-- Discussion containing changed information from previous version are highlighted. --
541
FXUS61 KRNK 130017
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
817 PM EDT Sat Jul 12 2025

.SYNOPSIS...
The weather pattern will generally remain unchanged through next
week. With a warm and moist airmass lingering across the
region, expect isolated to scattered shower and thunderstorms
each afternoon and evening. Temperatures across the area will
generally run around or just above normal values for this time
of year.

&&

.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
As of 800 PM EDT Saturday...

Key Message:

1) Patchy fog again tonight, more likely in the mountain river
valleys and where rain fell this afternoon/evening.

2) Additional widely scattered storms for Sunday, capable of
heavy rain and localized damaging winds.

Radar indicates that storms are diminishing in both intensity
and coverage with the loss of afternoon heating. Remaining
storms will linger as late as midnight before ending for the
evening.

Patchy fog will redevelop overnight, though coverage may not be
as widespread as previous nights given lingering mid- and high-
clouds. Regardless, fog may become locally dense in the
mountain river valleys, as well as at locations that received
significant rainfall this afternoon/evening. Otherwise expect
warm and muggy conditions typical of summertime.

Coverage of storms could be higher on Sunday as surface front
reaches the central Appalachians into the TN Valley in the late
afternoon. As such have higher rain chances, especially in the
north and west (I-64 west of Lexington to the far SW VA
mountains).

Again, storm motion and some multi-cell clusters could bring
localized flooding, but not enough coverage at this time to
warrant a flood watch. Severe threat is marginal as well, with
damaging winds the main threat, and if cloud cover moves into
the mountains earlier, the severe threat will be better in the
Piedmont.

Not much need to deviate from previous forecast and model blend
on temps as airmass remains the same, expecting highs Sunday in
the lower 90s east to lower to mid 80s west. Did adjust
dewpoints in the east down as enough mixing has been keeping
them lower than model blend, and this in turn will keep heat
indices below advisory levels but still around 100 degrees in
the Piedmont and perhaps Roanoke.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
-- Changed Discussion --
As of 1230 PM EDT Saturday...

Key Points:

1. Daily chances of showers/storms.
2. Isolated locally heavy rainfall/flooding possible.
3. Above normal temperatures.

A look at the 12 Jul 00Z NCEP Ensemble Mean 500mb Geopotential
Heights shows for Sunday night a longwave trough over Canada
with its axis extending from Hudson Bay to the western Great
Lakes region. Elsewhere across CONUS, expect a broad w-e
oriented region of high pressure. For Monday/Monday night,
expect little change from a synoptic standpoint. The Canadian
longwave trough holds firm. What changes a bit is the position
of shortwave troughs within the broader longwave pattern. By the
evening hours, the axis of one shortwave trough is expected to
be over Quebec/New England with another over British Columbia
and the Pacific NW. Broad ridging covers the southern half of
CONUS. For Tuesday/Tuesday night, again, little change other
than the position of the shortwave troughs within the greater
longwave pattern. The one over New England is expected to be
closer to Newfoundland. The one over the Pacific NW advances to
the Northern High Plains. Another shortwave trough moves onshore
the Pacific NW.

At the surface, a small region of weak low pressure is expected
to be eastern portions of VA/NC/SC Sunday night into Monday all
the while high pressure holds fast around it from southeast
through west. A cold front will also approach and cross into our
region during this same time period. For Monday night through
Tuesday night, while high pressure will remain stationary to the
southeast, the cold front will stall and/or wash out over our
region.

A look at the 12 Jul 00Z NAEFS Ensemble Situational Awareness
data shows 850mb temperatures will range from +19C to +21C,
across the region. Those areas within the top end of this range
will experience readings within the 90 to 97.5 percentile of the
30-year climatology.

