Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Blacksburg Virginia
638 PM EDT Fri Aug 23 2019
a cold front will move through the Appalachians and central mid
Atlantic region, bringing showers and thunderstorms to the
area into this evening. A wedge of high pressure will then
build in overnight and bring much cooler weather with some light
showers possible for the weekend.
Near term /through Saturday/...
as of 630 PM EDT Friday...
Removed a few counties from the Severe Thunderstorm Watch. The
remaining line of showers will clear Southside Virginia and northwest
NC Piedmont counties within the next hour.
As of 230 PM EDT Friday...
Visible satellite imagery shows that clouds have broken up and
allowed for destabilization ahead of the cold front which has
entered from the north and already cleared the Interstate 64
corridor. The current activity on radar is just starting to
encounter the more unstable environment so anticipate convective
trends will be increasing through the afternoon. Anticipate
clusters evolving into more of a linear Mode with a primary
threat of damaging winds, particularly east of the Blue Ridge
into Southside where better instability and shear will overlap.
Will also be watching for development of deeper cores which may
support large hail, as well as a small chance of rotating storms
especially in the vicinity of the enhanced shear along the
frontal boundary as it pushes in. Will also be alert for locally
heavy rainfall and potential Hydro issues.
A strong wedge then builds in overnight with lingering
sprinkles and some fog, along with much cooler temperatures for
Saturday. Expect highs tomorrow only in the lower 70s east of
the Blue Ridge with mid/upper 60s to the west.
Short term /Saturday night through Monday night/...
as of 230 PM EDT Friday...
The Wedge that will spread southwest through the region Saturday
will remain in place well into early next week as it appears at
this time. Temperatures will be much cooler than recent weeks,
actually below normal for high temperatures, closer to normal
for low temperatures. While the deeper moisture will be pushed
further south by Sunday, the remains considerable question as to
whether or not this moisture will remain far enough south of our
area to allow at least the northern parts of the County Warning Area to remain
dry and with less cloudiness. Areas south of the Blue Ridge are
most certain to remain cloudy through the period with periods of
rain and/or drizzle. Upslope moist easterly flow will likely
leave the eastern slopes of the Blue Ridge, especially from
Watauga northeast toward Floyd cloudy, cooler than normal, and
with frequent periods of drizzle and/or rain through the period.
Areas north of U.S. 460 should remain dry Sunday into Monday,
but moisture will start returning northward by Tuesday as the
frontal boundary dissipates. The entire period cloud end up
being cloudy, damp, and relatively cool in the southwest part of
the cwa, especially northwest NC, while areas closer to I-64
should see periods of sun and slightly warmer daytime
temperatures. Hazardous weather during this period appears
unlikely as the potential for thunderstorms will be minimal and
rainfall, at least at this time, should be modest with a non-
tropical atmosphere and lowered pwats, that is the deeper
moisture relegated further south of our County Warning Area.
With 850mb temperatures more in the +14c to +16c range compared
to the +20c readings of recent weeks, maximum temperatures
should be mainly in the 70s to lower 80s northeast, with lows
mainly in the 50s west to 60s east. These readings are just a
bit below normal.
Long term /Tuesday through Friday/...
as of 230 PM EDT Thursday...
A much cooler and drier period appears to be in store for the
into early next week. Highs will be 10 to 15 below what has
recently been experienced with daily highs in the 70s or even
upper 60s and overnight lows will be 50s west to low 60s east.
Will certainly feel different. The surface high will shift north
and east toward mid-week with increasing southerly flow and
warmer temperatures along with renewed chances for mainly
An approaching front toward mid- to late late week will
possibly trigger a few stronger thunderstorms in an increasingly
warm and unstable air mass. A trough of low pressure currently
along the Florida coast has been given a 30 percent chance of
tropical storm formation near the SC/NC coast in the latest NHC
5- day outlook but impacts on the local weather look to be
negligible or minimal at this writing.
Aviation /00z Saturday through Wednesday/...
as of 230 PM EDT Friday...
Frontal boundary is sagging southward through the region, and
will continue to make slow progress before pushing just south of
the region tonight as a cool wedge of high pressure builds in.
This will result in generally VFR conditions, but lower flight
conditions can be expected in showers and thunderstorms with
locally heavy rain and gusty winds this afternoon into the
evening. There will then be a fairly quick transition to IFR
conditions as The Wedge builds in with low cigs and some fog
overnight into Saturday. There may be some gradual improvement
in cigs toward the end of the period but will not get too
specific that far out.
Winds will be a bit gusty mainly along and west of the Blue
Ridge early due to convective mixing, then become a bit gusty
east of the Blue Ridge as The Wedge surges in on robust
northeasterly flow tonight.
Extended aviation discussion...
Improving conditions with more in the way of VFR will be
possible for Sunday, pending just how far south of the mid
Atlantic area the front progresses. Some MVFR showers are
possible in the southwest Virginia and northwest North Carolina
on Monday. Scattered showers and thunderstorms with MVFR
conditions are expected Tuesday.