522
FXUS62 KRAH 301959
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
359 PM EDT Tue Apr 30 2024

.SYNOPSIS...
A slow moving surface trough will shift across central NC through
Wednesday afternoon. Weak high pressure will linger over the area
through Friday before sliding offshore ahead of a cold front
Saturday into Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 245 PM Tuesday...

A compact shortwave is evident in water vapor imagery over the
southern Tennessee Valley and is forecast to drift east-southeast
across the Carolinas through tonight. The best H5 height falls (30-
50m) and DPVA near the core of the PV anomaly will traverse the
NC/SC border and shifting towards the coast by Wed morning. The
synoptic ascent associated with this feature will overlap with a
trough axis and weakly unstable airmass to initiate scattered
showers and isolated thunderstorms late this afternoon over western
NC and slowly shift east towards the Triad and southern Piedmont by
this evening. Storm organization will likely be limited to loosely
organized multi-cell clusters along common cold pools. Sub-severe
wind gusts and lightning will likely be the primary hazards.

Boundary layer cooling after sunset will likely limit surface based
convection, but the overall moist thermo-profile will support
elevated convection to continue for a few hours although with a
continuing weakening state through midnight. Dependent on the amount
of rain and potential clearing over the western Piedmont, some
patchy fog, dense in spots, would be possible especially for
locations that receive 0.5 to 1" of rain. Lows tonight will be
coolest in the Triad and southern Piedmont in the upper 50s with
low/mid 60s in the Coastal Plain underneath thick overcast.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 245 PM Tuesday...

The shortwave will be positioned over the Coastal Plain of the
Carolinas by Wed morning with the trough axis shifting out over the
western Atlantic by Wed evening. NWP models have come in slightly
stronger with the shortwave ridging building in behind the departing
shortwave. The result will be a stronger subsidence inversion
overspreading central NC through the afternoon and evening hours and
suppressing any showers potential over the Piedmont. Wed morning
into the early afternoon some showers/storms will be possible over
the NC Coastal Plain where the core of the shortwave will overlap
with 500 to 1000 J/kg of MLCAPE as well as a surface trough axis and
sea-breeze interaction. Once again, storm organization will likely
remain confined to multi-cell clusters along common cold pools given
15-25 kts of 0-6km shear, a majority of which is located above 700mb.

Low-level thickness will be on average around 1-3m greater compared
to Tuesday and with greater sunshine chances most places will be
able to rise into the low/mid 80s once again. Lows will be more
indicative of a radiational cooling night with mostly clear skies
and most locations able to go calm relatively early in the night,
supporting temperatures in the mid 50s to low 60s. Patchy to areas
of fog seem probable in the Coastal Plain by early Thurs morning
with the lingering rich low-level moisture in addition to moderate
radiational cooling.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 355 PM Tuesday...

Strong upper level ridge will influence the region Thursday and
Friday before moving offshore early Saturday. A series of shortwaves
will move across the region early next week. At the surface, high
pressure will influence the Mid-Atlantic region. Light calm winds
with mostly sunny skies will set up for warm days on Thursday and
Friday with highs well above average in the mid to upper 80s both
days. By Saturday morning confidence in the forecast becomes less
confident as models have been inconsistent. Latest data shows by
Saturday morning increased moisture values to 1.5+ ahead of a cold
front moving across the TN and OH valley will bring isolated to
scattered showers and storms to the area Saturday and continuing
into Sunday. The cold front will move across the region Sunday
before stalling across the region on Monday. Less coverage is
expected on Monday but depending where the front stalls, isolated to
scattered showers and storms could be possible. The stalled front is
expected to dissipate and most of Tuesday is expected to be dry, but
multiple long range models show another round of showers and storms
by late afternoon Tuesday ahead of another frontal passage moving
across the Southern Plains and Southeast. Temperatures over the
weekend will largely depend on timing and coverage of the
precipitation, but generally expect highs in the upper 70s to
low/mid 80s. Lows in the upper 50s and low 60s.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 155 PM Tuesday...

Early morning cumulus has lifted to VFR everywhere across central
NC. A unorganized line of showers and isolated storms are expected
to develop from the NC Foothills south into central SC and reach the
vicinity of INT/GSO around 21z and eventually FAY around midnight
with a little help from the seabreeze. Confidence is low whether
this line of showers will remain intact to affect RDU or RWI, but
best timing would be 4z and 7z respectively. Dependent on the amount
of rain and clearing behind this line of showers, some model
guidance is hinting at the potential for fog development near the
Triad terminals into the southern Piedmont late tonight, but
confidence is low at this time. Cumulus will again redevelop Wed
morning with a brief broken MVFR cig most probable at RWI and RDU.

Beyond 18z Wed, scattered showers and isolated storms will be
possible in the NC Coastal Plain, potentially impacting RWI, Wed
afternoon. Clearing skies, calm conditions and continued moist low-
levels may support the development of fog in the Coastal Plain early
Thurs morning. Scattered shower/storm chances increase late Fri
through Sat with the potential for sub-VFR conditions including
early-morning fog.

&&

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

&&

$$

SYNOPSIS...Swiggett
NEAR TERM...Swiggett
SHORT TERM...Swiggett
LONG TERM...CA
AVIATION...Swiggett/Hartfield