903
FXUS62 KRAH 121349
AFDRAH

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

.SYNOPSIS...
A frontal boundary over the region will pivot westward and stall out
over the western Piedmont tonight. The stalled front will weaken and
remain across the area Saturday, before diminishing Sunday. A lee
trough will then be in place across the western Piedmont into early
next week.

&&


.NEAR TERM /THROUGH TONIGHT/...
As of 948 AM Friday...

* Flood Watch remains in effect for all but the far western Piedmont
  counties until midnight tonight
* Potential exits for localized 4+ inches of rainfall over portions
  of the Piedmont and Coastal Plain

The MMIC-TPW satellite product displayed highly anomalous moisture
(2 to 2.5 inches; with some pixels of up to 3 inches) pumping off
the Atlantic into central NC this morning.

Most of this morning`s heaviest QPE was located along the quasi-
stationary front, which has stalled across our southern to northern
Piedmont. Radar-estimates in these areas have maximized in the 2 to
3 inch range, albeit rather isolated. Given the continued moist, WAA
regime, we`ll continue to see widespread showers and a few isolated
storms this morning. However, intensity has waned some the past hour
or so, and given latest guidance, it appears we could see a relative
lull in heavier rain rates through mid to late morning.

The low-level jet will pick up this afternoon, and moisture flux
into our area will maximize during this time.  Diurnal heating will
increase instability and coverage should fill in almost everywhere,
although best chances for rain would likely be for those along and
east of US-1.  While the overall mean cloud layer flow will be light
everywhere, forecast sounding-derived corfidi vectors show most
favorable conditions for flash flooding in the area between the
Triad and the Triangle. This is supported by the overnight HREF
(00/06Z) runs which depicted upwards of 40% probabilities for > 2
in/hr rain rates between ~19 and 23Z over our southern to northern
Piedmont. These areas also have a bit lower 1 hr FFG, and thus the
flash flooding threat could be maximized over these areas through
later today.

Regardless, 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 through this evening could be capable of producing highly
efficient downpours. This type of anomalous atmospheric environment
will easily encourage efficient warm-cloud processes and rain rates
capable of producing flash flooding, especially over urban areas.

While we are not expecting severe storms to materialize today,
isolated water-loaded downdrafts could produce brief stronger gusts
at the sfc. Additionally, backed flow near the sfc along the
boundary could produce some locally enhanced SRH, and thus a few
cells may show some rotation today.  Overall again though, the
severe threat today is near-zero.

Showers and storms will slowly pull off to the northeast late
tonight and through sunrise Saturday, with highest chances holding
on east of I-95 through early Saturday morning.

Cooler high temps are expected today in the upper 70s to mid 80s.
Overnight lows in the mid 70s are expected.

&&

.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 /12Z FRIDAY THROUGH TUESDAY/...
As of 640 AM Friday...

Largely MVFR to some brief IFR conditions are likely to start the
TAF period. Waves of showers and storms are expected through the day
and into the late evening hours, with activity waning after 03-06z.
While storm chances are possible nearly anytime today and tonight,
there are roughly two main time periods with the highest probability
of storms. The first main chance will be at the start of the 12z TAF
period between 12 and 14z. Based on current radar trends, the best
chance of VCTS or TSRA would be at RDU/FAY/RWI. The second and more
widespread storm potential will be this afternoon and evening,
between about 18-22z at GSO/INT/FAY, 19-23z at RDU, and 20-24z at
RWI. Outside of storms, conditions are likely to be MVFR, with even
some VFR this afternoon at the eastern sites (FAY/RWI). Some brief
IFR is also possible, largely confined with stronger storms. After
showers dissipate from west to east overnight tonight, ceilings are
expected to lower to between LIFR-IFR, lowest at GSO/INT/RDU. Some
patchy fog is possible, with the highest probability at GSO/INT.
Confidence, however, was too low to mention at this time.

Beyond 12Z Saturday: Morning LIFR/IFR stratus on Saturday will lift
to VFR with scattered storms in the aftn/eve, mainly at the eastern
terminals. Morning low stratus or fog is possible again 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...Kren
NEAR TERM...Luchetti
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...Kren
CLIMATE...RAH