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435
FXUS62 KRAH 211715
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
115 PM EDT Sat Sep 21 2024

.SYNOPSIS...
An upper level disturbance will track southeast through the Mid
Atlantic region late today and into tonight. A back-door cold front
will move south through the area late Sunday followed by surface
high pressure extending south into the area through much of the
upcoming work week.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1047 AM Saturday...

No major changes this morning.  The 12Z GSO soundings support our
current forecast highs in the low-mid 80s today.  Latest vis
satellite shows mainly clear to partly cloudy skies... with fair wx
expected through the duration of the afternoon.  PoPs still expected
to increase beginning this evening as noted below.

Prev AFD as of 325 AM: Today: Underneath NW flow aloft, weak sfc
high pressure across the area will move offshore late in the day.
Morning fog will burn off quickly with mostly sunny skies for much
of the day as afternoon highs generally top out in the mid 80s. With
1000-1500 J/kg MLCAPE forecast/maximized across the lee of the
southern and central Appalachians, isolated convective rain chances
should largely remain over the higher terrain.

This Evening and tonight: A low-amplitude mid-level shortwave trough
is forecast to move SE across the Northeast and down the mid-
Atlantic coast through early Sunday. There is growing model
consensus that weak impulses and increasing upper jet divergence
ahead of this feature could support a cluster of showers and storms
over VA that could propagate southeast into central NC during the
evening and overnight hours. While, unfavorable diurnal timing
should limit severe threat, deep layer shear of 30-35 kt is
sufficient to support a non-zero wind threat, mainly across the
northern Piedmont and northern coastal plain counties, before
weakening. Lows in the mid 60s.


&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
-- Changed Discussion --
As of 115 PM Saturday...

Aloft, the sub-tropical ridge will progress eastward through the
srn/ctl Appalachians and into the Carolinas through Sun night.
Central NC should be under nwly flow on the northeast periphery of
the ridge. At the surface, a low will continue sliding sewd through
central NC Sun morn/aft. A backdoor cold front should slide south
through the area Sun aft/eve, with high pressure ridging in behind
it. There could be some lingering showers across the east Sun
morning. Additional showers/storms could slide swd through the
Coastal Plain/far ern Piedmont Sun eve/night as the backdoor front
slides southward through the area. There could be about a 10 degree
spread in highs from SW to NE due to the front, around 90 degrees SW
to low 80s NE. Lows could drop to around 60 degrees in the northeast
Sun night, with generally mid 60s expected elsewhere.
-- End Changed Discussion --

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 140 AM Saturday...

Warm with isolated showers to start the week...

A trough brings a bit cooler temperatures late week, then
potentially wet weather again next weekend.

Ridging will build in from the Tennessee Valley region early in the
week, with a surface high pressure extending down the eastern
seaboard from eastern Canada. A weak backdoor front is expected to
move to southern NC and potentially stall Monday keeping the
southern tier in the 80s both Monday and Tuesday. Highs in the mid
70s to around 80 are favored over the northern and northeastern
sections. There is only a slight to low chance of mainly afternoon
showers/thunderstorms south and northwest Monday. The chance of
mainly afternoon and early evening showers/thunderstorms should
return to most areas Tuesday as the upper ridge moves east.

Wednesday into Thursday, models have slowed the cold front down a
bit with the 12z/Thursday cold front position potentially still over
western NC. This occurs as troughing develops from the
Mississippi Valley toward the Appalachians by the weekend. The
cold front is expected to push to the coast by Friday This would
favor the best chance of showers/storms Wednesday into Thursday
(capped POP for now at 40-50 percent), and highest during the PM
hours. POP would be lower behind the front Friday along with
with slightly cooler temperatures in the mid 70s to around 80 by
Friday and Saturday. Some lows will dip into the 50s over the north
and west.

An important note late week into the weekend, NHC is tracking the
potential development of a tropical depression (60 percent chance of
formation) over the northwestern Caribbean Sea and southern Gulf of
Mexico late next week. If something were to form, its energy could
get pulled northward into the Deep South by the aforementioned
trough next weekend.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
As of 640 AM Saturday...

Fog and associated sub-VFR restrictions should lift and dissipate
~13z with VFR conditions expected through the late afternoon. A
cluster of showers and storms developing upstream across the
southern mid-Atlantic could progress south into the area from the
between 00 to 08z, potentially resulting in a period of sub-VFR
restrictions, especially across the northern TAF sites(KINT, KGSO,
KRDU, KRWI). Patchy fog will be possible early Sunday morning,
especially in any areas that receive rain this evening and tonight.


Outlook: VFR conditions should generally prevail through mid-week,
with the exception of sub-VFR fog/stratus each morning. Light rain
or showers will be possible each day but those details remain fairly
uncertain at this time.

&&

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

&&

$$

SYNOPSIS...cbl
NEAR TERM...np/cbl
SHORT TERM...KC
LONG TERM...Badgett
AVIATION...cbl/KC