Area Forecast Discussion
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FXUS61 KRNK 301125
Area Forecast Discussion
National Weather Service Blacksburg VA
725 AM EDT Tue Aug 30 2016
A weak frontal boundary will move south and fade today. Tropical
depression eight off the Outer Banks of North Carolina will move
northwest and is expected to become a tropical storm this evening,
before moving away from the coast Wednesday. A stronger cold
front will approach on wednesday and arrive on Thursday. Another
tropical system emerging from the Gulf of Mexico on Thursday is
expected to remain to our south and move offshore over the
.NEAR TERM /THROUGH TONIGHT/...
As of 318 AM EDT Tuesday...
Weak boundary from northern Virginia into the Central Appalachians
will shift southward today. Moisture convergence along with aided by
a east to southeast flow should allow for more shower coverage,
mainly west of the Blue Ridge. Nonetheless, not seeing upper support
as ridge remains overhead and west of the area. Appears best threat
shifts to far Southwest Virginia along and west of I-77 this
afternoon, with isolated coverage across the Blue Ridge. Further
east, little to no coverage for showers or storms.
Sunshine will give way to scattered to broken clouds this afternoon
in the west with more sun in the east. High temperatures ranging
from the lower to mid 80s west to around 90 east can be expected.
Showers and storms will fade toward midnight over the mountains.
Tropical depression 8 expected to become a tropical storm this
evening per NHC as it moves toward the Outer Banks of NC. Should see
little impact on our forecast area except perhaps shifting some
higher moisture toward our piedmont counties overnight.
Lows should not be changing much ranging from the lower to mid 60s
west to upper 60s east.
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 145 AM EDT Tuesday...
Conditions on Wednesday will be comparable to those expected today.
the biggest difference will be a slight shift eastward in where the
focus for where the best convection will be. Activity will be
focused more along the crest of the Blue Ridge, with the best
coverage across the Mountain Empire region of southwest Virginia and
the Northern Mountains and Foothills of North Carolina. This will be
in response to a slight shift eastward of a nearly stationary
boundary across the region. This boundary will continue its slow
progression southeast through and out of the area. Precipitation
coverage will follow this boundary late Wednesday afternoon into the
evening, but coverage will be on the decrease around and past sunset.
No sooner does this boundary exit the area then a more substantial
cold front is on our northwestern border around sunrise Thursday
morning. In fact, the first isolated showers associated with it may
reach parts of southeast West Virginia prior to sunrise. This front
will progress southeast across the area on Thursday and be southeast
of the area by Thursday evening. Cooler and drier high pressure will
build into the area in its wake with a notably different airmass in
place by Friday and Friday night.
Temperatures during this portion of the forecast will continue to be
above normal through Thursday. Anticipate highs close to five
degrees above normal with low temperatures close to ten degrees
above normal. A cooler and drier airmass for Friday will yield highs
around or slightly cooler than normal with low temperatures around
normal for this time of year.
.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 400 PM EDT Monday...
Model consensus is for long wave trough in the eastern CONUS to
linger Saturday before upper ridging returns over the Labor Day
Weekend. At the surface, a 1030 mb surface high is progged to pass
across the Great Lakes and into New England, wedging down the east
side of the Appalachians. If the tropical system in the eastern
Gulf of Mexico tracks northeast into the western Atlantic as
forecast then this will result in a very dry northeast wind Saturday
between the building high from the north and the departing
tropical low to our southeast. At some point (Sunday?) we should
start to experience return flow on the back side of the high, the
building heights resulting in moderating temperatures.
With a dry airmass progged for Saturday, anticipate good
radiational cooling at night. This should allow for surface
temperatures to slip into the 50s for lows...and 70s to around 80
for highs. Sunday and Monday will feature warming temperatures
with lows closer to 60 and highs in the 80s.
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
As of 723 AM EDT Tuesday...
Will see any fog this morning dissipate between 12-14z. Weak
frontal boundary washes out over the area today but enough
convergence along it and flow out of the east favors widely
scattered convection over the mountains. Situation still favors no
mention in the tafs. VFR outside of convection through this
Fog once again should form in the valleys LWB/BCB after 06z with
typical VLIFR at LWB to MVFR/IFR BCB.
Extended aviation discussion...
Another front will move into the region Thursday with a better
chance for MVFR/IFR showers/thunderstorms, followed by cooler and
drier air for Friday and Saturday. Most of the period looks VFR
at this point, outside of the usual late night/early morning
fog/low clouds. At this time, it does not appear that any tropical
systems will impact the county warning area.