-- Discussion containing changed information from previous version are highlighted. --
819
FXUS62 KRAH 281832
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
232 PM EDT Tue May 28 2024

.SYNOPSIS...
A series of moisture-starved, reinforcing cold fronts will lead high
pressure from central Canada and the Great Lakes to the middle
Atlantic and Carolinas this week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1045 AM Tuesday...

The gridded morning forecast update was sent with no noteworthy
change from the previous forecast issuance. The 12Z-observed MHX
RAOB sampled a continued moist, moderately unstable, and generally
uninhibited thermodynamic profile that should support the development
of scattered convection with diurnal heating and convergence along
the sea breeze and surface trough/front, near and especially east of
Sampson Co., as noted in the previous discussion. It will be
continued warm but less humid otherwise and elsewhere in cntl NC
today.

.PREV DISCUSSION... /ISSUED 325 AM EDT Tue May 28 2024/

A low amplitude shortwave and PV anomaly currently pivoting across
southern GA is providing support for showers and isolated storms
over Coastal SC where a moderately unstable and weakly capped
airmass exists early this morning. Model guidance tracks this
mid/upper wave across SC and offshore by late Tues morning. 00z
model guidance suggest this regime may spread ENE towards the
southern Coastal Plain along effective outflows, but a majority of
the showers/storms will likely remain southeast of central NC.

A cold front, mostly a moisture boundary, will slowly work through
central NC this morning through the early afternoon hours. Ahead of
the front, a warm and humid airmass will be in place over the
central/southern Coastal Plain with dew points in the mid/upper 60s
that will support 1000-2000 J/kg of MLCAPE by the late morning into
the early afternoon. Surface convergence along the front in
combination with the seabreeze interaction will provide focus for
showers and isolated storms, but generally westerly mean wind,
backing wind profile (indicative of CAA), and abundant dry air
aloft, should keep coverage limited and any deeper storms moving
away from our area. Best chance to see an isolated storm would be in
the southern Coastal Plain near Sampson county.

Elsewhere, dry conditions are expected with mostly clear skies
filling in with scattered fair weather cumulus through the
afternoon. Low-level thicknesses remain fairly similar compared to
Mon with a dry downsloping component resulting in highs similar to
slightly warmer and peaking in the mid/upper 80s to low 90s, but dew
points will fall throughout the day especially across the Piedmont.
Overnight lows should fall into the upper 50s to low/mid 60s with
pockets of mid 50s possible in the typical cool spots in the
Piedmont.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 150 AM Tuesday...

An upper level trough will amplify as it shifts eastward into the
mid-Atlantic and Carolinas. A couple of shortwaves will move through
the area as they traverse the base of the upper trough, one early
Wed, the other Wed night/early Thu. At the surface, the cold front
should finally be east of central NC and offshore by Wed morning,
however a lee trough may briefly develop in the wake of the front
over the area during the day Wed. A dry, reinforcing cold front
should move through Wed night, pushing the trough offshore as cool
high pressure ridges in from the WNW. Highs Wed should be a category
or two below normal, ranging from mid 70s north to low/mid 80s
south. Lows Wed night in the low 50s north to around 60 degrees
south expected.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
As of 232 PM Tuesday...

A short wave trough pivoting across the eastern Great Lakes on
Thursday will move off the Northeast and Mid-Atlantic coastal
regions by early Friday and will be followed by sfc high pressure
building into much of the Eastern US during the rest of Friday and
into early Saturday.  This high will bring with it a relatively
cooler airmass into our region, which will result in high temps Thu-
Sat in the upper 70s to lower 80s, which is several deg below
normal.  The main forecast challenge is whether or not the
aforementioned s/w trough will have enough moisture or to work with
across our area to result in any shower activity with it`s passage.
The majority of the guidance suggests areas well north and east of
Raleigh will have the best chance to see a passing shower late on
Thursday or Thursday night, and the NBM keeps PoPs aob 14% across
our entire CWA.  For now will go with NBM keeping our forecast dry
during that time (PoPs below 15%), but if PoPs continue to trend
higher, they may be needed across our northeast and far eastern
zones.

Once the high moves offshore by mid-Sunday, look for a warming and
moistening trend with temps near normal for the rest of the period.
Both the GFS and ECMWF suggest a series of low-amplitude s/w troughs
will transit the westerly upper flow and may provide enough forcing
for some isold mainly diurnal shower/tstm activity late in the days
Sunday through Tuesday, but certainly not a washout during that time
with overall low QPF.
-- End Changed Discussion --

&&

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

Although a weak shower cannot be ruled out through this evening, as
a mid/upr-level trough pivots across the middle Atlantic, the
likelihood of any impacting any one location in cntl NC --should one
occur at all-- is less than 10 percent. The passage of another
disturbance in cyclonic flow aloft will result in a slightly higher,
~10-15 percent chance of a shower over the nrn half of cntl NC Wed
afternoon. Dry, wly flow will otherwise favor VFR conditions in cntl
NC through Wed.

Outlook: Canadian high pressure will build from cntl Canada to
the middle Atlantic and favor VFR conditions in cntl NC through Sat.
As the high shifts offshore, sly flow and increasing moisture will
increase the risk of patchy fog and stratus Sun morning and a chance
of showers/storms Sun afternoon-night.

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS/Swiggett
SHORT TERM...KC
LONG TERM...np
AVIATION...MWS