893
FXUS62 KRAH 200616
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
116 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 /TUESDAY THROUGH SUNDAY/...
As of 350 PM Sunday...

Dry conditions and mostly sunny skies are expected across central NC
on Tuesday and Wednesday as mid/upper ridging extends from the
western Gulf of Mexico to off the Mid-Atlantic coast. This ridging
will be in between a series of shortwaves moving across the northern
Plains and Upper Great Lakes and a cutoff low off the Southeast US
coast. At the surface, elongated high pressure will extend from the
NE down the Eastern Seaboard, initially bringing NE flow that shifts
more southerly on Wednesday as the high shifts SE to near Bermuda.
This will help increase high temperatures from lower-80s on Tuesday
to mid-to-upper-80s on Wednesday and upper-80s to lower-90s on
Thursday. Lows will also increase from upper-50s to lower-60s on
Tuesday night to lower-60s to upper-60s by Thursday night.

The pattern turns more unsettled from late this week into the
weekend. As one shortwave moves across the northern Great Lakes and
northern New England on Thursday/Thursday night, it will drag a cold
front that approaches the Appalachians. However, with the best upper
forcing to our north, only carry slight to lower chance POPs
(highest north). A better chance for showers and storms comes on
Friday and Saturday as a southern stream wave moves across the TN
Valley and potentially over our region. Carry high chance POPs on
these days, but didn`t feel comfortable going likely considering
timing differences between the different models and given this is
Days 6-7. POPs decrease a bit again on Sunday as the shortwave
exits, but still above climo. Temperatures are more uncertain during
this period and will depend on how far south the aforementioned cold
front is able to get, but the latest GFS and ECMWF keep it mostly
hung up to our north. So forecast highs remain near to slightly
above normal.

&&

.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...Danco
AVIATION...MWS