Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 280005

Area Forecast Discussion
National Weather Service Blacksburg VA
805 PM EDT Sat Aug 27 2016

High pressure will be the dominant weather feature into the first part
of next week with just a chance for an afternoon shower or thunderstorm
west of the Blue Ridge. A weak cold front will then approach from the
west and bring an increasing chance for more showers and storms for the
middle of next week, mainly west of the Ridge.


As of 330 PM EDT Saturday...

The weak backdoor front being pushed along by the wedge of high
pressure building down form the northeast is generating some scattered
showers/storms mainly across Southside VA and into NC. DCAPE values are
quite high and will allow for some storms to have gusty winds, but
overall dynamic support is lacking so the threat for any severe
weather is low. Expect the storms to continue migrating into the NC
mountains before dissipating this evening.

Behind this boundary direr air will work in from the northeast so do
not expect to see extensive fog development unless the pool of warm and
moist air gets hung up west of the Blue Ridge. Much more pleasant
conditions will settle over the region for Sunday with less humidity
and temperatures just slightly above normal. Lows tonight will
generally be in the upper 60s to around 70 degrees east of the Ridge,
with middle 60s to the west. Highs on Sunday will be in the upper
80s./near 90 east to generally mid 80s west.


As of 400 PM EDT Saturday...

Models are in relative agreement with a broad area of high
pressure persisting from the Mid-Atlantic westward into the
central CONUS early in the week. Wind flow during this period will
be from the northeast with models indicating relatively stable air
east of the Blue Ridge. A surface frontal boundary is forecast to
approach from the northwest Monday night into Tuesday, albeit

For Monday, can`t rule out an isolated shower or thunderstorm
west of the Blue Ridge, but support for anything greater in terms
of coverage appears lacking. Surface front drifting in from the
north should permit a bit more coverage Tuesday.

Temperatures through early week will remain quite warm with highs
in the 80s to near 90. Overnight will generally be in the 60s.


As of 400 PM EDT Saturday...

General model consensus for the second half of the week is for
the upper ridge to give way to some weak upper level troughing
over the eastern CONUS, progressive flow across the northern tier
states gradually whittling away at the eastern ridge. This should
allow for another front to come through from the northwest during
the period, although model uncertainty is high with respect to
timing per unresolved solutions ongoing in the tropics. As such
will keep the forecast pretty close to persistence with respect to
precip probabilities, but shave a degree or two off the
temperature per potential for drier air to infiltrate from the
north later in the week, temperature trending closer to normal.


As of 800 PM EDT Saturday...

Weak backdoor front associated with wedge of high pressure
building down from the northeast was generating some scattered
thunderstorms from southwest Virginia into southern North
Carolina. Cluster of thunderstorms crossing west through the
mountains at 00Z/8PM will push a gust front through the KBLF
airport before 01Z/9PM. The general trend will be for the storms
to weaken and dissipate before midnight with no impact to area
airport after 10PM.

Behind this boundary direr air will work in from the northeast
which will limit the potential for fog/stratus development
overnight. TAF sites west of the Blue Ridge may be lingering in
the moist air long enough to generate some degree of low clouds
and fog, but based on predictors in the meso models believe the
most likely scenario is for the drier air to move in fast enough
to prohibit the need to mention fog or low clouds. KDAN had rain
Saturday afternoon and the dew point depression at 00Z/8pm was
only 2 degrees so will be watching for fog formation at that
airport. It is possible that fog will develop shortly after sunset
then dissipate overnight as lower dew points arrive and the
surface winds increase from the northeast.

This is not a high confidence forecast and the potential for
below VFR conditions will be reevaluated with later model runs.
With the dry wedge in place for tomorrow, VFR flying conditions
are expected at all sites through the end of the TAF period.

Extended aviation discussion...

A weak west-east oriented front will drift south through the
forecast area Sun-Mon. Isolated diurnally driven convection will
be possible along the front, mainly north of I-64 Sun, toward the
I-64 corridor Mon, then toward the NC/SC border by Tue. Coverage
will be limited in duration and area on all days and have minimal
impact on the TAF sites. Late night/early morning fog/low clouds
are possible, but not a certainty. At this time, it does not
appear that any tropical systems will impact the CWA.




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