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000
FXUS62 KILM 171750
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
150 PM EDT Thu Aug 17 2017

.SYNOPSIS...
High heat and humidity will continue across the area through
Friday. Showers and thunderstorms will be on the increase during
the weekend ahead of a cold front. This front will get hung up
in close proximity early next week and then dissipate, keeping
at least scattered showers and thunderstorms in the forecast.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 145 PM Thursday...Minor changes included in current update
to account for increased coverage of showers and thunderstorms
and to update the Heat Advisory.

Previous discussion as of 1030 AM...Another hot and humid day
is in store for the forecast area, as latest obs are already
indicating temperatures in the mid to upper 80`s and heat
indices in the upper 90`s to lower 100`s. As a result, a Heat
Advisory is in effect for a majority of the forecast area
through this afternoon. Overall high temperatures today will
climb into the lower 90`s.

Upper level ridging will gradually move eastward towards the
Carolinas today. With a weak sfc low just south of our area, the
weak piedmont trough along with the afternoon sea breeze may
help trigger isolated to scattered showers and thunderstorms
this afternoon, similar to yesterday. Do not anticipate any
severe threat, but would not entirely rule out minor localized
flooding in any heavy downpour as PW values remain above 2
inches and storm motion is slower than yesterday.
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&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 300 AM Thursday...Still looks like a hot and humid day
Fri with a likelihood for another Heat Advisory. 850 mb temps
will be 20-21 deg C. This should result in highs in the mid 90s
with lower 90s at the coast. The dewpoints will again be high,
mainly mid and upper 70s with a few 80 degree dewpoints for
portions of the coast. This will again bring the heat index
above 105 and as high as 106 to 108 degrees. High temps should
back off a category or so on Sat with more in the way of clouds
associated with showers and thunderstorms. Dewpoints will still
be high and so heat index values should still climb above 100,
but few places should reach 105 degrees. Overnight lows will be
mainly in the mid and upper 70s, although if a large thunderstorm
outflow develops, lows may drop into the lower 70s for portions
of the area Sat night.

A deep trough will carve out across the eastern third of the
nation during this period. This will help drive a cold front SE.
The trough should begin to lift out during Sat. The seabreeze
and Piedmont Trough on Fri should allow for isolated to
scattered showers and thunderstorms during the heating of the
day. Fri night, a strong mid-level shortwave trough will be
moving across central NC and the upstate of South Carlina. This
feature will lift to the NE overnight. Expect showers and
thunderstorms to our NW should at least skirt portions of our
Forecast Area during the night. Sat morning, the cold front
should be on our door step. However, it does not look like the
front will be able to push through as the main driving
mechanism aloft will be departing. Another impulse will be
moving across Virginia and northern portions of North Carolina
Sat night. This should help to keep the front in close
proximity, but mainly to our N. We expect the risk for showers
and thunderstorms will be significantly higher Sat as compared
to Fri. However, it is too early to say it will be a washout.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 PM Wednesday...A cold front will show little movement
into Sunday, but height rises aloft will be underway. Overall
expect a downward trend in storm coverage and a warmer afternoon.

Attention to Monday`s forecast continues to increase each day
due to the solar eclipse. Unfortunately there isn`t much
different in the way of thinking and even less fortunate the
news isn`t great. True the front will be weakening but
convective signals in the models are still suggesting ample
moisture for considerable coverage of thunderstorms that
afternoon. The silver lining could be the rising heights aloft,
possibly capping thunderstorm formation until after the eclipse
or at least its peak. Even so all it takes is one vigorous
towering cumulus to ruin the view over a given location.

By Tuesday the front no longer appears in the models but a well
defined piedmont trough develops. Thunderstorms forming within
this boundary and moving east paired with seabreeze activity
calls for scattered POPs just about area-wide. By Wednesday some
mid level troughiness starts breaking into the area in
association with a large trough forming north of the Great
Lakes. A continued moist boundary layer paired with energetic NW
flow likely means a continuation of the unsettled weather.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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As of 18Z...Potential for periods of MVFR in any heavy
downpours and stronger storms this afternoon and evening.
Otherwise expect VFR.

Latest radar imagery depicts scattered showers and thunderstorms
across the area this afternoon, as heavy downpours are already
creating reduced visibilities at KILM. Expect trend to continue
throughout the rest of today as VCTS prevails in going
forecast, with TEMPO groups to account for scattered convection.

Into tonight, expect convection to dissipate, giving way to VFR
through into Friday morning, with passing mid level clouds.
Winds overnight will be light and variable.

Extended Outlook...Potential for MVFR/IFR through Friday as
unsettled weather continues, with chances increasing into the
weekend with a passing cold front. Would not entirely rule out
patchy stratus/fog towards the morning hours each day.
-- End Changed Discussion --

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1030 AM Thursday...Light southeast winds this morning up
to 10 kts this morning will gradually increase to 10 to 15 kts,
veering to the southwest by this evening. Seas around 2 ft are
expected.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 300 AM Thursday...The Piedmont Trough and seabreeze will
be the main driver of winds on Fri. An approaching cold front
Fri night and Sat should get hung up N of the waters through the
end of the forecast period. SW winds will be in place through
the period. The strongest winds are expected late Fri and Fri
night, on the order of 15 to 20 kt. Winds should tick down to 10
to 15 kt during Sat and to near 10 kt toward Sun morning. Seas
of 2 to 3 ft Fri will build to 3 to 4 ft Fri night and Sat
perhaps subsiding about a foot during Sat night.

LONG TERM /SUNDAY THROUGH MONDAY/...
As of 300 PM Wednesday...A front will be stalled over land
Sunday into Monday in a weakening state. This boundary will
serve a similar function to the Piedmont Trough normally seen
during the warm season and we should still see a fairly typical
southwesterly flow. Seas will run 2 to 4 ft for the most part,
highest offshore in the coast- parallel flow.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
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SC...Heat Advisory until 5 PM EDT this afternoon for SCZ017-023-024-
     032-033-039-053>056.
NC...Heat Advisory until 5 PM EDT this afternoon for NCZ087-096-099-
     105>110.
MARINE...None.
-- End Changed Discussion --

&&

$$

NEAR TERM...SGL
SHORT TERM...RJD
LONG TERM...MBB
AVIATION...SGL