293
FXUS61 KRNK 291720
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
120 PM EDT Fri Aug 29 2025

.SYNOPSIS...
High pressure will keep us below normal on temperatures through
the weekend, though moisture will start increasing as the flow
turns to the east. A front approaches the middle to end of next
week increasing our chances for showers and storms.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 112 PM EDT Friday...

Key Message:

1) Sunshine with fair weather clouds this afternoon, and a west
to northwest breeze.

2) Increasing moisture Sunday as flow turns east and an isolated
shower across the southern Blue Ridge.

High pressure over the Great Lakes continues to provide dry air
into the area this afternoon. There is a weak front/trough
across the Alleghany Front leading to some moisture convergence
mainly in the form of cumulus.

Just enough of a gradient to bring west-northwest winds gusting
to 15 to 20 mph in the mountains this afternoon.

Another shortwave arrives tonight with an uptick in clouds. This
will limit radiational cooling but still looking at lows 5 to 10
degrees below normal with mid 40s to lower 50s mountains to
mid to upper 50s in the Piedmont.

Saturday, flow works around to the east as the high shifts into
the northeast states. A few models are allowing for showers to
form in the afternoon across the southern Blue
Ridge/Appalachians. This may be a little fast as models tend to
rush precip back after dry air in place, so will allow for an
isolated shower in the NC mountains and into Grayson County.

Highs still running around 5 degrees below normal with lower to
mid 70s in the mountains to around 80 in the southern VA
Piedmont into NC.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 1230 PM EDT Friday...

Key Points:

1. Slightly below normal temperatures.
2. Showers and few storms expected mainly near and west of the
Blue Ridge on Sunday.
3. Coverage of showers/storms grows smaller on Monday to far
western sections.

A look at the 29 Aug 12Z NCEP Ensemble Mean 500mb Geopotential
Heights shows for Saturday night/Sunday a broad trough is expected
to be over the US East Coast. Ridging will cover much of central and
western CONUS. A weak disturbance may try to cross through the
northern part of this region and be situated over SD/IA Sunday
morning. Low pressure will be off shore the Pacific Northwest. For
Sunday night/Monday, ensemble averaging is painting a broader
depiction of the East Coast trough. However, this could be the
result of applying averaging to the approaching shortwave trough over
the mid-West. The axis of ridge shifts to only western CONUS with a
low still off the coast of the Pacific Northwest. For Monday night,
a broad trough is still depicted over much of eastern CONUS distinct
stronger troughs within this broader system. One such trough is
expected to be over New England with another over western Ontario
south into the upper Mississippi Valley. Ridging continues over
western CONUS with a low off the coast of the Pacific Northwest.

At the surface, for Saturday night/Sunday high pressure will be
situated over the Great Lakes region. Weak low pressure will be over
the Central Plains. For Sunday night/Monday, the center of the high
pressure shifts east to over PA/NY. The influence of the high is
expected to extend south to the Carolinas and west to the Upper
Mississippi Valley. A general weakness of low pressure is still
expected to be over the Central Plains. For Monday night, the center
of the high makes a small shift eastward. The weakness across the
Central Plains additionally begins to shift east.

A look at the 29 Aug 00Z NAEFS Ensemble Situational Awareness data
shows 850mb temperatures on Sunday around +12C to +13C, oriented
east to west across the region. For the southern half the region,
these values fall within with 2.5 to 10 percentile of the 30-year
CFSR climatology. Similar values are expected for Monday.

The above weather patterns offers the following forecast. The center
of an area of high pressure will pass north of the region, heading
west to east. Anti-cyclonic flow around the high will by Sunday
provide for an increasing southeast low level flow into our region
which will be tapping Atlantic moisture. As this moisture progresses
upslope across the mountains, paired with heating of the day, we are
expecting the development of showers in areas mainly near and
immediately west of the crest of the Blue Ridge. Additionally, the
presence of an upper trough over the region will add some increased
mid-level lapse rates over the region, helping to spawn a bit more
than simple upslope conditions. This feature may help provide enough
instablilty for some isolated thunderstorms as well, but these should
be minimal in coverage. By Monday, the upslope component will likely
not be as impressive. However, the disturbance which had been across
the Central Plains may reach the Lower Ohio Valley, and be close
enough to allow for the potential of shower/storm activity across
far western portions of the area during the afternoon. Temperatures
are expected to be a few degrees below normal for this time of the
year through the period.

