-- Discussion containing changed information from previous version are highlighted. --
805
FXUS61 KRNK 191818
AFDRNK

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

.SYNOPSIS...
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.

&&

.NEAR TERM /THROUGH FRIDAY/...
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.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
As of 125 PM EDT Friday...

Key Messages:

1: Scattered showers make return near the NC/VA border this
weekend

2: Moisture from Francine will lead to cloudy conditions,
cooling effect

Eyes are on Francine this week as she will drive a lot of the
weather conditions across the CONUS east of the Mississippi
River. Francine`s remnants will fall prey to a bit of a rex
block, with a stout mid-level ridge setting up shop over
southern Canada and into the OH valley. By this weekend, this
feature will effectively stall out Francine`s remnants around
the TN/MS/AL area. Wide surface high pressure over the northeast
will push down cooler and drier air via northeast flow into the
Mid- Atlantic. With the tropical moisture of Francine held down
south, and impinging drier air interacting on the east side of
that system, much of the moisture that might have made it into
our CWA will be eroded by the drier air mass. As such, rain
chances this weekend will be largely limited to areas around the
VA/NC border. Almost no rain will fall into the Piedmont and
towards central VA and Lynchburg.

The aforementioned evaporative effect will aid in cooling temps
down, and overriding moisture from Francine`s remnants will make
for a cloudy weekend. Daytime highs will only just reach into
the upper 70s east where cloud cover will be at its minimum, and
diurnal swings in the west will be restricted, with highs and
lows in the low 70s and upper 50s/low 60s respectively.
-- End Changed Discussion --

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
-- Changed Discussion --
As of 145 PM EDT Friday...

Surface high pressure over us starts the process of breaking
down on Tuesday, and the mid-level ridge over the plains
weakens as well while moving east. A Great Lakes low will travel
southeast into OH and PA, with an attendant cold front trailing
south of it. This front will enter the Appalachians sometime on
Thursday, and will be the next best chance for precipitation to
occur. Increasing dewpoints and temperatures will add to the
instability of the atmosphere. Timing of this system is still
unclear, and could change as there are a good number of moving
parts to its arrival.
-- End Changed Discussion --

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
As of 215 PM EDT Thursday...

Clouds have improved to VFR for most with LWB sitting right at
the cusp of MVFR/VFR. Instability and short waves aloft will
support scattered -SHRA/-TSRA through about 20/02z. Skies may
become party cloudy briefly, especially in parts of 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 it will be more 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.
-- End Changed Discussion --

&&

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

&&

$$

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