479
FXUS61 KRNK 202243
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
643 PM EDT Sat Jul 20 2024

.SYNOPSIS...
A stationary front extends west to east along the Virginia,
North Carolina border. This front will be the focus for clouds,
scattered to numerous showers and thunderstorms for the next
several days. The weather pattern stays active through the
beginning of next week with periods of showers and thunderstorms
and gradually warming temperatures.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 630 PM EDT Saturday...

Key Messages:

1) Areas of rain move out tonight.

2) Plenty of stratus and ground fog for the overnight into
Sunday morning.

A stationary front was draped across NC and just south of our
area. Positive vorticity aloft was supporting an area of rain
along and north of the front which was currently moving through
the Piedmont of VA and NC. Another, more convectively-induced
area of showers and isolated thunderstorms, was pushing south
over the Blue Ridge, but gradually falling apart as it did so.

A Flood Watch remains in effect until 8 PM as these areas of
rain make their way through the region, and we do not expect to
extend them. So far we have not had any additional flooding in
our area, with the heavier rain rates along the boundary
towards Winston-Salem. Showers remain in the forecast until
about 11 PM for NC. Expect dew points to drop off into the lower
60s for the mountains overnight. Even so, low stratus and
ground fog are expected overnight with plenty of moisture
trapped under an inversion. Temperatures will be in the low 60s
for the mountains, and the mid to upper 60s for the Piedmont.



As of 300 PM EDT Saturday...

Key Messages:

1) Stalled front remains along VA/NC border and will be focus
for clouds and periods of rain.

2) Heaviest of the rain to occur from slow moving showers and
thunderstorms along the VA/NC border.

3) Flood Watch for VA/NC border counties.

A stationary front near the Virginia, North Carolina, border
will be the focus for slow moving showers and thunderstorms
through this evening...with primary focus for heavy rain along
and south of the Highway 58 corridor. Much of this area needs
the rain (due to drought), but rain rates of 2+ inches an hour
will result in rapid response within small drainages and produce
flooding of poor drainage areas. As such will maintain Flood
Watch for flash flooding in this area until threat ends this
evening. PWATs near 2" will support high rain efficiency.
Any training of showers/storms may result in observed localized
rainfall of up to 4 inches.

Convective Allowing Models (CAMS) support continued deep layer
moisture convergence along and south of the VA border through
sunset. It appears the outflow from the morning deep convection
has forced outflow down to about the I-40 corridor, so this may
skew the new storm cell activity a little farther south this
evening, and favor the northern NC piedmont counties for this
next round of heavy rain. Regardless, will maintain flood watch
for the current configuration until 8PM.

Outside of this axis of heavy rain, the remainder of the CWA
will still experience considerable cloud cover with scattered
showers and a few rumbles of thunder. Tonight, loss of daytime
heating should allow weakening of deep convection. Clouds are
still expected to persist with stratus and fog after midnight.

For Sunday, looks like we will run a repeat cycle of the showers
and thunderstorms. There is an abundance of moisture, so with the
stationary front over or near the area expect another day of
clouds, showers, and afternoon storms. Risk for excessive
rainfall is marginal, so no need for a flood watch attm, but not
out of the question. Temperatures will continue to be muted by
the cloud cover, but overall MOS trend is up a few degrees
compared to Saturday.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 210 PM EDT Saturday...

Key Points:

1. Increasing chances of precipitation through the period.
2. Locally heavy rain possible.

Stagnant upper air pattern through the period with an upper level
positively tilted trough over the Mississippi Valley and a blocking
upper level ridge in the western Atlantic (Bermuda). This keeps the
Mid Atlantic and Carolinas in deep southwest flow and abundant
moisture. Precipitable water values will waver between 1.0 and 2.0
inches, generally as much as two standard deviations above normal.
Integrated water vapor transport and synoptic scale models do not
add any detail during this type of pattern. Confidence is high that
there will be a daily probability of showers and thunderstorms,
mainly in the afternoon and evening, as is typical. But no
particular surface boundaries or guidance to narrow down to a more
precise timing and location. While the potential for showers and
thunderstorms covers much of the mountains, southern Virginia and
northern North Carolina, the southern Blue Ridge will be the most
likely location for storm development. What storms do form will have
a good potential to produce very high rainfall rates, therefore
there is a prolonged low risk of flooding.

Highs temperatures will be near normal and while overnights will
remain muggy through the period.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 225 PM EDT Saturday...

Key Points:

1. Continued good chances of rain through at least Thursday.
2. Locally heavy rain possible, especially Wednesday and Thursday.

The weather pattern remains the same through Thursday with rain
chances remaining high. Models are hinting at a possible pattern
change Friday as high pressure builds over the Gulf and the upper
level trough tracks to the Mid-Atlantic coast.

Near seasonal temperatures through Friday, then a warming trend for
next weekend.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
As of 630 PM EDT Saturday...

A stationary front near the VA/NC border will be the focus for
persistent cloud cover and clusters of showers and
thunderstorms. CIGS/VSBYS will be highly variable through this
evening.

Through the TAF period expect widely varying flight categories
due to areas of showers and low clouds favoring sub-VFR.

AVIATION OUTLOOK...

An upper level trough over the Mississippi Valley and an upper
level ridge in the western Atlantic will keep an active weather
pattern through the beginning of next week with periods of MVFR
showers and thunderstorms.

Late night fog and stratus with result in IFR to MVFR
visibility, otherwise VFR.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch until 8 PM EDT this evening for VAZ032-033-043-044-
     058-059.
NC...Flood Watch until 8 PM EDT this evening for NCZ003>006.
WV...None.

&&

$$

SYNOPSIS...PM
NEAR TERM...PM/SH
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...PM/SH