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361
FXUS61 KRNK 211100
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
700 AM EDT Sat Sep 21 2024

.SYNOPSIS...
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.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 650 AM EDT Saturday...

Modest adjustments made to temperatures and cloud cover this
morning based on latest satellite and observation trends. Enough
cloud cover was present overnight to prevent fog formation from
becoming widespread, and what fog that did develop will burn
off quickly after 9 am given another day of strong heating.

As of 330 AM EDT Saturday...

Key Messages:

1) Patchy fog will dissipate after 9 am given strong daytime
heating.

2) Showers and thunderstorms will develop this afternoon and
evening, affecting portions of the southern Shenandoah Valley
and the Piedmont.

3) Some storms may become strong to severe, capable of producing
damaging winds and/or large hail.

Starting the morning off with the lower Mid-Atlantic situated
under weak high pressure as a low pressure system and associated
cold front pass across the Great Lakes region and Ohio River
Valley. Both IR satellite imagery and surface observations
indicate that fog is more localized this morning compared to
last night, though still some patchy dense fog developing in the
mountain river valleys and across locations were soils remain
moist from recent rainfall. Overnight temperatures will remain
mild, holding in the low to mid 60s for much of the area.

With any areas of fog burning off quickly after 9 AM, attention
turns to the potential for showers and thunderstorms developing
during this afternoon and evening. The cold front will advance
east today across the lower Great Lakes, supported aloft by a
moderately strong upper level disturbance. Greatest energy
associated with the disturbance will remain outside the service
area and more across northern Virginia, but there will still be
the potential for a broken line of showers and storms to develop
across the southern Shenandoah Valley during mid afternoon,
advance across the Highway 460 corridor during early evening,
and reach the Southside area after sunset. The stronger storms
will have the potential to produce locally damaging wind gusts
and/or large hail, and the Storm Prediction Center has most of
central Virginia highlighted in a Margin Risk of Severe
Thunderstorms as a result. In addition, with precipitable water
values reaching the 1.5 to 1.7 inch range, believe that storms
will have the potential of producing heavy downpours, and will
have to keep an eye out for localized flooding where storms are
slow moving. Strong heating ahead of cold front will make for
afternoon highs ranging from the mid 70s to the low 80s.

Showers are likely to linger mainly across the foothills and
the Piedmont into early Sunday. Otherwise, patchy fog will again
be a possibility across the region. Overnight lows will range
from the upper 50s to the low 60s.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
As of 130 AM EDT Saturday...

Key Messages:

1) Mostly dry on Sunday, but some clouds will remain in place.

2) Wetter pattern returns for Monday and Tuesday.

A brief dose of drier weather for Sunday behind a frontal
boundary and a weak backdoor front drops into Virginia through
the day. Will see winds shift back to the northeast for much of
the day, along with partly cloudy skies. Could perhaps see a few
late day showers as easterly flow increases Sunday evening, but
overall most areas will remain dry.

Southwest flow increases again Monday and a weak warm front
will be in the vicinity. Should see better coverage of rain and
maybe a few thunderstorms by Monday afternoon as moisture begins
to increase in response to the retreating warm front. Much of
the same for Tuesday as well, but slightly better coverage of
rain and storms as low pressure begins to develop and organize
over the Ohio Valley.

Warmest day will be Sunday with highs in the low/mid 80s, but
cooling off again Monday and Tuesday with highs in the mid/upper
70s. Lows through the period mild in the 50s and 60s.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 145 AM EDT Saturday...

Key Messages:

1) High uncertainty remains in the long term period.

2) Chance of rain lingers through much of the week.

Quite a bit of variance among guidance this morning for the
period beyond Wednesday. This does not lead to much confidence
in the long term forecast, however ensemble guidance continues
to paint a rather stagnant pattern featuring daily chance of
rain and perhaps thunderstorms through mid to late week.

With rain potential and cloud cover, temperatures remain
slightly on the cooler side, generally in the 70s during the day
and 50s/60s overnight.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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As of 655 AM EDT Saturday...

Little change in previous forecast analysis, with patchy fog
burning off after 13Z/9 AM given strong daytime heating. Will
be keeping an eye on developing showers and thunderstorms,
affecting the southern Shenandoah Valley during mid afternoon,
and much of the Piedmont during the evening. Storms will be
capable of damaging winds, large hail and heavy downpours
limiting visibility locally to less than 1SM. Outside of
convection, VFR conditions are expected into late Saturday
night, when patchy fog will redevelop.


EXTENDED AVIATION OUTLOOK...

Isolated to widely scattered showers and thunderstorms are
expected again 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 continue Monday through at least midweek as a slow-
moving cold front approaches from the west.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...NF
NEAR TERM...NF
SHORT TERM...BMG
LONG TERM...BMG
AVIATION...BMG/NF