Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRNK 191815
Area Forecast Discussion
National Weather Service Blacksburg VA
115 PM EST Sun Feb 19 2017
An upper low will cross the region this morning before exiting
to the southeast this afternoon. High pressure builds in from
the north behind this system tonight and remains into Monday
night. A weak frontal system will approach from the west by
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --As of 100 PM EST Sunday...
The biggest adjustment to the forecast for this afternoon has
been an adjustment of the forecast high temperatures. Have
decreased by a couple of degrees readings over parts of the
mountains from near Hillsville, VA, south into the Northern
Mountains of North Carolina. Readings have been trending below
forecast levels here, and cloud cover will slow any notable rise
for another hour or two. Have increased forecast highs by a
degree or two in the east where plenty of sunshine, and
increasing northwest winds should help temperatures to continue
Another adjustment based upon the latest observations includes a
removal of mention of patchy drizzle and patchy light fog
from the forecast this afternoon. The area between Richlands, VA
and Bluefield, WV has seen an end to these features, and they
are not expected to return this afternoon.
As of 1000 AM EST Sunday...
No major updates to the forecast this morning. We are still
expecting cloud cover to persist across the western sections of
the region through at least the remainder of the morning, and
mostly likely some hours this afternoon. What remains a question
is if areas near a line from Tazewell, VA to just west of
Lewisburg, WV will see any breaks in the cloud cover today. From
a look at regional weather observations and area web cams, looks
like a good call to maintain some patchy fog and drizzle across
this similar region into the afternoon, and also parts of the
Northern Mountains of North Carolina. Have also tweaked hourly
temperatures and dew points heading into the early afternoon
based upon the latest observations and expected trends into the
As of 215 AM EST Sunday...
Upper low will continue to pivot across the region early this morning
before exiting to the southeast by afternoon. Trailing deformation band
currently producing a band of showers across the far northwest should
also gradually shift east while slowly stretching/dampening out after
daybreak as the associated upper support pulls away. However decent
northwest flow in the wake of the upper system likely to keep low
clouds trapped over much of the west to start with some showers
northwest, and perhaps spotty light rain/drizzle elsewhere along the
far western ridges early on. Subsidence to gradually increase this
afternoon as ridging to the west starts to shift east and ongoing cool
advection weakens. This should help to erode the low cloud canopy over
the mountains with guidance profiles showing moisture pulling back to
the west allowing for mainly sunny skies east and decreasing clouds
west. Just how fast this occurs the key to high temps as MOS has
trended cooler western sections while keeping things quite mild east
per downslope under more insolation. Therefore edged highs from the
Blue Ridge west down a little with some spots likely staying in the 50s
espcly if clouds hold longer under a gusty northwest breeze.
Strong upper ridging to build in overnight as surface high pressure
bridges in from the north by daybreak. Models depict very strong
warming aloft as the next round of warm advection to the west
shifts east. Expect better subsidence to keep skies mainly clear
although some potential for low clouds to again get trapped
over the far west beneath the inversion aloft as warming comes
in above. Otherwise appears a bigger range in low temps from 30s
valleys to perhaps mid 40s at elevation likely with good
radiational cooling outside of warming aloft.
-- End Changed Discussion --
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
As of 208 AM EST Sunday...
An upper level ridge and lots of sunshine will allow Monday`s
temperatures to reach into the upper 60s to lower 70s. These
temperatures are 20F-25F warmer than normal. Records could be broken
at Bluefield and Blacksburg Monday. A light east wind will
keep Roanoke, Lynchburg and Danville from reaching their records.
The upper level ridge will slowly exit the region Tuesday. This
ridge is stubborn and has, by model standards, been slowing the
arrival of our next chance for rain, now set for Tuesday night. Dew
points recover quickly into the 40s Tuesday night, however, dry
prefrontal environment and the lack of lift will limit rainfall to
under a quarter of an inch. The front that will bring the rain is
weak and will likely washout over North Carolina Wednesday.
