445
FXUS62 KRAH 040614
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
213 AM EDT Tue Jun 4 2024

.SYNOPSIS...
A series of mid level disturbances will move east across the area
through mid week, as a weak surface trough and unseasonably moist
air mass holds over the region. A cold front will approach from the
west Thursday and move across the area Thursday night and Friday,
bringing drier and less humid conditions for the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 945 PM Monday...

No meaningful chances where made to the overnight forecast with the
evening update as the inherited forecast remains on track.

Regional radar shows a weakening trend with convection over central
NC. A weak mid-level ridge axis will pivot across the Mid-Atlantic
tonight with only 10-20m height rises but will usher in drier mid-
level air from the Ohio Valley and northern Mid-Atlantic. These
features should act to limit overnight scattered overnight showers
and result in most locations remaining dry. Isolated light showers
can not be ruled out however as a continued highly moist, unstable,
and weakly capped regime remains in place overnight. Hi-Res guidance
understandably struggles in these weakly forced regimes, but best
chances (5-15%) would be where low-level instability of 100-150 J/kg
will exist from upstate SC through the northeast Piedmont and
northern Coastal Plain of NC through the overnight hours. Lows
overnight will settle into the mid 60s by early Tues morning.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 230 PM Monday...

Tuesday should be a relatively average June day with a Bermuda high
in place and southerly return flow beneath weak ridging aloft.  A
weak backdoor cold front is forecast to settle down the Mid-Atlantic
coast but models have trended further north with its final push and
it doesnt quite reach Halifax and Edgecombe Counties, perhaps
stopping over southeast VA per NAM 925mb fields.  Aloft, there is a
weak circulation over TN today but it should drift more
northeastward tonight and doesnt appear to have much impact on
convective development tomorrow.  CAMs tend to slightly favor the
northeast CWA, again perhaps in closer proximity to the weak
convergence associated with the weak backdoor boundary.  PW will
increase to around 1.6, which is around the daily 90th percentile,
and thus will support a little better coverage or storms, which will
be slow moving given very weak tropospheric flow under the ridge.
Will trend 30-50 POPs toward the northeast CWA during the afternoon,
with otherwise partly to mostly cloudy skies once possible morning
stratus in the Piedmont burns off.  Highs will be in the mid to
upper 60s, falling only into the mid and upper 60s overnight with a
continued slight chance of a shower.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 250 PM Monday...

Shower/storm chances will peak mid week within warm and humid
conditions. We will then trend to dry weather and lower humidity by
Fri with the pattern shift to anomalously low heights over the Great
Lakes region and Ontario/Quebec, lasting through the weekend, albeit
with gradual air mass modification back toward normal by Sun/Mon.

Wed-Thu: Still appears that pops should be highest areawide Wed and
in the Coastal Plain on Thu. Northern stream troughing in the Upper
Midwest early Wed will continue to deepen and dig strongly to the SE
through the Great Lakes region through Thu, leading to gradually
strengthening WNW steering flow at our latitude and, especially, to
our W and NW, as a synoptic cold front slowly approaches from the
WNW. PW is expected to climb early Wed, nearing 2", near or
exceeding daily records, and we`ll have strengthening SW low level
jetting drawing greater moisture in from the Gulf. Models depict one
particular shortwave (perhaps an MCV from Mid Miss Valley
convection) swinging through the central and S Appalachians Wed
night into Thu morning, and with the in situ water content and low
level mass convergence amid improving mid level flow, it won`t take
much to kick off clusters of showers and storms. Will have pops
peaking at likely to categorical Wed into Wed night, then good
chance W to likely E Thu as 850 mb troughing pushes through the area
preceded by the low level jet shifting to the coastal Carolinas. A
few storms may be strong esp in the E Thu into Thu evening where
moderate to high MUCAPE is possible in tandem with the strengthening
mid level flow to 30-40 kts. Temps should be near to a category
above normal, with warm lows and clouds muting daytime heating a
bit.

Fri-Mon: The overall longwave pattern will shift to anomalously low
heights aloft across a large swath of the Great Lakes, adjacent
Canada and the Northeast as a deep northern stream low settles over
or just N of the Great Lakes. Deterministic models and ensemble
modeling systems are all in pretty good agreement on the overall
pattern, although differences persist regarding the amplitude,
wavelength, and orientation of the longwave trough axis, and these
differences show up well in the various model clusters. Generally,
though, with the cold front pushing to our SE, and a cooler air mass
moving in with lower dewpoints, confidence is high that we`ll have
generally dry weather starting Fri and going through the weekend,
although by Sun/Mon, minor perturbations within the fast NW steering
flow may knock down mid level heights briefly, resulting in bouts of
buoyancy along with passing DPVA, supporting a few diurnal showers
or storms, and will carry below-climo isolated afternoon pops both
days. Expect temps slightly below normal Sat, rebounding to near
normal Sun/Mon. -GIH

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
As of 210 AM Tuesday...

Areas of IFR stratus and/or fog will be possible again mainly over
the NC Piedmont and nrn Coastal Plain this morning, including most
likely at RWI, INT, and GSO. Isolated to scattered showers/storms
are likely to redevelop with daytime heating by early to mid-
afternoon, with the relative highest probability of occurrence along
an outflow boundary (lifting mechanism) supporting an ongoing
cluster of showers between RWI and RDU (centered around LHZ).

Outlook: A humid air mass in place through Thu will support a risk
of late night-early morning stratus and fog, especially where widely
scattered showers/storms occur the previous afternoon-evening.

&&

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

&&

$$
SYNOPSIS...Hartfield
NEAR TERM...Swiggett
SHORT TERM...BLS
LONG TERM...Hartfield
AVIATION...MWS