532
FXUS62 KRAH 131852
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
250 PM EDT Mon May 13 2024

.SYNOPSIS...
A warm front over the deep south will lift into the region Tuesday
afternoon and evening. An area of low pressure over the Midwest will
bring a cold front through Wednesday night to early Thursday,
followed by high pressure for the end of the week Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 250 PM Monday...

Afternoon surface and satellite imagery analysis reveals high
pressure offshore of NC/VA. A stationary front continues to be
present across the deep south, stretching from southern TX into the
FL panhandle. Along this boundary are two convective complexes, the
first from this morning now into the northern Gulf and over FL to
southern AL/GA. A secondary convective complex is just starting to
develop over southern TX. Both of these convective systems will not
impact us tonight, though the latter will influence us directly or
indirectly tomorrow. Both of these are tied to a mid-level shortwave
trough over the midsection of the country that will reach east-
central MO early tomorrow morning. Clouds will continue to be in
place tonight, increasingly lowering in bases as low-level WAA
increases as the trough shifts eastward. Isentropic ascent and some
weak elevated instability will favor isolated/scattered showers
developing overnight, spreading in from SW to NE. There could be a
few brief isolated showers over the west/southern Piedmont this
evening with activity upstream in western SC/NC, but most CAMs
dissipate this as it moves east in the more stable air. Lows tonight
will dip into the upper 50s to mid 60s.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 250 PM Monday...

A difficult forecast is in store Tue/Tue night, with uncertainty in
regards to timing, duration, and intensity of showers, as well as
severe potential. Synoptically speaking, the shortwave trough from
Mon over the Midwest is forecast in most of the guidance to reach
the southern Appalachians by early Wed, weakening as it moves east.
At the surface, the stationary front over the deep south Mon will
likely move north as a warm front into central GA and SC. The area
of convection presently over southeast TX is forecast in much of the
guidance to become a convective MCS somewhere over the deep south of
LA/MS or western FL. Several of the models, including the high-res
HRRR/ARW, indicate that as this convective MCS reaches the SE US Tue
morning and afternoon, a remnant MCV could remain and possibly
impact our SE counties Tue aftn/eve period. This remains to be seen
and is uncertain. Nevertheless, the aforementioned storm complex
could influence how much rain showers we get Tue morning, with the
HRRR/ARW, for example, indicating scattered showers in the morning
and the better chance of storms in the aftn/eve with the remnant
MCV. The NSSL CAM, on the other hand, suggests stratiform rain in
the morning, which could stabilize the atmosphere and limit
convection later in the day. This certainly makes for a difficult
forecast.

Our current thinking favors isolated/scattered showers in the
morning given lesser forcing aloft during this period. Better
chances of showers and even some storms would be favored in the
aftn/eve period as the mid-level trough inches closer and PW`s
increase along with the 850 warm front getting into the Carolinas.
As for the severe potential, SPC maintains a marginal risk across
the southern Piedmont and Sandhills, but perhaps the better risk
area could be from SW to NE over the eastern Sandhills to southern
Coastal Plain to capture any remnant MCV and possible gravity wave
favoring damaging wind potential or an isolated tornado. The NCAR
Neural Network favors this region as well. Highs are tricky but we
kept highs in the upper 60s to mid 70s.

There could be a lull in showers and storms by the late evening,
though guidance continues to hint at some storms over the higher
terrain and over eastern TN possibly impacting the western Piedmont
late Tue night in association with the trough and an attendant
front/trough in the TN valley. This will also be near nocturnal
stabilization so most activity would be isolated in nature. Lows in
the 60s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY...
As of 225 PM Monday...

...Unsettled Weather Pattern Potentially Continues Into the
Weekend...

Wednesday and Wednesday night: A compact shortwave trough centered
over the TN Valley will progress slowly eastward through the region
through Wednesday night. In the wake of the secondary/triple point
sfc low and attendant warm front lifting north and east of the area,
a lull in precip is looking increasingly probable through mid day,
with a noticeable reduction in PWATs noted across the area during
this time.

However, favorable diurnal timing of the upper trough dynamics and
surface front into the area from the west, should lead to a ramp up
of convective rain chances during the afternoon and evening.
Expected moderate destablization with deep layer shear of 30-40 kts
would be sufficient to support a few strong to severe storm
clusters, with the FV3/GFS ML probabilities maximized along and east
of US 1 from 3-9 PM. Damaging wind gusts and large hail will be the
primary threat. Rain chances will taper off west to east during the
late evening and overnight hours.

High will depend on breaks in cloud cover and timing of convective
Wednesday afternoon; ranging from mid/upper 70s north to lower/mid
80s south. Lows in the upper 50s to lower 60s.

Thursday and Thursday night: Drier conditions are expected on
Thursday, through weak perturbations on the back-side of the exiting
shortwave trough could result in some isolated showers and perhaps a
rogue thunderstorm Thursday afternoon. Temps should be very
comparable to Wednesday. Highs in the mid/upper 70s north to
lower/mid 80s south. Lows in the upper 50s to lower 60s.

Friday through Monday: Significant timing/phasing discrepancies
persist wrt the eastward ejection of a southern stream shortwave
trough from the SW US Thursday and into the SE US sometime during
the second half of the weekend, or possibly delayed until early next
week. Until the timing can be resolved, will advertise scattered
showers and storms each day with a decent chance that we could see
some convectively enhanced vorticity disturbances impacting the
area, well in advance of the synoptic scale trough. Seasonable highs
80-85. Lows in the lower to mid 60s.


&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
As of 112 PM Monday...

There is high confidence that VFR conditions will start the TAF
period. A few stray isolated showers could reach the terminals early
this evening, mainly at GSO/INT, but confidence is too low that any
sub-VFR conditions could develop given the dry air over the area
currently. A better chance of sub-VFR conditions will arrive during
the overnight period and into Tue morning/afternoon as a batch of
showers move in from the southwest tied to a warm front and low
pressure. Guidance, including high-res models, are not in agreement
on the timing, placement, and intensity of showers starting early
Tuesday morning and continuing into the afternoon. Therefore,
confidence lowers toward the end of the TAF period. As such, the
main change with this forecast was to slow the onset of IFR
conditions given the model spread/uncertainty. More widespread IFR
could develop after the TAF period with models showing a better
signal at this time.

Outlook: IFR/MFR conditions in showers and storms are favored Tue
afternoon and evening, with the best storm chance at FAY/RWI/RDU.
Sub-VFR conditions and possible fog is then possible early Wed.
Another period of showers or storms are possible Wed aftn/eve, along
with a chance of sub-VFR clouds early Thu. VFR should return Thu
aftn, with the next chance of showers possibly Sat.

&&

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

&&

$$
SYNOPSIS...Kren
NEAR TERM...Kren
SHORT TERM...Kren
LONG TERM...CBL
AVIATION...Kren