417
FXUS61 KRNK 301951
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
351 PM EDT Sun Jun 30 2024

.SYNOPSIS...
A cold front will move across the mid-atlantic region, with
scattered showers and thunderstorms through this evening. Less
humid air arrives Monday, along with cooler temperatures, fair
weather persisting into Tuesday. Temperatures start to heat up
again by the 4th of July.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 350 PM EDT Sunday...

Key Message:

1) Severe thunderstorm watch #491 until 11PM for eastern VA,
which includes Appomattox, Buckingham, Charlotte, and Halifax.

2) Hot and humid with scattered showers/storms through this
evening.

3) Cooler and less humid Monday.

Steamy airmass covers entire forecast area with dewpoints in
the 70s. Its uncomfortable to say the least... HVAC units having
to work a little harder to remove the moisture from the air.
This entire airmass is getting compressed ahead of an
approaching cold front...regional PWAT values AOA 2 inches.

Weather focus through this evening will be on the potential for
showers and thunderstorms. The airmass certainly supports them,
but there are limitations. The morning RNK and GSO soundings
indicated westerly winds both surface and aloft. Westerlies over
the mountains tend to suppress deep convection due to downward
motion lee off the ridges, but since there is no capping
inversion, think we will see at least some scattered activity
over the mountains until sunset. Better convergence is expected
over the piedmont where the westerlies over the mountains meet
the southwesterly winds over the piedmont. This lee trof or
convergent area should provide the better focus for deep
convection with main severe threat from Highway 29 east toward
the coast.

Another area to watch is a mesoscale convective vortex (MCV)
that is moving east-southeast along the KY/TN border. The
models do not seem to be picking up on this feature very well,
but experience would support clustering of deep convection
underneath and in advance of this feature as it moves east-
southeast through the NC High Country and Carolinas.

That said, will maintain at least chance pops for scattered
showers across the entire CWA but likely pops or numerous
showers and thunderstorms for the VA/NC piedmont, and across the
southwest mountains (Mount Rogers) of VA and into the NC High
Country. Whether any of this becomes severe will be highly
dependent on buoyancy and organization. Wind profiles are
unidirectional with little or no directional shear. This would
imply a predominantly multicellular storm mode. The high PWATs
suggest thunderstorm cores will be very rain efficient with
water loading resulting in some healthier downdraft winds.
Forecast SBCAPE of 2000 g/kg is respectable...so would think
damaging isolated severe gusts would be the modus operandi for
the stronger storm cells through this evening.

By in large today will be the best chance for getting any rain
(and that is not saying much). Once the front comes through
tonight, pops go way down until later in the week.

Until the front clears the area, humidity levels will remain
elevated. Temperatures will also remain quite warm (hot
actually) with oppressive dewpoints. Expectation is for a
wholesale change in airmass overnight with a much more pleasant
day Monday. Dewpoints are expected to fall at least 20
degrees...falling into the 50s for Monday! Temperatures will
also come down...a pleasant way to start the first day of July.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 200 PM EDT Sunday...

Key Messages:

1: Heat ramps up heading towards Independence Day

The first half of next week will be characterized by surface high
pressure 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. This period of
high temperatures and no cloud cover will only serve to worsen the
abnormally dry and moderate drought conditions we`re experiencing in
the region.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 230 PM EDT Sunday...

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 will likely exceed 100F for a few hours in the
afternoon Thursday and Friday. 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 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. Confidence is increasing for stormy conditions on
Independence Day to potentially disrupt activities. After
Independence Day, temperatures could moderate a bit, but still
expecting temperatures and heat indices well above normal.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
As of 300 PM EDT Sunday...

Scattered showers/storms to persist through sunset, then expect
clearing. Greatest coverage is expected south of I-64.

A wind shift will take place later this evening. A cold front
over the Ohio Valley will cross the mountains, winds ahead of
the front are out of the WSW. Expect them to shift to the north
overnight...then out of the northeast for Monday.

A wholesale change in airmass is expected for Monday...featuring
cooler temperatures, lower humidity, and clear skies.


Confidence in the above scenario is moderate to high.


EXTENDED AVIATION OUTLOOK...

Monday-Wednesday 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.
Storm chances increase by Thursday ahead of a front so sub-VFR
possible.

&&

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

&&

$$

SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...PM