Area Forecast Discussion
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FXUS61 KRNK 200947
Area Forecast Discussion
National Weather Service Blacksburg VA
547 AM EDT Thu Oct 20 2016
A front extended from New England through the Ohio Valley to a low
over the Southern Plains. This low will track across the Tennessee
and Ohio Valleys by Friday morning and will push a strong cold
front across much of the eastern United States Thursday night and
Friday. High pressure build in behind the low on Sunday and
.NEAR TERM /THROUGH TONIGHT/...
As of 500 AM EDT Thursday...
A strong upper level trough mid-conus will move east across the MS
Valley today. At the surface, low pressure will move northeast
through the Ohio Valley and into the eastern Great Lakes by
tonight. A strong cold front will trail the surface low and will
move east, crossing the Appalachian mountains tonight, then east
across the foothills and piedmont Friday. An extensive area of
showers with embedded thunderstorms will move east with the
front, this activity overspreading our CWA from west to east
beginning this evening (5-10PM time frame) west of Interstate 77,
then spreading across the New River, Greenbrier, and Shenandoah
Valleys between 10PM-2AM...before spilling east of the Blue Ridge
late. Per late arrival of any thunderstorm activity, do not
anticipate anything severe. The storm prediction center does
highlight areas mainly west of our CWA for fast-moving storm cells
and line segments capable of marginally severe wind or hail...this
threat focused on the eastern Oh/TN Valleys.
Today will be the last day of near record warmth with temperature
readings 10-20 degrees above normal. The unseasonable warmth will
come to an end with tonights frontal passage, temperatures taking
a noticeable tumble Friday.
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 350 AM EDT Thursday...
An upper trough will deepen and move into the East over the next
couple of days. A wave of low pressure will lift northward into New
England and push a strong cold front east across our region. The
cold front will push off the coast by Friday evening and move
further out into the Atlantic ocean on Saturday. Scattered showers
and a few thunderstorms will develop ahead and along the front.
The Day 2 convective outlook places general thunderstorms over
eastern portions of our Forecast area. However, Surface instability
looks quite limited given the morning timing of the fropa. Generally
it seems like a band of showers with front.
Used an non-diurnal temperature curve for Friday with falling
temperatures expected west of the Ridge throughout Friday, and
falling across the Piedmont by the afternoon. High temperatures
Friday will range from the lower 50s in the mountains to the mid 60s
in the Piedmont.
As a large area of high pressure over the Mississippi valley ushers
in significantly colder air behind the front, the low level flow
will become energized and make for blustery conditions for Friday
afternoon into Saturday. Expect about 40 kt of 850 mb flow during
the peak of the cold advection Friday afternoon to Saturday morning.
However, winds are expected to remain below wind advisory levels.
It is time for you to find your cold weather gear Friday night
with temperature readings dropping to lows from the mid 30s in the
west to the mid 40s in the east. There will also be the prospect
for the first snowflakes of the season Friday night into Saturday
morning at the higher elevations (above 3500 feet msl) west of the
Blue Ridge but no significant snow accumulations expected with
warm ground. But, low temperatures at or below freezing may well
end the growing season for some higher elevations west of the Blue
Ridge Friday night.
Light upslope showers will continue Saturday with cold advection
combined with lingering low level moisture in the Northwest flow.
High temperatures on Saturday will vary from the lower 40s in the
northwest mountains to the lower 60s in the Piedmont, with the
blustery wind making it feel even colder. Clear to partly cloudy
conditions will prevail Saturday night into Sunday morning. Low
temperatures will drop into the mid 30s in the mountains to the
lower 40s in the Piedmont.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 320 PM EDT Wednesday...
The upper pattern will be trending toward reestablishment of an
upper ridge over the eastern US through the middle of next week.
This will generally keep our weather quiet and dry through the
Return flow around high pressure to our south will push some warmer
temperatures into the region for Sunday and Monday. A fast moving
short wave will zip through the Great Lakes region and drive a low
through New England. This will swing a weak cold front through the
region later on Monday afternoon with any precipitation expected to
remain off to our north. Cooler high pressure will then build in on
Tuesday and take up a wedge position east of the Appalachians by
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
As of 600 AM EDT Thursday...
High pressure aloft will provide one last day of near record
warmth for the Mid-Atlantic. A deepening upper trough and
associated strong cold front sweep through the region tonight and
Generally VFR conditions are expected today after a brief period
of fog this morning. Local ifr/lifr due to dense fog will be found
in some of the river valleys early this morning. Fog is expected
to be shallow, and will burn off quickly after sunrise. Once the
fog has dissipated, expect VFR for the remainder of the day.
As for precipitation threat, all models suggest that associated
frontal convection/precipitation will remain west of the RNK CWA
(west of BLF/LWB) through sunset today. The air mass in advance
of the front is very stable with unseasonably warm temperatures
aloft providing a strong cap on convection as well as clouds.
Precipitation associated with the front will largely be post-
frontal, not pre- frontal. Thus, will not introduce any
precipitation until closer to midnight for BLF and LWB and well
after midnight for areas east of the Blue Ridge.
With respect to clouds, model soundings indicate a strong
inversion around the 850mb-800 mb layer, resulting in continued
SCT cloud development in the 5-7kft layer. This should be the
case throughout the day, becoming BKN late in the day western
areas as the frontal system approaches from the west. Cloud bases
are expected to remain mostly VFR until midnight. After midnight
cloud bases and vsbys will deteriorate with the arrival of the
Winds to remain mostly calm or light SSW-SSE through 14z/10am
this morning, becoming SW 7-10kts after 14Z, with low end gusts,up
to 15 kts, possible KBLF, KBCB, and KROA by mid afternoon.
Medium to high confidence in cigs/vsbys through the TAF valid
period. Medium to high confidence in wind direction/speed through
the TAF valid period.
Extended aviation discussion...
Showers, perhaps an isolated thunderstorm will develop over the
mountains toward midnight Thursday/Friday, with showers spreading
east of the mountains as the front moves east Friday morning.
The best chance of precipitation will be from midnight Thursday
night through noon on Friday. This will be the most likely period
of widespread MVFR to IFR ceilings and visibilities.
The strong cold front will move through the region from west to
east, mainly in the 06Z Fri to 15Z Friday time frame. A southwest
to northwest wind shift is expected to occur late Thursday night
across the region with gusty northwest winds behind the front
continuing into Friday night and possibly Saturday. Areas of sub-
VFR conditions will likely accompany the front and precipitation.
A return to VFR conditions is expected for most areas Friday
night into Saturday. The exception will be western parts of the
region where a healthy northwest upslope flow, and lingering low
level moisture, will prolong an IFR/MVFR ceiling during this time
period. Even the mountain areas will become VFR again for Sunday
As of 515 AM EDT Thursday...
Record maximum temperatures...
New record max temperatures were set at Blacksburg and
Danville Wednesday with 83 and 86 degrees, respectively.
Record temperatures are possible again today.
Location Record Max
Bluefield.....79 in 1993
Danville......88 in 1984
Lynchburg.....85 in 1993
Roanoke.......84 in 2005
Blacksburg....82 in 1985