The above weather patterns offers the following forecast. The
region will continue to be within an airmass that offers above
normal temperatures and plenty of moisture. At least diurnal
convection is expected during this period of the forecast. With
the introduction of a front across the area, especially the
southern half, there will be another source of a lifting
mechanism and convergence zone to entertain a better
concentration of showers/storms, during not only the daytime,
but a focus to continue them into the overnight hours. The front
will also be a place to watch for locally heavy rainfall which
could lead to isolated flooding.

Confidence in the above weather scenario is moderate to high
with the biggest question mark being to exact location of the
front each day.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
-- Changed Discussion --
As of 1230 PM EDT Saturday...

Key Points:

1. Threat of daily showers/storms continues.
2. Isolated locally heavy rain/flooding concern, especially Friday
into Saturday.
3. Above normal temperatures.
4. Heat Index values around 100F far eastern areas Thurs-Sat.

A look a the 12 Jul 00Z NCEP Ensemble Mean 500mb Geopotential
Heights shows for Wednesday/Wednesday night, we are expecting a
small southern shift in the base of a longwave trough over
Canada -- reaching the northern third of CONUS by the evening
hours. Shortwave troughs with the broader pattern are expected
over the Upper Mississippi River Valley and the Pacific NW. Much
of the southern half of CONUS will still under the influence of
a broad ridge of high pressure. For Thursday/Thursday night,
little change is expected on a synoptic scale. Ensemble
averaging starts to washout the weaker shortwave troughs. For
Friday/Friday night, the same general pattern is expected with a
longwave trough over Canada and a broad ridge over much of the
US south of 40 N latitude. A couple of small changes are
expected to be a stronger shortwave trough within the broad
longwave trough over British Columbia. Additionally, the ridge
is expected to strengthen over SE CONUS. On Saturday, little
chance is expected as compared to Friday. The center of the
ridge may shift west to over south-central CONUS.

At the surface, a weak front will remain over the area on
Wednesday, before lifting north of the region by Thursday. A
ridge of high pressure parked to our southeast will help
maintain an anti-cyclonic flow of moisture into our region from
off both the Atlantic and the Gulf. Friday into Saturday, a cold
front will approach and then cross our area.

A look at the 12 Jul 00Z NAEFS Ensemble Situational Awareness
data shows 850mb temperatures Wednesday-Saturday around +18C to
+20C.

The above weather patterns offers the following forecast. With
a frontal boundary remaining over the region on Wednesday, a
similar concentration of showers/storms as compared to Tuesday
is expected. With the front moving north of the area by
Thursday, we may briefly return to a diurnal coverage of
showers/storms. However, this will be short lived with the
approach and then return of a cold front to the area Friday into
Saturday. Temperatures will still be above normal for this time
of year. Combined with high humidity, late afternoon Heat Index
values may be around 100F across the far eastern sections of
the region during this time, especially from Thursday through
Saturday.

Confidence in the above weather scenario is moderate to high.
-- End Changed Discussion --

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
As of 745 PM EDT Saturday...

Coverage of storms is diminishing this evening with the loss of
afternoon heating. Expect lingering activity to fade away by
midnight.

Fog appears likely again tonight, including for the mountain
river valleys and anywhere that received significant rainfall
this evening. Visibilities will be variable over short
distances. Fog will burn off quickly after 1230Z with daytime
heating.

Cumulus field will develop as early as 15Z, with showers and
storms beginning to develop during early afternoon in widely
scattered fashion. Storms will again persist through the
afternoon and evening, capable of locally strong wind gusts and
LIFR visibilities in brief but intense rain.


.EXTENDED AVIATION OUTLOOK...

The weather pattern will change very little through early next
week, remaining conducive for isolated to scattered afternoon &
evening storms, with higher coverage on some days more than
others. Outside of storms, expect VFR conditions but with the
potential for locally dense fog and MVFR/IFR stratus developing
overnight, especially for locations that received significant
rainfall during the evening prior.
-- End Changed Discussion --

&&

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

&&

$$

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