270
FXUS62 KRAH 111949
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
348 PM EDT Thu Jul 11 2024

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

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 348 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.

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 /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 THURSDAY/...
As of 330 PM Thursday...

Much needed shower/storm chances lower as wet system moves away
Saturday.

Another heat wave expected to develop Sunday and last into mid-week.

Showers and thunderstorms are expected to become widely scattered
through the day Saturday as the wet system over eastern NC pulls
away. It will continue warm and humid with highs returning into 90-
95 range. Heat indices should reach/return 100 to 104 in the eastern
Piedmont and Coastal Plain.

Heights continue to rise Monday and Tuesday. The low level flow is
also more westerly. Heat Advisory criteria looks likely to be met in
the southern and eastern areas where index values should reach and
exceed 105 Sunday and Monday even with some mixing out of the dew
points in the afternoon, then possibly Excessive Heat Warning
criteria of 110 on Tuesday and Wednesday as the heat wave peaks.
Actual highs should reach the mid 90s to lower 100s Tuesday and
Wednesday. Lows in the mid 70s to lower 80s. Both could challenge
daily records.

There is only a small chance of isolated storms Sunday and Monday.
The chance of mainly afternoon and evening thunderstorms returns
Tuesday especially in the west. All areas have a chance by Wednesday
afternoon and evening. The chance of showers and thunderstorms will
increase on Thursday as a cold front will approach from the NW. Highs
will "cool" into the lower to mid 90s.

A potential wet period with less heat late next week into the
weekend.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
As of 215 PM Thursday...

Convection has largely stayed east of central NC today. Some light
rain and MVFR stratus is starting to near the eastern TAF sites.
Expect some showers and a few storms to develop near KFAY/KRWI and
perhaps KRDU through 00Z tonight. Associated low-level moisture
could produce periods of MVFR conditions at these sites as well
during this period. Beyond 00Z tonight, ceilings will drop at all
terminals to MVFR/IFR and hold through the end of the 24 hr TAF
period. Additional scattered to numerous showers and storms will
blossom across the area early Friday morning through the end of the
TAF period. Atmospheric conditions will support the potential for
heavy downpours which could cause brief aviation restrictions at any
site (although best chances appear at KRDU/KFAY/KRWI).

Beyond 18Z Friday: Additional showers and storms are likely through
late Friday night as an area of low pressure lifts through eastern
NC. A strengthening low-level jet will pivot over eastern TAF sites
Friday, but the strongest LLWS will reside east over the Outer
Banks. Rain chances (and perhaps morning stratus/fog as well) will
largely remain across the east this weekend. Convection
Monday/Tuesday should be fairly 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...
None.

&&

$$

SYNOPSIS...MWS
NEAR TERM...Luchetti
SHORT TERM...Hartfield
LONG TERM...Badgett
AVIATION...Luchetti
CLIMATE...RAH