-- Discussion containing changed information from previous version are highlighted. --
857
FXUS62 KRAH 210539
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
140 AM EDT Sat Sep 21 2024

.SYNOPSIS...
An upper level trough along the East Coast will shift slowly
eastward and offshore through Saturday morning, as a weak surface
high pressure ridge extends from New England down through the
central Carolinas. An upper level disturbance will track southeast
through the Mid Atlantic region late Saturday through Saturday
night. An upper level high pressure ridge will then begin to build
in from Texas across the Gulf and Southeast states through early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 841 PM Friday...

The isolated showers and thunderstorms have diminished in the past
couple of hours leaving only a few areas of residual cloudiness.
The mid-evening dew points ranged in the muggy mid 60s to lower
70s. Surface temperatures ranged in the 70s, except some 60s already
around Roxboro, Henderson, and Louisburg. A continued light NE flow
existed with the surface high pressure ridging into NC from the
north. Some slightly drier air was located over the DELMARVA region
southward into NE NC. Some of this drier air may be able to advect
into portions of the northern Coastal Plain and northeast Piedmont
later tonight. Regardless, patchy fog and some lower stratus is
anticipated later tonight with current conditions showing near
saturation in some areas. Lows generally expected to be in the 60s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 400 PM Friday...

Nwly flow aloft will result across cntl NC through the weekend,
between a mid-level anticyclone that will drift from s-cntl TX to
the cntl Gulf coast and a shortwave trough that will amplify from
the lwr Great Lakes to along and offshore the nrn middle Atlantic
coast Sat-Sat night. Glancing height falls of 10-20 m/12 hr and
seasonably strong, ~30-40 kt mid-level flow will occur over the srn
middle Atlantic late Sat-Sat night. That shortwave trough will then
be absorbed by a preceding cyclone that will wobble from near the
coast of srn New England today to near and north of Bermuda through
early next week.

At the surface, a narrow ridge initially extending across ern VA/NC
will drift to the coast and allow for the development of light, sly
flow across cntl and wrn NC Sat afternoon. That sly flow will be
directed into both an Appalachian-lee trough over wrn NC/VA and a
weak low and accompanying frontal zone that will extend from the OH
Valley to nrn VA. An associated lee low and closely-following
backdoor cold front will then drift across cntl and Southside VA Sat
night and through cntl NC Sun afternoon-evening. High pressure will
follow and extend from Atlantic Canada swwd and across the Northeast
and middle Atlantic Sun night-early next week.

The light sly, low-level flow will result in continued above average
temperatures to finish the summer, with highs mostly in the middle
80s and lows mostly middle 60s. Moisture, surface and deep, will
maximize along and east of the lee trough over wrn NC, where the
airmass will become moderately unstable with diurnal heating.
Although the greatest concentration of storms should result from the
VA Blue Ridge to cntl-nrn VA, along the intersection of the front
and lee trough, isolated cells will be possible into the nrn/nwrn NC
Piedmont Sat afternoon-evening. While nocturnal stabilization should
cause those storms to diminish through the evening, a weak warm air
advection regime above the nocturnally-stabilizing boundary layer
will support a continued slight chance of showers/storms over the ne
Piedmont and nrn-cntl Coastal Plain overnight.

Sun should again be unseasonably warm to hot ahead of the backdoor
front, with pre-frontal temperatures between 85-90 likely, ranging
to slightly less warm lwr 80s where the frontal passage may occur
prior to peak heating toward HNZ and IXA. The backdoor front may
also be accompanied by scattered showers/storms Sun afternoon-
evening, followed by patchy light rain from post-frontal, low
overcast late Sun night-Mon morning.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
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.
-- End Changed Discussion --

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 751 PM Friday...

Primarily VFR conditions are expected the next few hours as a few
isolated showers wane this evening. Dry conditions are expected
overnight. However, fog and stratus are likely to develop across
central NC overnight and especially between ~08 and 13Z Saturday
morning. As such, will continue the mention of IFR/LIFR ceilings and
visibilities over this temporal range at all terminals. It does
appear that KRWI may have the best chance for dense fog, but patchy
fog will be possible at all terminals.

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.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Badgett
NEAR TERM...Badgett
SHORT TERM...MWS
LONG TERM...Badgett
AVIATION...Luchetti/KC