-- Discussion containing changed information from previous version are highlighted. --
713
FXUS61 KRNK 032307
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
707 PM EDT Fri May 3 2024

.SYNOPSIS...
A frontal system will bring increasing clouds and rain chances
to our area beginning this afternoon and evening. Widespread
rain showers and a few thunderstorms are expected through the
weekend. Temperatures will be lower this weekend than they have
been, before switching back to warmer weather with daily showers
and thunderstorms possible for the work week.

&&

.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --
As of 645 PM EDT Friday...

Key Messages:

1. Scattered showers and isolated t-storms through this evening.

2. Cooler easterly flow will over much of the area tomorrow will
keep temperatures below normal.

3. Widespread moderate showers tomorrow with some scattered
thunderstorms tomorrow.

Thicker and more widespread cloud cover marches east this
evening, as well as a front. As the sun sets, clear skies are
also waning. Scattered, mostly single-cellular showers have
become more frequent since this afternoon. An occasional
lightning strike has been noted close to the proximity of what
amounts to a backdoor front in the I-64 corridor in WV. Expect
isolated thunder to continue during the overnight, and then on
Saturday to become more common, especially east of the Blue
Ridge where it will be free of the influence of a wedge.

With the encroaching cloud shield, prevailing winds have begun a
turn to the northwest, which will not last long as the
atmospheric setup is changing quickly.

From the previous discussion...

Vertically stacked low pressure was moving through southern
Ontario this afternoon. A ridge of high pressure was on its way
off the eastern seaboard as a short wave trough makes its way
towards the TN Valley. Warm air advection along with orographic
lift and marginal instability was triggering scattered showers
so far this afternoon, mainly over the southern Blue Ridge. An
area of convection closer to a warm front turned backdoor front
in draped over the Greenbrier Valley was more conducive to
thunderstorms, but lightning had not developed as of this
writing.

Increasing moisture on southerly winds will keep scattered
showers around as well as isolated thunderstorms through this
evening. After dark, winds come around to the east over eastern
and northern portions of the forecast area. This will stabilize
the air mass in these areas and as ceilings and visibilities
lower, the precipitation will take on more stratiform light
rain/drizzle/fog qualities. This will keep thunder from being an
issue throughout the day tomorrow where the wedge is strongest.
QPF amounts also look relatively light through the tonight and
into the early morning hours. After daybreak, additional
frontogenetic forcing and positive vorticity advection will
deliver widespread moderate rain with categorical to definite
PoPs throughout the day and evening, with some locations getting
around an inch by tomorrow night. There may be some breaks in
the precipitation, but these are difficult to pinpoint within
this messy set up.

Tonight, lows will range from the mid 50s to low 60s for most,
with cooler temperatures for the mountains and as you move
northeast through the forecast area. Easterly flow along with
the precipitation and clouds will keep highs tomorrow in the
upper 50s to mid 60s for most of the area. Northern NC may see
slightly warmer temperatures as it will be less under the
influence of the wedge of cooler air.

Confidence in the near term is moderate, but lower for showers
and thunderstorm timing.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 200 PM EDT Friday...

Key Messages:

1) Confidence is high for chances of scattered showers and
thunderstorms each day.

2) Temperatures will slowly warm as the new week begins.

The easterly flow should shift around to the south during
Saturday night into Sunday. Meanwhile, a stalled frontal
boundary will remain draped across the central Plains to the Mid
Atlantic throughout this forecast period. A cold front will try
to move eastward north of the Appalachian Mountains on Monday,
but the primary area of low pressure should stay well to the
north in Canada. As a result, this cold front will be
unsuccessful in changing the air mass and may only nudge the
stalled frontal boundary slightly southward.

Because of this prolonged period of unsettled weather, chances
of scattered showers and thunderstorms will occur each day.
The highest chance may come during Monday afternoon when the
cold front to the north provides extra dynamical lift in the
vicinity of the Mid Atlantic. Temperatures should slowly trend
upward as the flow becomes more southerly to increase warm air
advection despite the ongoing chances of rain and the
considerable cloud cover.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 200 PM EDT Friday...

Key Messages:

1) Confidence is moderate for chances of scattered showers and
thunderstorms each day.

2) Temperatures will head warmer by the middle of the week.

A stalled frontal boundary should still linger across the Mid
Atlantic through the middle of the week. Several weak waves of
low pressure will continue to track eastward along this
boundary to continue a daily chance of scattered showers and
thunderstorms. Meanwhile, ridging aloft and a southwest flow at
the surface should increase warm air advection to push
temperatures higher by Wednesday and Thursday. A cold front will
approach the Appalachian Mountains sometime during late
Thursday into Friday, which could spark a higher chance of
convection. The models continue to struggle with depicting when
this prolonged period of unsettled weather will come to an end
beyond this point.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 650 PM EDT Friday...

VFR clouds are on the increase with scattered SHRA this evening.
Expect some isolated TSRA at times this evening, with best
chances around and north of the I-64 corridor. Ceilings will
transition to MVFR as moisture fills in through the lower levels
of the atmosphere and showers become more common.

Ceilings and visibilities drop to LIFR/IFR generally after
08Z, and will likely stay there through Saturday and beyond as
an ill-defined frontal boundary remains over the region.

South southwesterly winds of 5-10 kts will become lighter and
initially variable tonight. A backdoor cold front will
introduce an easterly component to the wind after midnight.
Expect winds to remain largely out of the east 5-10 kt for
Saturday.

Confidence in the above scenario is moderate.


Extended Aviation Outlook...

SHRA/TSRA with periods of DZ, BR, and MVFR/IFR/LIFR conditions
continue after 18Z Sunday. More diurnally driven -SHRA/TSRA are
expected Monday through Wednesday. This will bring periods of
MVFR ceilings and visibilities at times. Winds Monday through
Wednesday will be SSW and gusty at times.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...PM/SH
NEAR TERM...SH/VFJ
SHORT TERM...PW
LONG TERM...PW
AVIATION...SH/VFJ