Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
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FXUS61 KRNK 151754
Area Forecast Discussion
National Weather Service Blacksburg VA
1254 PM EST Sun Jan 15 2017
A weak frontal boundary will drift back south through much of
the forecast area today, then lift back north Monday. Another
frontal system will move into the region from the west Tuesday,
then move slowly across the area Wednesday before finally move
east toward the coast by Thursday. Several more days of cloudy,
damp weather can be expected as a result of these frontal
systems lingering across the region.
.NEAR TERM /THROUGH TONIGHT/...
As of 1100 AM EST Sunday...
Thin spots in the overcast will yield some sun through mid
afternoon before thickening again this evening. Added solar
insolation will boost temperatures a few degrees higher than
previous forecast. Overall, not a bad afternoon as main rain
threat will hold off until tonight.
The wedge that was in place across most of the forecast area
Saturday has lifted back to the north. Temperatures have surged
into the mid and upper 50s across southwest VA and northwest NC
early this morning, while temperatures were about 10 degrees
cooler along the I-64 corridor. The retreat of the cooler air
to the north will not be for long, however, as another cell of
high pressure moves from the Ohio Valley toward New England.
This is already evident in the LAPS analysis with northeast
winds advancing westward from eastern VA. This wedge will
encompass about the same area that the previous one did and hold
in place overnight into the morning Monday before retreating
back to the north. Max temperatures today will be tricky with
the wedge affecting eastern areas fairly early while western
areas, especially west of I-77 may not see the wedge at all and
are already in the mid to upper 50s.
In spite of the tease of sunshine, extensive cloud cover
upstream of the forecast area will continue to overspread the
area as the baroclinic zone oscillates about the region and a
series of weak disturbances aloft drift east from a deep upper
low in the southwest U.S. It appears that the best period of
rain through this part of the forecast will occur later this
evening into the overnight hours, especially north of the U.S.
Minimum temperatures Monday morning will be largely determined
by the location of the wedge boundary, ranging from the mid 30s
north to the upper 40s around Richlands which will never see the
wedge. With temperatures remaining above freezing, there is no
threat of freezing rain with tonights rain event.
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
As of 315 AM EST Sunday...
Another faint shortwave will be spilling east across the area to start
Monday as surface high pressure translates down the Mid Atlantic coast
by the end of the day. This should result in higher chance pops from
west to east during the morning with rain tapering off during the
afternoon, leaving only spotty coverage in the far west by evening.
Locked in wedging could again result in cold enough deep valley temps
for a spot or two of ice across Bath/Greenbrier counties early Monday,
but very isolated if any occurs at this point, so likely wont mention.
Otherwise strong warm advection aloft combined with the high sliding to
the east should help slowly break down the wedge during Monday, but
likely not enough to scour things out east of the Blue Ridge given
clouds. Thus expecting a range in temps from the mild 50s to around 60
Interstate 77 corridor to only 40s from the Blue Ridge and points east.
Surface high to finally exit offshore Monday night into Tuesday ahead
of stronger shortwave ridging that will slide overhead in advance of
the next weak cold front off to the west. Expect this to reduce shower
chances Monday night with best lift still west of the mountains by
early Tuesday. However the residual wedge will likely persist into
Monday night out east before finally fading under even deeper warm
advection on Tuesday as mixing increases. Thus lows still chilly with
upper 30s/low 40s east to mid 40s west Monday night.
Models differ a bit on timing with the arrival of the pre-frontal axis
of showers Tuesday with a couple rounds of showers possible later
Tuesday into Tuesday night as the front slows up a bit and waves ripple
along the boundary. Latest 00z ECMWF remains faster with decent
coverage west Tuesday morning, while most other guidance including
ensembles take until afternoon to spill shower across the mountains.
Since best support will be lifting out to the north while shortwave
ridging holds in place, slowed down the onset of likely or higher pops
to the western third of the area Tuesday, with higher pops lingering
mountains, and chance east into Tuesday night. Highs Tuesday quite mild
given 850 mb temps near +10C and decent mixing that despite cloud
cover/showers should send highs well into the 50s if not warmer most
.LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 345 PM EST Saturday...
Surface front is forecast to cross the forecast area early Wednesday.
Attm, models do not indicate much in the way of cool air behind the
front, a few degrees drop at 850 mb, so once we dry out behind this
feature Wednesday, the afternoon should be fairly nice with
temperatures once again testing 60.
Beyond Wednesday, the weather pattern still looks mild. A new cutoff
low is forecast to take up residence within the southern stream over
the southwestern CONUS with ridging over the southeast States and Gulf
Coast. There are some model differences with respect to how far east
the southern stream trough will progress next weekend. This results in
timing differences with respect to precipitation. Per the mild pattern,
there should not be any P-type issues for our forecast area with any
precipitation falling in the form of rain. Forecast high temperatures
will run about 10- 20 degrees above normal Wednesday through Saturday.
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --As of 100 PM EST Sunday...
Overall flying conditions will range from continued sub-VFR
along the Blue Ridge and points west this morning to VFR/ocnl
MVFR across the east. Should also see pockets of light
drizzle over the mountains with ridges obscured attms. A
stationary front extends from west to east across the southern
Appalachians. Most of the Mid-Atlantic region resides north of
this front with widespread cloud cover prevailing. This front is
expected to gradually lift north tonight as a wave of low
pressure ripples east along the front. This will result in
lowering cigs and vsbys with areas of light rain developing
after sunset. ifr are likely during the overnight period with
pockets of lifr. The warm front will gradually lift north of the
area by monday afternoon with cigs/vsbys trending back to MVFR.
Extended Aviation Discussion...
A baroclinic zone will remain anchored across the region
sandwiched between a strong upper ridge over the southeast
states and an active jet stream from the southwest U.S. into the
northeast U.S. Thus, an unsettled, wet weather pattern is
expected to remain in place Monday into Tuesday. The frontal
boundary may lift north enough by Monday night for a brief
period of mainly VFR, but a stronger front will arrive By
Tuesday with more showers including widespread sub-VFR.
Generally looking at MVFR much of the period, although periods
of VFR as well as IFR-LIFR can be expected at times. Models
remain uncertain with timing of another wave along a passing
cold front during midweek. Some guidance showing another round
of showers with sub-VFR on Wednesday with improving conditions
Thursday. This while others slower with a break on Wednesday
before moisture returns from the southwest Thursday afternoon
into Thursday night.
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