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000
FXUS61 KRNK 231859
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
259 PM EDT Thu May 23 2019

.SYNOPSIS...
A weak cold front will progress across the forecast area later
tonight into Friday. Warm and humid weather under an upper-level
ridge of high pressure will maintain itself Friday, with limited
thunderstorm chances. A cold front will progress into the
northern mid-Atlantic region Saturday into Sunday.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 258 PM EDT Thursday...

Widely scattered showers and storms continue to form in two
main areas: now moving into Summers and Greenbrier Counties as
well as more isolated activity into the foothills of the Blue
Ridge west of Roanoke. Air mass is moderately unstable with
surface based CAPEs between 2000 J/kg with an axis of 3000 J/kg
just east of the Blue Ridge. Appears that westerly flow has led
to more limited surface convergence with coverage of storms
isolated to widely scattered. A few storms may still prove
capable of gusty winds especially north of Route 460 as ongoing
line moves into the more unstable air. After these initial
showers and storms move eastward, guidance also has some
consistency in bringing a second round of showers or storms
toward our far northwestern and western counties - the Alleghany
Highlands westward into the Greenbrier Valley - though they
differ on precise evolution and how far east into the forecast
area these showers/storms progress. The cluster of storms the
guidance is keying on which turns northwestward toward our area
perhaps is the cluster of storms now near the Louisville area.
So while trended the forecast dry for the overnight for most
areas west of I-81, kept a mention of showers and thunderstorms
going until midnight for the Highlands southwestward into
southeast WV. These aren`t likely to be severe but may still be
capable of evening lightning strikes through midnight. A rather
muggy evening tonight with lows in the mid-upper 60s and
dewpoints in the mid 60s.

The trough moving into the Northeastern states will
weaken/flatten the top of the Southeast ridge, with stronger
ridge axis across the Missisippi Valley into the upper Midwest.
This will encourage more of a northwesterly flow aloft for
Friday. After any leftover showers fizzle in the far western
mountains, most of the area sees mostly sunny skies. While the
atmosphere becomes moderately unstable again, models show a
little more capping along with less forcing for ascent. This
should keep any convection pretty well suppressed. A few models
were developing some showers or storms mainly southwest of I-77
running along or just south of the 500 mb height gradient; did
leave slight to low chance PoPs for showers and storms in this
area. This threat appears conditional on some triggering source
in the northwest flow aloft and/or residual low-level boundaries
left behind from today`s storms. GFS progs CAPE values around
1000-1500 J/kg with 0-6 km shear values less than 35 kts;
implication being that any storms may be more pulse variety than
organized. Highs into the 80s to low 90s; should have heat
indices in the mid 80s to mid 90s warmest in Southside.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 259 PM EDT Thursday...

The upper ridge over the eastern part of the country will remain in
place and keep the Appalachians and central mid Atlantic region with
summery weather through the weekend. A transitory surface wedge of high
pressure east of the mountains will push off the North Carolina coast
on Saturday. The circulation into the warm frontal boundary on the
backside of the wedge will fuel thunderstorm development especially
west of the Blue Ridge with some stronger storms possible thanks to
enhanced shear near the warm front. Convection will linger into
Saturday night before dissipating during the overnight hours as the
warm front pushes off a bit to our north.

Sunday looks to be mostly dry with a few isolated showers/storms.
However, indications are pointing to an MCS developing Sunday evening
along the lingering warm frontal boundary to our north. While the main
push of this MCS looks to be through OH/PA/northern WV, the southern
flank may sag far enough southward to impact southeast WV and the I-64
corridor Sunday night. Will be watching how this situation develops and
fine tune any potential severe weather impacts

Despite a wedge on Saturday temperatures will remain well above normal
through the weekend. By Sunday temperatures will once again be in the
low/mid 90s east of the Blue Ridge with generally mid/upper 80s to the
west.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 259 PM EDT Thursday...

The axis of the upper ridge will be to our east by Wednesday, then
flatten considerably as the pattern becomes essentially zonal by the
end of the week. Expect the depth of the warm air under the ridge to
help suppress convection with generally isolated/widely scattered
thunderstorms mainly in the mountains on Monday and Tuesday, though
will have to watch the lingering frontal boundary on Monday. Then by
midweek, the progressive zonal pattern will bring an increasing chance
for showers/thunderstorms ahead of a cold front that will move through
on Thursday.

Temperatures will remain well above normal for most of next week with
hazy, hot, and humid conditions. Highs will generally be in the low/mid
90s east of the Blue Ridge with 80s to the west. Lows will be quite
balmy with readings generally in the mid/upper 60s, a bit cooler in the
valleys west of the Ridge.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
As of 113 PM EDT Thursday...

Lingering low stratus has finally started to thin out away from
Southside into the NC Piedmont; but the main concern for the
remainder of the afternoon is for scattered strong/severe
thunderstorms. Threat appears greatest for most TAFs except
Danville, and have included SHRA VCTS in association with a
likely line of storms progressing eastward from central WV now
through 00z. Storms may be capable of lightning, gusty winds
capable of localized turbulence, and brief IFR visby from heavy
rainfall. Storms should weaken as instability wanes after
sunset, though a few additional showers capable of brief
restrictions toward Lewisburg late this evening. Kept TAFs at
mainly VFR, but will be quick to issue TEMPOs for any convective
threat this afternoon/tonight. Winds outside of thunderstorms
mainly southwest 6-10 kts.

Should see mainly VFR conditions through 18z Friday. May see
isolated thunderstorms build up southwest of I-77 into the
mountains of northwest NC very late in the 18z TAF period, but
not likely to affect any TAFs. Winds west to northwest 6-9 kts.

Forecast confidence is moderate on thunderstorm potential, and
moderate to high on aviation categories outside of thunder.


EXTENDED AVIATION DISCUSSION...

VFR conditions are expected across the region Friday thru
Sunday. Exception is with evening/overnight fog but confidence
low on development attm. SCT MVFR showers and thunderstorms are
possible Monday in the west.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...AL
NEAR TERM...AL
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...AL