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-- Discussion containing changed information from previous version are highlighted. --
933
FXUS61 KRNK 201831 CCA
AFDRNK

Area Forecast Discussion...CORRECTED
National Weather Service Blacksburg VA
231 PM EDT Fri Sep 20 2019

.SYNOPSIS...
High pressure will reside across our area through the weekend,
the shift offshore Sunday night. A weak cold front will drift
into the area from the northwest early next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 142 PM EDT Friday...

West to northwest flow into the mountains along a weak theta-e
boundary will keep scattered to at times overcast skies along the
mountains this afternoon, with skies clearing this evening. A few
sprinkles not out of the question, but deeper moisture appears to
stay west of the divide.

Expect another surge of clouds Saturday morning as a weak impulse
moves across the Ohio Valley/Central Appalachians. A few models
showing shower potential increasing with this feature but overall
system will be weak, so mainly going isolated/widely scattered
coverage across the mountains. Anticipate a mix of clouds and sun in
the mountains, with more sunshine in the piedmont, a little more
cloud cover along the ridges.

With high pressure moved east some, boundary layer will be slightly
more moist, so lows tonight will be in the 50s, with some 40s in
deeper valleys.

Saturday will mild/warm with upper 70s to lower 80s mountains,
though some lower 70s in the higher ridges. Should be reaching the
mid to upper 80s across the piedmont and Roanoke area.

Confidence in this forecast is medium to high.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 130 PM EDT Friday...

High pressure will be centered off the North Carolina coast during
Saturday night and Sunday. A large upper level ridge will also be
situated over the Mid Atlantic. Although the GFS tries to show a
couple pop-up showers west of the Blue Ridge during Sunday, the NAM
and ECMWF models do not show anything developing over the CWA. The
consensus of the NAM and ECMWF was preferred here as it should stay
dry throughout the day with the vertically stacked ridging in place.
High temperatures were bumped upward on Sunday by a few degrees to
accommodate the expected plentiful sunshine and light southwest flow
providing warm air advection.

By Sunday night, high pressure should head further out to sea, and a
weak cold front will arrive over the Appalachian Mountains during
Monday. The models continue to advertise a moisture-starved boundary
that will be lucky to provide any meaningful amounts of rain.
Sprinkles at the most may reach the I-81 corridor, and there is high
confidence that the Piedmont will remain dry throughout the frontal
passage. Thus, the unseasonably warm and dry trend from late summer
should continue into the first day of autumn. Any moisture will
dissipate during Monday night as high pressure returns from the west.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 153 PM EDT Friday...

Very few changes in this period since the last update. An upper
level trough that moves over the Great Lakes region Monday and
Tuesday will begin to shift into New England and exit off the coast
of Nova Scotia by Wednesday. Some leftover showers may stick around
in the mountains of West Virginia Tuesday morning from the weak NW
flow behind the front. A broad ridge then begins to build into
the southeast United States for Wednesday and especially Thursday.
There are still some model differences in regards to rainfall.
The GFS is finally advertising some rainfall due to a weak frontal
boundary draped west to east across the region and a generally
flatter flow at 500mb. However, the ECMWF is much faster in
building in the 500mb ridge and leaves our area with little to no
precip through this entire forecast period. Other than these
differences, the models tend to agree temperatures will likely be
above normal with 850mb temps reaching anywhere from +16 to +20.
Will likely side with the persistence of a dry pattern and go with
a blend of the ECMWF and NBM for this period.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 120 PM EDT Friday...

High pressure in control although working east and allowing some
clouds to move into the mountains as flow turns west-southwest.
Cu/Stratocu will be bkn/ovc around BLF, possibly LWB/BCB this
afternoon but should stay above 3kft. Cannot rule out a sprinkle
or very light shower, but no impact to terminals. Winds remain
light, and mainly variable or southwest.


Will see clouds wane this evening but another increase in cloud
cover will nudge into WV Saturday and possibly into the BCB area
by end of the period. MVFR seems possible around 09-12z at LWB.
Will have to watch for fog in the valleys, but given dry
ground, should be limited to near rivers, so backed off the
dense fog at LWB due to increased clouds.

Confidence is high for most of the period, but lower Sat morning
in the mountains for the cloud cover/vsbys.


.Extended Aviation Discussion...

High pressure to our northeast will continue to build southwest
over the region promoting mainly VFR into Sat afternoon into
Sunday. Only exceptions may be late night and early morning fog
in the mountain valleys which would impact the usual terminals
(e.g., KLWB and KBCB).

A weak cold front may bring scattered MVFR showers on Monday,
mainly in he mountains. Otherwise VFR.

&&

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

&&

$$
SYNOPSIS...RAB/WP
NEAR TERM...WP
SHORT TERM...PW
LONG TERM...BMG
AVIATION...RAB/WP