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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 070500
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
1200 AM EST Sat Dec 7 2019

.SYNOPSIS...
A weak cold front will depart offshore tonight. High pressure
should arrive to provide dry weather for the weekend. Another
cold front will provide a wet start to early next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 1150 PM EST Friday...

No significant changes needed. Clouds are hanging in across all
but the far northeast and eastern sections of the CWA. Models
hang on to the clouds across most areas west of I-81 overnight.
The main impact this has had is on the temperatures, with
northern areas running warmer than earlier anticipated. Raised
temperatures a few degrees, especially in the western part of
the I-64 corridor. Otherwise no significant changes made at this
time. Remaining light rain across WV continues to dissipate, so
trend toward < 15% pops looks good overnight.

As of 140 PM EST Friday...

A weak cold front will cross overhead this afternoon. Skies
should remain cloudy through the evening as light rain showers
linger west of the Blue Ridge. However, the echoes on radar
crossing the Blue Ridge into the Piedmont appear to be mostly
virga. Any shower activity outside of southeast West Virginia
will likely dissipate after sunset. Despite the cloud cover,
the warm air advection from a light southwest breeze is allowing
high temperatures to reach close to model guidance.

After the frontal passage, winds should shift around to the
northwest tonight. A little bit of upslope moisture should
provide a quarter of an inch of snow showers for western
Greenbrier County during the overnight hours. The snow showers
will subside after midnight as drier air arrives. Elsewhere,
skies will partially clear before sunrise as high pressure
begins to build from the northwest. Low temperatures were kept
slightly elevated compared to model guidance due to the clouds
holding for a good chunk of the night. Saturday should be dry
with near seasonable temperatures as high pressure takes control.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 315 PM EST Friday...

A large area of surface high pressure will slide from New England to
off the East Coast.  In concert with the approaching trough to the
west, these features will turn our large scale flow such that it is
southerly.  This will bring increasing amounts of Gulf moisture into
our area on Sunday, building cloud cover throughout the day.

Showers will begin late Sunday night or early Monday morning and
continue with varying strength until Tuesday night, when a strong
cold front passes over the area.  Most of the precipitation
associated with this event will be liquid.

Sunday will be slightly cooler than what is normal for this time of
year, but Monday and Tuesday will see a warm up into the 50s in the
west and even low 60s for parts of the southside.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 315 PM EST Friday...

Rain will continue throughout the day Tuesday, and as the cold
air behind the front approaches on Tuesday night, those west of
the Blue Ridge may see some snow. Overnight into Wednesday
morning some gusty winds will accompany the frontal passage,
especially affecting the higher ridges. Once the front has moved
on, the moist environment of the early week will be supplanted
by drier air and a new surface high heading our way from the
northern plains. The cold air mass behind the front will drop
our temps well below normal for December, so the end of the week
will be chilly.

The next opportunity for active weather will be late Friday or
early Saturday as a low pressure system comes to us from the
south. Guidance has been wavering from run to run on the track
and timing, but there is a good consensus that a surface low
will bring precipitation around next weekend.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
As of 1150 PM EST Friday...

A weak front will continue to sink southward through the region
overnight. Remaining light rain in WV is dissipating as there is
very limited upper-level support and downslope west winds east
of the Alleghany front. The WV precipitation is mainly due to
light upslope, which will dissipate overnight as the winds veer
to the northeast. Low-level moisture will linger west of the
Blue Ridge with MVFR ceilings likely to continue for many of the
TAF sites overnight, with the exception of KLYH and KDAN, which
should see some periods of VFR. KBLF will be up in the clouds
and expect IFR conditions with some fog and drizzle to become
established later tonight. A gradual trend back toward VFR will
begin after daybreak with all sites VFR toward the end of the
valid period. However, models hang onto the clouds pretty tough
on Saturday, so have advertised more pessimistic TAFs into the
afternoon than previously indicated. Ceilings may remain MVFR
throughout much of the day west of the Blue Ridge, but
especially along and west of the I-77/New River Valley area. No
precipitation is expected Saturday and fog is not expected
either, so any restrictions to visibility would be entirely the
result of a location obscured by clouds due to elevation.

Winds will veer to the northeast overnight and early Saturday at
all sites, but first across the Piedmont. Speeds will gradually
increase from 5kts overnight to 6-10kts during the day Saturday
with low end gusts possible across the Piedmont by afternoon.

/Confidence in Forecast Parameters/
Ceilings - Moderate to High,
Visibility - High,
Winds - Moderate to High.

.Extended Aviation Discussion...

High pressure should dominate the area Saturday with mostly VFR
conditions. Confidence continues to increase in poor flying
weather for Monday and Tuesday as a complex low pressure system
develops to provide low ceilings and rain. The cold front from
this low pressure system should cross overhead by Tuesday night
to bring gusty northwest winds for Wednesday.

&&

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

&&

$$
SYNOPSIS...PW
NEAR TERM...PW
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...MBS/PW/RAB