Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 132329

Area Forecast Discussion
National Weather Service Blacksburg VA
729 PM EDT Sat Aug 13 2022

High pressure will keep us dry with lower humidity into early
Sunday. Low pressure and a cold front approach the region late
Sunday into Monday. Through the remainder of the workweek,
temperatures are expected to be slightly cooler than normal,
with a daily chance of showers and storms.


As of 655 PM EDT Saturday...

    Added slight chance of thunder Sunday afternoon
    in the mountains.

High pressure over the Great Lakes extends south into NC and
will keep our area in a lower humidity regime for tonight.

With a trough axis moving to our east and us being in a
northwest flow regime at 5h, a shortwave will slide southeast
into the area by 12z/8AM Sunday bringing some increase in
clouds, but at the moment, no rain chances for the overnight

Rain chances increase by Sunday afternoon/evening as a secondary
shortwaves pushes southeast within a zone of persistent upper
level northwest flow. Rain does not appear it will be
particularly heavy and amounts through Sunday evening should
amount to 0.25" or less, but with the caveat of a few locations
seeing slightly more, especially across the mountains. But CAPES
will be in the 500-1000 J/kg along the western side of the
central Appalachians and Bufkit forecast soundings showed that
in the Bluefield and Richlands soundings after 18Z/2PM. So, have
added a slight chance of thunder for the afternoon.


As of 100 PM EDT Saturday...

   Below normal temperatures with showers and storms.

Sunday night into Monday a speed max on the western side of an upper
level trough will dive southeast along with an associated short
wave. At the surface, a poorly organized surface low and trough will
become oriented NE to SW along the Appalachians. There will be a
chance for showers and thunderstorms Sunday night over the northern
two-thirds of the area, but the better forcing will be to our north
still, and with the loss of daytime heating storms will be/become
elevated overnight. Not expecting any severe weather, but moderate
rain is likely.

Monday`s convection will be more widespread with the help of daytime
heating and the approach of the wave/front. Although we will have
some instability Monday, cloud cover from overnight will remain in
place, with breaks in the clouds at a minimum. Areas south of I-81
as well as west of I-77 will have better chances for some isolated
strong to severe storms with damaging wind gusts. Otherwise, PWATs
do increase from the fall-like half inch we have currently to about
1.3" or so Monday afternoon, so heavy downpours are likely with the
threat for localized flash flooding becoming more of an issue.

On Tuesday, we remain in the base of the trough, and will have
"leftover" enough moisture and instability for another round of
diurnal convection. The front from Monday will be south of us
by this point, so we will need to really on other forcing
mechanisms for storm initiation, and thus PoPs will be lower
than on Monday.

Temperatures each day will range from the low to mid 70s in the
mountains to the mid to upper 70s over the piedmont. Overnight lows
will range from the mid 50s to the mid 60s.

Confidence in the short term forecast is average.


As of 100 PM EDT Saturday...

 Daily showers and storms with a slow increase in temperatures.

The main upper level system will gradually lift towards New England
Wednesday and Thursday. Showers and storms will be possible each
afternoon and evening, but becoming less likely Thursday as the
system moves farther away and the upper level flow becomes more
confluent downstream.

By Friday and into the weekend, both a northern and southern stream
short wave attempt to dig into the central CONUS. These waves are
not expected to phase, but will keep us in enough upper flow to
support diurnal showers and storms each day, but they will be hit
or miss and diminish quickly with the loss of heating.

A warming trend begins Thursday through Saturday, with highs in the
upper 70s to mid 80s by the weekend.

Confidence in the long term forecast is average.


As of 700 PM EDT Saturday...

VFR conditions prevail this evening and overnight with high
pressure in control. Some patchy fog possible late tonight at
KLWB, depending on how fast the high cloud increase so have
kept MVFR vsby for now after 10Z/6AM.

Cigs lower tomorrow, but still should remain VFR through noon.
The chance of a showers and isolated thunderstorms increases
from west to east across the region, especially west of the
Blue Ridge during the afternoon. Have added the chance of
precipitation in at KBLF and KLWB after 18Z.

Average confidence in ceiling, visibility and wind.
Below average confidence in the occurrence of fog late tonight.

.Extended Aviation Discussion...

Mainly VFR next week, but best chances of sub-VFR will be late
Sunday night into Monday as another front pushes into the

More sub-VFR conditions are likely Tuesday through Thursday
with shower and storm chances during each afternoon and early




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