678
FXUS62 KRAH 120737
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
337 AM EDT Fri Jul 12 2024

.SYNOPSIS...
A nearly stationary front over the Coastal Plain today will pivot
westward and stall over the Piedmont tonight through Saturday.

&&


.NEAR TERM /THROUGH TONIGHT/...
As of 758 PM Thursday...

...A Flood Watch has been issued for most of central NC except those
in the far western Piedmont starting midnight tonight and extending
through midnight Friday night....

Latest radar data shows scattered showers and storms beginning to
move in from the southeast coast this evening. Changes to the
forecast with this update includes the current model data mixed in
with observational trends. Backed off on timing and coverage as
storm coverage hasn`t been impressive the past few hours. However,
with time, coverage of showers and storms are expected to increase
and continue through the night. Lows overnight will be in the low to
mid 70s.

As of 348 PM Thursday...Convection thus far today has largely
remained just east of our CWA and near the coast as convergence
tended to backbuild ese, as opposed to retrograde west.  However,
some convection is slowly approaching the northern Coastal Plain
currently.  The sfc boundary remains east of our area, but should
begin to ease westward through later tonight. The associated
instability axis will start to pivot inland as well, and thus still
expecting scattered showers and storms to migrate into our Coastal
Plain/Sandhills through this evening.

As we enter the overnight period, onshore moisture flux, as noted in
IVT model fields, should increase for those east and southeast of
the Triad. Additionally, weak mid-level impulses will pivot across
these areas near sunrise Friday morning.  As such, scattered to
numerous showers and storms will likely increase in coverage early
Friday morning, and blossom across the Piedmont/Sandhills/Coastal
Plain through Friday afternoon. the 12Z HREF LPMM QPF guidance
continues to paint the highest QPF potential for those east of I-95,
and a secondary axis of higher amounts somewhere between the Triad
and the Triangle.  The latter of which, may mostly materialize early
Friday morning.

While instability will wane some overnight, PWAT will remain 120 to
150 % of normal (>2 inches) area wide. Given forecasted freezing
levels >15,000 feet, tall-skinny CAPE profiles, warm-cloud layer
depths > 12,000 feet, and very slow mean-cloud layer flow (~5 kts),
any convection that develops tonight could be capable of producing
highly efficient downpours. Despite quite dry soils, this type of
atmospheric environment could easily encourage efficient warm-cloud
processes and rain rates capable of producing flash flooding.
Biggest concerns would be over urban areas, but any efficient, slow-
moving storm could produce localized flooding even in rural areas.

Highs today will still push the upper 80s/lower 90s but with lower
humidity for much of the day.  Overnight lows will dip into the
lower to mid 70s.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 330 AM Friday...

Though weakening, the stalled front will continue to bisect the
area. Meanwhile, the axis of anomalously high moisture/PWATS will
gradually shift eastward throughout the day. Following a possible
early day lull, diurnal destablization should lead to scattered re-
development of showers and storms during the afternoon and evening,
mainly from the Triangle eastward. Highs ranging from upper 80s NE
to lower 90s elsewhere. The moist/humid dewpoint air in the lower to
mid 70s east of the front will result in heat indices in the lower
100s from the Triangle eastward. Balmy lows in the lower/mid 70s.



.LONG TERM /SUNDAY THROUGH THURSDAY...
As of 330 AM Friday...

...Dangerous Heat Returns Sunday Through the Middle Part of Next
Week...

The main weather story will be the return of Dangerous Heat. Staying
under the influence of a ~591dm ridge and low-level W-SWLY flow,
1000-850 thicknesses and h8 temps are forecast to peak during the
Monday-Wednesday period, topping out ~1445m and 23-24C respectively.
Highs in the mid to upper 90s will be common place for Sunday
through Wednesday, with Monday or Tuesday currently forecast to be
the hottest day, with some lower 100s possible across central and
southern NC. There is a fairly strong and consistent model signal
for dewpoints to mix out into the lower 60s(and even quite possibly
into the upper 50s)across the western Piedmont each afternoon, which
should help to temper the heat risk over the western part of the
state. However, four consecutive days of heat indices in the 103 to
108 F degrees is likely from the Triangle eastward.

In terms of rain chances, a low-amplitude shortwave trough moving
slowly east through the mid-Atlantic region Sunday afternoon through
Monday will support isolated to scattered storm development Sunday
afternoon and evening, followed by mostly sea-breeze convection
Monday and isolated storms Tuesday, owing to the potential for weak
disturbances to move through the area. The approach of a front from
the NW and associated high rain chances late Wednesday and Thursday
will likely break the heat wave and could bring some widespread
significant rainfall to the area given the potential for the front
to slow down or stall out across the area to end the work week.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 206 AM Friday...

A mixture of IFR to VFR conditions are expected to start the TAF
period. These mixture of ceilings will trend to greater restrictions
of IFR toward sunrise Fri as scattered to numerous showers and
embedded storms penetrate westward into central NC with an area of
low pressure along eastern SC. The first wave of showers is
currently penetrating westward into the Coastal Plain. Most guidance
shows this band impacting the eastern terminals (RDU/FAY/RWI)
between about 08-13Z. We introduced a TEMPO group for storms during
this time for these terminals given a signal of embedded storms in
the high-res models. This wave of storms could form along or just
west of RDU between 10 and 13Z and near FAY/RWI between 08-12Z. A
better chance of widespread showers and storms will be during peak
heating, coincident when high-res models show the greatest coverage
of storms. It is at this time when restrictions should improve to
MVFR to even some VFR. Rather than indicate an entire period of
storms at the terminals, we focused the main storm risk when
probability was highest, roughly between 18-22Z at GSO/INT, and  18-
02Z at RDU/FAY/RWI. Showers and storms should decrease in coverage
between 00z-06z as energy starts to shift east of the terminals,
resulting in CIG/VIS lowering back to IFR or lower conditions.

Beyond 06Z Saturday: Lingering showers and embedded storms should
decrease by early Sat, followed by LIFR/IFR ceilings Sat morning.
Scattered storms are again favored Sat, mainly in the eastern sites.
Morning low stratus or fog is possible Sun morning. Storm chances
Sun-Tue will trend to be more isolated in nature.

&&

.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...
Flood Watch from midnight EDT tonight through Friday evening for
NCZ007>011-022>028-039>043-074>078-083>086-088-089.

&&

$$
SYNOPSIS...MWS
NEAR TERM...CA/Luchetti
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...Kren
CLIMATE...RAH