665
FXUS62 KRAH 200637
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
235 AM EDT Fri Sep 20 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 build in from
Texas across the Gulf and Southeast states through early next week.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 235 AM Friday...

Patchy ground fog will be an issue through mid morning, then expect
a largely dry day for most, with just isolated afternoon showers
primarily over the W and S Piedmont into the Sandhills.

A diffuse MSLP pattern persists over NC early this morning, and the
combination of this very weak near-surface flow fostering nocturnal
stabilization along with a damp ground has prompted patchy fog
formation, much of it shallow and pooled in low spots. Areas of mid
clouds have hindered prime radiational cooling over our far W and E
areas, but as these mid clouds continue to drift southward through
this morning, most places should see at least some fog, some of it
dense. Will monitor for the need for a dense fog advisory.

Otherwise, once the fog lifts and disperses by mid to late morning,
skies should be partly cloudy, but various models and ensemble
systems differ on rain chances. Deterministic models such as the GFS
and ECMWF paint a wide swath of precip across all but our far NE
this afternoon into early evening, with peaks in amounts over the SW
Piedmont, a solution mostly corroborated by the NAM and latest RAP
runs. But ensemble output such as the NBM and HREF show only a few
fleeting isolated showers today into tonight. Observational data
does show support for at least some weak forcing for ascent today,
with weak perturbations seen on current GOES layer WV imagery over W
PA on pace to drop through VA into N NC by this evening, and daytime
heating with surface dewpoints in the 60s and minor moisture flux
from a damp ground could result in a few hundred J/kg of SBCAPE
later today. Will include a period of isolated showers across the W
and S Piedmont into the Sandhills later today, with the dry mid
levels likely to curb most deep convection that could generate
lightning. Highs from the upper 70s to mid 80s. Any showers should
peter out and shift to our S early this evening, leaving dry
conditions overnight, however another round of patchy fog and low
stratus is probable late tonight, following persistence with little
change in antecedent conditions and surface wind. Lows generally 60
to 65. -GIH

&&

.SHORT TERM / /...
As of 105 PM Thursday...

To be updated shortly.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 325 PM Thursday...

Saturday morning, surface high pressure will be centered over
eastern Canada with a pressure ridge extending all the way to the
Gulf Coast. A weak front will move across the area Saturday night.
Am not terribly impressed by the depth of the moisture with the
front, but there are too many models, deterministic and ensembles,
to keep a dry forecast in that time period. Rainfall does not appear
to be substantial, but have gone ahead and added slight chance pops
across the northern half of the area. Sunday and Monday continue to
have a dry forecast as high pressure reestablishes itself, with just
the Triad being clipped on Tuesday with a slight chance of showers
in advance of the next front. Low pressure will move across the
Great Lakes during the middle of the week, and it currently appears
that the most likely timing for any showers or thunderstorms with
the upcoming cold front will be Wednesday night. Highs will be
slightly above normal for the weekend, then drop a few degrees below
normal for the weekdays. Lows will be near normal through the
extended period.
&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 100 AM Friday...

The chance for MVFR-IFR fog remain high early this morning (mainly
07z-14z), due to warm moist air and very light winds near the
ground. Areas of mid clouds currently cover the far W Piedmont
(including GSO and esp INT) as well as our NE sections, which is
helping to keep fog from becoming too widespread so far, however as
these mid clouds continue to push southward and break up, widespread
dense fog and areas of low cigs in stratus are likely. There are no
strong indicators favoring one particular terminal over another for
dense fog formation, but most guidance indicates the best chances
are E of the Triad, including RDU/RWI/FAY which have all seen some
rain in the last 24 hours to further moisten the ground. A gradual
dispersion and mixing out of fog/stratus will result in a trend to
VFR conditions by 16z, persisting through early tonight. Isolated
showers are possible later today, but overall the vast majority of
the area will stay dry. Surface winds will remain light (under 10
kt) mainly from the NE or ENE through tonight.

Looking beyond 06z Sat, another round of areas of early-morning fog
and stratus producing sub-VFR conditions is possible 08z-14z Sat
morning across central NC terminals, otherwise VFR conditions are
favored to dominate through early Sun night. A backdoor front will
drop through NC Sun night as high pressure noses in from the north,
bring another chance of sub-VFR conditions early Mon morning and
again early Tue morning. Mostly dry weather will persist, however,
through Tue. -GIH

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...
LONG TERM...Green
AVIATION...Hartfield