198
FXUS62 KRAH 042325
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
725 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 /UNTIL 6 AM FRIDAY MORNING/...
As of 245 AM Thursday...

* Hot and humid conditions will continue into this evening.
* Scattered thunderstorms will drift into north-central NC this
  afternoon and move into the NC Piedmont this evening as they
  weaken.
* Storms will be efficient in producing strong gusty winds.

The latest surface analysis continues to show high pressure centered
across the western Atlantic extending west into the eastern
Carolinas and the eastern Gulf of Mexico. A cold front extends from
the eastern Great Lakes southwest across the western OH Valley and
into the MO Valley. A weak lee trough extends from central VA into
central NC. Further aloft an anomalously strong west to east 500mb
ridge was centered across the Deep South. The main belt of
westerlies extend from a trough across across western KS/NE and into
the Great Lakes.

The air mass across central NC this afternoon is warm and relatively
moist with PW values of around 1.75 inches or around 120% of normal.
The air mass has become moderately unstable in most locations with
MLCAPE values of around 1000-1500 J/Kg. Mid level laps rates are
rather anemic but low level lapse rates have steepened as the
boundary layer has heated with temperatures in the lower to mid 90s
in many locations.

Regional radar imagery showed an isolated shower or two along the
lee trough near Hoke and Scotland Counties and in Halifax County.
This precipitation will likely be short lived and transient. Other,
more notable and likely impactful areas of convection have developed
across the Blue Ridge in northern NC and southwestern VA. This
convection is likely being driven by differential heating and some
mid level disturbances moving around the periphery of the upper
level ridge.

The thunderstorms along and just east of the Blue Ridge will shift
south and east into northwest Piedmont and VA border counties over
the next few hours. The convection may strengthen a bit as it
approaches the Triad between 4 and 8pm. With a lack of forcing for
ascent, the convection will begin to weaken later this evening as it
approaches the Triangle and Rocky Mount areas between 6 and 10pm
with the convection dissipating before midnight as it moves toward
the Fayetteville area. The best chance of precipitation will be
across the northern tier and Triad areas. With strong heating today
and deep boundary layer mixing, inverted-V thermodynamic profiles
are expected supporting DCAPE in excess of 1000 and likely resulting
in efficient production of strong gusty winds with convection.

Skies will be partly cloudy overnight with a mix of some patchy high
clouds and perhaps some patchy stratus or low clouds across the
south and southeast. It will remain warm and muggy tonight, with
lows mainly in the mid 70s. -Blaes

&&

.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...Blaes
SHORT TERM...Swiggett
LONG TERM...NP
AVIATION...Hartfield