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779
FXUS61 KRNK 200726
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
326 AM EDT Fri Sep 20 2024

.SYNOPSIS...
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Weak high pressure will remain nestled over the Appalachian
chain through the weekend, maintaining a mix of clouds and
sunshine, in addition to a low probability for rainfall. A cold
front will gradually approach up the Ohio River Valley during
the early half of the next workweek, resulting in a higher
chance of showers and thunderstorms that will persist into next
weekend.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 255 AM EDT Friday...

Key Messages:

1) Fog will burn off by mid to late morning, making for a mix
of clouds and sunshine with highs in the mid 70s to the low 80s.

2) Widely scattered and brief showers and a few thunderstorms
will develop this afternoon into the evening, mainly over the
mountains.

Starting the morning off with weak high pressure established
across the lower Mid-Atlantic region. Mostly clear skies and
light winds have allowed temperatures to fall anywhere from the
upper 50s to the mid 60s. With moist soil conditions from
rainfall earlier this week, patchy dense fog has developed
across the entire service area, particularly in the mountain
river valleys. Radar is mainly clear, though can`t rule out an
isolated shower through the remainder of the night as a warm
front passes up the Ohio River Valley.

For today, fog will burn off during mid- to late-morning given
a mix of clouds and sunshine and decent daytime heating that
will allow our afternoon highs to reach into the mid 70s to the
low 80s. Latest rapid update models are in agreement that enough
moisture will be present today to support isolated to widely
scattered showers and a few thunderstorms during the afternoon
and evening, with slightly better chances for any activity to
form along the mountains ridges. That stated, there is very
limited atmospheric energy for this activity to work with, and
believe that any showers/thunderstorms that do develop will be
brief and rather weak. The loss of daytime heating this evening
will cause most of this activity to fade away, though a few
showers will linger into late evening.

Tonight, with no change in airmass expected, redevelopment of
areas of fog are likely under mostly clear skies and light
winds. Overnight temperatures will again range from the mid 50s
to the low 60s.
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&&

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

Key Messages:

1) Confidence is moderate for a chance of showers and
thunderstorms on Saturday.

2) Drier weather may be possible on Sunday, but more showers
and thunderstorms may return in the mountains by Monday.

Although an upper level ridge will try to nose eastward from
the southern Plains on Saturday, it will be blocked from
advancing further as a shortwave trough dips southeastward from
the Great Lakes. This shortwave trough should spark a chance of
showers and thunderstorms with the highest chances north of
Route 460. Some weak ridging may arrive by Sunday to bring drier
weather. However, the flow should turn towards the east as high
pressure from the New England states wedges against the eastern
slopes of the Blue Ridge. A cold front is forecast to move
eastward from the central Plains by Monday to bring increasing
chances of showers and thunderstorms west of this high pressure
wedge. After a milder weekend, temperatures may dip a little
lower on Monday due to the rise in cloud cover.
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&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
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As of 200 AM EDT Friday...

Key Messages:

1) Confidence is moderate for a daily chance of afternoon
showers and thunderstorms as a cold front approaches.

2) The timing of the eventual frontal passage still remains in
doubt due to large uncertainty in the models.

There are still notable timing discrepancies among the models
regarding an eventual frontal passage later this week.
Nevertheless, with a cold front approaching the Appalachian
Mountains during Tuesday and Wednesday, the chance of showers
and thunderstorms will continue and become more widespread. The
flow should eventually turn towards the south and erode a
lingering wedge of high pressure east of the Blue Ridge, but it
is likely that this erosion process will not happen quickly.
Despite the aforementioned timing discrepancies, the best model
consensus seems to suggest a frontal passage perhaps by
Thursday. Lingering chances of showers were kept through
Thursday in case this model consensus is still too fast.
Temperatures will remain near or slightly below seasonable
values.
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&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
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As of 230 AM EDT Friday...

Surface observations indicate that areas of IFR to LIFR
stratus/fog have developed in the mostly clear skies and light
winds across the lower Mid-Atlantic, combined with moist soils
from recent rainfall. These conditions will persist through the
night before burning off during mid to late this morning.

Isolated to widely scattered showers and a few thunderstorms
will redevelop early this afternoon, mainly across the
mountains. With limited energy for this activity to work with,
believe any showers/storms will mainly be small in coverage and
brief in duration. Still, localized downpours limiting
visibility to less than 1SM and gusts to 25kt may accompany any
of this activity. Coverage is low enough though that did not
include mention in the TAFs. Most showers and storms will fade
during evening with the loss of heating, but a few will linger
into the night. Areas of IFR fog and stratus are likely to
redevelop tonight across the lower Mid-Atlantic.


EXTENDED AVIATION OUTLOOK...

Isolated to widely scattered showers and thunderstorms are
expected Saturday and Sunday afternoon/evening. Otherwise, VFR
during the day then areas of MVFR/IFR fog and stratus at night.

Daily chance of showers, thunderstorms, and lingering sub-VFR
conditions increases beginning on Monday through at least mid-
week as a slow-moving cold front approaches from the west.
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&&

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

&&

$$

SYNOPSIS...NF
NEAR TERM...NF
SHORT TERM...PW
LONG TERM...PW
AVIATION...NF