620
FXUS62 KRAH 051612 RRA
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1211 PM EDT Sun May 5 2024

.SYNOPSIS...
A quasi-stationary front across the area this morning will retreat
northward through the afternoon as a series of mid and upper-level
disturbances traverse the area. A low amplitude shortwave trough
will progress east into the area late Monday and into Tuesday,
bringing additional chances of showers and storms. Drier conditions
are expected by mid week, leading to increasing heat as upper level
ridging returns.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1030 AM Sunday...

* An area of showers associated with an MCV will move northeast
  across the Piedmont through early afternoon.
* Convection including some thunderstorms focuses across the east
  and northeast areas this afternoon with less active conditions and
  widely scattered showers and storms elsewhere.

The latest water vapor satellite imagery and morning RAOB
data/regional radar VWP data shows a well defined vortex/MCV that is
tied to convection that moved across northeast GA/Western SC last
evening. This feature is located across the southern Piedmont of NC,
just northeast of KCLT this morning and is driving the cluster of
showers and embedded heavier rain across much of Stanly, western
Moore, Randolph and western Chatham Counties. At the same time, the
surface boundary lingering across the region since yesterday
retreated west overnight and extends from south-central VA to near
KTDF, just east of KBUY to near KCLT. West of the boundary winds are
northeast to northwesterly with dew points in the lower 60s and low
clouds with IFR to LIFR CIGS of 2-900 feet. East of the front it`s a
warmer and more humid air mass with dew points in the mid to upper
60s, a southeast wind, and higher cloud bases with some breaks of
sunshine in the Coastal Plain near Clinton, Goldsboro and Rocky
Mount. The air mass has become weakly unstable southeast of the
front with MLCAPE values now near and just in excess of 500 J/Kg in
a tongue extending from eastern SC north into the Sandhills and
eastern Piedmont.

The band of showers extending from southwest to northeast across the
western Piedmont this morning will continue for the next few hours,
but as the MCV rides northeast, the more widespread rain/showers
should lift northeast across Chatham, Alamance and Orange counties
into Durham and Person Counties with shower activity waning in the
subsidence to the west and southwest. In addition, scattered showers
will develop over the next hour or two across northeast SC,
Sandhills and southern Coastal Plain and spread northeast. This
convection is more apt to become deeper and support some
thunderstorms toward early to mid afternoon. By mid to late
afternoon the focus for convection will likely shift northeast
across the central and northern Coastal Plain near Rocky Mount and
Roanoke Rapids. Given the modest mid level lapse rates and weak to
possibly moderately unstable airmass, a few stronger storms are
possible. Further west, it will trend less active with a widely
scattered shower or possibly a storm during the afternoon. Highs
today will range from the lower/mid 70s across the Triad and VA
border areas to the upper 70s to around 80 in the east and
southeast.

Upper level forcing wanes this evening and overnight with some weak
mid level ridging extending across the area. The axis of deepest
moisture slips east slightly but PW values remain near 150% of
normal overnight. Can`t rule out an isolated shower overnight and
there is a signal for convection that may develop in far western NC
to hold together and move into the western Piedmont as it fades late
this evening. Otherwise, clouds will thicken up again tonight and it
will be muggy. Overnight lows will range in the lower to mid 60s.
-Blaes


&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 330 AM Sunday...

...Elevated Rain/Storms Chances Again Monday...

The southern stream shortwave trough associated with the expansive
MCS over the southern Plains and Texas will become increasingly
sheared as it ejects eastward across the middle MS and Tn Valley
Monday afternoon and then across the central and southern
Appalachians and into mid-Atlantic region Monday evening and night.
Renewed moisture advection ahead of this wave will lead to a
resurgence of anomalous moisture into the region with PWATs 1.6-1.8,
near record daily maximum.

Stronger daytime heating should result in more robust instability of
1000-2000 J/Kg across the area. There is the potential for an area
of deep moist convection(DC) to propagate east into and across the
area during the afternoon and early evening, with additional
development possible along convective outflow. Shear will increase
slightly, with models indicating a pocket of enhanced shear of 25-
30kts along the potential DC feature. Thus, cannot rule out an
isolated severe cluster or two Monday afternoon and evening. Storms
intensity and coverage should decrease after sunset, with some
lingers isolated showers possible Monday night.

