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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 210539
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
139 AM EDT Wed Oct 21 2020

.SYNOPSIS...
Upper level ridging will increase across the Southeast and mid-
Atlantic tonight and tomorrow, contributing to a warming trend
that will push temperatures well above normal through the
remainder of the work week. A cold front is expected to arrive
on Saturday, bringing a modest cool down to the region and
a chance of rain.

&&

.NEAR TERM /THROUGH TODAY/...
As of 1250 AM EDT Wednesday...

No big changes are planned for the forecast during the remainder
of the overnight period. We are still expected the development
of patchy fog towards daybreak, that will not last very long
after sunrise. Have tweaked hourly temperatures, dew points,
wind/gusts, sky cover grids over the next few hours based upon
the latest observations and expected trends.

As of 1030 PM EDT Tuesday...

High pressure still in control today as a weak wedge continues to
remain in place east of the mountains. Stalled cold front over
the Ohio River Valley will retreat back north as ridging along
the southeast United States builds in for Wednesday.

A weak east/southeast flow keeping enough shallow Atlantic
moisture in place to see fog development again tonight. At the
moment, mountain river valleys along with the Piedmont of
Virginia and North Carolina have the best chance for patchy
dense fog through sunrise. Higher elevations and areas to the
west should remain mixed well enough to limit fog to the river
valleys late tonight.

Temperatures will remain a couple to several degrees above normal
today and tomorrow as a 588dm upper-level ridge remains in place
over the southeast coast. Warmer tomorrow with some locations
reaching the low 80s. Tonight should remain rather mild east of
the Blue Ridge as fog and high clouds could hinder some cooling.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
As of 130 PM EDT Tuesday...

The big story of the short range portion of the forecast will be
above average temperatures as high pressure underneath a broad ridge
allows for ample warming to take place. As of now, Thursday looks to
be the warmest day of the week, with areas out east nearing the 80
degree mark.

Later in the period, Friday, an advancing front from a low tracking
from the central Plains, toward the Great Lakes region, approaches
the Mid-Atlantic. As this nears, high pressure over the region
weakens and shifts eastward. As high pressure shifts, frontal
advancement is expected to slow, holding any real rain chances off
until Saturday. Any earlier rain chances would be dependent on
return flow interacting with the southern Blue Ridge/NC mountains to
spark isolated showers Friday afternoon. Greatest rain chances and
amounts Saturday with the front will be for the west, as the front
dries out in the Piedmont.

Forecast confidence is moderate.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 130 PM EDT Tuesday...

Guidance since yesterday in the long range has come into better
alignment, with GFS coming into better agreement with the ECMWF and
Canadian: the trough over the Great Lakes/Canada shifts northward.
This prevents waves within the flow from really impacting our area.
Instead, a bulk of the precipitation will fall to our west, though
at this time range it is too early to rule out at least some
rainfall for the western slopes. The rest of the area will remain
under a mix of clouds.

Tuesday into Wednesday, the trough is expected to dig slightly
south, pushing a front into the area, increasing rain chances. At the
same time, a LLJ is projected to set up over the Mid-Atlantic,
bringing windy conditions for the area.

Overall, temperatures during this period will be cooler than the
short range`s, but still remain above average. Increased cloud cover
should especially help keep nighttime temperatures mild.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
As of 130 AM EDT Wednesday...

Weak southeast flow will keep a shallow layer of moisture near
the surface overnight with sub-VFR conditions entering the
region and lingering until daybreak. For now have in MVFR fog
across much of the foothills and piedmont of Virginia and North
Carolina. LIFR fog is possible again at KLYH and at KBCB.

Much of the low clouds and fog will begin to mix out around
15Z/11AM but it may take longer in central and eastern Virginia.
VFR conditions are expected in the mountains and foothills for
the afternoon.

A return to some patchy MVFR fog is possible by late in the
valid TAF forecast period concluding at 06Z/2AM Thursday.

Confidence in the above aviation scenario is moderate to high.
The biggest question mark is the coverage of the sub-VFR
conditions in the east through daybreak.

.Extended Aviation Discussion...

Some sub-VFR conditions early Thursday will give way to VFR
conditions throughout the remainder of Thursday, with possibly
more fog Thursday night/Friday morning. Isolated MVFR showers
are possible mainly in the mountains Friday night. These
conditions look to spread east by Saturday as our next front
crosses through the area.

&&

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

&&

$$
SYNOPSIS...NF
NEAR TERM...AMS/BMG/DS
SHORT TERM...RR
LONG TERM...RR
AVIATION...AMS/BMG/DS