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873
FXUS61 KRNK 191701
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
101 PM EDT Thu Sep 19 2024

.SYNOPSIS...
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Low pressure will linger over the western Atlantic, while high
pressure remains wedged along the eastern Unites States through
early next week. These features will keep a low probability of
precipitation over the area through the weekend. Next week, a
frontal system approaching from the central United States will
result in a higher chance of showers and thunderstorms.
Temperatures will be near to slightly above normal through the
weekend.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 100 PM EDT Thursday...

Key Messages:

1) Scattered showers and thunderstorms this afternoon and
evening.

2) High confidence in overall forecast and fewer showers/storms
on Friday compared to today.

A southern stream trough was located over the eastern seaboard,
while an associated upper low was located over the western
Atlantic. This troughing moves east tonight and into Friday,
putting us in NW flow ahead of ridging parked over TX. At the
surface, high pressure was still mostly in control over the
Appalachians, supporting plenty of cloud cover and cooler
temperatures. For the mountains and to the NW, more breaks in
cloud cover have developed, and this sunshine will help fuel
instability for convection this afternoon and evening, as will
energy moving through NW flow aloft.

The majority of showers/storms will fire along the higher
terrain this afternoon, before drifting south and dissipating
later tonight. Convective cloud cover diminishes tonight,
setting the stage for redevelopment of very low stratus (less
than 500 ft) for much of the area late tonight into Friday
morning...extending to the ground at times.

Erosion of any remaining stratus/fog will occur by mid morning
Friday. Expect isolated showers and storms tomorrow afternoon
and evening, as CAMs are much less keen on coverage compared to
today. This is likely due to the trough edging east and a
minima of upper level energy during the day. For both today and
tomorrow, localized, brief moderate rainfall may lead to urban
and small stream flooding, but more significant flooding, as
well as other severe weather types, are not expected. This is
supported by a PWAT above the 90th percentile and very light
winds on this morning`s KRNK sounding.

Lows will be in the 50s to low 60s tonight. We should reach the
mid 70s to low 80s Friday.
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&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 200 AM EDT Thursday...

Key Messages:

1) Confidence is moderate for isolated showers and thunderstorms
each day.

2) Temperatures trend back towards normal values.

An upper level low should slowly head offshore on Friday, but
lingering moisture convergence and instability along the Blue Ridge
may spark isolated afternoon showers and thunderstorms. Drier air
could arrive by Friday night, but the latest models do not push the
upper level ridge from the southern Plains further east compared to
previous runs. Instead, a weak shortwave trough will spiral around
the periphery of the ridge and reach the Mid Atlantic on Saturday.
While rain chances will remain isolated in nature, the daily threat
of afternoon showers and thunderstorms along the Blue Ridge may
continue throughout the weekend. Since there will be some periods of
sunshine, temperatures should moderate back near normal values.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 200 AM EDT Thursday...

Key Messages:

1) Confidence is moderate for higher chances of showers and
thunderstorms each day as a cold front approaches.

2) More clouds could nudge temperatures a little below normal.

High pressure over the New England states should wedge against the
eastern slopes of the Blue Ridge by Monday, and the easterly flow
should be enhanced by a stalled upper level low spinning offshore.
Meanwhile, a cold front will develop across the central Plains and
head eastward. The models are not in agreement with the timing of
the frontal passage for the Appalachian Mountains later in the week.
Nevertheless, the chance of afternoon showers and thunderstorms will
rise as the cold front draws closer, especially west of the Blue
Ridge. Coverage of this convection will also increase once the flow
can be swung from the east to the south, but the wedge may prove
rather difficult to budge at first. The higher cloud cover should
nudge temperatures slightly below normal.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
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As of 1215 PM EDT Thursday...

Clouds have improved to VFR/MVFR today.

Instability and short waves aloft will support scattered
-SHRA/-TSRA through about 20/02z. Skies may become party cloudy
 briefly, especially in the mountains, once convection ends
 tonight.

IFR to LIFR stratus/fog is expected to develop for most of the
area overnight, dissipating mid morning Friday. -SHRA/-TSRA/sub-
VFR conditions are expected again Friday afternoon and evening,
though they will be very isolated and mainly in the mountains.

Average confidence for the TAFs.


EXTENDED AVIATION OUTLOOK...

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

The chance of showers, thunderstorms, and lingering sub-VFR
conditions increases on Monday, starting from the north, as a
frontal system nears.
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&&

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

&&

$$

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