-- Discussion containing changed information from previous version are highlighted. --
768
FXUS61 KRNK 161358
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
958 AM EDT Mon Sep 16 2024

.SYNOPSIS...
Potential Tropical Cyclone Eight moves onshore today and drifts
through the Carolinas through Wednesday bringing a prolonged
period of rain to the area. A low probability of rain remains in
the forecast through the end of the week as high pressure
wedges down the Appalachians.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 950 AM EDT Monday...

Key message:

    - Rain spreading in this afternoon and evening
    - Northeast-east winds increasing with gusts to 20-35 mph


Low centered off the SC coast this morning still expected to
move inland this afternoon between CHS-ILM. Rain already
reaching the Triad area but will be mainly light through early
afternoon before enhancement with lift arrives by mid-late
afternoon. Still looks like winds stay below advisory levels but
upped gusts a little especially over our NC and southern VA
counties based on latest high-res models. Some gusts over 30 mph
may lead to weaker trees or limbs to fall. Rainfall of 1-3+"
over a 24-36 hr period should limit flooding concerns given how
dry we have been, so no flood watches at this time.

PWATS off our 12z RNK sounding hasn`t changed much since last
night hanging around 2/3" but should jump to over an inch by
this evening and over 1.5"-2.0" tonight.

Nudged pops up to categorical this afternoon along-south of US
421 from Wilkesboro to INT. Bulk of rain arrives tonight.

Previous discussion from early this morning...

Increase in winds from the east through a deep layer brings
moisture and lift to the area and therefore rain. Precipitable
water values that will be advected in by late today and through
tonight will be in the 1.5 to 2.2 range. Leaning to the 3KM NAM
and WPC/NHC for the timing and location of Potential Tropical
Cyclone Eight, as well as WPC for the precipitation location and
amounts.

Expecting a combination of isentropic lift, upper diffluence and
strong upslope tonight. Variety of models showing the potential for
localized pockets of heavier rainfall amounts along the southern
Blue Ridge and a shadow effect resulting in lighter amounts through
the Greenbrier Valley.

Will be increasing probability of precipitation across the area
tonight and wind speeds at higher elevations. Not planning on
adding any thunder to the forecast as there is little to no
instability. Little opportunity for heating today. Highs will
again be below normal. No need to adjust much from NBM
temperatures for maximum or minimum temperatures.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 345 AM EDT Monday...

Key Messages:

1) Confidence is high for ongoing chances of showers due to the
remnants of Potential Tropical Cyclone Eight.

2) A risk of flooding exists if there are repeated rounds of heavy
downpours during the middle of the week.

The remnant low from Potential Tropical Cyclone Eight will slowly
wobble northwestward towards western North Carolina on Tuesday. The
models have trended further southwestward with the track in recent
runs, and the remnant low may stall somewhere close to the North
Carolina and Tennessee border sometime on Wednesday. The lingering
upper level low will be blocked by an upper level ridge building to
the north. Of course, there are still some uncertainties regarding
this track, but this solution appears to be the latest consensus.
Rain bands may be the heaviest on Tuesday across the Mid Atlantic
but should start to weaken towards Wednesday. Wind gusts up to 30
mph may be possible along the higher elevations on Tuesday
morning but should weaken thereafter.

Rainfall amounts still remain a challenge due to the changes in the
track and the fact that a cool wedge of high pressure will have to
be overcome on Tuesday. This wedge could limit rainfall amounts in
some locations but also provide an easterly upslope enhancement
across portions of the Blue Ridge. At the moment, it appears that
the southern Blue Ridge should witness the highest total amounts
with one to three inches and locally higher amounts possible. There
may even be a hint of instability as the week progresses and the
wedge weakens to spark a slight chance of thunderstorms. A risk of
flooding is possible if there are repeated rounds of heavy rainfall
during this time, but the dry antecedent conditions allow a good
amount of room for some rainfall. Temperatures will remain below
normal for this time of year.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 345 AM EDT Monday...

Key Messages:

1) Confidence is moderate for lower chances of showers.

2) Temperatures still remain near or slightly below normal.

The upper level low resembling the remnants from Tropical Cyclone
Eight will hover over the Mid Atlantic into Friday. Upper level
ridging to the north will keep blocking the low and eventually start
to shove it southward by the weekend. Rainfall chances should
continue to lessen compared to earlier in the week but may not
vanish completely. Meanwhile, another area of surface high pressure
could build across the New England states and start another cool
wedge against the eastern slopes of the Blue Ridge. Temperatures
will likely stay near or slightly below normal and might trend
further downward if the wedge strengthens in later model runs.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
As of 620 AM EDT Monday...

MVFR ceilings were spreading north across the area at this
time. Ceilings will continue to gradually lower throughout the
day as Potential Tropical Cyclone Eight moves slowly towards the
Carolinas.

Generally east to northeast winds today and tonight. Winds
become gusty again this morning, gusts between 20 to 25 knots
are possible for KDAN and KLYH, and 30 to 40 kts the along the
Blue Ridge.

Light rain from the tropical system reaches the VA and NC
Piedmont this afternoon but is more likely after 00Z/8PM.

Forecast confidence is average for ceiling, visibility, and
wind.

EXTENDED AVIATION OUTLOOK...

Periods of sub VFR conditions are possible through Thursday, as a
low pressure system brings rain and clouds to the area through the
midweek. Widespread rain continues into Tuesday A lower chance
of rain remains in the area through rest of the week.

&&

.EQUIPMENT...
As of 145 PM EDT Sunday...

The Lynchburg ASOS (LYH) is still experiencing data transmission
issues, mainly at night. Please use caution when using data
from this site, as some may be missing. Technicians continue to
investigate the problem. No estimated date for return to full
service at this time.

&&

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

&&

$$

SYNOPSIS...AMS
NEAR TERM...AMS/WP
SHORT TERM...PW
LONG TERM...PW
AVIATION...AMS/AS
EQUIPMENT...AS/SH