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fxus61 krnk 221756 

Area forecast discussion
National Weather Service Blacksburg Virginia
156 PM EDT sun Sep 22 2019

isolated showers are possible west of the Blue Ridge on Monday
afternoon and evening, and again on Thursday as a series of
weakening cool fronts drift southeast through the area; otherwise,
the weather over the mid-appalachian and mid-Atlantic region will be
dominated by high pressure. As a result, most areas will remain
dry for the entire upcoming week, with little to no significant
rainfall expected.


Near term /through Monday/...
as of 155 PM EDT Sunday...

Surface ridge of high pressure will remain anchored from the
southeastern states to off the mid-Atlantic coast tonight into
Monday before being suppressed somewhat as a short wave trof moving
east through the Great Lakes drives a cool front southeast into the
western flanks of the Blacksburg forecast area late in the day.

As has been the case for a couple of months now, the front may
be preceded and accompanied by weak isolated showers as it
encounters the western flanks of the appalachians; however,
lower tropospheric winds will be from the southwest or west - so
any precipitation that is fueled by enhanced upsloping across
the western mountains will quickly dry out/dissipate long before
crossing the Blue Ridge, and even then, rainfall amounts will be
scant - perhaps only a few hundredths of an inch at most.

Until the frontal passage, a dry airmass with light winds at
night and adequate mixing by day will ensure a continuation of
large diurnal temperature swings of 30-35f between morning lows
and afternoon highs - with afternoon readings remaining 10-15f
above seasonal normals.


Short term /Monday night through Wednesday night/...
as of 155 PM EDT Sunday...

Surface high pressure behind the exiting cool front will build east
into/over the Blacksburg forecast area during the short-term period -
maintaining dry conditions with only a slight and temporary reduction
in temperature which will still average about 5f above normal
on Tuesday - trending back toward 10f above normal on Wednesday.


Long term /Thursday through Sunday/...
as of 155 PM EDT Sunday...

Another short wave trof will swing east through southern Canada
Thursday into Thursday night, supporting yet another weak cool
front that should pass southeast through the Blacksburg forecast
area late Thursday afternoon and evening. This front will again
be preceded by southwest to westerly lower tropospheric winds
such that any precipitation will remain isolated, confined to
the western mountains, and with scant rainfall amounts.

High pressure following the front will then build east into the
forecast area on Friday, and then linger over the region for at
least all of next weekend, and likely beyond, as a large and
anonymously strong high pressure aloft builds over the southeastern
and south-central portion of the nation - once again maintaining a
prolonged period of unseasonably warm and dry weather which may very
well linger into at least the beginning of next month.


Aviation /18z Sunday through Friday/...
as of 155 PM EDT Sunday...

Mainly VFR weather with unrestricted flight conditions are
expected to prevail at all terminal forecast points within the
Blacksburg forecast area with exception of typical late
night/early morning IFR/LIFR restrictions due to fog in some of
the deeper mountain valleys.

Highest probability of late night IFR/LIFR impact would be
at/near klwb, and have included in forecast. A somewhat lower
possibility exists at/near kbcb toward daybreak, but at the
present time, confidence of occurrence is not yet high enough
to insert in forecast.

If fog occurs at Blacksburg, it will likely only be for a
couple of hours - in the 10-12z/6-8 am EDT timeframe - and
probably not lower than 3sm visibility.

All remaining terminal forecast locations (kblf, kroa, klyh,
and kdan) are expected to remain VFR through the period.

Forecast confidence is high through the 24 hour forecast period
ending at 18z/2pm EDT on Monday - but somewhat lower for kbcb
due to existing uncertainty in whether fog will redevelop late
tonight in the New River valley that would be close enough to
actually impact the Airport.

Extended aviation discussion...

Mainly VFR conditions expected to persist at all terminal
forecast locations through the extended period which carries
through Friday. A few hours of limited/isolated IFR/LIFR late
night restrictions in some of the deeper mountain valleys can't
be ruled out, such as at klwb, and possibly at/near kbcb, but
otherwise no restrictions to flight are expected across the
entire region as a series of surface high pressure systems
linger over the area.

Rnk watches/warnings/advisories...



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