Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 270219
Area Forecast Discussion
National Weather Service Blacksburg VA
919 PM EST Sun Feb 26 2017
High pressure will cross the area overnight before passing
offshore Monday morning. A warm front will lift northeast
toward the region Monday night and Tuesday resulting in an
increasing chance of light precipitation. By Wednesday and
Thursday, low pressure tracking east out of the Great Lakes will
drag a trailing strong cold front east across the eastern United
.NEAR TERM /THROUGH MONDAY/...
As of 915 PM EST Sunday...
Making downward adjustments to low temps given some of the
deeper valleys already in the mid 20s with a few added hours of
good radiational cooling to go per very dry dewpoints under
light winds/clear skies. Latest satellite pics also show
mid/high clouds to the west struggling to move east into the
very dry air aloft seen on evening soundings. Thus appears
models a bit fast to bring moisture east which should allow most
to see little more than thin high clouds for a while longer
until more of the mid cloud canopy arrives late. This cloudiness
should finally put a lid on temp falls after midnight so running
with some steadying or rises in readings before daybreak espcly
west. Otherwise lows ranging from the low/mid 20s valleys and
eastern outlying spots to low 30s ridges before clouds increase.
Previous update as of 634 PM EST Sunday...
High pressure centered over southeastern TN will remain in
control through the evening. However, watching increasing mid
-/high-level cloudiness associated with a low-amplitude
shortwave over central KS advect quickly eastward, its eastern
extent now into central KY/OH. I therefore opted to increase sky
cover, essentially a west-east increase in cloud cover
beginning just before midnight in our far western zones and into
the overnight hours elsewhere. However worth pointing out that
this sky cover will be nothing more than mid- level altostratus
at worst. What that will do is curb what should be strong
radiational cooling, the strongest of which should take place in
the next few hours now that the sun has gone down. Temps should
then begin to stabilize. I did raise lows up 1-2 degrees based
on an increase in sky cover but idea that ridges should stay
comparatively milder to the lower valleys looks good.
Previous near-term discussion issued at 220 PM follows...
Cold high pressure will be centered over the region this evening,
then drifts off the VA/NC coast Monday morning. Warm moist air from
a disturbance tracking across the Tennessee Valley will bring thick
mid level clouds to the area Monday morning. If isentropic lift can
increase, a few mountain locations may see a few light showers for
the morning commute. However, this moisture must overcome some very
dry low level air which will limit precipitation to scattered
sprinkle/flurries across southeastern West Virginia. Best lift moves
north during the afternoon, but clouds likely to stick around into
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 320 PM EST Sunday...
Warm front over the Gulf Coast states to lift north to the KY/TN
area by Tuesday morning while high pressure retreats eastward well
off the mid-Atlantic coast. Will see some in-situ damming possibly
into Tuesday as clouds increase Monday night with an drizzly/light
rain scenario expected. The low level wedge erodes Tuesday afternoon,
but expect cloudiness to stick around with threat of showers moving
in, as warm front lifts north. Some instability arrives toward the
southern and central Appalachians in the afternoon, so not out of
the question for a few thunderstorms mainly west of I-77.
As we head into Tuesday night and Wednesday will see less coverage
over the piedmont but strong sfc low works northeast across the
midwest into teh Great Lakes. Very strong energy with this system in
terms of winds, with cold front tracking from Illinois to Arkansas
Wednesday morning to the mountains by late Wednesday afternoon. SPC
highlighted our area for Wednesday with threat of squall line and
mainly damaging winds. Given timing of the sfc front, not out of the
question to have some severe winds around Wednesday
afternoon/evening, as shear is good as are low level lapse rates.
However, the question is thermodynamics and how much, if any
sunshine we get. Think with strong southwest flow in the low levels
the areas along/east of the Blue Ridge should break out in the
sunshine, as temperatures soar into the mid-upper 70s. Will
highlight svr thunderstorm threat in the HWO.
The line races east of the forecast area by midnight with showers
lingering in the east and upslope side of the west. The EC model
favored as GFS is quicker, nonetheless even with EC its shifting
things east of us overnight Wed night.
Winds crank up overnight as well as strong cold air advection
arrives along with 6 hr pressure rises of 6-8mb and 8h winds 40-
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 120 PM EST Sunday...
Sharp cold front expected to be off the coast by Thursday morning
with brisk and cold winds for Thursday, with some lingering moisture
in the west for a few snow showers.
We will see moisture erode by afternoon with a weak high pressure
center moving across the mountains.
On the heels of this is a northern stream front that moves across
Friday morning. Appears moisture and lift will be further north of
the forecast area, but some rain and snow showers could spill into
the mountains of WV to the Alleghanys.
Strong high pressure works in from the midwest for Saturday then
shifts south across the southeast U.S for Sunday. After a period of
cooler temperatures near to just below normal Thu-Sat, we will warm
back up for Sunday.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
As of 634 PM EST Sunday...
VFR conditions the rule through the TAF period. West to east
increase in BKN/OVC mid-/high-level clouds mainly after 05z,
which should stay through the TAF period. Northwest winds
5-10 kts initially trends to calm tonight, with an expected
veer/increase to southeast/south 5-8 kts later Monday.
Extended Aviation Discussion...
A warm front is expected to lift northeast toward the region
Monday night into Tuesday before passing to the north on
Wednesday. This will keep a threat of showers in place
including periods of sub-VFR Tuesday into Wednesday. A cold
front pushes east into the area Wednesday into Wednesday night
with potential for more widespread MVFR/IFR in showers and
thunderstorms. Strong northwest winds along with mountain sub-
VFR in upslope low clouds and light precip will likely follow
the front for much of Thursday. Expect downslope drying to
return VFR to eastern locations by Thursday afternoon.