835
FXUS61 KRNK 121044
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
644 AM EDT Mon Aug 12 2024

.SYNOPSIS...
High pressure will cover the Northeast and Mid Atlantic states
through Tuesday morning. This will result in dry weather and
near normal temperatures. The next chance of showers and
thunderstorms arrives toward the middle of the week as a low
pressure system approaches from the Ohio Valley.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 200 AM EDT Monday...

Key Messages:

-Dry and tranquil weather to continue through tonight.

High pressure centered over the Ohio Valley continues to supply
less humidity and near to slight below normal temperatures to
the region. A stalled front still remains across the Carolinas
this morning and will slowly drift southeast through the day, so
expecting rain chances to be confined to south of the area.

Perhaps some patchy areas of fog this morning, quickly
dissipating after daybreak. Highs today in the upper 70s/low 80s
for the mountains. Mid 80s for the lower elevations.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 115 AM EDT Monday...

Key Points:

1. Near normal temperatures.
2. Isolated/Scattered showers/storms on Tuesday.
3. Mainly dry Wednesday.
4. Isolated/Scattered showers/storms Thursday and Thursday night.

A look at the 11 Aug 12Z NCEP Ensemble Mean 500 mb Geopotential
heights shows a long wave trough moving east of the region Tuesday
into Wednesday as an upper ridge builds over the Upper Mississippi
River Valley. Wednesday into Thursday, an upper trough remains
positioned over the western Atlantic, while ridging shifts east to
over the Ohio Valley. A weak shortwave trough deepens over the Upper
Mississippi Valley Thursday night. At the surface, a high pressure
center is depicted strengthening over the Great Lakes/Ohio Valley
region Tuesday through Thursday, but each day progress slowly
eastward in position.

Output from the 11 Aug 12Z Ensemble Situational Awareness Table
shows 850mb temperatures will average +14C to +16C across the region
Wednesday and Thursday. Precipitable Water values will average 1.00
to 1.25 inches across the region during this portion of the forecast.

The above weather pattern should allow for some isolate to scattered
showers/storms on Tuesday as daytime heating interacts with the
passage of the trough axis. Wednesday should be dry for most of the
region with the trough axis to our east, and high pressure build
into the Ohio Valley. Thursday still should be primarily dry.
However, as the ridge axis shifts east, and an upper level trough
approaches from the west, expect the low level flow to take on more
a southerly component. This may allow for a bit more more moisture
into the region. Combined with daytime heating, isolated/scattered
afternoon showers/storms will be possible. Rather than dying out at
sunset, with the continued approach of the shortwave trough Thursday
night, the activity is expected to continue into and through the
overnight hours.

Confidence in the above weather scenario is moderate to high.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 115 AM EDT Monday...

Key Points:

1. Near or slightly cooler than normal temperatures.
2. Daily chances of showers/storms with best chance west.

A look at the 11 Aug 12Z NCEP Ensemble Mean 500 mb Geopotential
heights shows the weak shortwave trough over the Ohio Valley
remaining nearly stationary, but increasing in amplitude Friday
through Sunday. At the surface, through Sunday, the center of high
pressure shifts east into the western Atlantic while low pressure
develops over the Lower Ohio Valley.

Output from the 11 Aug 12z Ensemble Situational Awareness Table
shows 850mb temperatures inch upward slightly to an average of +16C
across the area by the weekend. Precipitable Water values will trend
higher over the weekend with numbers closer to the 1.25 to 1.50 inch
range.

A slow eastwardly moving upper trough over the Great Lakes/Ohio
Valley will keep our region within a moist, mild, and unstable
airmass heading into and through the weekend. Each day shower/storm
coverage should be greatest over western sections. For temperatures,
lows should trend slightly milder as dew point values increase.
However, a greater abundance of cloud cover and better chances of
precipitation may mean high temperatures slightly cooler than those
expected mid-week.

Confidence in the above weather scenario is moderate.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 640 AM EDT Monday...

Widespread VFR this morning and VFR is expected to continue into
tonight outside of patchy river valley fog around daybreak this
morning. Some fog development possible again late in this 24
hour TAF period, mainly for LWB.

Light winds from the northwest today, less than 10kts. Winds
light to calm again tonight.


AVIATION OUTLOOK...

Scattered showers and thunderstorms may occur during Tuesday
afternoon, mainly along the southern Blue Ridge. Chances of
afternoon convection could continue into Wednesday and Thursday.

A more organized low pressure system will approach the area by
Friday bringing the potential for more precipitation and
widespread sub-VFR flight conditions.

&&

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

&&

$$

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