Highs 80-85. Lows in the 60s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 1211 PM Sunday...

Upper pattern for the extended: A short-wave will exit to our east
early Tuesday, behind which mid-level ridging will build back over
the southeast through late Wednesday.  The ridge will de-amplify as
a strong vort max digs into the Midwest Thursday, eventually
ejecting eastward through the northeast US. This feature will induce
increasingly swly flow aloft over central NC Friday into Saturday.

Temperatures: Hot and humid conditions will persist Tuesday through
Thursday under the anomalous mid-level ridge.  The NBM still
continues to highlight high probabilities for >90 degrees for
locations south and east of Raleigh both Wednesday and Thursday (The
GEFS, EPS, and GEPS are less enthused, but generally depict a
similar geographic area with highest probabilities (10-30%)). Given
dew points will peak in the upper 60s/lower 70s, heat indices will
likely pop up into the mid 90s both Wednesday and Thursday
afternoons. Thus, make sure to take frequent breaks in the shade and
hydrate if spending a lot of time outdoors these days.

Temps will "cool" off a bit Friday and into the weekend as the
aforementioned upper vort max/trough dips into the southeast. Highs
in the mid 80s are currently expected Friday, followed by mid to
upper 70s on Saturday. However, these may need to be modified some
as we get closer and guidance comes into better agreement/confidence
increases.

Precipitation: POPs will be lower Tuesday and Wednesday under
general ridging aloft (and some nwly flow in the lower levels should
lower PWAT a bit). However, can`t rule out some isolated/scattered
diurnally driven showers/storms along any differential heating
boundaries including late day sea breeze migration into our area.
Some guidance depicts some energy aloft trickling through our area
late Wednesday which could maybe generate a bit more activity.
However, will keep POPs capped at low chance for now.

As we progress into the Thursday through Saturday timeframe, there
is some uncertainty wrt to the evolution of the aforementioned
strong vort max/trough and an associated cold front. However, the
general consensus among ensembles/deterministic output is that this
upper feature does look strong enough to possibly induce an airmass
change for our area later this weekend (i.e. a stronger cold front
actually making it`s way to the coast). As such, showers and storms
are likely ahead of and along the cold front as it moves through.
While we`ll need a bit more updated model guidance to get into
specifics, it does appear at this point that some severe storms will
be possible Thursday and Friday as guidance suggests an uptick in
mid-level lapse rates and bulk-layer shear in this time frame.
Again, a bit too far out for specifics, but we`ll continue to
monitor as we get closer to later next week.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
As of 640 AM Sunday...

Upper level disturbances interacting with anomalously moist air in
place will continue to result in adverse aviation conditions
through the forecast period.

A band of moderate showers with the potential for some embedded
lightning currently over western and central Piedmont of NC will
progress slowly eastward through the remainder of the morning and
afternoon hours, and should impact all terminals through 21z.
Additional showers and thunderstorms will likely develop outside of
the primary band, but should be more scattered in nature through the
remainder of the afternoon and evening.

Expect gradual lifting of the widespread LIFR to MVFR as the front
draped across the area begins to lift north. Outside of any
convection, flight conditions should lift to VFR at KFAY and KRWI
during the late morning and early afternoon. KGSO, KINT, and KRDU
will also show some improvement, but could very likely remain MVFR
through the afternoon and evening.

Widespread LIFR to MVFR restrictions are expected to re-develop
Sunday evening/night.

Outlook: Scattered to numerous showers and storms are expected again
Monday. Rain chances should become more diurnal and scattered in
nature Tuesday and Wednesday. Continued moist air will support the
potential for restrictions associated with widespread fog and/or low
clouds each morning



&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$


SYNOPSIS...CBL
NEAR TERM...BLAES
SHORT TERM...CBL
LONG TERM...Luchetti
AVIATION...CBL