Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 281416

Area Forecast Discussion
National Weather Service Blacksburg VA
1016 AM EDT Wed Jun 28 2017

High pressure moves east to the coast this evening. Will start
to see a return to the heat and humidity by Friday into the
weekend. Our weather pattern may stay active into early next
week as a frontal boundary stalls over or near the region.


As of 1000 AM EDT Wednesday...

The river valley fog that formed early this morning over parts
of the Greenbrier Valley and a few parts of the New River
Valley, has dissipated. Sunny skies prevail across the region,
and for the most part, that is how it will remain the throughout
the day. The exception will be over parts of the Northern
Mountains of North Carolina, northeast near the spine of the
Blue Ridge to around Floyd County Virginia. This part of the
area is more likely than other areas to experience some cumulus
development, but still, the sky will still be mostly sunny in
nature. Later today, western sections of the region may see some
thin cirrus clouds invade the region from the west. But here
too, mostly sunny, or even sunny, will be the best descriptor of
the sky. Have made minor tweaks to hourly temperatures, dew
points, sky cover and wind heading into the early afternoon
hours based upon the latest observations and trends into the
early afternoon.

As of 300 AM EDT Wednesday...

High pressure overhead this morning exits to the coast this evening.
Still drier air will stick around to allow for another less humid
day before we start to see dewpoints edging up late tonight. Aside
from a few cirrus skies will be sunny today and clear tonight.
Cannot rule out some river valley fog early this morning. A few cu
not out of the question late this afternoon over the southwest
mountains of VA into the NC high country.

Going to experience a warm day but still around 5 to 8 degrees below
normal with highs ranging from the mid to upper 70s across the
mountains, to around 80-lower 80s east of the Blue Ridge.

Tonight, southerly flow starts to increase on the west side of the
high, mainly over the higher terrain while valleys stay light/calm
winds. Should see temps a little milder than this morning but think
the piedmont could actually sink into the 50s once again if the high
slows down. 50s are likely in the mountains as well but should be
about 5 to 10 degrees warmer than this morning. Valley to higher
ridge temp difference could still be 10 degrees given increasing
southerly flow allowing fog steep inversion Thursday morning.
Also with light/calm winds again in the valleys, fog appears more
likely, but still patchy in nature since we have dried out the past
few days.


As of 314 AM EDT Wednesday...

An upper level ridge builds over our area through Friday night,
bringing a return to warmer and more humid conditions. The surface
high continues to migrate east Thursday resulting in a southerly
flow and the advection of moisture. While there is some modest
recovery in PWAT values, forecast values are still expected to be 75-
100% of normal. The combination of solar heating, orographic lift
and some low level moisture may create isolated to widely scattered
showers and thunderstorms across the higher terrain of Northwest
North Carolina Thursday afternoon. High temperatures Thursday will
range from the mid 70s in the mountains to the mid 80s in the

Moisture will continue to surge into our region Thursday night into
Friday around the high center off the coast. Light winds and low
level moisture may contribute to the development of some low clouds
and patchy fog Thursday night, along with warmer temperatures.
Low temperatures Thursday night into Friday morning will vary from
the mid 50s in the mountains to the mid 60s in the Piedmont.

A weak disturbance will push out of the western Gulf of Mexico and
undercutting the upper ridge, moving toward our region on Friday.
This weakness combined with increased instability and richer
moisture could generate widely scattered to scattered thunderstorms
Friday. High temperatures Friday will be near normal with readings
from the upper 70s in the mountains to the upper 80s in the
southeast. An isolated shower is possible in the west Friday night.
It will be a mild night with temperatures from near 60 degrees in
the west to around 70 degrees in the east.


As of 310 AM EDT Wednesday...

During this period of the forecast, our region will be between a
large upper ridge off the southeast U.S. coast and an upper trof
that pushes east from the upper midwest Saturday, into eastern
Canada into New England by Tuesday. This will result is series of
upper level disturbances moving over area and keeping a daily chance
of afternoon and evening showers and thunderstorms. The long range
models all show differences in timing and strength of these systems,
but the GFS appears to show slightly more run to run consistency,
especially later in the long term period.

The best chance for showers and storms during the long term period
will be Saturday as a surge of higher PWAT air that the GEFS
indicates in about 2 standard deviations above normal move into
areas east of the Blue Ridge. The GFS and ECMWF indicate an upper
level wave entering the west late on Saturday.

By Sunday, there is modest agreement that a sfc boundary (likely not
the true cold front) moves into our area bringing slightly drier
air. Therefore kept lowest POPS on this day of the period.

Monday into Wednesday, a low level south flow is re-established
pushing up dew points/PWAT values/instability. All the long range
models and ensembles hint that at least one upper level wave moves
through sometime during this time which may result in slightly more
organized convection Monday.

With 850mb temps climbing to 1-2 standard deviations above normal
late in the period (Monday-Wednesday), went a degree or two above
guidance during this time. These temps combined with higher humidity
levels will likely push heat index values at least into the mid 90s
in the east for the first half of the week including the 4th of


As of 701 AM EDT Wednesday...

High pressure shifts east to the coast tonight. Some LIFR fog at
LWB will become VFR by 1330z. Expect VFR through tonight, though
some fog at LWB/BCB possible as dewpoints creep up.

Extended Aviation Discussion...

VFR conditions expected through at least early Friday. Small
chance of patchy late night/early morning mountain or river
valley fog.

Friday afternoon through Sunday, especially Saturday, showers
and storms return to the forecast as well as an increase in low
level moisture in general. Anticipate better chances of sub-VFR
ceiling and visibilities. Most of these during the day will be
temporary, associated with conditions immediately under any of
the stronger showers and storms. Overnight, chances of MVFR/IFR
late night/early morning fog will be greater.




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