Area Forecast Discussion
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FXUS61 KRNK 281802
Area Forecast Discussion
National Weather Service Blacksburg VA
202 PM EDT SAT MAY 28 2016
High pressure stays overhead today into tonight. A tropical
depression arrives to the South Carolina coast by Sunday morning
then stays situated along the Carolina coast through midweek.
.NEAR TERM /THROUGH TONIGHT/...
As of 1145 am EDT Saturday...
Morning RNK/GSO soundings verify that we are in subsidence zone,
with strong cap and large dewpoint depressions in excess of 40
degrees above the inversion. Aside for some fair weather cu, it
should be a nice afternoon.
For this afternoon, forecast area will remain in a subsidence
zone between the tropical depression off the southeast coast, and
the storm system moving across the upper midwest. We may see a
shower or two possibly pop up in the WV mountains, but not really
seeing enough evidence in the models to add pops. Expect to see
mostly sunny skies as temperatures warm into the upper 70s to
lower 80s west to mid 80s east.
Tonight, the tropical system moves toward the South Carolina
coastline. Models showing increasing clouds and allow for showers to
basically move in from the southeast after midnight at least as far
west as the southern Blue Ridge in VA and NC east toward Southside
Virginia. We should stay dry across the northwester CWA tonight,
with only slight chance across the New River Valley and near
Lynchburg. With clouds increasing lows will stay elevated in the 60s
across most of the region, though some upper 50s possible in the
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
As of 430 AM EDT Saturday...
T.D. #2 will be the main focus through the first part of this
period. Leading edge of associated moisture will reach the
southeast part of the CWA around daybreak Sunday...then spread
north-northnortheast through the day. Limited instability...but
deep tropical moisture and upslope flow along the Blue Ridge
should support likely to categorical pops...with mostly chance
pops west of the Blue Ridge not directly in the path of the
tropical system. Several of the models suggest that it will be
mainly the upper-level feature as opposed to the surface feature
with the tropical system that will track northwest into our
region...with the surface low remaining closer to the coast
throughout the lifecycle. Instability is limited with abundant
cloud cover...thus have only included isold thunder for now.
Better thunder threat may be around the western periphery of the
tropical system where the pops are lower but the air mass will
likely tend to be slightly more unstable.
With respect to rainfall...looking at less than an inch west of
the Blue Ridge to around an inch to the east...with locally higher
amounts. WPC rainfall seems a little high given the track of the
deeper moisture and higher PWATS closer to the coast. Am not
overly concerned about flooding issues...especially since the
heavier rainfall will be east of the Blue Ridge/Piedmont areas.
The main area to watch for flooding would be along the Blue Ridge
in the Meadows of Dan area northeast toward Bedford and Amherst
Sunday will be muggy in the tropical air mass with min temps well
above normal in the 60s...but max temps will be a little
cooler...mainly in the 70s.
For Monday...the upper-level feature associated with the tropical
system has moved northeast of the region...fairly well agreed to
by all of the models. Even the GFS...which for multiple
consecutive previous days indicated that the tropical system/upper
low would drift into western SC/NC and stall for several days next
week...has come on board with the other models in lifting the
feature quickly to the northeast by Monday. Tropical associated
rainfall Monday should be limited to the northeast part of the
CWA...with isold-sct diurnal convection mainly across the
mountains. Much of the CWA could actually come under subsidence by
Monday afternoon/evening...inhibiting precipitation.
Tuesday will see the region under weak high pressure and little if
any dynamic support. Expect just isold-sct diurnal
convection...most favored across the mountains. The main upper-
level support will remain across the central/western U.S. in
association with a persistent upper-level trough.
Temperatures Monday and Tuesday will be warmer and well above
normal with lows in the 50s mountains and 60s elsewhere...with
highs in the 70s mountains and 80s elsewhere.
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
As of 445 PM EDT Saturday...
Quite a bit of change from previous days as Wednesday and Thursday
the region is left under weak high pressure aloft and limited
dynamics. The air mass will be very warm and humid...which will
support scattered diurnal convection...most numerous across the
By late Thursday...and especially into Friday...scattered to
numerous convection can be expected as the Midwest trough finally
moves into the region and taps into the deep tropical moisture
present across the region. Any threat for flooding and/or severe
weather would likely be on Friday.
Temperatures will be above normal through the period and it will
be humid...with lows mainly in the 60s and highs in the 80s.
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 200 PM EDT Saturday...
Main concern next 24 hours will be movement of tropical system
along the southeast atlantic coast and potential for impact to mid
atlantic. Attm, it appears VFR will persist through at least the
first 12 hours of the valid TAF period, which means little or no
weather concerns through midnight tonight. Meanwhile, moisture
will be advancing northwest form the South Carolina Coast...rain
and multiple cloud layers moving into North Carolina tonight, then
north and northwest into VA early Sunday. Models put primary focus
for MVFR/low cigs/rain along and east of the Blue Ridge on Sunday
with little impact in the west. Attm, all models keep deeper
tropical moisture confined to areas east of the Appalachian
Divide, so this will put KBLF-KLWB on the western periphery of
the cloud shield and best chance from maintaining VFR.
Mid/High clouds will thicken from the southeast overnight in
advance of T.D. No. 2. However...most of the rain will not reach
the Piedmont counties until after daybreak...but have introduced
-RA into KDAN around 10Z and -DZ into KROA by 11Z. Cigs/vsbys will
remain VFR through 12Z...and the mid/high clouds should prevent
fog development at KBCB and KLWB Sunday morning.
Low confidence on flight category for Monday-Thursday. Models
indicate low pressure will stall over the eastern mid-atlantic and
linger through mid week. Our forecast area will be on the western
periphery of this feature which suggests best flight conditions
will be over and west of the Blue Ridge.