Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRNK 252352
Area Forecast Discussion
National Weather Service Blacksburg VA
752 PM EDT SAT JUN 25 2016
Weak high pressure will continue to build into the area from the
north tonight before sliding offshore Sunday into Sunday night.
This should result in somewhat drier weather through the remainder
of the weekend. Another cold front will approach from the west on
Monday with additional showers and storms likely into Monday night.
.NEAR TERM /THROUGH SUNDAY/...
As of 740 PM EDT Saturday...
Shower activity was limited early this evening to parts of
Greenbrier County WV and the Northern Mountains of North Carolina.
Little in the way of additional areal coverage is expected as we
approach and then pass sunset. With sunset will come a gradual
trend in decreasing coverage. By midnight, these isolated showers
are expected to have dissipated. Temperatures will fall into the
low to mid 70s by midnight.
As of 218 PM EDT Saturday...
Seeing low clouds gradually eroding from west to east this afternoon
with the help of heating and easterly mixing as high pressure to the
northeast slowly builds in. Latest analysis also showing limited
instability due to earlier clouds with only weak moisture convergence
across the south/southwest where have see shallow/isolated showers
develop from time to time. Latest meso models continue to limit added
convective coverage under the dry air aloft seen on water vapor with
focus mainly along the I-77 corridor and far southern sections where
could pop isolated coverage through sunset but iffy. Otherwise expect
clouds to diminish over the next few hours before perhaps seeing
another swath work westward toward the Blue Ridge overnight within the
onshore flow. However with even added drying aloft, expecting less
widespread low clouds, with patchy fog in the valleys, and out east if
clouds are less. Low temps should be similar if not a little cooler
under a bit more clearing with upper 50s to lower 60s likely.
Axis of the surface high from offshore will become stronger across the
region Sunday under building heights aloft. This should again tend to
put a lid on convection as guidance showing even less instability and
better drying through the column per latest forecast soundings. Appears
an isolated shower or two not totally out of the question over the far
west where weak convergence under low level southeast flow will be best.
However since moisture quite shallow, chances limited so lowered pops
even more. Elsewhere should be mainly sunny after low clouds/fog fade
and a little warmer under more insolation/warming aloft. This should
push most spots outside of the higher elevations into the more uniform
80s across the board.
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 245 PM EDT Saturday...
Ridging both surface and aloft will begin to slowly break down Sunday
night as the onset of a digging upper low well to the northwest starts
to shift a surface cold front toward the region late. Latest model
timing would suggest that most of Sunday night should stay dry with the
arrival of the leading edge of any pre-frontal showers holding off
until after daybreak if not longer.
Guidance then shifts a deeper axis of moisture across the region from
Monday afternoon into Monday evening with progged pwats of around 2
inches within a narrow band. Rather slow steering aloft would suggest
another round of slow moving showers and storms with progs indicating
qpf of another .50 to more than an inch across the region which is of
concern over/near areas that received flooding last week. Thus plan to
add mention to the HWO about heavy rainfall for now. Otherwise overall
shear and instability look quite marginal which may help out with less
severe and perhaps organization for heavy rainfall. Thus will keep a
broad swath of likely pops most areas from west to east Monday into
Monday evening with coverage tapering behind the front later
Monday night. Highs closer to the warmer side of mos given the
slower expected arrival of clouds/showers on Monday.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 1230 PM EDT Saturday...
Broad upper trough will re-establish over the region by midweek and
persist into next weekend as added impulses rotate through bringing
periodic rounds of showers/storms after midweek drying. Secondary cold
front looks to cross Tuesday under the leading edge of initial digging
shortwave energy that will represent the arrival of somewhat
cooler/drier air Tuesday night into Thursday. Appears perhaps enough
lingering moisture to support some chance of showers and possible
storms later Tuesday espcly south/east with less across the mountains.
Pocket of cool advection progged at 850 mb should arrive Tuesday night
into Wednesday on drier northwest flow and better subsidence making for
a couple of cooler overnights and a mainly dry Wednesday. More
uncertainty in regards to rain chances will develop Thursday-Saturday
as moisture returns and added impulses swing toward the region around
the residual upper system to the north. Latest models have backed off
on much organized convection with more in the way of mostly diurnal
showers/storms each day. This supports the return of mostly low chance
pops with the region still under weak high pressure between the initial
boundary to the south, and another front swinging in from the north by
day7. Temps to remain near seasonal overall except slightly below midweek
with some comfortable overnights as well given lows 50s to near
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --As of 745 PM EDT Saturday...
Aviation conditions generally expected to improve through the TAF
valid period, but there will still be areas of low clouds and fog
overnight and into the mid-morning hours Sunday.
High pressure will remain anchored along the Mid-Atlantic seaboard
through the period, gradually drifting southward. This will keep a
maritime easterly flow across the forecast area through the TAF
Potential exists for mainly low clouds and some fog to develop
again overnight, but confidence in such as less than last
night/Saturday morning. Somewhat drier air appears to be advecting
southwest through the region as winds tend to back to the
northeast overnight, then veer back to the southeast after
daybreak Sunday. Will continue with previous concept of some low
clouds/fog developing overnight, generally MVFR at most locations,
but potential for IFR-LIFR, mainly at KLWB/KBLF. Confidence in
low clouds/fog forming is least at KLYH/KDAN. Cigs should improve
by mid to late morning Saturday, leaving mid-level CU and VFR
conditions most sites after 17Z.
Not expecting any showers or thunderstorms Sunday.
Winds ENE 4-7kts overnight, becoming ESE-SE 6-8kts after 14Z
Medium confidence in cigs and vsbys through the TAF valid period.
Medium to high confidence in wind dir/spd through the TAF valid
The next cold front will move into the region early Monday, then
move slowly through the CWA Monday into Monday night. Appears
most showers will stay west of the region Sunday night with sub-
VFR developing mountains by Monday afternoon, and continuing
across the region at times into at least Monday evening.
Widespread showers/storms should exit Monday night giving way to
more isolated coverage including periods of MVFR Tuesday with a
passing secondary cold front. Expect a return to more widespread
VFR behind the front on Wednesday.
-- End Changed Discussion --
As of 305 PM EDT Saturday...
Extensive flood damage has occurred especially in Greenbrier
county West Virginia and some roads remain impassable. A flood
warning remains in effect through 630 pm this evening as flooding
continues especially between Rupert and Rainelle with lots of
standing water across the region as well. Water levels are
continuing to recede along the Greenbrier River as well as other
smaller creeks and streams which should finally help alleviate
any ongoing flooding this weekend.