829
FXUS62 KRAH 050739 RRA
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
338 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 330 AM Sunday...

...Unsettled Conditions Continue Today...

The next wave of shortwave impulses, with an embedded MCV over
upstate SC, will cross central NC through the afternoon. A prominent
band of moderate rain showers, with some embedded lightning
potential, is accompanying this feature and has moved into the
western Piedmont of the Carolinas. This band will progress slowly
eastward through the morning and afternoon hours. Outside of this
primary convective rain band, additional showers and thunderstorms
will likely develop but should be more scattered in nature through
the remainder of the afternoon and evening. While weak elevated
instability exists area-wide to support thunder, the quasi-
stationary front bisecting the area has significantly muted surface
base instability across the northern half of the forecast area(along
and north of HWY 64). Thus, the best chance of thunder through
daybreak will be south of the front, across our southern counties.
Thereafter, tempered heating/insolation should result in more
equitable thunder chances as weak sfc base instability of 500-1000
J/kg develops across the area, though the primary convective band
should continue to provide the best forcing.

Latest forecast guidance suggests the stalled front draped across
the area may linger a bit longer than previous forecasts suggested.
Thus, it`s not surprising to see models trending cooler across the
northern counties. Highs ranging from lower/mid 70s north to around
80 south.

Convection should largely wane/diminish after sunset, with what
appears to be lull/intermission from the upper disturbances and
waves. The airmass remains very moist however and models indicate
the potential for some isolated convection overnight. Cloudy and
mild overnight with temps in the 60s as stratus re-develops across
the area.


&&

.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 /06Z SUNDAY THROUGH THURSDAY/...
As of 155 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 showers with some embedded lightning has moved into the
western Piedmont of the Carolinas. This band will progress slowly
eastward through the morning and afternoon hours, and some 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.

The ongoing LIFR to IFR ceilings at KGSO, KINT, and KRDU should
spread into RWI over the next few hours. Meanwhile, KFAY could remain
predominately VFR until around daybreak or after, when showers/rain
start to move in from the west. Outside of convection, expect
gradual lifting 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...CBL
SHORT TERM...CBL
LONG TERM...Kren
AVIATION...CBL