274
FXUS62 KRAH 060106
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
905 PM EDT Sun May 5 2024

.SYNOPSIS...
An upper-level disturbance will approach the mid-Atlantic on Monday
and exit the region on Tuesday. High pressure will extend into the
region during the mid week before a cold front approaches late in
the work week.

&&

.NEAR TERM /TONIGHT/...
As of 905 PM Sunday...

The remnants of an MCV has moved over the eastern portion of the
forecast area, with scattered showers and an isolated thunderstorm.
Otherwise, the region is dry right now. Much of the western half of
the area is clear, and with calm/light wind, have already seen
visibilities go below a mile at Sanford and Roxboro. With the wind
not expected to remain calm overnight, some stirring should allow
the fog to mix out. However, plenty of low level moisture remains
and low stratus is expected to develop near the Virginia/North
Carolina border by midnight and expand to the south, eventually
covering all locations. The scattered showers will likely persist
around Rocky Mount through midnight, then just an isolated shower is
possible along the eastern and western edges of the region with
little in the way of forcing mechanisms to generate precipitation.
It will be a muggy night with overnight temperatures in the low to
mid 60s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
As of 210 PM Sunday...

Aloft, the sub-tropical ridge will try to briefly build over the
Southeast US on Mon, but will then be pushed eastward again as the
s/w to the west moves eastward across the Appalachians and into the
mid-Atlantic late Mon/Mon night. This s/w trough may become slightly
negatively tilted as it swings through the region. At the surface,
high pressure will sit over Bermuda, ridging swwd into the Southeast
US through Mon night. A quasi-stationary frontal zone will extend
from the Northeast US, wswwd through the OH Valley and mid-MS
Valley, remaining north of the area through Mon night. Expect sly to
swly flow over central NC Mon/Mon night, resulting in continued
advection of warm, moist air into the area.

Precipitation/Convection: With the continued feed of warm, moist air
into the area, MUCAPE of 800-1500 J/Kg is forecast by both the NAM
and GFS across the area during the day, while effective shear is
forecast to be about 15-20 kts. After a brief drop in PWATs tonight,
they should climb back into the 1.5-1.75 inch range on Mon. All of
the ingredients will be present for storms to develop, contingent on
forcing. The best forcing for ascent will be with the s/w aloft,
however the models vary with the timing of that feature. The hi-res
model guidance from 12Z suggests showers and storms may develop over
the Piedmont during the afternoon, then move eastward through the
evening. A secondary round of showers and storms moving across the
mountains Mon eve could continue eastward through the area Mon
night. For now, central NC remains in general thunder from the SPC
and the hi-res guidance varies on the coverage and intensity of
convection. Given all of the above, cannot rule out an isolated
strong/severe storm should all the ingredients come together at the
right time Mon aft/eve, before loss of heating and nocturnal
stabilization commences.

Temperatures: Expect largely broken/overcast skies through Mon
night. Highs should range from the upper 70s NW to mid 80s SE, with
lows mainly in the low to mid 60s Mon night.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 1211 PM Sunday...

Upper pattern for the extended: A short-wave will exit to our east
early Tuesday, behind which mid-level ridging will build back over
the southeast through late Wednesday.  The ridge will de-amplify as
a strong vort max digs into the Midwest Thursday, eventually
ejecting eastward through the northeast US. This feature will induce
increasingly swly flow aloft over central NC Friday into Saturday.

Temperatures: Hot and humid conditions will persist Tuesday through
Thursday under the anomalous mid-level ridge.  The NBM still
continues to highlight high probabilities for >90 degrees for
locations south and east of Raleigh both Wednesday and Thursday (The
GEFS, EPS, and GEPS are less enthused, but generally depict a
similar geographic area with highest probabilities (10-30%)). Given
dew points will peak in the upper 60s/lower 70s, heat indices will
likely pop up into the mid 90s both Wednesday and Thursday
afternoons. Thus, make sure to take frequent breaks in the shade and
hydrate if spending a lot of time outdoors these days.

Temps will "cool" off a bit Friday and into the weekend as the
aforementioned upper vort max/trough dips into the southeast. Highs
in the mid 80s are currently expected Friday, followed by mid to
upper 70s on Saturday. However, these may need to be modified some
as we get closer and guidance comes into better agreement/confidence
increases.

Precipitation: POPs will be lower Tuesday and Wednesday under
general ridging aloft (and some nwly flow in the lower levels should
lower PWAT a bit). However, can`t rule out some isolated/scattered
diurnally driven showers/storms along any differential heating
boundaries including late day sea breeze migration into our area.
Some guidance depicts some energy aloft trickling through our area
late Wednesday which could maybe generate a bit more activity.
However, will keep POPs capped at low chance for now.

As we progress into the Thursday through Saturday timeframe, there
is some uncertainty wrt to the evolution of the aforementioned
strong vort max/trough and an associated cold front. However, the
general consensus among ensembles/deterministic output is that this
upper feature does look strong enough to possibly induce an airmass
change for our area later this weekend (i.e. a stronger cold front
actually making it`s way to the coast). As such, showers and storms
are likely ahead of and along the cold front as it moves through.
While we`ll need a bit more updated model guidance to get into
specifics, it does appear at this point that some severe storms will
be possible Thursday and Friday as guidance suggests an uptick in
mid-level lapse rates and bulk-layer shear in this time frame.
Again, a bit too far out for specifics, but we`ll continue to
monitor as we get closer to later next week.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 815 PM Sunday...

24-hour TAF period: VFR conditions will prevail for most of central
NC this evening outside of the far northern Piedmont (including INT
and GSO) where some MVFR stratus remains, but even there some
periods of VFR will be possible. The other exception will be one
last cluster of showers and storms currently moving E/NE into the
Coastal Plain that will affect RWI over the next hour or two with
brief sub-VFR conditions possible.

After that cluster passes through, it will be mainly dry through the
overnight hours other than maybe an isolated shower. However, with
plenty of low-level moisture still in place, widespread IFR to LIFR
conditions from low stratus are expected to begin redeveloping after
about 04z and spread into the region from north to south. The
highest confidence in LIFR is across the far northern and western
Piedmont (including INT and GSO), which is also where the highest
chance exists for some fog.

Conditions will improve to MVFR in most places by mid to late
morning and should improve to VFR by early to mid afternoon, slowest
to improve in the Triad. However, more scattered showers and storms
are expected to develop tomorrow afternoon and evening, which may be
accompanied by sub-VFR conditions.

Outlook: Rain chances decrease for Tuesday and Wednesday with just a
limited threat of an afternoon/evening shower or storm before rain
chances increase on Thursday. With a moist airmass in place, areas
of fog and stratus are possible on Tuesday morning with reduced
chances during mid week.

&&

.CLIMATE...

Record High Minimum Temperatures:

May 8: KGSO: 66/1938 KRDU: 68/1930 KFAY: 70/2003

May 9: KGSO: 68/2002 KRDU: 70/1936 KFAY: 71/2009

&&

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

&&

$$

SYNOPSIS...Blaes
NEAR TERM...Green
SHORT TERM...KCP
LONG TERM...Luchetti
AVIATION...Danco/Blaes
CLIMATE...RAH