020
FXUS61 KRNK 182342
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
742 PM EDT Wed Sep 18 2024

.SYNOPSIS...
Low pressure centered over the southern Appalachians will drift
northeast through Thursday, bringing additional clouds and
precipitation. The low moves offshore by Friday, lowering the
probability of precipitation. Dry weather and seasonal
temperatures are expected for Saturday and Sunday.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 730 PM EDT Wednesday...

Ongoing rain showers and a few embedded thunderstorm downpours
continue this evening. Should begin to see convection wane a bit
with loss of heating and instability, but pockets of heavier
downpours could continue though at least midnight.

Likely to have fairly widespread fog overnight with ample
amounts of low-level moisture in place.


As of 230 PM EDT Wednesday...

Key Messages:

1) Light showers/isolated storms possible through this evening.

2) Localized urban and small stream flooding possible tonight,
with a lower flash flood threat compared to yesterday.

A vertically-stacked low pressure system was centered near
Greenville, SC. Moisture from the Mid Atlantic continued to be
drawn westward towards the Appalachians. Lift provided by
energy rotating around the low was generating convection for
parts of the piedmont of VA and the southern Shenandoah and
Greenbrier Valleys.

Precipitable water had backed off some here (1.23 inches on this
morning`s RNK sounding) compared to last night. The better
moisture and instability was pooling to our east, but breaks in
cloud cover should generate enough instability for showers and
isolated storms this afternoon and evening, generally NE of a
line from Hinton, WV to Danville, VA. Heavy rain leading to
localized flooding appears to be the main concern once again
through this evening, especially if any convection forms in
areas which received substantial rains last night. Showers and
storms should diminish overnight, with lows again in the 50s
and 60s.

Abundant low level moisture remains in place across the region
through Thursday. Any skies that have scattered out will quickly
fill back in tonight through mid morning tomorrow with low
clouds and ground fog. Another round of convection is likely
tomorrow afternoon and evening. Highs Thursday should warm into
the low to upper 70s.

Confidence in the near term is moderate, but lower for QPF.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 215 PM EDT Wednesday...

Key Messages:

1) Rain will begin to wind down Thursday night into Friday as
the  upper-low moves east and offshore.

2) Confidence is high that mostly dry conditions will occur on
Friday and Saturday with temperatures increasing with more
sunshine.

Scattered rain chances will continue for Thursday night, but
will dissipate into the overnight hours. On Friday, drier
weather will be in store across most of the CWA with mid-level
RH values lowering due to the upper-low moving offshore.
However, showers and a slight chance of storms will remain
possible in far southwest Virginia and in the mountains of North
Carolina due to the increased instability from less cloud cover
along with a light upslope flow. Any convection will be short-
lived, and quickly dissipate after sunset. Due to the limited
cloud cover, high temperatures will be near to slightly above
normal, with highs in the 70s and low 80s while lows will be
mainly in the 50s as radiational cooling will allow temps to
fall at night. Similar conditions are expected on Saturday,
though lower dewpoints will reduce rain chances across the RNK
CWA, with most areas likely seeing no rainfall. Model ensemble
means have QPF totals around 0.10 inches through late Saturday.
Overnight Saturday will see a very slight increase in rain
chances as mid-level moisture increases briefly, but any showers
will remain very isolated.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 200 PM EDT Wednesday

Key message:

1) An upper level trough and associated cold front will approach
the region early next week, and provide daily chances for
isolated shower and thunderstorm activity.

Starting Sunday, there is good ensemble guidance between the
GEFS and EPS suggesting that the region will be wedged between
an upper level troughs centered off the Northeast coast, and
the northern Great Lakes region. This will keep the region
temporarily under the influence of upper level ridging. This
will keep temperatures above normal across the region on Sunday,
with highs climbing into the low to mid 80s. Models do seem to
diverge starting Monday, as the timing of the upper level trough
across the Great Lakes approaching the area is still uncertain.
Regardless of the timing of the upper level trough and
associated cold front early next week, some prefrontal shower
and thunderstorm activity looks possible as appreciable PWATs in
the 1.4-1.6 inch range look to linger across the region. With
surface high pressure centered over southeast Canada, weak
wedging down the eastern Appalachians look to create some
easterly flow across the region, which may enhance the
aforementioned shower and thunderstorms on Monday and Tuesday.
The upper level trough across the upper Great Lakes region looks
to lift north late Monday and into Tuesday, which may leave a
stalled cold front across the western Blue Ridge, and provide a
focus for shower and thunderstorm development through the middle
of the week. These showers will generally be diurnally driven,
and should diminish after sunset. Temperatures each day will
generally climb into the low to mid 70s, and lows look to fall
into the low to mid 50s.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 740 PM EDT Wednesday...

Mix of VFR and MVFR outside of any heavier pockets of rain.
Still expecting most terminals to go sub-VFR overnight as low
cigs and vsby become more common. Fog seems likely and could
persist even through a few hours after daybreak. Low level
clouds should be slow to erode, so could hang onto MVFR cigs
through mid-day tomorrow.

Less coverage of rain tomorrow, but still could have pockets of
drizzle within the vicinity of the Blue Ridge.

Northeast winds of less than 10 kts will drop to light and
variable to calm overnight. North winds tomorrow, still less
than 10kts.


EXTENDED AVIATION OUTLOOK...

We may still see residual moisture trapped under an inversion
Thursday night into Friday morning, leading to patchy fog and
stratus.

VFR conditions and dry weather is expected to return for
Saturday and Sunday. By Monday, -SHRA will be possible for the
mountain terminals (BLF/LWB) as a warm front lifts north.

&&

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

&&

$$

SYNOPSIS...SH
NEAR TERM...BMG/SH
SHORT TERM...EB
LONG TERM...JCB
AVIATION...BMG/SH