105
FXUS62 KRAH 050034
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
835 PM EDT Thu Jul 4 2024

.SYNOPSIS...
A hot and humid air mass will hold over the region into the weekend.
Shower and storm chances will increase for Friday and through the
weekend as an upper level trough and surface front slowly approach
our area from the northwest.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 835 PM Thursday...

* Scattered storms diminishing by late evening
* The strongest storms capable of wind gusts of 35 to 45 mph.

Radar trends the last few hours depict a few features worth noting
for the near term update. A well-defined outflow boundary currently
stretches from the far western Piedmont, east into Siler City and
into RDU, then northeast into eastern Franklin and central Halifax
Counties. Earlier convection that moved into the Triad has since
showed dissipating trends both on radar and via satellite with
diminishing instability. Gusts in the Triad ranged between 35 and 38
kts at GSO/INT. Another report of 36 kt was observed at Burlington
with the line of storms/outflow. Storms will continue to weaken in
the Triad and northwest Piedmont owing to stable conditions behind
the rain-cooled air. Further to the east-southeast over the Triangle
and northern Coastal Plain, isolated to scattered storms will be
possible into late evening, between about now and 11 pm, as storms
fire along the outflow. While instability is waning, there is still
some 1500 J/kg of CAPE east of the boundary. An inland moving sea-
breeze could also bring a few spotty storms over the central Coastal
Plain. All storm activity should wane by midnight or so as forcing
wanes. The strongest storms tracking ESE will be capable of gusts of
35-45 mph, owing to some dry air at low-levels favoring high DCAPE.
Overnight lows will remain muggy in the low to mid 70s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
As of 310 PM Thursday...

* Heat Advisory is in effect for Friday with dangerously hot
  conditions expected.
* Widespread heat index values of 105 to 109 are expected for
  several hours during the afternoon.
* Temperatures wont fall back into the lower 80s until around
  midnight.

The mid and upper level ridge across the Deep South will persist but
deamplify a bit on Friday as a broad trough and embedded closed low
move across the northern Plains. At the surface a lee tough will
extend south across the western Piedmont of VA and the Carolinas. A
cold front will advance slowly east into the eastern OH and TN
Valleys on Friday afternoon. The air mass across the Carolinas warms
additionally on Friday with morning low level thickness values
ranging in the 1420 to 1428m range along with 850 mb temperatures
that climb to between 20 and 24 C Friday afternoon. This air mass
should support highs in the mid 90s to around 100 with low 100s
expected in some of the typically hotter locations such as KRDU,
KFAY, and KMEB. Combining the hot temperatures with elevated dew
points will result in widespread heat index values of 105 to 109.

Scattered thunderstorms are apt to develop across western NC during
the afternoon and slowly push east into the western Piedmont late in
the afternoon and especially during the evening. Other more widely
scattered thunderstorms may develop across the northern Coastal
Plain. The airmass across central NC will be moderately to strongly
unstable with MLCAPE values ranging from 1500 to 2500 J/kg. Profiles
suggest a primary threat of damaging winds with steep low level
lapse rates and elevated DCAPE. The convection is apt to continue
into the evening before dissipating overnight. Outside of the
thunderstorm cooled areas, temperatures are likely to linger in the
upper 80s to lower 90s through at least mid evening and wont fall
into the lower 80s until around or a little after midnight. Low
temperatures should eventually fall into the mid to upper 70s by
daybreak Saturday. -Blaes
&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 226 PM Thursday...

Saturday may offer an opportunity for above-climo PoPs with
scattered showers/tstms as a prefrontal trough moves into our area
ahead of an upper s/w trough moving NE across the eastern Great
Lakes region.  The rain will be welcome due to recent dryness, but
also to limit the intensity of the daytime heating, particularly
across our western and Triad zones where rain will arrive earlier in
the afternoon.  There, highs in the lower 90s...vs upper 90s east
where rain will arrive later in the day.

The aforementioned trough will weaken and stall Saturday night with
a broad pressure trough lingering over the Piedmont for Sunday. This
pattern will yield another round of afternoon/evening scattered
showers/tstms with highs a bit lower than prev days (in the lower
90s) given the anticipated cloud cover and scattered showers/tstms.

Next week`s pattern will be very near climo, both daily PoPs and
daytime high temps, given an active daytime Piedmont trough which
will result in scattered showers/tstms each afternoon and evening
and resulting clouds, rain, and outflows which will keep temps in-
check near, or just above climo values.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 725 PM Thursday...

The primary aviation concern at this hour is the broken band of
showers and storms tracking southeastward into and through the Triad
region (INT/GSO). Sub-VFR cigs/vsbys with this activity will be
short-lived, however a period of erratic blustery winds and gusts as
high as 25-35 kts are possible at INT/GSO prior to 02z. These
showers and storms are expected to slowly weaken as they head
further ESE, and the risk of a shower or storm is lower at RDU/RWI
and very low at FAY. However, brief gusts to 20-30 kts are still
possible at RDU prior to 03z. Otherwise, mid and high clouds will
remain sct to bkn through tonight and much of Fri areawide, but
other than a small risk of shallow ground fog near INT/GSO 08z-11z,
the risk of sub-VFR conditions is very low. Another round of
scattered to numerous showers and storms is expected late Fri, after
21z, but confidence in the details of this are low. Outside of any
storms, surface winds will be mostly light and variable or from the
SW or WSW.

Looking beyond 00z Sat, the risk of local sub-VFR conditions in and
near sct showers and storms will persist through Fri evening and
possibly lingering just after midnight. Sub-VFR cigs are possible at
northern terminals early Sat morning. Greater coverage of showers
and storms is expected Sat, starting earlier (in the mid afternoon)
and lasting into the night. Brief periods of isolated sub-VFR cigs
are again possible each early morning Sun through Tue, with a risk
scattered afternoon and evening storms each day. -GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM to 8 PM EDT Friday for NCZ007>011-
021>028-038>043-073>078-083>086-088-089.

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Kren
SHORT TERM...Blaes
LONG TERM...NP
AVIATION...Hartfield