-- Discussion containing changed information from previous version are highlighted. --
387
FXUS62 KRAH 171710
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
110 PM EDT Mon Jun 17 2024

.SYNOPSIS...
High pressure will build over the Mid Atlantic and Carolinas through
much of this week. A wave of low pressure will track westward into
the Southeast on Thursday into Friday, bringing rain chances to our
southern sections.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 909 AM Monday...

Morning water vapor imagery reveals a strengthening upper level
ridge centered over NC, with the surface high positioned off the VA
coast. Across the region, some isolated sprinkles/very brief showers
have developed primarily across the western Piedmont within an area
of weak isentropic ascent and elevated instability (500-1000 J/KG
MUCAPE per latest RAP analysis). A few of these sprinkles have made
it as far east as the Triangle but recent MRMS radar trends suggest
all of this precip is rapidly dissipating as the showers move
eastward into an increasingly stable environment.

Through the remainder of the day, expect cloud cover to gradually
thin out with another day of hot/mostly dry weather expected.
Today`s highs should reach the lower 90s area-wide. Additional
isolated showers and storms are possible later in the afternoon
across the western Piedmont where surface dewpoints will be highest
but most of the activity will be confined to areas west of the
forecast area. PoPs in the 15-20 percent range were included for
portions of western Forsyth Co this afternoon whereas elsewhere it
should be too stable to support any precip.

Cloud cover (either remnant low cloud cover in the western Piedmont,
or high clouds in the east) will likely linger this
evening/overnight resulting in another mild night. Look for lows to
bottom out in the upper 60s to lower 70s.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 313 AM Monday...

The anchored mid-level ridge will strengthen to ~2 standard
deviations above climatology on Tuesday, amplifying across New
England. Anomalous moisture will continue to migrate north and west
of our area, promoting dry conditions across central NC.  Some drier
air may mix into our eastern areas, promoting decent mixing of dew
points Tuesday afternoon (into the lower 60s). This should keep heat
indices contained to the upper 80s/lower 90s. Still, the actual
temperatures will rise once again into the upper 80s/lower 90s.
Given the persistent hot conditions, we continue to advise those
spending considerable amount of time outdoors to practice heat
safety.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 AM Monday...

Still anticipate below normal rain chances for much of this week,
with increasing heat potentially reaching dangerous levels by the
weekend.

Wed-Thu aftn: A strong mid level anticyclone will be stretched
across PA/NJ/MD early Wed. It will remain quite strong through Thu
and drift only slightly S, its center over the Delmarva by Thu
evening with the ridge oriented W-to-E. Meanwhile, at the surface, a
strong high centered out over the NW Atlantic well E/offshore of New
England will continue to extend ESE through NC, weakening a bit
heading into Thu. As we`ll have low level thicknesses slightly below
normal Wed/Thu capped by anomalously warm/dry/stable mid levels and
below normal PW, convection chances will be extremely limited, and
will maintain a pop-free forecast. The long-fetch low level easterly
flow won`t be particularly strong through Thu but may still draw
enough Atlantic moisture into southern NC for a few more clouds
there, but otherwise skies should be no worse than partly cloudy.
The low level thicknesses offset by decent sunshine should result in
temps near to slightly above normal.

Thu evening-Fri: Our focus briefly shifts to a possible low level
inverted trough or a closed surface low that is expected to develop
on the southern end of the surface ridge a few hundred miles E or
ENE of the northern Bahamas by mid week. Such a low or trough, if it
forms, may be tropical (warm core) in nature, not an unexpected turn
of events given long easterly low level fetch, the time of year, the
extremely warm ocean waters, and the models` consensus of very weak
upper level shear in this area. The latest runs of deterministic
models and ensemble systems generally favor an inverted trough
pushing W onto the Southeast coast Fri morning, which could result
in increasing clouds Thu night and a chance of showers and isolated
storms across our SE and far S sections Fri. But there is far from a
model consensus on this, and the low level flow on the NW side of an
onshore-moving trough could actually result in a backing low level
flow in our area to northeasterly with a reinforcement of low level
dryness and stability in central NC. Will lean toward the NBM`s
solution of low chance pops in our SE and S Fri afternoon for now.
With the mid level heat dome drawing closer, expect further warming
Fri to highs from around 90 to the mid 90s.

Sat-Sun: While we`ll start to see rain chances gradually trending
back toward climatology, the big story this weekend will be the
increasingly oppressive heat. Model differences predictably grow at
this range, but most indicate the mid level ridge center drifting SW
and expanding across NC Sat/Sat night before yielding a bit to a
broad northern stream trough and associated surface cold front
tracking through the Great Lakes region by Sun. The surface high
will push further out over the Atlantic, as a lee trough forms
through the W Piedmont well out ahead of the cold front. Our
thicknesses are expected to climb to around 10-15 m above normal Sat
and to 15-25 m above normal Sun, as our dewpoints rise through the
60s into the upper 60s/lower 70s. Shade air temps are expected to
peak at 94-100F both days, with heat indices of 95-106F and warm
lows mostly in the 70s, which when combined with sunshine and a
limited breeze will contribute to an increased risk of heat
illnesses. Regarding convection chances, with the trend to confluent
steering flow from the SSE through SSW and surface ESE flow pulling
in both Gulf and Atlantic moisture, the initially low PW through Fri
will rebound back over 1.5" over our far E and SE Sat and areawide
Sun. This, with lowering heights aloft due to the weakening mid
level ridge and approaching trough, will support small chance pops
mainly across the S each afternoon into early evening. -GIH

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
As of 110 PM Monday...

MVFR cigs have been stubbornly persistent across the western
Piedmont but are gradually showing signs of thinning out and/or
rising above 3kft. Once they reach VFR (BTWN 19-20z), expect VFR
conditions at all sites through tonight. There are suggestions in
today`s 12Z guidance that additional MVFR cigs will develop at
INT/GSO late tonight but outside of those locations, no weather-
related aviation impacts are expected.

As for storm chances today, most of the ensemble guidance keeps any
storm development west of INT. Can`t entirely rule out a stray
shower drifting through the vicinity but confidence is too low to
introduce in the TAF for this afternoon. Elsewhere it should remain
dry with no storms anticipated.

Outlook: Outside of the potential for morning MVFR cigs, especially
at INT/GSO, VFR weather is expected at all sites through the end of
the week. Moisture should increase late in the week/this weekend
which could promote showers/storms/non-VFR weather at RDU/FAY/RWI at
times this weekend.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...Hartfield
NEAR TERM...Leins
SHORT TERM...Luchetti
LONG TERM...Hartfield
AVIATION...Leins