Area Forecast Discussion
Issued by NWS Blacksburg, VA

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566
FXUS61 KRNK 232332
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
632 PM EST Fri Feb 23 2018

.SYNOPSIS...
A strong cold front will slowly approach the Appalachians and
central mid Atlantic region from the west, as high pressure
remains wedged down east of the mountains. This will keep
temperatures generally well above normal with an increasing
chance for showers through the weekend. The front will push
through the area on Sunday and after some lingering showers on
Monday, high pressure will build in with gradual improvement
and cooler temperatures for the first part of next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 615 PM EST Friday...

Convection fairly isolated at the moment over SE WV, and seeing
lack of deep moisture convergence will lower pops across the
west this evening, following close to the Consshort. Otherwise,
seeing clouds continue to erode early this evening, but should
see another surge west toward the west overnight, with mid/high
clouds moving in from the west/southwest.


Previous discussion from early afternoon...

Wedge is eroding along the periphery and as a consequence,
temperatures range from the middle 70s well west of the Blue
Ridge to the middle 40s in the piedmont. Expect the erosion to
continue with the central portion of the wedge persisting
through the afternoon. Starting to see some showers popping up
in the west thanks to some shortwave energy and weak instability
where heating has occurred. Expect the chance for a
shower/possibly a rumble of thunder to extend just about up to
the Blue Ridge by late in the day.

The main frontal boundary will continue to reside off to our
west, but weak synoptic forcing and some short wave energy will
continue to stream over the region from the southwest with
lingering effects of the wedge across the piedmont. Expect this
will result in an increasing chance for showers overnight,
followed by a good chance for showers/perhaps isolated thunder
on Saturday enhanced by good isentropic lift.

Expect temperatures to be a bit more uniform tonight and
Saturday as the wedge loses some character, but we will remain
well above normal for late February.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 215 PM EST Friday...

Residual surface front will remain across far northern sections of the
region Saturday night ahead of a stronger cold front that will approach
from the west late. This should allow most of the area to stay within
the warm sector overnight with best chance of showers north early on
followed by increasing pops over the far west toward daybreak with the
pre-frontal showers. Lows mild, mainly 50s under clouds and strong
southwest flow aloft which may keep some spots above 60 for lows.

Weakening cold front looks to cross the region Sunday aided by a narrow
ribbon of shortwave energy while best support lifts well out to the
north. Models continue to trend a bit slower while producing less
rainfall with the GFS/Euro both showing the best swath of showers west
of the Blue Ridge through midday and then mainly southern sections in
the afternoon where a bit more weak instability will reside. Still iffy
on any thunder chances given the overall weakening trend and deep
westerly flow but will leave in an isolated mention from UKF to around
MTV for now. Otherwise likely to categorical pops with QPF of a quarter
to half inch mountains at best and generally less than a quarter inch
out east. Will again be quite warm with highs 65-70 west to mid 70s
southeast pending any sunny breaks.

Still a lot of uncertainty to start early next week as the passing
front gets caught up in southwest flow aloft and stalls across the
Carolinas Sunday night into Monday. Guidance continuing to
maneuver around with another wave along the boundary to our
south as disorganized shortwave energy gets sheared northeast
ahead of a bit stronger northern stream trough. Blend would
suggest better rainfall chances near the VA/NC border with some
drying north and more clouds in between. However latest
ensembles support deeper moisture farther north and since
carrying at least chance pops across most of the area will stay
the course and await later trends at this point. Will cool down
by Monday night as the final wave exits with lows in the 30s,
otherwise lows 40s/low 50s Sunday night and highs 50s/low 60s
Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 100 PM EST Friday...

Initial shortwave ridging within the fast westerly flow aloft will
bring a brief drying period for Tuesday into early Wednesday as surface
high pressure passes overhead Tuesday and to the coast by early
Wednesday. However the run of quiet weather looks to be brief as the
flow again backs/amplifies by midweek ahead of a strong upper low that
will eject out of the southwest states into the Great Lakes and Mid-
Atlantic region by Friday. Pieces of mid level energy ahead of the main
upper system will give rise to overrunning across a warm front
to the southwest by later Wednesday with this boundary crossing
the region Wednesday night/Thursday as the main surface low
tracks into the upper Midwest. Quick return of deeper moisture
per model Pwats suggests an increasing threat for showers/rain
from southwest to northeast later Wednesday and across the
region Wednesday night into Thursday ahead of the trailing cold
front. Upper trough looks to deepen across the region with a
switch to colder northwest flow by Friday in the wake of the
cold front. This likely to produce some upslope rain/snow
showers with breezy/windy conditions elsewhere with more
sunshine returning out east.

Temperatures mainly 50s/60s for highs early on with warmest Thursday
under strong southwest flow ahead of the front and then much cooler
Friday under cold advection resulting in highs 40s mountains to low/mid
50s east.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 620 PM EST Friday...

Ceilings will vary from MVFR/IFR at LYH/DAN this evening to VFR
elsewhere, but should see Roanoke drop to near 1kft ceilings by
midnight, but halt the lower cigs east of BCB.

Showers approach from the west late tonight into Saturday
spreading across a corridor north of a BLF-LYH line. Mainly VFR
at most locations, though will take longer for improvement east
of the Blue Ridge where could stay MVFR at best all day.
Showers to lead to MVFR cig/vsbys most of the time as well in
the west.

Winds will be light through the TAF period and will take on a more
southerly component over the course of the TAF period.

Confidence is medium to high on cigs/vsbys thru the period.

Extended:

VFR conditions should persist through early Sunday morning for
locations outside of any showery activity. During the day
Sunday, showers become more widespread as a cold front crosses
the region from the west. Sub-VFR conditions may well extend
through Monday as the front stalls out to the south allowing for
showers to linger in the region throughout the day. High
pressure builds over the region Monday night into Tuesday which
should bring drier conditions, at least temporarily.

&&

.CLIMATE...
Plethora of records yesterday. Please reference past Record
Event Reports for details.

Record high was tied at Bluefield today, with a reading of 74.


Friday 2/23/2018
Site MaxT/Year HiMin/Year
BLF    74/1975    51/1975
DAN    73/2017    50/1981
LYH    74/1943    52/1925
ROA    76/1943    54/1925
RNK    69/1980    46/1990

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...MBS
NEAR TERM...MBS/WP
SHORT TERM...JH
LONG TERM...JH
AVIATION...JR/MBS/WP
CLIMATE...PM



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