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000
FXUS61 KRNK 091424
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
1024 AM EDT Tue Apr 9 2024

.SYNOPSIS...
Disturbances in the upper atmosphere, combined with increased
moisture, will produce rain showers today and Wednesday. A
strong low pressure system will bring the possibility of heavy
rain, as well as thunderstorms for Thursday. Some showers may
linger into Friday, mainly in the west and north, and closer to
the track of the low as it exits the region. Once the low
departs, conditions should dry out for the weekend.

&&

.NEAR TERM /NOW THROUGH TONIGHT/...
Issued at 1024 AM EDT Tue Apr 09 2024

Moisture continues to stream into the region late this morning
thanks to the broad southwesterly flow aloft. Weak isentropic
ascent, noted along the 300K surface, was occuring, which has
aided in the development of showers. Radar shows this
shower/rain area continuing to move north and east into the
forecast area. I expect many areas, especially along and west of
the Blue Ridge, to see some light rain through the afternoon. High-
res CAMs continue to suggest a break in the widespread precipitation
this evening, before the next round develops closer to midnight.

By in large, the forecast remains on track, with only a few
tweaks here and there to account for observational trends.


As of 300 AM EDT Tuesday...

Key Messages:

1. Increasing chance of showers today.

2. Another round of showers again later tonight.

Southwesterly fetch will allow for Gulf moisture advection with an
upper disturbance and some low level isentropic upglide to kick
in today east of a broad developing low pressure system. CAMs
are in good consensus with showers increasing in coverage from
the SW beginning near daybreak and spreading across the majority
of the CWA by afternoon. There is some progged weak instability
mainly near the northern tier this afternoon as well so have
just a slight chance thunder mentioned. Overall QPF with this
first wave look fairly low and tolerable with mainly a quarter
to a half inch possible along and west of the Blue Ridge.

Expecting a lull in shower coverage for this evening, then another
weaker disturbance may increase development again for overnight into
Wednesday morning. The greatest chances look to be mainly across the
western mountains.

Temps in the period should have limited diurnal range given the
increased moisture and precip potential with highs today generally
be near climo norms, then above normal lows tonight.

Forecast confidence is medium to high.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 300 AM EDT Tuesday...

Key Messages:

1) High confidence for showers and thunderstorms Thursday.

2) There is a potential risk of flooding along the Blue Ridge due to
heavy rain on Thursday.

A developing low pressure system over the southern Plains will
track northeast across the central U.S. midweek before
advancing through the Ohio Valley, Great Lakes and across the
Appalachians later in the week. The upper trough is expected to
become negatively tilted as it crosses the Appalachians
resulting in a deep south-southeast fetch of warm moist air up
against the Blue Ridge. This will likely fuel showers and a few
strong fast moving storms, but will also allow for training
along Blue Ridge and spine of the Appalachians. Rain amounts may
be locally excessive, but relatively dry antecedent conditions
with stream levels running average to below average for the time
of year should provide a cushion.

Models have yet to converge on an solution for QPF placement. It
appears that most of Wednesday and into early Wednesday night
will be dry with just a chance for showers. Most of the action
will initially favor the west side of the Appalachians into the
OH/TN/MS valleys. But as thunderstorm evolution takes place
there it will move downstream and across the Appalachians as
early as Thursday morning. At that time expect a wholesale
increase in coverage and onset of heavier rain with opportunity
for thunderstorms. Activity Thursday morning may inhibit solar
insolation, so not sure if severe weather will become an issue,
but if there is a break and the sun pops out, then would expect
renewed development along the actual cold front Thursday
afternoon or evening.

A 50-60 kt low level jet is forecast ahead of the front
Thursday. If any of this mixes to the ground it will become
quite breezy. Attm think the strongest winds will be across the
ridgetops, then mix to the surface later in the day with the
passage of the cold front. At that time we may need a headline
for wind, not necessarily for potential mixing from the LLJ,
but for the post frontal winds associated with the pressure rise
Thursday night.

Breezy conditions with lingering clouds and showers can be
expected friday, especially across the mountains. The surface
low will eventually move far enough away, so would anticipate
the wind to start diminishing Friday night.

Mild temperatures are expected prior to the passage of Thursday`s
cold front...readings in the 60s/70s both Wednesday and Thursday.
A cool down takes place Friday with a day or two of seasonal
numbers Friday into Saturday.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 330 AM EDT Tuesday...

Key Messages:

1) Fair weather is expected for the weekend.

2) Temperatures moderating.

High pressure is expected to pass over the southern Appalachians
Saturday. A weak front is forecast to move across the northern
Mid-Atlantic Sunday. Attm think most of the clouds and precip
associated with the front will remain north of the region, but
can`t rule out a stray shower or thunderstorm late in the
weekend as the front washes out over the area. The weather then
looks relatively benign until at least Thursday of next week
with an opportunity for a significant warm-up early in the week
with temperatures in the 70s for most and possibly nudging 80
for the Blue Ridge foothills and piedmont.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
As of 645 AM EDT Tuesday...

NOTE : AMD NOT SKED added to KDAN taf as ceilometer is producing
erroneous ceiling heights. Use with caution.

Initial VFR conditions and some cigs near 6-10 kft. Area of rain
showers/light rain is most likely for western and central sites
mainly in 17-23z period (could start earlier for KBLF and could
linger on for KLWB after). Cigs in this period and area also
look to be MVFR. Otherwise there looks to be a lull in precip
and possible cig improvement after 23z, then a return of
rain/showers and lowering cigs later Tuesday night (possibly
near IFR). Winds generally 5-10 kts out of the SW through much
of the period.

Forecast confidence is average.


EXTENDED AVIATION OUTLOOK...

Wednesday and Thursday: Greater likelihood of restrictions due
to lower CIGs/VSBYs in SHRA/TSRA. Wind speeds also increase from
the south by Thursday.

Upslope showers linger into Friday night with sub-VFR mainly in
the mountains. Saturday will start to clear out to VFR.

West-northwest winds will be pretty gusty Friday-Sat morning.

&&

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

&&

$$

SYNOPSIS...DB
NEAR TERM...DB/AB
SHORT TERM...PM
LONG TERM...PM
AVIATION...AB