-- Discussion containing changed information from previous version are highlighted. --
850
FXUS62 KRAH 180616
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
215 AM EDT Wed Sep 18 2024

.SYNOPSIS...
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The remnants of the coastal low will gradually dissipate across the
mid-Atlantic through the end of the work week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
As of 820 PM Tuesday...

The training band of showers and storms over northern portions of
the coastal plain and Piedmont is starting to fizzle out, but not
before producing a narrow corridor of 1 to 3 inches and
nuisance/minor flooding. Some shower activity may linger into the
overnight hours towards the Triad as the occluded low and mid-level
forcing begins to wobble back east. Otherwise, expect widespread low
clouds to re-develop across the area. Additionally, fog, potentially
dense, may develop along and north of the front, generally across
the northern Piedmont and coastal plain. Overnight lows in the lower
to mid 60s.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 315 PM Tuesday...

The remnants of PTC 8 and the associated upper low will be over
upstate SC Wednesday morning, with the axis of best deep moisture
shifting north into VA. An occluded front over the Piedmont today
will remain mostly unchanged. The upper trough is forecast to weaken
and open up as it, along with the weak surface reflection, drift
east during the day, with the trough axis likely to be somewhere
over the coastal plain by Thursday morning. Scattered showers will
continue to rotate around the low and will increase in coverage as
some weak instability develops during the day, with the potential
for best coverage near a occluded front/convergence axis that
lingers across the Piedmont.  The best instability is forecast to
spread north from SC into the southern coastal plain during the
afternoon and that is where the depth and coverage of showers or
isolated storms could be best.  The overall deep layer wind field
will be weak and any storms are not expected to be very strong. Deep
moisture is forecast to increase again from the south, as the upper
low/trough begins to slide east, so showers will be heavy, and there
are some indications from the HREF PMM that some showers could
produce up to 2 inches of rain, although they will be isolated and
not likely to cause much of a flooding concern on the whole.

Consistent with the area of better destabilization, the best heating
will be across the south and east as clouds are more likely to
linger in the north and west.  There is good model agreement on
highs ranging from the mid 70s to mid 80s.

The showers will likely continue to the overnight hours in the
vicinity of the upper low and a convergence axis across the northern
portions of the area. Lows will be in the mid to upper 60s with some
decent signals in the SREF for fog north of the boundary as well.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 315 PM Tuesday...

With the exception of Thursday, the majority of the extended
forecast has continued to trend drier. Temperatures will start out
near to slightly above normal, trending slightly below normal late
in the period into early next week. No high-impact weather is
currently anticipated through the period.

On Thursday, we`ll still be under a trough of low pressure aloft,
with its center near New England. The trough axis will bisect the
area, while at the surface, an ill-defined remnant trough is
forecast to be oriented along the I-95 corridor. Isolated to
scattered showers and embedded thunder will be possible in the
aftn/eve, primarily in over the eastern Piedmont, Sandhills, and
Coastal Plain. A secondary area of widely scattered showers may form
over the higher terrain of western NC and impact the Triad. Shear is
lacking so this activity will wane by sunset as instability wanes
and the trough axis shifts east.

From Fri through early next week, the trough near New England and
the Mid-Atlantic is forecast to slowly edge east and off the
Atlantic coast as ridging over the southern Plains and lower MS
valley builds into the Deep South. Weak high pressure will get
replaced by a cool continental surface high from Quebec and
Newfoundland that will nose down into the Mid-Atlantic Sun into
early next week. This will favor pleasant September highs late in
the weekend to early next week of mid to upper 70s to around 80,
about 2-5 degrees below average. Lows will also follow a similar
trend at this time, with some low to mid/upper 50s. Prior to Sun,
we`ll see highs close to seasonal average in the upper 70s to low
80s.

As for rain chances outside of Thu, it looks minimal. Some ensemble
solutions keep the offshore trough closer to the coast, and thus a
few showers could develop inland across the Coastal Plain over the
weekend, but most members are dry. Some solutions also bring
troughing over the OH valley early next week, but keep most of the
energy to our northwest and consequently, dry. We may need to watch
for something later in the week as the operational GFS/CMC and some
EPS/GEFS members show a tropical system coming out of the Caribbean
Sea and into the Gulf. But that`s far enough way and too uncertain
at this point.


&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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As of 215 AM Wednesday...

While showers have exited central NC, a decaying low pressure system
currently centered over the western Carolinas will continue to bring
anomalous low-level moisture. This will result in widespread sub-VFR
ceilings and visibilities overnight across the north (including INT,
GSO, RDU and RWI) where an associated front is also set up. Ceilings
there have already dropped to LIFR, with IFR and LIFR visibilities
also being reported from fog. Farther south around FAY, clearing has
taken place, but this could still aid in some patchy fog formation
later tonight. Conditions will gradually improve in the morning and
early afternoon, but some MVFR ceilings should linger for much of
the day across the north. A period of scattering to VFR will be
possible, especially at RDU and RWI. VFR is expected across the
south including FAY. Sub-VFR ceilings and visibilities will again
overspread the region from north to south in the evening. Scattered
showers and isolated storms will also be possible in the afternoon
and evening.

Outlook: An unsettled period will continue through Thursday with
areas of overnight and early morning stratus and a risk of some
afternoon showers and possibly a storm. Aviation conditions will
generally improve for the weekend.
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&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Blaes
NEAR TERM...CBL
SHORT TERM...BLS
LONG TERM...AK
AVIATION...Danco/Luchetti