Confidence in the above weather scenario is moderate.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 1230 PM EDT Friday...

Key Points:

1. Gradual increase in daily chances of showers/storms through
mid-week, maximizing on Thursday.
2. Temperatures remaining on the cool side normal.

A look a the 29 Aug 12Z NCEP Ensemble Mean 500mb Geopotential
Heights shows for Tuesday through Tuesday night amplification is
expected to take place within the trough over the eastern half of
CONUS. A more distinct longwave trough axis pattern is expected to
be centered over or just east of the Mississippi Valley late Tuesday
night. Ridging is expected over western CONUS with low pressure off
the coast of the Pacific Northwest. For Wednesday/Wednesday night,
little change is expected in the overall synoptic pattern across
CONUS as compared to Tuesday. For Thursday/Thursday night, the
longwave trough, perhaps due to model averaging, is not expected to
be as amplified, but pivot slightly east in its location. Its trough
axis is expected to extend from roughly Michigan to Tennessee late
Thursday night. The ridge across western CONUS starts to flatten a
bit as a trough/low starts to move onshore the Pacific Northwest.
For Friday, the longwave trough continues to shows signs of being
less amplified with its axis shifting east to just west of our
region by late in the day.

At the surface, for Tuesday/Tuesday night, high pressure shifts east
to the East Coast and an inverted trough/weak low may be near the
mid to lower Mississippi Valley. For Wednesday/Wednesday night, a
ridge axis is expected to remain parked near the East Coast from ME
to the Carolinas. Low pressure and associated cold front may be near
Michigan late Tuesday night, along with another weakness across the
mid-Mississippi Valley/Lower Ohio Valley. For Thursday/Thursday
night, the ridge axis along the east coast shifts eastward into the
western Atlantic. Low pressure moves east into southern Quebec with
a trailing cold front. An additional area of high pressure is
expected to be across the Central to Northern Plains states. For
Friday, A front/trough crosses the region a little before daybreak
Friday and heads east with high pressure building into the region
from the west later in the day.

A look at the 29 Aug 00Z NAEFS Ensemble Situational Awareness data
shows 850mb temperatures on Tuesday around +13C. Values increase for
Wednesday to around +14C. For Thursday, the gradient increases a
little with a range of +12C to +14C. The low end of this range
touches the 2.5 to 10 percentile of the 30-year CFSR
climatology. On Friday, values trend slightly lower to +11C to
+13C again with western sections of the area within the 2.5 to
10 percentile of climatology.

The above weather patterns offers the following forecast. Coverage
of showers/storms is expected to increase (west to east) as we head
through mid-week with the approach of the axis of a longwave trough.
The system`s associated surface cold front is expected to cross the
area sometime in the Thursday night time frame. However, the upper
trough axis will have yet to cross the region on Friday. Despite
high pressure building into the region at the surface, there may be
enough instablilty aloft for some diurnal showers/storms, especially
across the mountains.

Temperatures are expected to trend milder through Thursday, but
still be slightly below normal for this time of year. Values dip
slightly on Friday behind the cold front.

Confidence in the above weather scenario is moderate.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
As of 119 PM EDT Friday....

VFR conditions look to prevail at all terminals with the
exception of LWB through 18z Saturday. LWB again could have IFR
or lower fog but some clouds arriving with an upper disturbance
tonight may allow for less coverage. WNW winds this afternoon
will gust at times to 15-20kts, then drop off around sunset.

Forecast confidence is high, but smaller for fog at KLWB.

.EXTENDED AVIATION OUTLOOK...

VFR conditions should continue into next week, though some
wedging of high pressure may bring enough moisture for a few
showers/storms to the mountains late in the weekend into next
week with potential sub-VFR cigs.

&&

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

&&

$$

SYNOPSIS...EB/WP
NEAR TERM...WP
SHORT TERM...DS
LONG TERM...DS
AVIATION...WP