291
FXUS62 KRAH 111040
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
640 AM EDT Thu Jul 11 2024

.SYNOPSIS...
A cold front will stall out over the Coastal Plain this morning.
This front will push back westward into the Piedmont later today,
but will generally hold over the western and central Carolinas
through Sunday, as it slowly weakens.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 300 AM Thursday...

Increasing rain chances will spread in from the E through the day
and particularly tonight, although areas along and W of Hwy 1 will
stay mostly dry through mid afternoon.

A cold front (trailing from the Beryl remnant low) currently bisects
the forecast area, separating the light/variable winds and dewpoints
in the 70s to its east from the largely NW surface flow and upper
50s and 60s dewpoints over the west. AS a dampening mid level
shortwave trough moves through NY/PA with its tail end brushing NC,
this front should continue a slow eastward progression today before
stalling somewhere over the NC Coastal Plain, or over the E edge of
the CWA. The sub-70F dewpoints and sub-2" PWs are expected to spread
over much of the area through noon, although areas along and E of I-
95 should see dewpoints no lower than the lower 70s with a PW
hovering near 2". Meanwhile, low pressure from the surface up
through 850-700 mb will slowly develop just off the Southeast coast,
along a weak low-mid level trough currently stretching from central
NC SE to ENE of the Bahamas. As this low deepens a bit, the low-mid
level southeasterly fetch of Atlantic moisture into NC will deepen,
strengthen, and elongate, and as this low drifts WNW today through
tonight, it will push the frontal zone slowly westward, reaching the
Piedmont by this evening, according to recent hi-res model runs, and
the westward spreading of pops will follow suit later today. SBCAPE
will initially be very low along and W of I-95, although moderate
CAPE will shift west into our eastern third this afternoon, with
marginal CAPE then overtaking nearly the whole CWA this evening
through tonight as the 70s dewpoints and 2+" PW surge back westward.
The chances for showers/storms as well as amounts will be greatest
after nightfall, and especially overnight, when mid level flow
becomes increasingly weak, leading to slow storm motions, in tandem
with increasing PW to well over the 90th percentile (and nearing
daily records), bolstered by the deep Atlantic moisture fetch, and
added forcing for ascent from the marginal buoyancy and moist
upglide along the low level frontal zone. Expect good chance to
likely pops to push to the Hwy 1 corridor by late afternoon/early
evening, then areawide tonight with some categorical values over the
NE Piedmont. All but our W areas remain in a marginal excessive
rainfall outlook, with the HREF showing our Coastal Plain within a
50-90% chance of over a half inch of rain through tonight.

Expect highs today from the upper 80s E (clouds and earlier rain
limiting heating) to the mid 90s SW. Lows tonight in the lower to
mid 70s. -GIH

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 340 AM Thursday...

* Heavy rainfall leading to localized flooding remains possible
  across north-central and eastern portions of central NC through
  Fri into Fri night.

Confidence is growing that we`ll see high rain chances across
central NC from late tonight through Fri. As the surface front sits
roughly steady with subtle wavering over the W Piedmont, the
aforementioned low level low center expected to be near the SC/GA
coast early Fri will continue a drift to the WNW, propelled inland
by a mid level inverted trough to its W well off the Southeast coast
as it too tracks WNW around the deep/strong anticyclone over the NW
Atlantic, all of which will help to draw copious moisture into the
eastern half of NC. Deterministic models agree on a continued deep
low-mid level SE flow riding up and over the surface front,
including a 20-30 kt low level SSE jet, as anomalously high PWs
(likely surpassing daily records) around 2.5" become focused through
the central and eastern Carolinas. With the combination of slow
storm motions (10-15 kt steering flow at 850-500 mb), weak DPVA from
the mid level trough moving in from the SE, marginal SBCAPE over our
area, high integrated vapor transport into E NC, a projected very
deep warm layer (LCL-0C) over 4 km, and weak moist upglide over the
surface frontal zone, heavy rainfall remains a high concern over
much of our area. If these model signals persist in later runs, a
flood watch may be needed for late tonight through Fri. Rainfall
totals of 1-2" are expected over much of our area, particularly over
the N Piedmont, W Sandhills and the Coastal Plain, and the LREF has
a 60-90% chance of an inch or more from FAY through the Triangle
toward Kerr Lake and Lake Gaston. By Fri night, the surface front
will hold through central NC while the mid level trough/low weakens
while tracking northward from E NC to the Delmarva/NJ. With a
reduction in forcing for ascent including lessening moist upglide,
we should see rain trending downward in coverage and intensity from
S to N overnight, and will depict a trend back down to just chance
pops Fri night. Expect below normal highs from the upper 70s N to
low 80s S, followed by lows once again in the low-mid 70s. -GIH

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 235 AM Thursday...

