NC Piedmont.
Rainfall amounts will then taper further north and west to
around 0.50 inches up near the Interstate 64 corridor. All in
all, another beneficial rainfall for the region.
The system will be moving briskly and expect precipitation to
taper off quickly Sunday morning with improving conditions
during the afternoon, leaving behind a wedge of high pressure
that will linger through Monday. By Monday night, a vigorous
cold front will start pushing in from the west accompanied by
another round of widespread showers as it passes through early
Tuesday. While most of the energy of the front looks to surge
northward before reaching our region, there remains a good
amount of shear as it moves into the lingering wedge. However,
BUFKIT soundings do not show any substantial support for
convection with instability largely absent. Will have to watch
the evolution of this system closely since any trends toward a
more unstable solution could increase our potential for severe
weather due to embedded convective elements. Winds become quite
blustery as colder air moves in behind the front.
Temperatures will be near normal through the period.
Long term /Wednesday through Friday/...
as of 300 PM EDT Friday...
High pressure will bring generally quiet weather to the Appalachians
and central mid Atlantic region with temperatures around seasonal
normals through the latter portion of next week. Our next chance for
rain arrives later Friday into Friday night with another energetic
system moving out of the deep south.
Aviation /19z Friday through Wednesday/...
as of 135 PM EDT Friday...
High pressure will provide VFR conditions this afternoon into
Saturday. Winds will become light and variable tonight. Rain
will spread north into the forecast area after 18z Saturday
afternoon into Saturday evening.
High confidence in ceilings,visibilities and winds during the
Extended aviation discussion...
VFR conditions will lower into MVFR with rain Saturday evening
into Saturday night. Tropical moisture accelerates toward the
area from a storm that is forecast to move out of the Gulf of
Mexico and across the southeast states Saturday evening. This
will likely result in sub-VFR weather Saturday night into
Sunday...especially for areas south and east of Roanoke, Virginia.
Increasing northeast winds are likely as well for locations
southeast of Roanoke.
A physical break in the rain is expected Sunday night into
Monday before the arrival of a cold front which will likely be
associated with more rain and sub-VFR Monday night into Tuesday.
Dry weather is expected for Wednesday.
Virginia...frost advisory from 2 am to 9 am EDT Saturday for vaz007-
NC...frost advisory from 2 am to 9 am EDT Saturday for ncz001-002-
WV...frost advisory from 2 am to 9 am EDT Saturday for wvz042>044-