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733
FXUS61 KRNK 060835
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
435 AM EDT Mon May 6 2024

.SYNOPSIS...
-- Changed Discussion --
An upper level trough of low pressure, over the lower Ohio
and Tennessee Valleys, will move east and across the mid
Atlantic Region today.  This will result in the formation
of scattered to numerous showers and thunderstorms this
afternoon and evening.  Storms this afternoon may contain
heavy rain and small hail.  The weather pattern will remain
unsettled for much of the upcoming week with a daily threat
of afternoon and evening thunderstorms.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 230 AM EDT Monday..

Shower development over the NW NC piedmont may creep into
southside VA early this morning. CAMS bring it through
Martinsville and Henry CO prior to daybreak and then fade
between LYH-DAN by 13Z/9AM. Elsewhere, dealing with patchy fog
and sct-bkn cloud cover. HRRR suggests dense fog possible over
parts of the piedmont east of highway 29 early this morning...
so will have to monitor for that hazard, otherwise no
significant weather hazards until formation of deeper convection
later this afternoon.

Key Messages:

1. Scattered showers and thunderstorms this afternoon.

2. A few strong storms possible between 3PM-7PM with small hail
and heavy downpours.

In spite of areas of low level stratus and fog this morning the
wedge of stable air east of the mountains is pretty much gone.
No longer see any easterly component to the winds at the
surface, and once mixing begins later this morning should see
southerly winds at the surface promoting rapid warm up. Short
wave trough which brought heavy rain to TX is now crossing the
lower OH and TN Valleys, this upper support progged to cross our
forecast area later this afternoon and evening. Current forecast
is for scattered to numerous showers and thunderstorms and for
the most part this sounds reasonable. Concern is that timing of
the vort axis and max PVA will occur during the peak heating
leading to MUCAPE of 1500 j/KG and possibly a little higher over
the piedmont. This suggest potential for a few strong pulse
type storms and/or cluster or two of loosely organized storms
which may produce small hail and heavy rain. PWAT forecast of
1.30 RNK to 1.70 GSO will be tracking near max value for the
time of year, so would expect very rain efficient airmass and
potential for localized heavy downpours. In this environment,
QPF will be highly variable, but can`t rule out localized
thunderstorm which may dump up to 3 inches of rain causing flash
flood scenario. In general thinking a marginal threat for
severe if MUCAPE exceeds 1500 and marginal threat for excessive
heavy rain if PWATs verify 90th percentile or higher.

Used the warmer MAV MOS for temperatures this afternoon. MET
MOS looks too cool per loss of wedge. Dewpoints in the 60s are
forecast areawide, so it should feel rather humid.

Upper trough will exit the region tonight, showers/storms fading
with the loss of daytime heating. Will taper pops by midnight
with little or no activity after midnight.

&&

.SHORT TERM /TUESDAY 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 /09Z MONDAY THROUGH FRIDAY/...
As of 230 AM EDT Monday...

Shower development over the NW NC piedmont may creep into
southside VA early this morning. Models bring it through
Martinsville and Henry CO prior to daybreak and then fade
between LYH-DAN by 13Z/9AM. Elsewhere, dealing with patchy fog
and sct-bkn cloud cover. HRRR suggests widespread dense fog
possible over parts of the piedmont east of highway 29 early
this morning with area of LIFR just east of LYH/DAN. Also seeing
some river fog with LIFR vsby within the mountain valleys, with
impacts to LWB/MKJ/TNB.

After morning stratus and fog, expect cloud buildups early
afternoon. Upper level trough over the lower OH and TN valleys
will cross the Appalachians during the peak heating of the day
so would anticipate formation of scattered to numerous showers
and thunderstorms this afternoon and persisting until loss of
daytime heating. Cloud bases will be highly variable today,
favoring sub VFR as a whole. Winds sfc and aloft will be from
the south and southwest, under 10 kts at the surface, but with
higher speeds/gusts near thunderstorms. Do think the showers and
storms may become loosely organized with clusters of storms
producing small hail and downpours of heavy rain.

Showers/storms are expected to fade will loss of daytime heating.
However, clouds will linger with reformation of sub-VFR stratus
and fog after midnight .

Forecast confidence is average, but lower on specific locations
of showers and storms this 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...PM
SHORT TERM...SH
LONG TERM...SH
AVIATION...PM