-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 191041
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
6405 AM EDT Fri Apr 19 2024

.SYNOPSIS...
-- Changed Discussion --
A weak backdoor front over northeast North Carolina will slowly lift
back north as a warm front this afternoon. A cold front will cross
the region late tonight into early Saturday, and then settle just to
our south late Saturday. A wave of low pressure will track along the
front Sunday into Monday, bringing unsettled conditions and cooler
temperatures.
-- End Changed Discussion --

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 330 AM Friday...

Confidence in the coverage and precise timing of the shower/storm
chances today/tonight is lower than usual, based on a few factors. A
poorly defined surface pattern persists over the Carolinas, with
baggy low pressure over the SW Piedmont while a weak backdoor front
has progressed well into our NE sections, bringing a stratus deck in
from the NE associated with narrow but strong high pressure nosing
in, its northeasterly flow reinforced by a strong low E of the
Delmarva. This backdoor front is still expected to lift slowly back
northward and dissipate by this afternoon, with the stratus deck
mixing out and dissolving, as the high to the NE loses its grip. A
weak perturbation passing through this morning will spread sct-bkn
mid and high clouds into our area, partly convective debris clouds
from convection from S MI through the Ohio Valley into W TN that is
associated with an incoming strong surface cold front stretching
from NW OH to central TX, and beneath a broad but strong mid level
trough axis extending from James Bay through the Midwest. This mid
level trough has with it a fairly strong mid-upper level speed max
tracking through its base, although much of this wind aloft will
hold to our NW through tonight, with the 80-100 kt mid level speeds
holding N of the Ohio River, while our 500 mb winds are likely to
peak at just 30-40 kts this evening, adequate but not impressive.
And there is little evidence of anything more than just very weak
upper divergence potential this evening. Another factor limiting
coverage today is the low level moisture, which will be minimal
today; while surface dew points are expected to creep up into the
mid-upper 50s far N and lower 60s far S, the 925-850 mb flow will be
quite weak, with little to no moisture flux, which will keep most
cloud bases high (except for this morning`s stratus in the NE, of
course). But a few factors do support isolated light showers midday-
early afternoon evolving to scattered showers and storms from mid to
late afternoon into the evening, including decent heating (through
mostly thin or sct clouds) pushing afternoon MUCAPE to 500-1000
J/kg, along with improving PW (packed mostly above 850 mb, though).
The mid level flow, while not high, may still be sufficient to
support organized convection, with 25-35 kt of deep layer bulk shear
expected. Steep surface-based lapse rates could contribute to high
DCAPE, boosting downburst wind potential. What this means in terms
of sensible weather is that we should see a few showers moving into
the NW by early afternoon (including some developing and moving off
the higher terrain), with this convection growing upscale to
scattered storms progressing E through the area, most likely from
mid afternoon through mid evening according to rough average timing
from the CAMs and the UH plots from the HREF. Straight line winds
will be the greatest threat with any storms that can become robust
and deep. Activity should shift into the Coastal Plain and E
Sandhills while diminishing with loss of heating by late evening or
near midnight, with lingering clouds but largely dry weather
expected after 1 or 2 AM. Expect highs today from the upper 70s N to
the mid 80s S, followed by upper 50s to mid 60s for lows. -GIH

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 350 AM Friday...

The weekend will start out partly to mostly cloudy before becoming
mostly cloudy to cloudy with slight rain chances easing in. The cold
front will have pushed into our SE sections by Sat morning and will
progress SSE, settling into N SC as low pressure drifts southward
into the SC Midlands. A much cooler air mass will gradually build
in, although the most dense air will initially be held up by the
higher terrain, allowing for good afternoon mixing and highs that
will be cooler but still a bit above normal, in the 70s with near 80
in the far S. Despite the westerly mid level flow on the S side of
the broad trough, PW across the S and SE, near the surface front,
will remain elevated, at or over 1" through Sat night, as the
noticeably cooler air finally pours in from the NNW. While forcing
for ascent is largely quite weak or even absent heading into Sat
night, we will see slowly improving moist upglide across the south,
up and over the low level frontal zone, resulting in a reinforcing
of low level stability and groundward moistening of the column,
necessitating low chances for light rain, mainly S of Hwy 64,
starting late Sat going through Sat night. Lows from the upper 40s
N to upper 50s S. -GIH

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 219 AM Friday...

Sunday: Flow aloft turns swly Sunday and Monday increasing low-level
moisture advection into the southeast. Ensembles and deterministic
guidance are in pretty good agreement at this point pinning a sfc
cold front, instability, and the highest anomalous moisture along
the coastal areas and offshore. Rain chances will still increase
throughout the day Sunday (highest POPs still across our far
southeastern zones) but primarily light to moderate stratiform rain
is expected through Monday morning. Sfc flow will remain nnely,
promoting a cool, wet, and breezy day with highs in the upper 50s to
lower 60s. QPF ranges from a few tenths of an inch (N) to about a
half of an inch (S).

Monday through Thursday: Any lingering rain Monday morning will pull
off to our east by early afternoon.  A few additional scattered
showers may be possible Monday afternoon/evening with the passing of
a strong vort max, but overall Monday should largely be dry. Tuesday
will follow suit under nwly flow aloft.  By Wednesday, a sheared
vorticity feature will ride through the Mid-Atlantic. This may spawn
a few scattered showers, but overall coverage should be minimal. Dry
weather continues under nwly flow aloft on Thursday.

Temperatures Monday will remain cooler than normal be cool in the
mid 60s. Temps will rise into the mid 70s Tuesday through Thursday.

&&

.AVIATION /12Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 645 AM Friday...

INT/GSO: VFR conditions are likely to hold through the next 24 hours
at INT/GSO, with clouds thickening early this morning and remaining
largely broken through this evening, but with VFR bases. Isolated
showers are possible from late morning through mid afternoon (15z-
19z) at INT/GSO, followed by a potential for isolated storms into
early evening (19z-02z) as a cold front approaches. Shower/storm
chances will end by mid evening, as the front pushes to the E.
Surface winds will be light, under 10 kts, starting from the NE
before shifting to SE, then SW, then NW after nightfall behind the
front.

RDU/RWI/FAY: These sites will see continued IFR to low-end MVFR
stratus early this morning, lasting through much of the morning,
until around 15z, with the longest duration at RWI and a slightly
earlier end at RDU/FAY. VFR conditions are expected to return by
17z, but with thickening clouds. Isolated showers are possible
starting in the mid afternoon (mostly after 18z), with a few
thunderstorms possible from mid afternoon through late evening
(mainly 20z to 03z), ending thereafter with dry conditions expected
after 05z tonight. Another round of MVFR to IFR conditions is
expected across the NE and E late tonight (starting around 05z)
through Sat morning, particularly affecting RWI/FAY. Surface winds
will be light and variable, under 10 kts.

Looking beyond 12z Sat, after mostly dry weather Sat (except a
slight rain chance at FAY) as the front settles just to our S, a
wave of low pressure tracking along the front will bring a high
chance of sub-VFR conditions and rain from Sun afternoon through
early Mon. Rain chances may linger esp at FAY Mon night, but
otherwise VFR conditions are expected Mon through Tue. Showers and
storms are possible Wed ahead of a cold front. -GIH
-- End Changed Discussion --

&&

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

&&

$$

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