Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 260356
Area Forecast Discussion
National Weather Service Blacksburg VA
1156 PM EDT Tue Apr 25 2017
Low pressure centered over the eastern North Carolina will slowly
drift northeast and off the coast tonight into Wednesday. High
pressure will build in Wednesday and continue for the second
half of the week. This will result in a considerable boost to
the temperature with above seasonal warmth expected by the
.NEAR TERM /THROUGH WEDNESDAY/...
As of 950 PM EDT Tuesday...
Patchy sprinkles across parts of the mountains are continuing to
a decreasing trend on radar, and there are few reports within
the surface observations. Bluefield, WV had some light rain a
little while ago. The latest report is from Hillsville, VA.
Little if any sprinkles are expected to survive after midnight
as cloud cover starts to erode across western sections of the
region first. With winds becoming light and variable or calm,
plenty of surface moisture, and clearing skies, we are
anticipating fog development to be common across the region
overnight. Have tweaked hourly temperatures and dew points based
upon the latest observations and expected trends into the early
morning hours of Wednesday.
As of 640 PM EDT Tuesday...
The low pressure system that has affected the entire area through
this past weekend is situated over the North Carolina coast and is
forecast to slowly move out of the area during the overnight hours.
Currently on radar, areas are seeing some lingering drizzle that
will make way to patchy fog in the morning hours before clearing out
for the day on Wednesday. Most recent solutions of the HRRR and RAP
models show precipitation ending sooner in the Piedmont with only a
few lingering sprinkles along and west of the Blue Ridge
Mountains. Therefore, have adjusted the forecast accordingly.
As of 255 PM EDT Tuesday...
WSR-88D showed showers are diminishing or dissipated across
most of the forecast area. However, there are still some pockets
of drizzle and light rain. Low pressure centered over eastern
North Carolina this afternoon will move northeast off the
Atlantic coast tonight into Wednesday. High pressure over the
Ohio Valley will build east tonight into Wednesday.
HRRR and Hiresw-arw-east try to develop some isolated showers across
the high terrain this afternoon into this evening. Believe any
shower or light rain/drizzle will be limited. Mid level ridging
builds in from the west this evening into tonight. For tonight, any
clearing will set the stage for fog formation. Unless the stratus
persists, anticipate development of fog per wet ground, diminishing
winds and radiational cooling from the departing mid/upper level
cloud cover. Low temperatures tonight will range from the mid 40s in
the mountains to the lower 50s in the Piedmont.
High pressure will build over the Southeast States Wednesday. Any
fog Wednesday morning will quickly dissipate leaving sunshine for
Wednesday afternoon. With increasing heights and warming
thicknesses, 85h temperatures will climb to near +15 deg C for
Wednesday. Temperatures may be a degree or two cooler than one would
think, as the initial surge of warmth will go into latent heating
and an attempt to evaporate all of this moisture laying around from
the multiday rain event. High temperatures will vary from near 70 in
the mountains to the upper 70s in the Piedmont.
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 258 PM EDT Tuesday...
A low amplitude upper ridge will give way to a broad trof over the
upper midwest with short wave shearing off to our northwest. This will
drive a surface low from the Great Lakes into Canada and drag a
trailing cold front into our region late Thursday into Thursday night
with basically high chance POPs for scattered showers/some thunder.
High pressure brings us a basically dry day for Friday before a warm
front lifts north through the region Friday night with chance for
By Friday, we develop a Bermuda high off the coast with ridging aloft
and a deepening trof/closed low over the midwest. This will develop a
deep southerly flow of warm and moist air that will pump the heat and
humidity up by late in the week. Expect highs Friday to reach the mid
80s east of the Blue Ridge with upper 70s/lower 80s to the west.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 258 PM EDT Tuesday...
We will be in a very summerlike pattern this weekend with very warm and
humid conditions and an increasing chance for showers and thunderstorms
each day, especially along the Blue Ridge. By Monday, the vertically
stacked upper closed low over the midwest will move into the Great
Lakes region. This will push a vigorous cold front into the area from
the west with a good chance of showers and thunderstorms through Monday
afternoon. High pressure will then build on for Tuesday with cooler
weather and windy conditions.
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
As of 730 PM EDT Tuesday...
MVFR ceilings with pockets of IFR, light rain, drizzle and fog
will continue until about midnight. The upper level low will
slowly drift northeast tonight and away from the area Wednesday.
The pressure gradient across the region will start to weaken,
allowing winds to become light and variable overnight into
Areas of low clouds and fog will develop tonight with IFR conditions
expected into Wednesday morning. Conditions will become VFR by
Wednesday afternoon. Winds will remain light and variable.
Moderate confidence in ceilings, visibilities and winds during
the TAF period.
Extended Aviation Discussion...
Better flying weather is expected for the second half of the
week, though another front may bring scattered MVFR
showers/storms Thursday afternoon and evening across the
mountains. Drier and much warmer weather will return for Friday
and Saturday with temperatures much above normal for the
weekend. Can not completely rule out an isolated MVFR
thunderstorms along the southern Blue ridge. Scattered MVFR
showers and thunderstorms are possible Sunday and Monday.
As of 1145 PM EDT Tuesday...
The upper low has finally moved out of the area and any
remaining precipitation is generally in the form of drizzle.
Additional QPF from this synoptic system will no longer be a
factor. Main concern at this point is runoff into the lower end
of the Dan and Roanoke River basins. Coordinating with SERFC and
AEP, expected water releases from Smith Mountain Lake and
Leesville Reservoir will be insufficient to push Alta Vista or
Brookneal into flood stage, and in fact, the river at both of
these locations is already falling and is just at action stage
at this point. Further downstream at Randolph on the Roanoke,
flooding will continue for a couple more days and the river will
just touch moderate flood stage by Wednesday afternoon.
More significant concerns along the lower end of the Dan River
continue and will for a couple more days. The river has crested
at Danville, just a tad under major flood. At Paces, the
situation is a bit more serious as the river is now forecast to
crest near 28.6 feet, well above the major flood level. Viewing
the crest history, this is only the 9th time of record that the
river has crested in the above the major flood level. Finally at
South Boston, the current forecast has it cresting just below
major flood. It is interesting to note that most of the previous
major floods were associated with a tropical system, such as
Hurricane Agnes in 1972 or Hurricane Fran in 1996.
Will also continue the Areal Flood Warning for a bit longer
along the upper reach of the Dan River due to continued flooding
at points such as Wentworth, NC.
For additional details on the river flooding, please refer to
the AHPS page and specific FLS/FLWs issued from this office.
As of 258 PM EDT Tuesday....
Significant rainfall has ended across the region allowing water levels
to gradually subside at all locations except along the Dan and Roanoke
The Dan is expected to crest early tonight above major flood stage at
Danville, then begin falling later tonight. Crests at Paces and South
Boston are not expected until late Wednesday. Further upstream, the Dan
crested at moderate flood stage at Wentworth and will be falling slowly
The Roanoke river at Randolph will experience moderate flooding with a
crest late tomorrow.
Please refer to the latest flood statements for further details.