Heights will rise on Sat as the broad troughing at mid-levels from
Fri shifts east mainly along the NC coast. West to southwest flow at
500 mb will ensue thanks to a weak trough axis stretching from the
Great Lakes into the Midwest. While this would normally reduce storm
chances, most model guidance shows that the low-level circulation
from Fri will be located roughly over eastern NC. While it will be
in a weakened state, a low-level convergence axis will still be
present, draped from NE to SW from roughly Roanoke Rapids to
Wadesboro. At the surface, there may be a weak surface low as well
along the Coastal Plain or along the coast. Forecast soundings show
relatively weak CIN and MLCAPE of 1200-1500 J/kg. This along with
the convergence axis and sea-breeze should favor another day of
scattered showers and storms. Chances would appear highest along and
SE of the convergence axis, roughly along/east of US-1. Coverage
should diminish after sunset with loss of heating. Highs should warm
into the upper 80s/90 in the east to low 90s W.

On Sunday, the flow at mid-levels roughly stays the same with
westerly flow. The low-level convergence axis is forecast to shift
offshore, with any surface boundary from Sat washed out by this
time. This along with lower PWATs should favor less overall chances
of storms. The best chance appears in the Sandhills to central
Coastal Plain as guidance shows a fairly robust sea-breeze
potential. Highs should warm with more sunshine and rising low-level
thicknesses to the low and mid 90s. Heat indices will also get close
to advisory criteria in the Triangle and Coastal Plain between 100
and 105.

Precipitation chances become more isolated in nature and more
diurnally driven Mon through Wed. Storms appear to be mainly focused
along the western Piedmont/Foothills along a persistent lee trough
setting up at the surface, as well as along the sea-breeze over the
southern Coastal Plain. Rain chances, however, look limited thus far
with forecast soundings showing a capping inversion. Downslope flow
and lowered PWATs may also limit coverage. The next best chance of
showers/storms may not come until late Wed or Thu as ensembles show
a potential cold front approaching. Outside of this, it will be hot
and humid, with highs in the mid to upper 90s to even some lower
100s over the Triangle. Lows will also be rather muggy and warm in
the mid/upper 70s, which could challenge some record high mins.
Dewpoints should mix out into the upper 60s W to low 70s E in the
afternoon under the westerly downslope flow, however heat indices
look to still be rather unbearable between 103 to 109 along/east of
US-1. The prolonged hot weather will increase the risk of heat-
related illnesses.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
As of 640 AM Thursday...

VFR conditions are expected to mostly dominate central NC
terminals through this evening, although a downturn to IFR is likely
starting later this evening, esp over central and eastern TAF sites.
A band of storms which has formed just east of the forecast area in
the last hour or so is just E of a front which has shifted into the
Coastal Plain. These showers and isolated storms are expected to
expand and begin to edge westward later today, as the front pushes
westward back into the Piedmont, and brief sub-VFR conditions with
erratic winds are possible in and near any storm. The westward push
of the front will result an east-to-west trend toward IFR cigs and
scattered showers and storms starting around 00z-02z at RWI/FAY and
around 03z-04z at RDU. INT/GSO should remain VFR with dry weather
through 06z, before dropping to IFR around 09z. Surface winds will
be mainly from the N and NE today, with a few gusts to 15-20 kts
through early afternoon, then shifting slowly east-to-west to be
from the ENE or E from this evening through tonight.

Looking beyond 12z Fri, sub-VFR conditions and numerous areas of
showers and isolated storms, including locally heavy rain, will
prevail Fri morning through Fri night at all sites, as the westward
moving front slows then stalls over the W Piedmont or Foothills,
where it will linger into the weekend. Shower/storm chances will
persist, mainly each afternoon through evening and primarily in the
E Sat/Sun. Mon currently appears mostly dry with only isolated
storms. Morning sub-VFR fog and low clouds are possible mainly E
early Sat/Sun with fairly low chances Mon. -GIH

&&

.CLIMATE...
Record High Temperatures:

July 15:
KGSO: 97/1974
KRDU: 99/1997

July 16:
KGSO: 99/1915
KRDU: 101/1887
KFAY: 103/1937


Record High Minimum Temperatures:

July 11:
KGSO: 75/1992
KRDU: 77/1981
KFAY: 76/2019

July 12:
KGSO: 76/2011
KRDU: 78/2011
KFAY: 80/1935

July 13:
KGSO: 75/2017
KRDU: 78/2017
KFAY: 78/2017

July 14:
KGSO: 77/1981
KRDU: 77/2017
KFAY: 80/2017

July 15:
KGSO: 74/2019
KRDU: 76/1992
KFAY: 78/2015

July 16:
KGSO: 75/2010
KRDU: 77/2010
KFAY: 78/1992

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...Hartfield
LONG TERM...Kren
AVIATION...Hartfield
CLIMATE...RAH