490
FXUS61 KRNK 060027
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
827 PM EDT Sun May 5 2024

.SYNOPSIS...
An upper level trough of low pressure is slowly moving across
the Mid-Atlantic region, resulting in mostly cloudy skies,
areas of rain and rain showers, and a few thunderstorms.
Rainfall amounts will be highly variable, with the heaviest
occuring along and east of the Blue Ridge. Daily afternoon
showers and thunderstorms are possible through much of the
upcoming week.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 700 PM EDT Sunday...

Scattering cloud cover across the mountains this afternoon
allowed temperatures to spike some 5 to 8 degrees over the span
of a couple hours, and triggered spotty showers with an isolated
rumble of thunder or two. These lingering showers will persist
through around 10 pm and will gradually fade heading into late
evening with the loss of heating. Still looking for clouds to
redevelop overnight, with patchy fog forming more so after
midnight.


As of 145 PM EDT Sunday...

Key Messages:

1. Scattered showers and thunderstorms this afternoon and again
Monday afternoon.
2. Warmer temperatures Monday.

The wedge of high pressure will finally erode by later today,
and the warm front lifts northward, putting the area in the
broad warm sector behind the front. So, through this afternoon
and evening, scattered showers and isolated thunderstorms can be
expected, with the highest probabilities along and west of the
Blue Ridge. Thunderstorm coverage will depend on how much the
atmosphere can destabilize through diurnal heating from any
breaks in the clouds. Right now, some pockets of sunshine and
thinner cloud cover is observed west of the Blue Ridge, in far
southwest VA and northwest NC mainly. Most of the showers and
storms will diminish by tonight, but plenty of residual moisture
will lead to overcast skies and patchy fog, especially over the
higher terrain, through the overnight and into tomorrow
morning.

A cold front is currently situated from the upper Ohio Valley
into the Tennessee Valley, with the surface low in the ArkLaTex
region. By tomorrow, this low will track northeastward along the
front and closer to the Mid Atlantic, moving just west of the
forecast area by Monday afternoon. Monday will start off dry as
mid level ridging builds in overhead, and generally low level
southwesterly flow brings warmer and more moist air into the
area. However, heating throughout the day will help to increase
instability, with SBCAPE forecast to reach around 1000 J/kg by
the afternoon, highest along and east of the Blue Ridge.
However, the better upper level dynamics will be closer to the
surface low, mainly over the western mountains, and closer to
the frontal boundary, which will be draped across the upper Mid
Atlantic region. That all being said, thinking for Monday
afternoon is showers beginning first in the west and expanding
eastward into the Foothills and Piedmont, but with a higher
potential for some thunderstorms in the east where the greater
instability will be.

Temperatures overnight will be mild, with overcast skies
preventing much radiational cooling. Highs Monday will be warmer
than today, as south and southwesterly flow ahead of the cold
front increases and mid level ridging builds overhead.

Forecast confidence is moderate, but lower on specific locations
of thunderstorms this afternoon and tomorrow.

&&

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

Key Messages:

1. Showers and thunderstorm possible each day, especially in the
afternoons and evenings.

2. Moderate rainfall possible as well as damaging winds and
marginally severe hail.

3. Warm temperatures continue.

Monday night into Tuesday, a short wave will cross the forecast
area, helping to steer an elongated baroclinic zone towards us
from the north. This will keep scattered to numerous showers and
thunderstorms in the area. Another short wave moves through
Tuesday afternoon and evening, and this will trigger some
stronger thunderstorms, mainly over the western mountains.
However, antecedent cloud cover and rain as well as weak ridging
aloft and westerly winds should keep a lid on the severe
potential, but an isolated damaging wind gust or marginally
severe hail will be possible, along with moderate rainfall.

On Wednesday, we remain in the warm sector, and a surface
trough crossing the area should help organize convection. Expect
showers and storms to develop during the afternoon and evening,
with MLCAPE increasing to between 500 and 1000 J/kg over the
southern Shenandoah Valley and the Piedmont based on GEFS
probabilities. Dew points will be in the 50s to low 60s for the
mountains, so prolonged thunderstorm activity there looks less
likely. Forecast soundings indicate tall, skinny CAPE each day,
along with unidirectional westerly flow, which would indicate
more linear bowing structures could develop with damaging winds.
Very slow storm motion as well as PWATs approaching our
recorded maximum for these dates indicate urban, small stream,
and flash flooding may be a concern.

Temperatures during this time will be on the warm side, with
70s and 80s each day, reaching the mid to upper 80s for areas
east of the Blue Ridge Wednesday.

Confidence in the short term is moderate.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 200 PM EDT Sunday...

Key Messages:

1. Warming trend to start the work week, cooler and dry next
weekend.

2. Showers and thunderstorm chances each day.

Thursday into Thursday night we will see more chances for
showers and thunderstorms. A slowly filling surface low will
move west to east across the OH Valley, putting us just south of
the triple point and well under dense cloud cover for most of
the area. Instability looks best for our northern NC counties,
which may see some strong thunderstorms. The initial short wave
trough associated with the upper level system will be positively
tilted and crosses the Appalachians Friday and Saturday,
pushing a cold front ahead of it. This will mean more widespread
rain and thunderstorms. While there are mixed signals as far as
severe thunderstorm chances, the chances for moderate to heavy
widespread rainfall leading to flooding increases each day
during this wet period, and at the moment looks like the bigger
threat.

High temperatures gradually decrease each day Thursday through
Saturday with overcast skies and the passage of the front. We
may finally see the sun either late Friday or Saturday. The
weekend looks cooler and drier with dew points dropping into the
30s and 40s, and this is supported by NAEFS situational
awareness projections.

Confidence in the long term is moderate for most parameters,
but lower for timing of showers and storms.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 820 PM EDT Sunday...

Radar depicts a few remaining showers and isolated
thunderstorms this evening across the mountains, while surface
observations indicate a mixture of low VFR and MVFR ceilings
across the lower Mid-Atlantic. A cold front continues to drift
along the Ohio River slowly eastward toward the central
Appalachians.

Through tonight, the remaining precipitation will diminish in
coverage, leaving only isolated coverage at best of showers
passing across the region overnight. Moisture pooling ahead of
the approaching cold front will again result in lowering
ceilings to the IFR/low-end MVFR range overnight, as well as
reduced visibilities from patchy fog for most of the forecast
area.

Visibilities will improve after sunrise, with ceilings then
gradually lifting/scattering during late morning into early
afternoon Monday. Rapid update weather data suggests a line of
showers with embedded thunderstorms developing across the
mountains on Monday afternoon as a wave of low pressure passes
along the approaching cold front, and therefore entered mention
of -TSRA in the TAFS for Monday afternoon into early evening.

Forecast confidence is average, but lower on specific locations
of showers and storms on Monday afternoon and evening.

Extended Aviation Outlook...

Unsettled weather is expected for much of the upcoming week.
Daily threat of SHRA/TSRA Tuesday through Friday. This will
bring periods of MVFR/IFR ceilings and visibilities at times.
Winds through Wednesday will favor a SW direction and may be
gusty at times.

&&

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

&&

$$

SYNOPSIS...PM
NEAR TERM...AS/NF
SHORT TERM...SH
LONG TERM...SH
AVIATION...AS/NF