Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 140435
Area Forecast Discussion
National Weather Service Blacksburg VA
1135 PM EST Mon Feb 13 2017
Weak high pressure will build across the region tonight into
Tuesday allowing for continued dry weather under diminishing
winds. The high exits offshore Tuesday evening, ahead of
another cold front arriving from the northwest, and low
pressure passing to the south into Wednesday. These features may
combine to bring some light rain or snow by midweek followed by
blustery and cold weather under high pressure by Wednesday
night and Thursday.
.NEAR TERM /THROUGH TUESDAY/...
As of 950 PM EST Monday...
High pressure will slide through the region tonight and bring us quiet
weather through Tuesday. Temperatures will be a bit tricky tonight as
it looks like we will see very good radiational cooling conditions
early tonight, but mid/upper level moisture will be increasing as a
warm air advection pattern develops. Temperatures will level
off once more high clouds arrive with the higher elevations
starting to warm late. Will go with an early low around 30 east
of the Blue Ridge with low/mid 20s in the colder locations west,
with some gradual warming late.
A strung out frontal boundary will then move into the region tomorrow
as one area of low pressure moves through the Great Lakes region and
another low moves through the southern Mississippi Valley along the
Gulf coast. Low level moisture will remain limited so aside from
increasing clouds, there will only be a slight chance for a late day
shower/sprinkle for the Mountain Empire of Va and the mountains of NC.
Highs Tuesday will be a bit above normal with middle 50s east of the
Blue Ridge and upper 40s/lower 50s to the west.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 230 PM EST Monday...
Moisture will quickly increase from the west Tuesday night as energy
shears east ahead of the residual upper low heading east out of the
southwest states. This just in advance of a sharply digging northern
stream trough/cold front that will attempt to link with the opening
southern wave by early Wednesday within the split flow regime.
Models remain rather consistent in tracking the southern surface
low from Louisiana Tuesday evening to across South Carolina by
late Wednesday before getting absorbed into the frontal boundary
offshore Wednesday night. Still appears that much of the precip
at least initially will tend to outrun the cold advection
behind the front, with most seeing ptype start out as rain over
the western third Wednesday evening before spreading east
However soundings do show more isothermal nature espcly across
the higher elevations after midnight, with the snow levels
lowering by daybreak Wednesday. This as the front arrives and
prior to drier air aloft winning out from northwest to
southeast during the day. Also with guidance shifting a bit more
QPF farther north to start, have boosted snowfall amounts a
little mainly above 3000 feet with a couple inches possible
from far southwest VA into the NC mountains. Could also see some
of the higher peaks farther east see some light accumulation as
well as upslope areas across the west with northwest flow
behind the front. Otherwise slowed pops down a little Wednesday
evening given low level dryness, then spread chance to likelys
across much of the region similar to the latest European solution.
Expect most precip to finally shunt off to the southeast by
early afternoon Wednesday as the front catches up, so only low
chances by Wednesday afternoon far south and across the northwest
slopes for now. Lows mostly 30s to around 40 Tuesday night with
some 20s on the ridges. Then quite chilly Wednesday under
increasing northwest winds and deepening cold advection which
should hold much of the west in the 30s/lower 40s and 45-50
Blustery and cold conditions continue behind the front on gusty
northwest winds in the wake of the strengthening low exiting New
England and high pressure well to the southwest. May again be close to
wind advisory levels along the southern Blue Ridge espcly with guidance
showing stronger upper troffiness and more of a pressure gradient
during the overnight. However with the jet not overly impressive
and subsidence weaker, local guidance suggests just below
criteria at this point. Also with an even stronger shot now of
cold advection than this last event, expect lows in the 20s with
a few teens possible and highs 30s mountains to mid 40s east
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 145 PM EST Monday...
Last of the ongoing cold advection in the wake of the exiting cold
front from midweek will gradually fade Thursday night as the upper
trough lifts out and weak high pressure builds in from the south. This
will make for a cold night Thursday night with lows mainly in the 20s
before building heights and developing ridging takes hold for late week
into the weekend per latest model consensus. Only concerns may be with
a weak wave undercutting the eastern ridging along the southeast coast
by Saturday night, followed by a passing northern stream shortwave
trough associated with a backdoor front on Sunday. Could see a few
showers with the southern wave Saturday night, otherwise running dry
and very mild from Saturday into early next week with a transitional
warmer day on Friday. Given decent warming aloft and westerly flow,
going with highs mostly 50s Friday and overall 60s Saturday-Monday and
perhaps around 70 piedmont by Sunday.
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --As of 1135 PM EST Monday...
VFR conditions this TAF period with increasing mid and high
clouds over southern Virginia and northern North Carolina
Tuesday. As low pressure tracks across the Gulf Coast region,
ceilings will lower and rain will spread into the Virginia and
the Carolinas. Medium confidence on the arrival time of the
rain. Best chance will be across southern Virginia and north
North Carolina be after 00Z/7PM Tuesday. A cold front will
approach the area Wednesday morning with enough cold air behind
it to change the precipitation to snow at KLWB. High confidence
that this will not occur until after the end of 06Z TAF forecast
period. Low confidence concerning the extent of MVFR or lower
ceilings. Mist likely period of these lower ceilings will be
after 06Z/1AM Wednesday.
Extended Aviation Discussion...
The cold front will move in from the west on Wednesday and may
bring sub VFR conditions west of the Blue Ridge. Passage of the
front and coastal low will bring another round of stronger winds
and colder temperatures for Wednesday night and Thursday. The
northwest flow will continue to promote some MVFR cigs in the
mountains through Thursday. Friday and Saturday will be milder
and dry with VFR conditions.
-- End Changed Discussion --
As of 300 PM EST Monday...
Very dry conditions remain in place this afternoon with
humidity levels below 30 percent in most spots and in the teens
along and east of the Blue Ridge. Gusty northwest winds also
persist with lowering fuel moisture levels under the strong
However expect ongoing gusty west/northwest winds to diminish
by early this evening as high pressure shifts toward the region.
This should allow a gradual recovery in humidity overnight but
still likely below 50 percent in spots until after midnight
when better radiational cooling develops.
Very dry conditions will persist again on Tuesday although
winds will be much lighter and generally westerly at 10-15 mph
except still likely breezy along the higher ridges where gusts
to 25 mph could occur. This should allow for added drying of
fuels during the day, and again especially east of the
mountains where winds will maintain a downsloping component.
The next chance for any wetting precip will come Tuesday night
into midday Wednesday as a storm system passes to the south of
the region. Some light rain or snow looks likely especially
across southern and western sections where up to one quarter of
an inch of liquid could occur. Expecting a sharp gradient
farther north with less than a tenth of an inch elsewhere.
Another passing cold front by Wednesday afternoon will usher in
the next round of increasing northwest winds into Thursday with
stronger gusts and lowering humidity likely.