778
FXUS61 KRNK 171806
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
206 PM EDT Sat Aug 17 2024

.SYNOPSIS...
Widely scattered showers and storms will occur this afternoon
and evening ahead of a cold front. Another round of storms
possible on Sunday as the front moves across Virginia. Rain and
clouds may linger through Monday as the front slows, but drier
high pressure will move in by mid-week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 145 PM EDT Saturday...

Key Messages:

1) Storms are possible this afternoon and evening.

2) Storm chances will continue into Sunday.

Upper trough centered over the Great Lakes today and southwest
flow overhead continues to reinforce warming temperatures and
humid air into the region. Multiple pieces of upper energy in
advance of the main trough will enhance the potential for
afternoon and evening storms.

Already rather unstable this afternoon as clouds have cleared
and now seeing strong surface heating across the entire area.
As a result, RAP analysis already indicating SBCAPE/MLCAPE in
the 1000 to 2000 J/kg range along with increasing bulk shear.
This should support a few strong storms this afternoon/evening.
Coverage and intensity of storms decrease with loss of heating
tonight.

Some fog development again tonight and may start the day on
Sunday a little more cloudy than today. Upper trough amplifies
by Sunday and will pass overhead Sunday evening. Associated
surface front will also pass across the region and this will be
the focus for a renewed round of thunderstorms in the afternoon.
Better synoptic support may result in slightly better storm
organization, but limiting factors to storm development will be
residual cloud cover in the morning and the timing of the
front. Currently, best storm probabilities will be along and
east of US29 tomorrow afternoon and evening and a few storms
could be capable of strong damaging winds.



&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 510 AM EDT Saturday...

Key Messages:

1). Wet weather expected through Monday,

2). A few strong storms and heavy rainfall possible mainly
Sunday

2). Temperatures suppressed below normal from clouds and
precipitation.

A deepening trough across the Great Lakes will continue to be
the dominate weather feature through the period. The trough will
deepen through the period resulting in increasing chances for
precipitation. The trough will only move very slow eastward
through the period, prolonging the period of cloudy, damp,
dreary weather conditions. As long as the trough axis remains to
the west of the area, cyclonic flow, short waves, and positive-
vorticity advection will keep the clouds and rain showers in
place. Sunday into the first half of Monday look to be the
wettest periods.

SPC has outlooked areas mainly along/east of the Blue Ridge both
Sunday and Monday for a marginal risk of severe thunderstorms.
Main concern Sunday would be wind as some linear organization
will be possible with better dynamics in place in advance of the
main trough. Monday, as the upper low digs further southward,
cold air aloft will support a better chance for hail where any
heating of significance occurs and steepens lapse rates.

Temperatures will average slightly below normal through the
period thanks to persistent cloud cover and precipitation.
Morning lows will be a bit on the muggy side with high humidity
and high precipitation water values. After high temperatures
will show the greatest departure from normal thanks as a result
of the clouds and precipitation.

/Confidence Levels in Forecast Parameters/
- Moderate to High Confidence in Temperatures,
- High Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction and Speed,
- Moderate Confidence in Thunderstorm Potential,
- Low Confidence in Severe Potential.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 530 AM EDT Saturday...

Key Messages:

1). Much drier, cooler, fall-like weather expected through most
of the period.

2). No severe, heavy rain, or tropical threats expected through
the period.

The high amplitude and deep upper trough anchored over the
region by the end of the week will shift east by Monday
afternoon. Thus, for the remainder of the week, as the flow
deamplifies but remains slowly progressive, the forecast area
will shift to the west side of the upper trough, putting the
area in a frier northwesterly flow. A large area of surface high
pressure will build southward from central Canada as well
resulting in an extended period through at least the first half
of the week in cooler temperatures and much lower humidity
levels. A touch of the coming fall to come!

With dewpoints dipping into the 40s and 50s, the warm
temperatures in the 70s and 80s over the weekend will drop into
the 60s and 70s. The much drier air will allow nighttime
temperatures to drop into the 40s in the usually favored valleys
such as Burkes Garden and Lewisburg, with mostly 50s elsewhere,
reminding us that Fall is just around the corner!

/Confidence Levels in Forecast Parameters/
- Moderate Confidence in Temperatures,
- High Confidence in Precipitation Probabilities
- Moderate Confidence in Wind Direction and Speed,
- Moderate Confidence in Thunderstorm Potential.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 200 PM EDT Saturday...

VFR across the region early this afternoon and overall VFR
should continue into the evening and early overnight hours.
However, scattered afternoon thunderstorms will be possible,
which could briefly reduce vsby. Very limited confidence on
storm coverage so opted to not add into TAFs.

Some lower cigs and fog again tonight and sub-vfr seems likely,
especially across the mountains. Clouds linger through the
morning and some MVFR stratus could remain through late in the
TAF period.

.EXTENDED AVIATION OUTLOOK...

Showers and thunderstorms with MVFR conditions will continue
into Monday with the passage of a cold front.

MVFR clouds and upslope showers are expected to remain over the
mountains through Monday. Ceilings should be VFR east of the
Blue Ridge.

Confidence is higher for dry and VFR conditions Tuesday and
Wednesday as high pressure builds in.

&&

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

&&

$$

SYNOPSIS...BMG
NEAR TERM...BMG
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...BMG