A reinforcing shot of cool easterly flow and increasing cloud cover
will keep temperatures in the low to mid 60s Tuesday. Despite
Tuesday being cooler than Monday, temperatures will still be 15F
warmer than normal. Temperatures will rebound Wednesday as the
washed out front gives way to warm southerly flow.
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
As of 230 AM EST Sunday...
Residual moisture with the weak front across the region looks
to dry up Wednesday night into Thursday as ridging re-
establishes over the southeast states. This leads to a more
amplified 500 mb pattern for the end of the week with a
deepening trough moving across the central United States and
more spread showing up in the models by that time frame.
Increasing southwest winds Thursday into Friday will increase
moisture and keep temperatures way above normal ahead of the
front with 60s to near 70 likely west and well into the 70s
east. Timing of the frontal passage across the Appalachians
looks to be on Saturday morning with precipitation along and
ahead of the boundary at this point.
Colder air comes in behind the front for the end of the
weekend but again not overly impressive and likely limited in
duration per latest warmer 19/00z ECMWF. However the
combination of a modest low level jet and strong cold air
advection will result in strong gusty winds behind the front
into late Saturday with a brief return to more normal temps to
start the weekend.
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --As of 1240 AM EST Sunday...
VFR conditions currently prevail east of the crest of the Blue
Ridge. As high pressure continues to build into the region, this
pattern is expected to continue through at least the duration of
the valid TAF period. Winds in this region will be close to 10
kts this afternoon from the northwest, with some gusts in the 15
to 20 kt range. Anticipate calm or light and variable winds
overnight through Monday.
Across the mountains, most areas were experiencing decreasing
coverage of ceilings that ranged from LIFR to MVFR. Drying from
aloft will help to continue to the trend of decreasing coverage
as the afternoon progress with ceiling levels increasing mainly
to MVFR and low end VFR. As the night progresses, moisture that
becomes trapped under the nocturnal inversion will allow
ceilings to redevelop and spread eastward. Levels again will
return to LIFR to MVFR levels. However, drier air will
eventually win with clouds decreasing in coverage towards
daybreak. VFR conditions are expected across the mountains on
Monday. Winds this afternoon in this region will be generally
from the northwest around 10 kts with gusts in the 15 to 25 kt
range. Overnight and on Monday, anticipate calm or light and
variable winds. VFR visibilities are expected for much of the
region. Some late night valley MVFR fog is possible in areas
near and south of KBLF.
No low level wind shear is expected during the TAF period.
No precipitation is expected during the TAF period.
Confidence levels of forecast parameters during the TAF time
period include the following.
Ceiling...Moderate to High.
Low Level Wind Shear...High.
Extended Aviation Discussion...
High confidence of VFR conditions Monday afternoon through
Moderate to high confidence of patchy MVFR conditions across the
mountains Tuesday afternoon into Wednesday with the passage of a
cold front. East of the Blue Ridge, mainly VFR conditions will
Thursday into Thursday night, moderate confidence of patchy
light rain returning to the area, with ceiling and visibilities
remaining mainly VFR. Some patchy MVFR is possible.
Friday, moderate to high confidence of precipitation trending
more showery, as low level jet increases in advance of a strong
cold front. Expect a mix of MVFR and low end VFR ceilings and
mainly VFR visibilities with isolated, brief sub-VFR
visibilities under heavier showers. Surface wind gusts of 20 to
30 kts possible across the higher terrain.
-- End Changed Discussion --
As of 307 PM EST Saturday...
Record High Temperatures and Year of Occurrence
Blacksburg, VA..65 in 1994
Bluefield, WV...66 in 1994
Danville, VA....73 in 1981
Lynchburg, VA...76 in 1939
Roanoke, VA.....77 in 1939
Blacksburg, VA..68 in 1984
Bluefield, WV...67 in 1986
Danville, VA....74 in 1971
Lynchburg, VA...76 in 1930
Roanoke, VA.....75 in 1939