225
FXUS61 KRNK 121406
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
1006 AM EDT Fri Jul 12 2024

.SYNOPSIS...
A front along the East Coast drifts back to the west today as
low pressure tracks along the boundary. This will bring
widespread rain to parts of central and eastern Virginia and
North Carolina. The front should retreat further east for
Saturday and limit precip chances to parts of the east and
south. Sunday looks mostly dry. Afternoon thunderstorm chances
return Monday through Tuesday, while another system brings more
widespread rain towards the middle of next week. Temperatures
will be cooler today but increase again for the weekend, with
heat index values approaching 100 degrees in Piedmont again for
much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM EDT Friday...

Key Messages:

1) Forecast is on track; areal increase in activity expected the
next few hours.

2.) Instability limited.

A dense and overcast cloud shield associated with a trough of
low pressure and a stationary front along the coast covered most
of the forecast area this morning. The deeper convection and
lightning was located to our east and stretched from just east
of Charlotte, NC to southern NJ. Additional activity will bulge
westward for a few hours this afternoon as an area of vorticity
lifts north. Period of heavier rain and increased chances for
showers and storms mainly east of the Blue Ridge are supported
by isentropic lift forecasts and deep tropical moisture feeding
into the system. As such, the holes in precipitation currently
seen on radar out east will tend to fill in. Still seeing
potential for high rain rates and amounts between 1 to 2 inches
mainly SE of a line from Danville to Lynchburg. Isolated higher
rainfall amounts are possible, causing urban and small stream
flooding.

Areas west of the Blue Ridge will be lucky to see a tenth or
more of precipitation. Made a few changes to the forecast,
mainly for sky cover and PoPs, and to add fog overnight.



As of 330 AM EDT Friday...

Key Message:

1. Shower and storm chances on the increase today.

Frontal boundary and enhanced deep layer moisture axis is
advecting westward into the eastern CWA this morning and
already triggering some shower development. Expecting the trend
to continue into today with increased shower and thunderstorm
potential for mainly the eastern two thirds of the area and have
likely to categorical pops mainly along and east of the Blue
Ridge. PWATs should increase to greater than 2 inches so any
convection should be quite precip efficient with hydrometeor
loading and localized heavy rainfall. For now thinking QPF
amounts of mainly a half to 1.5 inches in parts of the Piedmont
should be maintainable and welcomed in the dry antecedent
conditions, though will need to be monitored if higher amounts
may warrant any increased chance of a flood watch. By tonight
into early Saturday the aforementioned front and moisture axis
should meander back east and allow for a gradual decrease in
convective coverage.

Temps today will be limited due to the precip and cloud coverage
so highs are actually only expected to make it to the low 80s
for much of the area.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 AM EDT Friday...

Key Messages:

1. Above normal temperatures Saturday and Sunday.
2. Increasing confidence for drier weather over the weekend.

By the start of the weekend, a ridge of high pressure aloft over
the Atlantic starts to shift east, and expands farther across
the southeastern US, while ridging develops over the Rockies. A
weak upper trough digs southward into the Mid Atlantic through
the weekend, but eventually flattens out by Sunday. At the
surface, a stationary front situated north-south lingers along
the eastern US coast through Saturday, and will be the focus for
showers and thunderstorms. How far west the shower and storm
activity will expand is uncertain at this time, as most guidance
shows mostly westerly and northwesterly winds across the area,
which is usually unfavorable for thunderstorm development in the
Piedmont, so most of the showers and thunderstorms looks to be
over eastern VA and NC, although a few isolated showers and
storms can`t be ruled out in the Southside by the afternoon
Saturday. By Sunday, this front will move farther from the area,
decreasing precipitation chances even farther areawide, though
diurnal heating and increasing moisture may spark some isolated
showers and storms mid afternoon.

Return flow around surface high pressure over the Atlantic will
contribute to increasing moisture over the area through
Saturday, and an increase in dewpoints, and precipitable water
values exceed the 99th percentile relative to climatology by
late Saturday, especially over eastern VA and NC. Temperatures
start increasing again to above normal values, making for a hot
weekend ahead.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 300 AM EDT Friday...

Key Messages:

1. Above normal temperatures continue through midweek.
2. Increasing chances for showers and storms by Wednesday.

A 500mb ridge expands into the Mid Atlantic from the west to
start the work week, and surface high pressure builds over the
southeastern and Mid Atlantic states, which will keep the
weather mostly dry over the area through at least the beginning
of the work week. Afternoon showers and thunderstorms are
possible during the afternoons with peak daytime heating, mainly
along the higher terrain, due to orographic forcing. With
subsidence from the high pressure overhead, hot, above normal
temperatures will continue through at least midweek. A strong
cold front drops southward into the area from the Great Lakes
region Wednesday or Thursday, which will bring increased
probabilities of more widespread coverage of showers and
thunderstorms. With better forcing and wind shear from stronger
front, there is greater probabilities of more severe
thunderstorms, but, that being said, mesoscale details are too
uncertain at this time frame to give specifics. Overall, the
middle of the week looks to have more active weather at this
time.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
As of 655 AM EDT Friday...

Cigs should lower into the MVFR/IFR range this morning along
with increased shower chances for the eastern sites and central
sites. Have TS potential by late morning into afternoon.
Coverage of precip should be less farther west along with VFR
conditions - maybe just some alto clouds or cu 4-7 kft. Winds
should be generally NE to east under 10 kts. Tonight into
Saturday morning could have some reduced vsbys and LIFR cigs.

Forecast confidence is medium on western extent of precip
coverage and cigs.

AVIATION OUTLOOK...

The weekend looks drier with morning fog possible. Afternoon
TSRA chances increasing again Monday.

&&

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

&&

$$

SYNOPSIS...SH
NEAR TERM...AB/SH
SHORT TERM...AS
LONG TERM...AS
AVIATION...AB/SH