-- Discussion containing changed information from previous version are highlighted. --
468
FXUS61 KRNK 181051
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
651 AM EDT Wed Sep 18 2024

.SYNOPSIS...
Low pressure centered over the southern Appalachians this morning
will drift northeast today and Thursday bringing more clouds and
precipitation. The low moves offshore by Friday, lowering the
probability of precipitation. Dry weather and seasonal temperatures
are expected for Saturday and Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 315 AM EDT Wednesday...

Key message:

    - Thunderstorms isolated this morning, scattered this afternoon

    - Lower threat of flooding today

The upper low and occluded surface low were stacked over the
southern Appalachians early this morning. This system will drift
northeast today and tonight with little change in intensity.

Satellite water vapor images showed a small short wave rotating
around the upper low into central Virginia. Slightly colder air
aloft and surface convergence from a decaying occluded front were
providing enough lift for isolated thunderstorms. Will be adding
some thunderstorms in for this afternoon since the models were
showing an increase in Convective Available Potential Energy from
noon through 8PM.

Abundant low level moisture remains in place across the region today
and tonight. There should be some breaks in the clouds this
afternoon across the mountains, southern Virginia, and northern
North Carolina. Areas north of Route 460 in Virginia nay see
little, is any sunshine. Clouds fill back in tonight. Will stay
below guidance for most areas for highs today and close to NBM
numbers for lows tonight.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
As of 240 AM EDT Wednesday...

Key Messages:

1) Confidence is moderate for the chance of showers to slowly
decrease by the end of the week.

2) Temperatures should gradually rise back to near normal values for
this time of year.

An upper level trough will slowly drift eastward on Thursday as an
upper level ridge builds from the west. Enough moisture and
instability remains to produce scattered showers with a couple
thunderstorms on Thursday afternoon. The upper level trough should
finally head offshore during Thursday night, and drier will arrive
by Friday. The increase in heat from more sunshine along with
orographical lift may still overcome the drier air mass to spark an
isolated thunderstorm along the southern Blue Ridge on Friday
afternoon. High pressure will take more control by Saturday with
temperatures peaking in the mid 70s to the lower 80s.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 240 AM EDT Wednesday...

Key Messages:

1) Confidence is moderate for high pressure wedging against the
eastern slopes of the Blue Ridge on Sunday.

2) A low pressure system could approach from the west to bring an
increasing chance of showers by early next week.

High pressure could wedge against the eastern slopes of the Blue
Ridge by Sunday to bring a cool easterly flow. This flow may persist
into Monday. The models diverge significantly beyond Monday due to
increasing uncertainty on when a low pressure system could approach
the Appalachian Mountains from the west. Some models hold the wedge
firm and slow the advance of the low pressure system, while others
weaken the wedge and allow the system to arrive sooner. The slower
scenario seems to be the more logical choice, but the chance of
showers should steadily rise west of the Blue Ridge during Monday
and Tuesday. If the flow can be swung around towards the south more
quickly on Tuesday to weaken the wedge, then instability could
increase to push thunderstorm chances higher.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
As of 645 AM EDT Wednesday...

Primarily LIFR to IFR ceilings across the region. This trend is
expected to continue this morning.

The southern edge of the cloud shield around the upper low was
approaching the Virginia/North Carolina border from the south.

Ceilings will lift back to MVFR this afternoon. Clouds may also
becoming scattered west of the Appalachians, including for a few
hours at KBLF and KLWB. Scattered showers and isolated
thunderstorms are possible in areas that get some heating and
some better instability.

Stratus and fog will redevelop across the region this evening
with fog and LIFR ceilings. LIFR fog is likely at KLWB and
potentially at KBCB and KBLF.

Winds will be from the east to northeast this morning, with a
few gusts up to 20 knots. By this afternoon and evening, wind
speeds will be less than 10 kts.

Average confidence for ceiling and wind.
Below average confidence for coverage of any thunderstorms this
afternoon and LIFR fog overnight.


EXTENDED AVIATION OUTLOOK...

Thursday and Friday less coverage of showers is expected.
Ceilings will improve to VFR by Friday.

VFR conditions and dry weather is expected to return for
Saturday and Sunday.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...PW
LONG TERM...PW
AVIATION...AMS/DS