539
FXUS61 KRNK 300041
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
841 PM EDT Sat Jun 29 2024

.SYNOPSIS...
High pressure off the Atlantic coast will keep us in a southerly
flow of moisture today, with increased humidity and a chance of
showers and storms. A cold front pushes through late Sunday with
a better chance of storms. Less humid air arrives Monday.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 805 PM EDT Saturday...

Key Messages:

1) Showers and storms possible in the early morning hours,
especially for SE WV and the southern Shenandoah Valley of VA.

2) Convection redevelops in the afternoon, with strong to
severe storms possible for the Piedmont of NC and VA. The
greatest concerns will be damaging winds and heavy rainfall.

3) It is possible the stronger storms develop east and south of
our forecast area.

Large scale lift is on the increase tonight as initial PVA
aloft moves in from the west. We remain in a broad warm sector
along with the southeastern quarter of the U.S. Convection in
our area has been weak and mostly in the form of showers, likely
due to very weak shear and a lack of a forcing mechanism at the
surface.

For tonight, expect increasing cloud cover everywhere. Overnight
lows will be warm with highs in the low to mid 70s for the
Piedmont, and in the mid 60s to low 70s for the mountains.

Showers and thunderstorms now developing in KY and southern OH
will reach our northern counties in the early morning hours.
These storms were firing along a pre-frontal trough and outflow
boundaries, and most CAMs show this area of convection falling
apart as it reaches the mountains. Moderate to heavy rain is
possible as this occurs. We should see a break in precipitation
after the initial wave of convection disintegrates in the
morning hours. After that, expect showers and storms to
redevelop as the surface cold front arrives. The best forcing
for ascent and instability will be over the Piedmont of VA and
NC in the afternoon and early evening, where strong to severe
storms will be possible where the front restrengthens after
crossing the mountains. Again, brief heavy rain is expected, and
damaging downburst winds will be possible.

Confidence in the above scenario is high, but there is a chance
the stronger storms stay east and south of our forecast area
tomorrow.



As of 1130 AM EDT Saturday...

Key Messages:

1) Humid today with spotty storms this afternoon, with best
coverage across the mountains.

2) Increased confidence in organized line of the showers and
thunderstorms developing Sunday afternoon east of the Blue
Ridge.

Latest radar imagery is clear, with satellite imagery
indicating that clouds are gradually transitioning from the
blanket of low clouds to a mix of clouds and sunshine. Humid as
well as dewpoint temperatures per latest surface observations
range from the upper 60s to low 70s. Between the widespread
clouds and the high dewpoints, we are looking at the potential
for record high minimum temperatures for this date in the
Blacksburg and Bluefield areas.

Our warm & muggy conditions are thanks to deepening southerly
windflow around high pressure that is pushing east off the
Atlantic coast, while a low pressure system moves across the
upper Great Lakes, dragging a cold front eastward in its wake.
As daytime heating continues to increase, surface-based CAPES
will push into the 1,200-1,500 J/Kg range, supporting
development of spotty & disorganized showers and thunderstorms
that will develop after 2pm. Steering winds of 10 to 15 mph
will keep these cells moving, however still a potential for
locally heavy downpours as precipitable water values continue to
climb, reaching 1.5 to 1.7 inches this afternoon. Given
increasing humidity and scattered clouds, highs today will range
from the mid to upper 80s along and west of the Blue Ridge, and
reach into the low 90s further east.

Expect muggy conditions to remain tonight as moisture pools
ahead of the approaching cold front. A pre-frontal wave of
energy passing along the Ohio Valley tonight will trigger
showers and thunderstorms, with highest chances across southeast
West Virginia into southwest Virginia, potentially reaching as
far east as the Blue Ridge before fading away. Overnight lows
will hold in the upper 60s to the mid 70s.

As an upper level trough approaches during Sunday afternoon,
will then be keeping a eye out for redevelopment of
thunderstorms across the Piedmont, with scattered cells
developing in the foothills, then gradually increasing in
coverage as they approach a line stretching from Lynchburg to
Martinsville. Given these storms will develop around maximum
daytime heating, potential exists for wet microbursts to produce
damaging wind gusts. Heavy downpours are also likely as
precipitable water values increase to around 2 inches, or 2
standard deviations above normal for late June, though storms
are expected to remain progressive across the Piedmont.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 200 PM EDT Saturday...

Key Messages:

1: Heat ramps up heading towards Independence Day

The first half of next week will be characterized by surface high
pressure behind a front that moved through the Mid-Atlantic on
Sunday. In addition, there will be an intensifying subtropical ridge
growing out of the southern plains and covering most of eastern and
southern CONUS. This will result in daily increases in temperature
as well as dewpoint. Highs on Monday will grow from the mid 80s/
upper 70s, and become 80s and low 90s by Wednesday July 3. Summer
will make its presence known. All of this ridging and high pressure
will keep skies clear and prevent shower formation, so shade and
remaining indoors will be the only  reprieve from the heat.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 230 PM EDT Saturday...

Key Messages:

1: Independence Day hot with potential for storms

2: Unsettled second half of the week

Independence Day (Thursday) will likely be the hottest day of the
week, and even  the hottest of the season so far. Highs east of the
Blue Ridge will be well into the 90s. Heat indices towards central
VA and Southside VA could be >100F. At the same time a front looks
to finally break through the ridging over the southern CONUS,
bringing the next shot of showers and storms since this weekend.
Following the ridge weakening and surface high pressure being
displaced, several waves with indeterminate timing, as of this
discussion`s writing, will keep showers and storms in the forecast
from Thursday on through the weekend. Timing of showers will be
monitored closely as we forecast for holiday activities. After
Independence Day, temperatures could moderate a bit, but still
expecting temperatures and heat indices well above normal.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 830 PM EDT Saturday...

A disturbance will bring a round of showers and thunderstorms
across southeast West Virginia into southwest Virginia, most
likely during the 30/08Z to 30/12Z timeframe. The best chances
for this activity occurring will be for BLF/LWB. Lower chances
for ROA and LYH as the activity diminishes in the downslope
flow. Westerly wind shift behind this activity will also make
for MVFR ceilings at BLF/LWB and possibly BCB that will linger.

Coverage of showers/thunderstorms and associated MVFR flight
conditions redevelop in the afternoon, mainly east of the Blue
Ridge as a cold front moves through. Most likely timing of this
activity is between 30/18Z and 30/23Z, before activity exits to
the southeast.

Confidence in the above scenario is moderate to high.


EXTENDED AVIATION OUTLOOK...

Monday and Tuesday appear to be VFR as high pressure works in
from the north. Could be some fog Monday night in the river
valleys and for areas that received significant rainfall. On
Wednesday, isolated TSRA is possible in the mountains as a warm
front and pre-frontal trough nears, but still mainly VFR.

&&

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

&&

$$

SYNOPSIS...NF/VFJ/WP
NEAR TERM...NF/SH/WP
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...NF/SH