-- Discussion containing changed information from previous version are highlighted. --
453
FXUS62 KRAH 021335
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
935 AM EDT Thu May 2 2024

.SYNOPSIS...
Deep high pressure will build over the Carolinas and Southeast
states through Friday, resulting in very warm temperatures. A series
of weak upper level disturbances will move through the region Friday
evening through Sunday, bringing periods of unsettled weather.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
-- Changed Discussion --
As of 933 AM Thursday...

The Dense Fog Advisory has expired as of 9 AM as visibility has
rapidly improved this morning. Today will likely rival the warmest
day of 2024 so far this year. Low-level thicknesses this morning
from region RAOBs are 10-20m greater than 24 hours ago and 850mb
temperatures at GSO are equal to the moving 90th percentile for
early May. The steep early morning surface inversion is rapidly
eroding and has resulted in air temperatures rising 5-10 degrees
from 12 to 13z. A steady climb is expected through the afternoon
hours with highs reaching to upper 80s in most locations with some
locations able to reach 90 degrees for the first time this year. The
previous forecast remains on track with only minor tweaks made to
the sky and hourly temperatures for the mid-morning update.

Previous discussion as of 135 AM Thursday...

Only cosmetic changes needed to today`s forecast. Still expect
patchy to areas of fog to develop over the Coastal Plain early this
morning, in an area that saw ground-wetting showers/storms yesterday
and where dewpoint depressions are lower. The latest surface
analysis shows a very diffuse pressure pattern over the region, with
weak ridging to our W and E and a very weak and subtle low level
trough between, more evident at 925-850 mb, separating dewpoints in
the mid 50s to near 60 over the W Piedmont from the low-mid 60s over
the far E Piedmont, Sandhills, and Coastal Plain. Observed mid level
trends noted on 00z UA analyses support model progs of building
ridging aloft over the Carolinas, including drying and sinking mid
levels in conjunction with decreasing PW over the area. With a dry
column and neutral to sinking air, clouds will be few and far
between today, limited to high-based flat convective clouds, mostly
scattered except more numerous near an expected inland-moving sea
breeze in the mid-late afternoon. This strong heating will allow
temps to reach well into the upper 80s to around 90, with low level
thicknesses nearly 25 m above normal. Expect generally clear skies
tonight, with only light fog expected in the far SE due to slightly
higher dewpoint depressions (due to slightly warmer temps) and a
slight stirring with a very light SE breeze overnight. Lows will be
just a bit higher than this morning, 60-65. -GIH
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 230 AM Thursday...

The mid level ridge axis stretching over the Carolinas today is
expected to shift ESE by early Fri, kicked to our E by the series of
weak mid level perturbations riding through the base of the mean
broad W CONUS trough and into the Mid South and western Carolinas.
Latest model runs agree on continued low PW over the area Fri with a
lack of both SBCAPE and forcing for ascent, although this starts to
change late in the day and into Fri night, as the low-PW air shifts
to E NC with increasing deep layer moisture spreading in from the
west, in conjunction with the arrival of the first mid level wave
(likely a dying MCV from today`s S Plains convection) into and over
the central and southern Appalachians late Fri into Fri night. This
wave will be further dampening as it arrives with poor mid level
flow and modest low level moisture flux, but with moisture amount
and depth increasing aloft and most long-range CAMs and larger scale
models showing scattered convection shifting into the NC Foothills
and eastward after 00z Sat, will bring in slight chance pops in the
Triad region in the evening, spreading further E with chance pops
over the W Piedmont overnight. Skies should still be fair for much
of the day with high clouds abundant but thin, and with thicknesses
still 25-30 m above normal, expect highs again in the upper 80s to
around 90. Lows in the low-mid 60s with increasing clouds. -GIH


&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 320 AM Thursday...

Unsettled weather is expected over the weekend into early next
week, but confidence in the timing of showers and storms, as well as
total rainfall amounts remains somewhat low.

A strong upper ridge over the eastern US this week will shift
offshore this weekend and give way to wswly flow and better deep
layer moisture, along with the passage of some relatively weak
disturbances aloft.

A weak cold front is forecast to move into the area on Saturday,
then linger and wash out through Sunday. Increased moisture
transport around high pressure off the East Coast is expected to be
greatest over western North Carolina, where PW rises to near 2
inches. While afternoon heating on Saturday may be limited by
widespread cloud cover, the presence of the front and moisture along
with weak instability will result in decent coverage of showers and
storms late Saturday and Saturday night. Given the slow moving
nature of the frontal zone, it is possible that some of the rainfall
could be locally heavy.  Those details will become clearer in the
next couple days, but there is a decent signal in the NAM, GFS and
experimental MPAS ensembles of 1-2 inches of rain  in the western
Piedmont.

The frontal zone turned trough should remain a weak catalyst for
continued showers and storms on Sunday before we ridging aloft
builds back over the southeast US Monday and more so
Tuesday/Wednesday and reduces the chance of showers and storms.
Another cold front, and perhaps a stronger one, is possible by late
next week.

Highs on Saturday and Sunday will be closer to normal in the upper
70s and lower 80s, but the reprieve from the warmth is brief as
temperatures are expected to rise back into the 80s and even lower
90s by the middle of next.
-- End Changed Discussion --

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
As of 555 AM Thursday...

IFR vsbys in fog are expected to persist at FAY/RWI through mid
morning, given the combination of high RH, weak winds, and clear
skies. Fog is also possible near RDU during this time window, but
confidence remains lower there, and it may manifest into just
shallow dense ground fog over bodies of water. INT/GSO should remain
fog-free this morning. Otherwise, VFR conditions are likely areawide
from mid morning through tonight, with weak high pressure at the
surface and stronger high pressure building in aloft, keeping cloud
cover minimal. Surface winds will stay light, under 10 kts.

Looking beyond 12z Fri, VFR conditions are likely to hold through
Fri, although mid/high clouds will gradually increase from the west
as the high pressure ridge aloft gets pushed to our east by incoming
upper level waves moving in from the W and SW. The chance for sub-
VFR conditions within scattered to numerous showers and storms will
increase starting Fri night, lasting through Mon, as a series of
disturbances passes over the region. Areas of early-morning fog are
also expected. -GIH

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Swiggett/Hartfield
SHORT TERM...Hartfield
LONG TERM...BLS
AVIATION...Hartfield