660
FXUS62 KRAH 200712
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
311 AM EDT Mon May 20 2024

.SYNOPSIS...
High pressure will extend across and offshore the Middle Atlantic
through Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 PM Sunday...

Only minor tweaks were made to hourly temperatures and sky cover as
stratocumulus deck has persisted longer in the Coastal Plain while
widespread clearing has occurred across the Piedmont. Otherwise the
forecast remains on track for areas of fog develop across northern
portions of the Piedmont with patchy fog elsewhere.

As of 400 PM Sunday...

Water vapor imagery shows multiple embedded waves within an
elongated trough axis extending from off the Northeast coast through
the Mid-Atlantic with a compact shortwave at its base over the SC/GA
coast. One wave sliding through south-central VA will continue
southward and over central NC through this evening with some Hi-Res
guidance indicating a light sprinkle or two, but most locations will
remain dry as RAP point forecast soundings show multiple weak
inversions aloft and relatively dry thermodynamic profile.

Widespread afternoon cumulus is expected to dissipate with loss of
boundary layer mixing, minus pockets light rain/sprinkles and
associated cumulus clouds, will briefly lead to mostly clear skies
early overnight. Light northeasterly flow overnight will advect
marine layer stratus into the Coastal Plain towards daybreak. West
of this cloud deck, lingering rich boundary layer moisture and
mostly clear skies will favor the development for areas of fog,
potentially dense is some locations, from the Triangle towards the
Triad by daybreak Monday morning. Overnight lows will settle in the
mid 50s to low 60s.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 152 PM Sunday...

High pressure ridging will be in place at mid-levels for our Monday.
High pressure at the surface off the east coast will continue to
nose down into the area, resulting in a NE flow once again. We will
see some stratocumulus develop for the daytime, but more sunshine is
expected as deeper mixing ensues, especially across the Coastal
Plain. The airmass will warm some too, but highs should still be
about a degree or so below seasonal norms in the upper 70s to low
80s, lowest in the NE Piedmont to northern Coastal Plain of perhaps
mid 70s. Clear skies and light winds in the evening and overnight
will favor lows a touch below average in the mid to upper 50s,
except low to mid 50s in the NE Piedmont and northern Coastal Plain.
Lingering low-level moisture could favor fog development from the
Triangle eastward into the Coastal Plain for early Tue morning.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 311 AM Monday...

Upper pattern through the extended: Mid-level ridging over the
eastern US will shift offshore through Wednesday evening. A low-
amplitude upper trough will then lift through the Great Lakes
Thursday.  A short wave will then move through the TN Valley and
wash out over central NC Friday into the weekend.

Wednesday: The western ridge of an offshore sfc high will extend
light sswly flow across central NC on Wednesday.  Void of forcing
for ascent and lingering below normal PWAT, Wednesday will remain
dry.  Given the sswly flow, however, temps will begin to steadily
rise reaching the mid 80s Wednesday afternoon. Warm overnight lows
in the lower 60s is expected.

Thursday through Sunday.  Ensembles continue to suggest the
potential for periods of rain over this time as upper forcing from
the aforementioned upper features move overhead. On Thursday, an
upper trough will lift through the Great Lakes. Some mid-level
energy associated with this feature may trickle down into our
northern locations and promote showers/storms later in the day.
However, the better forcing and low-level moisture transport appears
to stay well to our north, and thus continue to maintain just slight
chance to low chance POPs across our central to northern areas
during this time.

From Friday onward, ensembles continue to simulate a potentially
potent short wave riding through the TN Valley and eventually over
central NC through Sunday. Periods of rain look promising over this
temporal period, the details of which are hard to pin down at this
point.  Severe weather parameters are not popping off the charts at
this point, but periods of higher shear could promote some isolated
stronger storms especially Friday afternoon/evening.

There is high probabilities amongst ensembles that temperatures will
exceed the mid 80s both Thursday and Friday.  The quartile spread
widens a bit more over the weekend, likely due to differing
solutions wrt to any sfc boundaries. Regardless, temps will likely
remain in the 80s this upcoming weekend.


&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 115 AM Monday...

A band of IFR-MVFR stratus now over ern VA/NC, and as far west as
RWI, will continue to spread wwd and across cntl NC this morning.
Visibility restrictions will develop both on the ern edge of that
cloud band, and also in preceding, patches of shallow, radiation fog
ahead of it. A separate area of multi-layered, stratocumulus and
altocumulus over wrn NC/VA, and as far east as INT/GSO, will
probably inhibit radiational cooling sufficiently to keep any sub-
VFR restrictions at INT very brief around daybreak, if at all. The
depth of the associated stratus/fog layer, where it occurs, should
be much shallower and consequently disperse more quickly to VFR than
that of Sun morning - likely by 13-14Z.

Outlook: A risk of late night-early morning fog/stratus will
continue especially over ern and e-cntl NC through mid-week,
followed by a chance of afternoon-evening showers/storms Thu and Fri.

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...Swiggett/Green
SHORT TERM...Kren
LONG TERM...Luchetti
AVIATION...MWS