Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 231150
Area Forecast Discussion
National Weather Service Blacksburg VA
650 AM EST Thu Feb 23 2017
Weak high pressure off the Mid Atlantic coast will cover
Virginia and North Carolina today and tonight. A front across
the Great Lakes into the southern Plains shifts slowly southeast
to the Ohio Valley by Friday. The main cold front approaching
from the Midwest will pass through our area Saturday.
.NEAR TERM /THROUGH TONIGHT/...
As of 430 AM EST Thursday...
No changes planned to Dense Fog Advisory. Numerous locations
reported visibility of one half mile or less. The few exceptions
were on the western slopes from Bluefield to the Mountain
Empire area and along the peaks of the Blue Ridge which were
higher than the depth of the fog.
Models showed a modest improvement in visibility after 10AM. A
few breaks in the clouds are possible from Charlotte County
Virginia to Yadkin County North Carolina late this afternoon.
With little to no heating today...temperatures rise will be
limited. Have trimmed maximum temperatures today and may still
need them lower depending on cloud cover.
Some isentropic lift forecast today from Kentucky into western
Pennsylvania. Otherwise little forcing so have lowered
probability of precipitation.
Bufkit forecast soundings and visibility guidance showed
reformation of fog again late tonight. Have added larger
coverage of fog after midnight.
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 300 AM EST Thursday...
Weak shortwave ridging will build over our area Friday, as a mid-
level trough/low is forecast to move into the Great lakes and Ohio
Valley. It will remain unseasonably mild and generally rain free.
The only exception is a few locations near the crest of the Blue
Ridge thanks to local upslope flow. trimmed back pops a little
friday and shaped towards the NAM. High temperatures Friday
afternoon will range from the lower 60s in the mountains to the mid
70s in the Piedmont.
A cold front will approach the region from the west Friday night and
reach the mountains Saturday morning. Showers and a few
thunderstorms will develop along and ahead of the cold front. The
Day two convective outlook brings general thunderstorms into western
portions of the forecast area. The marginal threat clips a few far
western counties. It still looks like the best instability will
remain north of the Ohio River. Low temperatures Friday night into
saturday morning will vary from the mid 40s in the northwest
mountains to the the 50s in the Piedmont.
A cold front will move east across our area Saturday with scattered
showers and thunderstorms. The mention of thunderstorms remains
support by the sfc best lifted index and computed cape values.
The latest Day 3 Convective Outlook places portions of cwa in a
5 percent chance of severe weather, Marginal threat. The main
threat is for convective lines with damaging winds. High
temperatures on Saturday will warm to the mid 50s in the
mountains to the lower 70s in the Piedmont.
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. At this
time, it appears that winds will remain below wind advisory levels.
With colder air pushing into our region, any 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. Little or no accumulations
expected with any snow showers. Low temperatures Saturday night
will be near normal with readings from the lower 20s in the
mountains to the mid 30s in the Piedmont.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 AM 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. Behind the cold
front in the northwest flow, a few rain and snow showers may linger
in the western mountains Thursday.
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 /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --As of 645 AM EST Thursday...
Widespread LIFR conditions this morning across southwest
Virginia, northern North Carolina and southeast West Virginia primarily
due to dense fog and stratus. Air mass has dried out above the
shallow moist surface layer. Several models and Bufkit forecast
shows fog lifting slowly this morning. High confidence that
ceilings will remain below MVFR levels through at least
15Z/10AM. MVFR may not be reached at KROA/KBCB and KLYH until
18Z/1PM. More clearing is expected during the late afternoon and
evening then fog will redevelop overnight. Medium to low
confidence about how low visibilities will drop after midnight.
Winds will be light today and tonight.
Extended Aviation Discussion...
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 on Friday.
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
As of 440 AM EST Thursday...
The automated observation system at Lynchburg(LYH)had multiple
sensor failures. Electronics technicians will be performing
repairs on the system this morning.
VA...Dense Fog Advisory until 10 AM EST this morning for VAZ007-
NC...Dense Fog Advisory until 10 AM EST this morning for NCZ001>006-
WV...Dense Fog Advisory until 10 AM EST this morning for WVZ042>044-