468
FXUS62 KRAH 171032
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
632 AM EDT Tue Sep 17 2024

.SYNOPSIS...
An area of surface low pressure will drift west across
northwestern South Carolina through tonight. The remnants of
this system will linger and gradually dissipate across the mid-
Atlantic through the end of the work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 350 AM Tuesday...

* Last large band/region of showers and storms spreading across the
  northern Coastal Plain and the northern Piedmont.
* Flooding threat has abated and Flood Watch will be cancelled.

The latest surface analysis shows the center of the surface low
located just south of Charlotte, near Lancaster SC. A surface trough
or occlusion extends east of the surface low with a narrow tongue of
instability extending east to west, from near KEWN to near
KGSB, just north of the boundary. In and north of this axis, the
last band of showers and a few embedded thunderstorms are
streaming west across the central and northern Coastal Plain and
into the eastern portions of the Triangle.

This band/region of showers and some thunderstorms will shift north
during the morning, perhaps beginning to exit much of the Triangle
area around the morning commute with generally dry weather to the
south. By midday and continuing into the afternoon hours, most of
the convection should be focused across the far northern Piedmont
and VA border counties. The narrow region of instability will also
transition north. With the wind field becoming less favorable into
the afternoon, any lingering severe weather and tornado threat
should transition north and fade away this morning. Will need to
keep an eye on cells in Wayne, Wilson and Edgecombe counties this
morning but the threat has decreased greatly.  Additional rainfall
amounts today will range around a half inch north of U.S. route 64,
perhaps a little more near 0.75 inches across the northern Coastal
Plain with rainfall amounts of a tenth or two south of U.S. 64. With
the widespread precipitation amounts decreasing we plan on canceling
the flood watch. Showers and a few storms across the north this
afternoon will gradually diminish into the evening hours. A much
less active radar is expected this evening and tonight although some
spotty rain associated with the remnant low level circulation may
spread a few showers across the far western Piedmont tonight.

Gusty northeast to easterly winds early this morning will
decrease from south to north during the morning and especially
this afternoon. A few gusts through around daybreak in the
northern Piedmont and especially the Triad may range between 25
and 30 mph. Highs today will range from the lower 70s in the
western Piedmont and VA border counties to the mid 70s to around
80 in the east. Lows tonight will range in the mid to upper
60s. -Blaes

&&

.SHORT TERM /WEDNESDAY/...
As of 355 AM Tuesday...

The surface and mid/upper low impacting the region over the past few
days will weaken into Wednesday as it shifts north and east. A
weak surface trough will extend from southeastern VA southwest
into the remnant low circulation across western SC on Wednesday
afternoon. Abundant moisture across the region will result in
widespread low clouds and perhaps some fog to start the day on
Wednesday morning. With some breaks in the overcast developing,
especially in the southern and eastern areas, the air mass will
becoming moderately unstable during the afternoon and support
scattered showers and thunderstorms. With a very weak low level
wind field and a unidirectional southwesterly flow in the mid
levels don`t expect much in the way of strong storms. Afternoon
highs will range from the upper 70s in the Triad to the lower
80s in the Coastal Plain. -Blaes

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
As of 345 AM Tuesday...

Mid/upper troughing will extend down the Eastern Seaboard including
into central NC from Wednesday night into Thursday. Meanwhile a
surface low will linger off the northern Mid-Atlantic coast. This
will bring one last day of upper forcing for ascent and above-normal
PW values, so POPs on Thursday are generally in the 30-40% range,
highest east and maximized during peak heating. There could be
enough instability for a few storms. QPF amounts in the models are
not impressive, so not concerned about an additional heavy rain
threat, and looks fairly low impact overall.

As a mid/upper ridge over the Plains begins to move east on Friday,
it will begin to push the trough east and offshore. This will result
in NW flow and much drier air moving into central NC, with PW values
trending below normal. At the surface, high pressure will gradually
nose down from SE Canada into the Mid-Atlantic from Friday into
Monday. Overall this pattern supports limited rain chances at best,
which is a significant change from last night when the models
depicted the mid/upper low moving back south across the area. Now,
they keep it and the associated surface low well to our east in the
western Atlantic. Instability looks minimal to non-existent as well
given the cool wedge of high pressure and NE flow near the surface.
The best chance for clouds and isolated showers looks to be in the
Coastal Plain closer to the low and where there will still be moist
onshore flow in the low levels, but even there POPs are only slight.
The GFS does try to bring a shortwave through the area on Sunday, so
POPs are slight that day areawide.

As for temperatures, highs should be within a few degrees of normal
from Thursday through Saturday, in the upper-70s to lower-80s. Lows
will gradually trend downward as the air mass turns drier, from mid-
to-upper-60s on Wednesday night to upper-50s to lower-60s by
Saturday night. On Sunday and Monday when the cool wedge of high
pressure really takes hold, forecast highs are only in the 70s with
lows in the mid-50s to lower-60s. If the raw GFS is to be believed,
some places won`t even get above the 60s on these days, but would
like to see more support from ensemble guidance before buying into
this too much.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
As of 630 AM EDT Tuesday...

Widespread MVFR to IFR conditions primarily from low CIGS are noted
across central NC early this morning. A broad area of light
rain showers with a few embedded heavier showers extend from the
northern Coastal Plain west across the northern Piedmont. An
isolated thunderstorm is possible across the central Coastal
Plain, near but mainly east of the KRWI terminal. Low CIGS are
expected to persist for much of the day although cloud bases
will lift during the late morning and early afternoon with MVFR
CIG restrictions still commonplace during the afternoon. Some
brief improvement with VFR CIGS are expected late in the
afternoon across the Coastal Plain and Sandhills impacting the
KRWI and KFAY terminals. There is a limited risk of additional
showers and perhaps a storm this afternoon primarily near
KINT/KGSO and KRDU. Another round of MVFR to IFR CIGS are
expected to return tonight and continue into Wednesday morning.

A low pressure area is expected to track northwest across northern
SC through tonight. This will maintain a northeasterly surface wind
with gusts of 10 to 20kts at times early this morning with
gustiness and winds diminishing from south to north later this
morning and especially this afternoon. A prolonged period of
LLWS has largely abated this morning and is excluded from the
TAF.

Outlook: After another period of IFR/LIFR CIGS early Wednesday
morning, an unsettled period will continue through Thursday with
area of late night and early morning stratus and a risk of some
afternoon showers and possibly a storm. Aviation conditions will
generally improve on Friday and Saturday. -Blaes

&&

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

&&

$$

SYNOPSIS...Blaes
NEAR TERM...Blaes
SHORT TERM...Blaes
LONG TERM...Danco
AVIATION...Blaes