022
FXUS62 KRAH 152345
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
745 PM EDT Wed May 15 2024

.SYNOPSIS...
A cold front will move through the region tonight, followed by weak
high pressure on Thursday. A storm system will approach from the
southwest Friday and possibly linger into Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 230 PM Wednesday...

Afternoon surface analysis reveals the surface frontal boundary is
likely draped just north of Stanly County and extends ESE to near
Harnett/Lee. Low stratus has persisted north of this boundary,
though there are breaks in the overcast across the northeast
Piedmont and northern Coastal Plain.

Upstream convection has already started to develop over the NC
mountains tied to the upstream shortwave tied to the mid-level
trough over the lower OH valley. These storms upstream will continue
to track ESE across the western/southern Piedmont, Sandhills, and
southern Coastal Plain. The storms south of the boundary will tap
into 1500-2000 J/kg of CAPE, along with 40-45 kts of deep-layer
shear. The main severe risk and corresponding highest storm chances
are favored over the southern Piedmont, Sandhills to Southern
Coastal Plain, where straight hodographs will largely favor damaging
winds and large hail. A severe thunderstorm watch is in effect until
at least 8 PM this evening over these areas. An isolated tornado
cannot be ruled along the stalled frontal zone. Lastly, we will need
to monitor for a flash flood threat, given high PW`s and antecedent
saturated soils. This would largely be favored in low-lying or poor
drainage areas, as well as urban areas.

The severe threat should diminish after 8 PM, though lingering
showers and isolated storms are still possible over the eastern
Piedmont and Coastal Plain as another low-level frontal zone out of
VA slides SW and a shortwave tied to the trough swings southeastward
from SW VA. Convection should die out after midnight, with lows in
the mid 50s in the NE to low 60s in the SW.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 150 PM Wednesday...

A weak surface high will be across North Carolina Thursday into
Friday. It appears that there could be some differential heating
along the Appalachian mountains Thursday afternoon, and have
maintained a slight chance of thunderstorms across the Triad. The
rest of the region should remain dry. Skies should be mostly clear
Thursday night before clouds increase in advance of the next
approaching system. While most locations will have a chance for
showers and scattered thunderstorms Friday afternoon, it appears
that the bulk of the rain should hold off until Friday evening in
the Triad and after midnight elsewhere. Both highs and lows should
be slightly below normal on Thursday then warm a few degrees on
Friday as flow switches from northerly to southerly.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 210 PM Wednesday...

Saturday and Sunday: Aloft, the sub-tropical ridge along/off the
East Coast will shift east as a potent s/w progresses generally
eastward through the central Appalachians and mid-Atlantic this
weekend. There are still some fairly significant differences between
the medium range model solutions wrt the timing and character of the
s/w. The GFS solution shows a closed low over the mid-MS Valley
early Sat, while the ECMWF has an open trough over the OH/TN Valley.
Consequently, the ECMWF is quicker to bring the s/w through the
region (Sat night) than the GFS (Sun). Also, the GFS low lingers off
the NC coast Sun night through Mon night, while the EC s/w lifts NE
out over the Atlantic. This will subsequently impact when the sub-
tropical ridge over the MS Valley is able to shift eastward. It
follows that the surface pattern is similarly variable between the
model solutions. Generally expect a warm front to lift newd through
the area early Sat, while a low (NAM and ECMWF) may also track enewd
through central NC Sat aft/eve. The GFS shows more of a weak surface
wave lifting through. In the GFS, the more potent surface low comes
through on Sun, while in the EC high pressure over the Northeast is
already ridging into NC. Either way, expect a low offshore Sunday
night, with cool high pressure ridging into NC on the back side of
it. Highs will generally range from low 70s to low 80s, while lows
in the upper 50s to mid 60s Sat night could decrease to mid 50s/low
60s for Sun night.

Off the GFS forecast soundings: PWATS will be in the 1.6 to 1.9 inch
range from Sat morning through at least Sun afternoon, possibly
longer in the east. MUCAPE ranging from 200 J/Kg to 500 J/Kg, with
effective shear peaking around 40 kts Sat aft/eve. While there is
not a day 4 area of interest from the SPC, the discussion for
Saturday does mention some severe potential with the s/w, mainly
well to the south over GA/FL, but given the model differences there
is still a high degree of uncertainty. For Sun, the MUCAPE is
higher, generally around 1000 J/Kg, while effective shear may be
more in the 30-40 kt range. So, if the GFS solution comes to
fruition, there could be continued potential for storms again on
Sunday.


Monday onward: As the upper low/trough continues to drift offshore
and over the Atlantic, the sub-topical ridge will gradually shift
eastward, ridging through the mid-Atlantic through Tue night. A
couple of shortwaves will track eastward through the Great Lakes
from late Mon night through Wed, largely staying north of the area.
However the second, stronger s/w could clip central NC Wed/Wed
night, resulting in the next potential for showers/storms across the
area. Expect temperatures to moderate through mid-week.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 745 PM Wednesday...

24 hour TAF period: The strongest showers and storms should be south
and east of KFAY through the remainder of the evening, with some
light/moderate rain and isolated thunder possible through about 06Z
or so at KFAY and possibly KINT and KGSO. Convective activity should
dwindle after midnight, though some spotty showers could persist
through the night. Expect MVFR/IFR cigs to once again spread across
the area tonight, possibly dropping into the LIFR range around
daybreak. Cigs should lift to VFR around 15Z Thu. A period of some
MVFR vsbys will also be possible late tonight, lowest west. -KC

Looking ahead: VFR conditions should prevail through Friday. Showers
and sub-VFR conditions will return late Friday into Sunday, with
largely dry conditions returning sometime Monday. -Kren

&&

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

&&

$$
SYNOPSIS...Kren
NEAR TERM...Kren
SHORT TERM...Green
LONG TERM...KC
AVIATION...KC/Kren