Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 170717

Area Forecast Discussion
National Weather Service Wilmington NC
317 AM EDT Thu Aug 17 2017

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.


As of 300 AM Thursday...The northwest flow aloft will continue today
with little in the way of boundaries or forcing initially at
the surface. There is some mid level divergence moving across
the area later this morning and afternoon which has been picked
up by the models. This should trigger a mid to late morning
start to convection which should continue through the afternoon.
With weak shear do not anticipate any significant severe threat
but with PW`s near 2.20 inches some localized flooding is
possible. Convection should diminish with the loss of daytime
heating tonight.

Temperature guidance has cooled slightly with the 00 UTC cycle
however still warm enough to hoist a heat advisory for most areas.
As was the case Wednesday, the 105 criteria may be just for an hour
or two and if the convection develops as expected, a plethora of
outflow boundaries may actually keep numbers below 105.


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.


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.


As of 06Z...Expect mostly VFR conditions through the period.
Guidance is once again showing fog inland for the morning hours
although not necessarily IFR. I did include TEMPO groups for LBT
and FLO to address. With some mid level forcing moving through
later this morning convection should develop early on and be
somewhat more widespread than Wednesday. All stations have VCTS
for some parts of the daytime hours.

Extended Outlook...A brief period of MVFR/IFR conditions can
not be ruled out in isolated to scattered showers and
thunderstorms through Friday afternoon and evening. More
widespread convection is expected this weekend.


As of 300 AM Thursday...Very light wind fields continue across the
coastal waters this morning with buoy reports showing speeds less
than five knots. Winds will shape up gradually through Friday
morning with a decent southwest flow of 10-15 knots later tonight.
For today winds will be mostly driven by the sea breeze. Significant
seas will be around two feet at best.

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.

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.


SC...Heat Advisory from noon today to 5 PM EDT this afternoon for
NC...Heat Advisory from noon today to 5 PM EDT this afternoon for



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