135
FXUS62 KRAH 180539
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
140 AM EDT Sun Aug 18 2024

.SYNOPSIS...
A cold front approaching from the northwest will move gradually
eastward through the region today through Monday. A cooler and less
humid air mass will settle into the area from Monday night through
Friday.

&&

.NEAR TERM /TONIGHT/...
As of 940 PM Saturday...

Water vapor imagery this evening depicts continued troughing along
the eastern seaboard. Several embedded mid-level perturbations
continue to generate convection over the Charlotte area southward
into central SC.  Additional showers and storms associated with a
broken MCS continue to track ese over sw VA/central to eastern TN.

Thus far this evening, convection has largely developed and quickly
collapsed/diminished outside of central NC.  With CIN largely
encompassing the area at this point, the overnight hours should
remain largely dry.  The best chance for any showers/isolated storms
in the next few hours would be perhaps some of the convection near
Charlotte trickling into the far southwest Piedmont. However, even
in these locations the POPs remain relatively low.  This cluster
should move southeast of our area and diminish by ~06Z. Otherwise,
isolated showers/storms could develop along the outflow of the
aforementioned upstream MCS and maybe trickle into the Triad
overnight. Odds of this occurring are low though.

Otherwise, the guidance suggest a good potential for stratus to
develop overnight which should keep overnight lows warm in the lower
70s.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 230 PM Saturday...

...There is a slight risk (level 2 of 5) for severe storms from
Raleigh south and east Sunday afternoon and evening...

...There is also a risk for Isolated Pockets of Heavy Rain and Flash
flooding along and east of US 1...

An unseasonably strong()~3 S.D. below normal) and amplifying upper-
level trough will dig SEWD into the Eastern US Sunday during the
period.  At the surface, a  pre-frontal sfc trough in the lee of the
Appalachians will get overtaken by the accompanying cold front that
will move east across central NC during the late afternoon and
through the overnight hours. As daytime heating commences, moderate
destabilization is expected area-wide, maximized across the
Sandhills and southern coastal plain. Coincident with the arrival of
the cold front and core of the stronger 40-50 meter H5 falls into
the area, showers and storms are expected to develop across the
western Piedmont between 18-21z, with convection thereafter
increasing in coverage and intensity(becoming better organized) as
the progresses eastward into the central Piedmont and western
Sandhills between 20-00z, and then across eastern Sandhills and
coastal plain counties between 23-04z. Deep layer shear of 30-35 kts
will likely favor multi-cellular severe threat, with damaging winds
the primary threat. Given recent wetness and with area streams and
creeks still running high, the convective downpours could also lead
to some instances of flash flooding, especially in poor-drainage and
urban areas. The severe threat appears greatest between 3 to 10 pm
with generally dry conditions after midnight.

Highs ranging from mid 80s north to lower 90s south. Lows in the
mid/upper 60s to lower 70s south.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 200 PM Saturday...

Sat/Sat night: A mid/upper level trough will be positioned over the
eastern CONUS with the trough axis extending from southern Quebec
trough the Mid-Atlantic and into FL. A leading effective front from
prior convection is expected to be situated near the coast with lee-
troughing extending through the Piedmont. Surface dew points within
and east of the lee-trough should still be in the mid 60s to near 70
and result in 500-1500 J/kg of MLCAPE through daytime heating. A
disturbance rotating through the backside of the trough will overlap
this weakly unstable airmass and a reinforcing cold front pivoting
across central NC to initiate scattered showers/storms during the
afternoon/evening hours.

The best overlap of synoptic forcing and available instability will
be over Northeast Piedmont into the northern/central Coastal Plain.
Mid-level flow in the core of the trough will be relatively weak,
but some directional shear (20-30kts of 0-6km shear) may lead to
some storm organization in this region where clusters organized
along a common cold pool will be most probable. DCAPE and theta-e
differences will be lower than previous days (around 600 J/kg and
20K, respectively) and lead to a marginal/conditional threat for
severe wind gusts.

Tues through Sat: The passage of a reinforcing front will mark a
pattern change with dropping low-level thicknesses through Tues.
High pressure will then shift over the Northeast and ridge down
through the Mid-Atlantic through much of the work week. Highs in the
upper 70s to mid 80s will become common each afternoon with dew
points in the 50s to near 60. Overnight, pockets of calm conditions
and clear skies will favor radiational cooling Tues night into Fri
morning with lows falling into the mid/upper 50s to near 60.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
As of 137 AM Sunday...

Generally VFR conditions with some higher cloudiness can be expected
through 18z today. The exception will be between 09z and 13z in
which some stratus (IFR) is expected. Scattered thunderstorms are
expected this afternoon and evening, with brief IFR conditions
possible.

Looking beyond 00z Mon, Some lingering storms are expected through
04z/Monday. Otherwise, stratus is possible again around daybreak
Monday. Another round of scattered storms is possible at all sites,
but mainly RWI/FAY, Monday afternoon. VFR conditions should return
Mon night and prevail, with high confidence, through Thu.

&&

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

&&

$$
SYNOPSIS...Hartfield
NEAR TERM...Luchetti
SHORT TERM...CBL
LONG TERM...Swiggett
AVIATION...Badgett