Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 230012
Area Forecast Discussion
National Weather Service Blacksburg VA
712 PM EST Wed Feb 22 2017
Weak high pressure off the mid-Atlantic coast will stay
situated here through Thursday morning. A frontal boundary
across the Great Lakes into the southern Plains shifts slowly
southeast to the Ohio Valley by Friday. The main cold front
across the midwest will pass through our area Saturday.
.NEAR TERM /THROUGH THURSDAY/...
As of 228 PM EST Wednesday...
Been seeing decreasing trend and southward trend in rainfall. Models
hang onto some isentropic lift over the southern CWA through early
evening then moisture and lift become shallow/weak. Main issue
overnight could be fog. Forecast soundings showing very shallow
moisture near/at the surface and hints of dense fog are there as
well. With weak wind flow added more fog in the east overnight and
along the Blue Ridge. Still with cloud cover, coverage of dense fog
is iffy so no advisories planned with this forecast. Lows tonight
will be about 5-10 degrees cooler than 2pm temperatures this
afternoon, ranging from the mid to upper 40s most locales.
Thursday, frontal boundary situated from the Eastern Great Lakes,
southwest to the Southern Plains, in the morning, will slowly
advance south to a PIT-IND-TOP line by late in the day. Models break
the in-situ wedge as sfc flow turns more southwest. Will see more
sunshine in the piedmont in the afternoon, with sunshine at times in
the west followed by more clouds ahead of a shortwave that passes
across KY into Ohio in the afternoon. This shortwave combined with
some low level convergence across the mountains may lead to some
showers and even thunderstorms in the afternoon, mainly from the
Alleghanys southwest to southern WV, with limited coverage southeast
to the foothills. As wedge erodes, expect temperatures to soar to
the lower to mid 70s east of the mountains, with mid to upper 60s
across the west. Some record high temps may be approached and/or
broken. See climate section below. Even record warm low temperatures
will be possible for Thursday 2/23.
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 250 PM EST Wednesday...
Thursday night through Friday night, the area will be under a region
of deep south to southwest flow, with its origins from the eastern
Gulf of Mexico. A warm front will lift north of the area Thursday
night. While some patchy light rain will be possible early in the
evening for the area of the region west of the Blue Ridge, coverage
will decrease through the night as the front continues heading north
of the area. Lingering upslope light rain will remain possible near
the crest of the Blue Ridge, especially in areas southwest of Floyd,
VA into the Northern Mountains of North Carolina.
On Friday, most of the area will be precipitation-free, save a few
locations near the crest of the Blue Ridge thanks to local upslope
Friday night into early Saturday, a cold front will approach the
region from the west, and cross the area during the day Saturday.
Look for increasing chance of rain showers with the approach and
passage of this feature. There will also be a slight chance of
thunderstorms with the passage.
By Saturday night, the front will be to our east, and northwest
winds will be on the increase. The northwest winds will yield some
gusts approaching 40 to 45 mph at the highest elevations. Also,
colder air will start working its way into the area. Lingering
upslope rain showers across parts of southeast West Virginia, south
into the Northern Mountains of North Carolina are expected to
transition to snow showers by Sunday morning.
Temperatures Thursday night through Saturday are expected to average
about twenty degrees above normal. Saturday night, behind the cold
front, temperatures will fall to readings near normal.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 PM EST Wednesday...
Gusty winds will continue into early Sunday behind Saturday`s cold
frontal passage. These winds will weaken quickly during the day and
back southwest as the next upper level trough deepens across the
This same upper trough will move east and be over the Ohio Valley by
mid-day Monday. A warm front in advance of this system will head
north through our region, bringing a return of patchy light
precipitation to the area during the day Monday. There may be an
issue of a brief period of a wintry mix across the northwest section
of the area early Monday as a potential warm nose develops over a
sub-freezing boundary layer and surface. For now, will keep things
simple by reflecting a rain versus snow forecast based solely on
whether the forecast surface temperatures is above or below
Monday night the system`s associated cold front is expected to cross
the area. Look for the precipitation to become more showery Monday
night into early Tuesday.
Model guidance for the remainder of Tuesday into Tuesday evening is
not clear. The GFS is progressive with the cold front making
significant headway east of the region. The ECMWF is not
progressive, stalling the feature over the area, all while
suggesting another wave will move northeast along this boundary,
keeping a generous coverage of rain across the area Tuesday
afternoon into Tuesday night. Our forecast will reflect a blend of
these solutions. While rain will be forecast Tuesday afternoon and
evening, it will not be to the degree offered by the ECMWF.
For late Tuesday night into Wednesday, model agreement improves with
solutions bringing yet another upper low/trough from the Central
Plains states into the Ohio Valley. Warm frontal rain is expected
late Tuesday night into early Wednesday, with a generous coverage of
showers and some isolated thunderstorms across the area Wednesday
afternoon coincident to the cold frontal passage.
Temperatures Sunday and Monday will be normal for this time of year.
Reading moderate through mid-week with temperatures some ten to
fifteen degrees above normal expected.
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --As of 710 PM EST Wednesday...
Lingering precipitation associated with a trof passing by to our
south sending short wave energy riding over a wedge of high
pressure at the surface will dissipate to a few sprinkles early
this evening. However, earlier widespread precipitation has left
the boundary layer quite moist. Believe as mid/high clouds pull
away with the departing trof, cooling will allow the boundary
layer and fog/stratus will set in at all TAF sites late tonight
and persist through daybreak. The expected progression of
dissipating precipitation, departing upper clouds, cooling,
and formation of fog/stratus will likely yield a good degree of
variability in vsbys/cigs until IFR conditions become firmly
established. thus, will choose to keep TAFs on the pessimistic
side and be reluctant to amend upward.
The fog/stratus looks to burn off Thursday morning with a return
to VFR conditions by the afternoon. However, a weak frontal
boundary will brush the region as an area of low pressure moves
through the Great Lakes region tomorrow. This may bring a shower
to locations west of the Blue Ridge so will include VCSH after
18Z all sites except KDAN and KLYH. Winds will be light through
Extended Aviation Discussion...
Thursday night-Friday, we will be well into the warm sector
with VFR conditions and much above normal temperatures. Surface
wind gusts of 20 to 30 kts possible across the higher terrain.
Band of showers and isolated thunderstorms with MVFR conditions arrive
late Friday night into early Saturday along and ahead of a
strong cold front. Drier weather and increasing northwest winds
follow behind the front on Saturday afternoon through Sunday.
Approach of another front Monday will provide increasing clouds
and possibly showers and MVFR cigs to BLF/LWB late in the day.
-- End Changed Discussion --
As of 245 PM EST Wednesday...
Warm temperatures set to occur again Thursday with increase in
westerly flow in the low levels. Question will be cloud cover. At
the moment with some sunshine look for highs and lows to approach or
break records for Feb 23rd.
Site Record High/Year Record Warm Low/Year
Bluefield 74 1975 51 1975
Danville 73 1980 50 1981
Lynchburg 74 1943 52 1925
Roanoke 76 1943 54 1925
Blacksburg 69 1980 46 1990