Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 191649
Area Forecast Discussion
National Weather Service Blacksburg VA
1249 PM EDT Tue Jul 19 2016
A weak cold front will drift south across the region this
afternoon before passing to the south overnight. Additional
showers and thunderstorms are expected along the front into early
this evening. Weak high pressure follows the front with drier
weather for mid and late week.
.NEAR TERM /THROUGH TONIGHT/...
As of 945 AM EDT Tuesday...
Main concern again with convective potential this afternoon as a
weak front to the north pushes south into the area during peak
heating and shortwave energy glides through from the northwest.
Morning raobs do show deeper moisture now across much of the
region with much drier air aloft supportive of better DCAPE once
strong heating gets going. However forecast convergence remains
weak until things coincide over far southeastern sections late
with meso models again having a tough time in resolving where
better storm clusters/bands will occur.
Again appears per early clouds south will see differential
heating aided convection to initialize along and just east of the
Blue Ridge with coverage spilling east ahead of the front folding
over from the north. This should focus more organized coverage
along/south of Highway 460 in the east closer to the front, and
bounded by the Blue Ridge in the west where pwats will start to
lower later in the day. Forecast severe parameters also point to
stronger convection over the south/east where moisture will be
deeper along theta- ridging and perhaps far enough removed from
ongoing downslope later to allow more organization to occur. Thus
upped pops slightly where upgraded to slight risk for this
afternoon given downburst potential despite weak winds aloft.
Looks like most widespread coverage will quickly shift to the
south by early this evening with drying filtering in from the
north. Otherwise another rather hot day under intervals of
clouds/sun with thickness again showing at least low 90s out east
ahead of the boundary, and well into the 80s west pending early
clouds and later convection.
Previous discussion as of 327 AM EDT Tuesday...
An upper level trough will move east across the Northeast today as a
cold front advances southward into our region. Scattered showers and
thunderstorms will form ahead and along the cold front especially
this afternoon into this evening. SPC has most of county warning
area in the marginal risk for Severe thunderstorms in the Day One
Convective Outlook. The main threats will be gusty winds, hail and
Outside of the isolated convection this morning, scattered showers
and thunderstorms will develop along the Blue Ridge Mountains by
early afternoon, then translating into the east as the axis of
higher pwats leans over along the front. High temperatures this
afternoon will range from the mid 70s in the northwest mountains to
the lower 90s in the piedmont.
As a wave of low pressure pushes out into the Atlantic ocean this
evening into tonight, the cold front will move south of our area
reaching South Carolina by Wednesday morning. The convection will
taper off as high pressure build south from Pennsylvania in the
wake of the front. Low temperatures will drop into the upper 50s
in the mountains to the upper 60s in the Piedmont.
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 245 AM EDT Tuesday...
During this part of the forecast, an upper ridge builds across
the central portion of the country while expanding its influence
eastward toward our region. We are expecting northwest flow aloft
on the east side of this ridge across our region all while height
build. Anticipate a trend towards higher temperatures each day with
numbers on Friday some five degrees above normal for this time of
Precipitation chances will be minimal Wednesday and Thursday.
Guidance varies on the degree to which isolated to scattered
convection will develop. Any activity is expected to be confined
primarily to orographical influence along and near the crest of the
Blue Ridge. Wednesday coverage is expected to be confined to mainly
the northern mountains of North Carolina with better expanse north
through Virginia on Thursday.
Friday an upper low/trough is progged to round the top of the upper
ridge and travel into New England. Guidance offers a solution that
brings its associated trough axis into and through our region on
Friday and Friday night. Isolated to scattered showers and storms are
forecast for areas along and west of the Blue Ridge, including
southeast West Virginia, where coverage Wednesday and Thursday will
.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 330 PM EDT Monday...
As the upper trof over the Pacific northwest moves east late in the
week it will flatten the ridge across the midsection of the country,
leaving us in weak quasi zonal flow on the hot side of the jet stream.
This will allow the heat to build throughout the weekend with air
temperatures well into the 90s and heat index values over 100 east of
the Ridge, a bit cooler to the west. Our chances for showers and
thunderstorms will also be increasing through the weekend, especially
as we head into Monday with a cold front approaching from the northwest.
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --As of 1230 PM EDT Tuesday...
Weak cool front continues to sag toward the region from the north
preceded by quite a bit of mid cloudiness along/east of the Blue
Ridge in response to lift within weak difluence aloft. However
expect this canopy to push southeast shortly while giving way to
a developing scattered to broken VFR cumulus field between 4-6K
feet this afternoon.
In addition, heating combined with this low level moisture ahead
of the boundary should result in development of at least scattered
showers and storms during the afternoon. This should make for
periods of MVFR/IFR espcly across eastern/southern sections with
the KLYH-KDAN corridor, and points south/east the most likely
area to have a tsra impact an airport directly into early this
evening. Therefore inserting a tempo group for localized lower
conditions in convection with some gusty winds also possible. More
isolated nature coverage expected west of the Blue Ridge where
will just include a vicinity mention of a shra/tsra this
afternoon. Most organized convection if any should move south by
sunset with drier air aloft spilling in from the north overnight.
However moist ground conditions along with possible lingering
higher dewpoints across the south/east likely to give rise to
more fog/stratus east and patchy valley fog west late. This
supports a period of MVFR/IFR in spots late with uncertainty at
KBLF about seeing any low clouds/fog so including less there than
Drier air should win out on Wednesday with widespread VFR once low
clouds and fog burn off during the morning. An isolated mountain
shower or storm may still be possible with heating but not enough
to include any mention Wednesday afternoon.
Extended aviation discussion...
Strong high pressure aloft will bridge east across the region
Thursday into next weekend. Cant totally rule out an isolated
storm each afternoon/evening through the period but appears
overall VFR outside of the typical late night valley fog in spots.
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