304
FXUS62 KRAH 051435 RRA
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1030 AM 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 SATURDAY/...
As of 245 AM Sunday...

An active pattern persists in the extended, particularly the latter
portion of the week with several chances for showers and storms.
Somewhat drier conditions will start the period, along with
temperatures well above average, followed by near to possibly below
normal highs by the weekend.

Tuesday will feature a weakened shortwave trough from Mon over
VA/NC, with the axis roughly along/east of the Coastal Plain. With
time, the trough will move out over the coast by the evening, with
ridging building in Tue night/early Wed. There is not much forcing
outside of the trough. However, most models indicate weak capping
and 1000-1500 J/kg of MLCAPE, maximized over the Sandhills, eastern
Piedmont and Coastal Plain. This along with 20-25 kt of shear should
favor isolated/scattered activity over the region, which could
interact with a sea-breeze. Suspicion is that activity would be
largely focused east of US-1, but activity could occur just about
anywhere. Highs should turn warmer and above average in the 80s.

Ridging Tue gives way to an increasingly perturbed southwest flow
aloft for the latter part of the week with troughing over the Plains
and ridging over the Gulf. As we go into Wed and especially Thu/Fri,
models/ensembles indicate that the trough will slowly migrate ESE
into the Great Lakes and OH valley region, eventually reaching the
Mid-Atlantic by the weekend. At the surface, lee troughing will
gradually give way to a cold front trying to make its way through
late Fri or early Sat. Upstream convection Wed/Thu over the
Midwest/southern Plain complicate the exact timing/location of these
perturbations in the southwest flow. Shortwave energy could arrive
as early as Wed night, with the GFS/GEFS showing more influence from
the trough versus the EC/GEPS. Better agreement, though, is noted
Thu/Fri where additional perturbations impact the region as the
trough/front inch closer. All of this is to say that we cannot fully
rule out a chance of storms Wed/Wed night, and storm chances will
remain Thu/Fri, albeit with low confidence on timing/location given
model spread on shortwave features. With increasing shear and higher
instability Thu/Fri in the strong kinematic flow, severe storms are
possible ahead of a convectively reinforced boundary slowly sliding
eastward from the TN valley. Wed/Thu should still hover well above
average in the mid/upper 80s to low 90s, though given the
uncertainty in upper-level features, the NBM 90+ degree
probabilities are highest at 50-60% on Wed.

By Sat, model solutions still show spread in the location of the
trough, with the GFS/GEFS/GEPS faster than the EC, which keeps the
main trough over the Great Lakes OH Valley versus near Long Island
in the former solutions. A drier pattern appears favored with NW
flow, but upstream energy in the EC could favor low-end stratiform
rain chances. Highs are currently expected to trend closer to normal
or a touch below in the 70s.

&&

.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...Kren
AVIATION...CBL